MSc_Thesis_Luke Martin

The Technical and Economic Feasibility of
Siting an Anaerobic Digester at UCD
Luke Martin
A thesis submitted to
University College Dublin
in fulfilment of the requirements
for the degree of
Master of Science
College of Engineering and Architecture
School of Biosystems and Food Engineering
Supervisor: Dr Kevin P McDonnell
Head of School: Prof Colm P O’Donnell
August 2015

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Abstract
The major research institutions of Ireland have a key role to play in the modernisation of
the country’s infrastructure. Piloting an innovative renewable technology such as an
anaerobic digester at UCD will have a combined effect of determining the feasibility of
the technology whist simultaneously providing a template for prospective commercial
stakeholders to assess. A technical and economic feasibility study carried out on
anaerobic digestion discovered that the construction of a digester at UCD is not only
feasible but is also a financially attractive investment. Projected payback periods were
estimated at 5 years for the campus scenario and 8.5 years for the Lyons estate scenario.

ii
Contents
Abstract............................................................................................................................................i
Acknowledgments.........................................................................................................................v
List of Acronyms..........................................................................................................................vi
List of Figures.............................................................................................................................viii
List of Tables ................................................................................................................................ix
Executive Summary ......................................................................................................................1
Document Overview ....................................................................................................................3
2.1 Purpose of this document.............................................................................................3
2.2 Multi-functional technology .........................................................................................3
Background of Anaerobic Digestion..........................................................................................5
3.1 Anaerobic digestion: the process .................................................................................5
3.1.1 Parameters of AD...................................................................................................7
3.1.2 Feedstock Characteristics ....................................................................................11
3.1.3 Logistics of AD.....................................................................................................13
3.1.4 AD Technologies..................................................................................................16
3.2 Legislation and Policy..................................................................................................19
3.2.1 National Renewable Energy Drivers .................................................................19
3.2.2 Renewable Energy Feed-In Tariff (REFIT) .....................................................21
3.2.3 Animal By-Products.............................................................................................22
3.2.4 Nitrates Directive: Directive 91/676/EEC......................................................25
3.2.5 National Waste Management Policy ..................................................................26
3.3 Advantages of Anaerobic Digestion..........................................................................30

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3.3.1 Societal Benefits....................................................................................................30
3.3.2 Agronomic Benefits .............................................................................................32
3.4 Barriers to AD..............................................................................................................33
3.4.1 Complex Legislation.............................................................................................33
3.4.2 Non-competitive Incentives ...............................................................................33
3.4.3 Stakeholder Uncertainty ......................................................................................34
3.4.4 Lack of Access to Capital....................................................................................34
3.5 Vision for Ireland.........................................................................................................35
Objectives and Outcomes..........................................................................................................39
Scope and Methodology.............................................................................................................41
5.1 Methodology.................................................................................................................41
5.1.1 Estimation of Investment Costs.........................................................................41
5.1.2 Estimation of Biogas Input Data .......................................................................42
5.1.3 Determination of the Cost of Biomass .............................................................43
5.1.4 Revenue Streams and Finance Plans..................................................................43
5.1.5 General Business Costs........................................................................................44
5.2 Site Selection.................................................................................................................44
5.3 Constraints....................................................................................................................44
5.4 Assumptions .................................................................................................................45
Cost-Benefit Analysis..................................................................................................................46
6.1 Rationale of Inputs ......................................................................................................46
6.1.1 Investment Costs..................................................................................................46
6.1.2 Biogas Input Data.................................................................................................48
6.1.3 Cost of Biomass....................................................................................................49
6.1.4 Revenue Streams and Finance Plans..................................................................49
6.1.5 General Business Costs........................................................................................50

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6.2 UCD Campus Scenario ...............................................................................................51
6.3 Lyons Estate Scenario .................................................................................................53
6.4 Sensitivity Analyses......................................................................................................56
Options and Alternatives ...........................................................................................................59
7.1 UCD Campus Scenario ...............................................................................................59
7.1.1 Technical Description..........................................................................................59
7.1.2 Implementation at UCD......................................................................................61
7.1.3 Advantages ............................................................................................................62
7.1.4 Disadvantages .......................................................................................................63
7.2 Lyons Estate Scenario .................................................................................................64
7.2.1 Technical Description..........................................................................................64
7.2.2 Implementation at UCD......................................................................................66
7.2.3 Advantages ............................................................................................................66
7.2.4 Disadvantages .......................................................................................................67
Project Timeframes.....................................................................................................................68
Risks ..............................................................................................................................................71
9.1 Planning Permission ....................................................................................................71
9.1 REFIT Alternative.......................................................................................................72
9.3 Competition..................................................................................................................73
Recommendations.......................................................................................................................74
Conclusions..................................................................................................................................75
References ....................................................................................................................................76
Appendix 1 - Waste Management Methods for European Countries .................................84
Appendix 2 - Detailed Calculations of the Lyons Estate Scenario.......................................85
Appendix 3 - Detailed Calculations of the Campus Scenario ...............................................86

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Acknowledgments
I would like to thank all those whose help and support have contributed to this thesis. In
particular, there are a number of people to whom I owe special thanks:
Firstly, my supervisor, Dr Kevin McDonnell, for his guidance, support and
encouragement throughout the duration of my Masters. Despite his hectic schedule he
has always had time to discuss my work and provide assistance. An hour spent in his
office was more valuable than a day spent in the library. It is baffling how one person can
have so much knowledge in the field of sustainable energy. He has been an excellent
mentor and to him, I express my most sincere thanks.
John O’Halloran, from the UCD School of Chemical and Bioprocess Engineering for his
invaluable advice on the intricacies of anaerobic digestion. It is always excellent for the
creative process to have somebody to bounce ideas off and John, given his extensive
knowledge on AD was the perfect person for this.
Gary Smith, from campus services his assistance in retrieving waste management data
from the UCD campus.
Tom Canning, from ESB international for his explanation on the grid connection
process.
Ann Gallagher, a sustainability architect for her generous support and for her assistance
in outlining the planning process.
Hannah Martin, for proof reading the first draft and extended thanks goes to the rest of
my family for their support and encouragement along the way.
Finally, I would like to dedicate this thesis to my mother Mary Martin, for without her
support throughout this intensive year of study, I would not have been one tenth as
successful.

vi
List of Acronyms
Technical Acronyms:
AD Anaerobic Digestion / Anaerobic Digester
BMP Biomethane Potential
BOD Biological Oxygen Demand
CHP Combined Heat and Power
CSR Corporate Social Responsibility
GHG Greenhouse Gas
GW Gigawatt
HRT Hydraulic Retention Time
I-SEM Integrated Single Electricity Market
kW Kilowatt
kWh Kilowatt Hour
MEC Maximum Export Capacity
MSW Municipal Solid Waste
OFMSW Organic Fraction of Municipal Solid Waste
OLR Organic Loading Rate
PEIO Primary Energy Input Output ratio
PSO Public Service Obligation
MW Megawatt
REFIT Renewable Energy Feed In Tariff
RES Renewable Energy System

vii
Organisational Acronyms:
CER Commission for Energy Regulation
DAFM Department of Agriculture, Food and the Marine
DoELG Department of Environment and Local Government
DCENR Department of Communications, Energy and Natural Resources
DPER Department of Public Expenditure and Reform
DIT Dublin Institute of Technology
DSO Distribution System Operator
EC European Commission
EPA Environmental Protection Agency
ESB Electricity Supply Board
EU European Union
HEA Higher Education Authority (of Ireland)
IEA International Energy Agency
OGP Office of Government Procurement
SEAI Sustainable Energy Authority of Ireland
TSO Transmission System Operator
UCD University College Dublin

viii
List of Figures
Figure 1: The four stages of anaerobic digestion (Al Seadi et al., 2008).............................................................. 6
Figure 2: Benchmark methane yields of organic waste types (Preißler et al., 2007) ........................................12
Figure 3: Primary Energy Input/ Output ratio of AD supply chains (Pöschl et al, 2010).............................14
Figure 4: Schematic of a typical biogas plant with a single-stage digester (Blogspot.ie, 2013)......................16
Figure 5: Waste Management Hierarchy (DoELG, 2004)...................................................................................26
Figure 7: (a) Projected vs Empirical biogas production; (b) Projected vs Empirical biogas production. ...57
Figure 8: Flexibuster mobile AD (Innovation Showcase, 2015)........................................................................60
Figure 9: Plan view of proposed AD at Lyons research farm ............................................................................65
Figure 10: Effect a reduction of electricity price will have on profitability of an AD at Lyons Estate. ......72
Figure 11: Influence of gate fees on profitability of the propose AD at Lyons Estate..................................73

ix
List of Tables
Table 1: Optimum system type for each scenario.....................................................................2
Table 2: Common temperature ranges for AD.........................................................................7
Table 3: Pre-treatment methods for feedstocks (Zhang et al., 2014)....................................13
Table 4: REFIT rates applicable to AD (DCENR, 2015) .....................................................21
Table 5: Summary of the main regulations from ABP legislation (EC No. 1774/2002)...23
Table 6: Fertilizer and storage capacity regulations (DAFM, 2006).....................................25
Table 7: Cost of waste permits for a bio-degradable waste facility ......................................29
Table 8: Irish feed-in tariff rates compared to the rest of Europe (Caslin, 2013)..............33
Table 9: Economics of biogas plants in UK, Germany, Denmark and Ireland .................47
Table 10: Break-down of investment costs for each scenario...............................................48
Table 11: Characteristics of feedstocks considered for every scenario................................49
Table 12: Cost-benefit of UCD campus scenario...................................................................51
Table 13: Cost-benefit analysis of Lyons Estate scenario......................................................53
Table 14: Food waste generated by UCD, TCD and DIT per annum ................................54
Table 15: Energy characteristics for UCD on campus scenario ...........................................62
Table 16: Timelines required for each planning parameter ...................................................69
Table 17: Timelines for construction and consultancy ..........................................................70

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CHAPTER 1
Executive Summary
UCD has the potential to become the Irish centre of excellence for anaerobic
digestion. This technology; which utilizes local wastes as a resource to generate renewable
energy is on the brink of penetrating the Irish market on a significant scale. The key
barrier to overcome is uncertainty amongst stakeholders which is inhibiting any major
investment in the technology.
Complex legislation, uncompetitive government incentives and unfamiliarity with
the technologies associated with the AD process are thought to be the causes of such
uncertainties. By building an anaerobic digester at one of its premises, UCD can
demonstrate to all the relevant stakeholders, the many benefits of this technology and
alleviate any of their concerns.
This report describes and evaluates the possible AD systems and supply chains
which could be readily integrated into either the college campus at Belfield or the
research farm at Lyons Estate.
As a bare minimum, any scenario was expected to utilize the organic wastes
generated by UCD annually. Potential co-substrates were then considered in an effort to
boost technical and economic performance. Scenarios were assessed on a cost-benefit
basis initially using the “Big-East” biogas calculation tool. Any system configuration which
proved financial feasible was outlined in greater detail.

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The cost-benefit analysis revealed that the construction of a digester both on the
UCD campus as well as on the Lyons research farm were economically feasible. Table 1
summarises the key results from each scenario. The Lyons Research Farm scenario
considered the co-digestion of 8000 t/a of slurry produced on the farm along with 2800
t/a of organic waste sourced from the UCD campus and a potential commercial partner
from the food processing industry. The campus scenario considered the treatment of
organic municipal waste originating from UCD and as the possibility of importing
additional feedstocks to improve the system’s performance.
Table 1: Optimum system type for each scenario
Lyons Research Farm UCD Campus
System Type CSTR Flexibuster by SEaB Energy
Investment Cost €1.15 Million €424,000
Electrical Output 173 kWe 28kWe
Annual Turnover €132,368 €86,000
Payback Period 8.5 years 5 years
Despite having a longer payback period, the Lyons research farm scenario was
recommended as the most ideal scenario for UCD. This recommendation was based on
the fact that it engaged more of the stakeholders relevant to the AD industry in Ireland
hence would be more beneficial to the AD industry as a whole. It is anticipated that the
successful implementation of this system will provide a valuable template for potential
investors to work off; will pave the way for new research avenues and add an extra level
of prestige to the UCD School of Agriculture and Food Science.

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CHAPTER 2
Document Overview
2.1 Purpose of this document
The purpose of this document is to present a clear and concise evaluation of the options
available to UCD for the implementation of an anaerobic digester at one of its facilities;
either on campus at Belfield or on the college research farm at Lyons Estate Co. Kildare.
2.2 Multi-functional technology
Anaerobic digestion (AD) is the breakdown of organic material in oxygen-deprived
conditions. The products of this process include biogas, which can be used to generate
heat and power, and digestate which can be used as a soil conditioner and fertilizer,
offsetting chemical fertilizers. Although AD does not contribute to the field of
sustainable energy in a massive way, compared to RES such as wind or hydro, when the
vast spectrum of additional benefits are taken into account, the installation of such
becomes a worthwhile venture.
Despite its potential of contributing to slurry management, waste management and
sustainable energy production simultaneously, the uptake of AD in Ireland has been
extremely limited. Research carried out on countries where the technology is more

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popular has suggested that lack of stakeholder and investor awareness in AD coupled
with uncompetitive REFIT rates are key factors inhibiting this technology from taking
off.
By building a fully functioning digester at one of its facilities, UCD can aid the
stimulation of stakeholder interest in AD by demonstrating the massive potential this
technology has.

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CHAPTER 3
Background of Anaerobic Digestion
3.1 Anaerobic digestion: the process
Anaerobic Digestion (AD) is a biochemical process involving the breakdown of complex
organic matter into simpler molecules under oxygen starved conditions by a variety of
anaerobic microorganisms. These ‘simpler molecules’ form the basis of two valuable end
products in the form of biogas and digestate. The biogas production process involves
four distinct stages, outlined in figure 1.
As illustrated, hydrolysis is the first stage in the process in which the initial
feedstock of complex organic matter is broken down into simpler molecules by
hydrolytic microorganisms (Al Seadi et al., 2008).
These simpler molecules of fatty and amino acids along with glucose (sugar) are
then acted upon by fermentative bacteria in the acidogenic phase to form methanogenic
substrates. Certain molecules are more difficult to break down and must undergo
acetogenesis in order for the methanogens to act upon them.
Methanogenesis is the final step in the process, yielding the desired end product
biogas, predominantly composed of methane and carbon dioxide along with traces of
other gases.

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Each one of these stages are intrinsically linked however bearing in mind that this
is a biological process, each of the respective organisms have differing optimal
environments. According to Al Seadi et al., (2008), methanogenesis is a particularly
sensitive step which is influenced by operating conditions such as temperature, pH,
organic loading rate and the composition of the feedstock.
Organic Matter
Fats, Proteins, Carbohydrates
Soluble Organic Molecules
Fatty Acids, Amino Acids, Sugars
Acetic Acid,
CO₂, H₂, NH₃, NH₄, H₂S
Carbonic Acids,
Volatile Fatty Acids, Alcohol
Methane and Carbon Dioxide
BIOGAS
Hydrolysis
Methanogenesis
Acetogenesis
Acidogenesis
Figure 1: The four stages of anaerobic digestion (Al Seadi et al., 2008)

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The most popular reactor type is a single stage tank reactor. In this configuration, all of
these stage occur in the same environment. The key here is to find a happy medium by
creating an environment in which all microorganisms can be productive (Azbar et al.,
2001). Other system configurations such as a two-stage digester have two reactors in sync
with one another; the first optimized for hydrolysis and acetogenesis while the second
has favourable conditions for the more sensitive methanogenic bacteria (Nizami et al.,
2009).
3.1.1 Parameters of AD
It is useful to point out that the AD process occurs naturally in the stomach of a
ruminant. An important difference however between a cow and a metal tank is that the
cow’s system is regulated by homeostasis to ensure favourable methanogenic conditions.
Homeostasis essentially needs to be mimicked artificially in the metal tank reactor to
ensure maximum biogas production. There are many parameters which need to be
maintained such as temperature, pH, hydraulic retention time and organic loading rate
(Abu-Dahrieh et al., 2011).
Temperature
Table 2 highlights the three temperature ranges which are applied to AD. The
temperature range selected will have a bearing on the retention times of substrates in the
digester.
Table 2: Common temperature ranges for AD
Process Temperature Min. Retention Time
Psychrophilic <20°C 70 to 80 days
Mesophilic 30-42°C 30 to 40 days
Thermophilic 43-55°C 15 to 20 days
Obviously the lower the retention time, the more productive a biogas plant can
potentially be. The thermophilic range with the lowest retention time is also most
efficient for the reduction of pathogens and weed seeds enhancing both biogas and
digestate produced. The low retention time is a result of methanogenic bacteria’s
preference for higher temperatures; hence more substrate is digested, enhancing biogas
production (Angelidaki, 2004). The disadvantage of this range is the cost of maintaining

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these temperatures year round can reduce the economic feasibility of the plant (Patterson
et al., 2009). In addition the AD process tends to be more unstable at higher
temperatures, increasing maintenance costs and plant downtime. The mesophilic
temperature range can be maintained without the use of additional heaters in warm
climates however in Ireland, a heater will most definitely be required. The retention times
associated with psychrophilic ranges are usually considered too lengthy to justify the AD
process from an economic perspective.
pH Value
pH values within the digester affect the growth of microorganisms and the dissociation
of ammonia and hydrogen sulphide (Comparetti et al., 2013). Methanogens prefer a pH
value of 7.0 (Lee et al., 2009) but can maintain activity between 5.5 and 8.5, while the
optimum pH for hydrolytic and acetogenic microbes are in the 5.5-6.5 range (Kim et al.,
2003). This reaffirms the importance of gaining a happy medium especially with single
reactor configurations.
The substrates fed into the digester obviously have a significant influence on the
system pH. This parameter can be controlled either by carefully managing the substrate
going into the reactor or by installing ‘bicarbonate buffer system’ (Al Seadi et al., 2008).
Co-digestion of different feedstocks can also have a stabilising effect on the overall
reaction (Cuetos et al., 2008).
Organic Loading Rate
This is the amount of feedstock fed into the digester per unit volume of the digester per
time, typically expressed as kg VS m³ d. This rate is limited by the amount of time
required for the microorganisms to decompose the substrate. Considering the dynamics
of microorganism duplication rates it is generally uneconomical to design a system aiming
for total substrate decomposition (Al Seadi et al., 2008).
BR = m * c / VR
BR organic load [kg/d*m³]
m mass of substrate fed per time unit [kg/d]
c concentration of organic matter [%]
VR digester volume [m³]
Equation 1(Al Seadi et al., 2008)

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Hydraulic Retention Time (HRT)
This is the average amount of time that any given substrate resides in the digester. This
parameter is correlated to the reactor volume and the organic loading rate (Al Seadi et al.,
2008). Equation 2 suggests that HRT is determined by the size of the reactor and the rate
at which fresh material is loaded into the reactor.
HRT = VR / V
HRT Hydraulic retention time [days]
VR Digester volume [m³]
V Volume of substrate fed per time unit [m³/d]
Equation 2 (Al Seadi et al., 2008)
This equation is an over-simplification; HRT must be greater than reproduction rates of
the slowest growing bacteria involved in decomposition in order to maintain digestion
rates. Veeken & Hamelers (1999) identify hydrolysis as the rate limiting step in AD. If the
feedstock is ejected quicker than the microorganisms can multiply and spread, there may
be insufficient microbes to act upon the next batch of fresh material (Friehe et al., 2010).
Furthermore some substrates are more susceptible to decay than others. A feedstock
containing mostly fats and carbohydrates will require a low retention time as they degrade
rapidly. Feedstock high in cellulose, are tougher to break down, hence require a longer
retention time. For these reasons it is necessary determine if a constant and uniform
feedstock is available during the preliminary stages of a biogas project as it will have a
profound impact on the choosing a suitable digester type. There is a close correlation
between OLR and HRT.
Solids Content
This parameter affects the mixing regime within the digester. Postel et al (2010) maintains
that the optimum DM content of the feedstock in a typical wet digester is 12% for ease
of “pumpability” of the medium. Mixing ensures even heating of the substrate,
uniformity of the substrate composition and prevention of a scum layer and solids
deposition (Igoni et al., 2008). Excessive mixing can lead to shear forces, which are
detrimental to the productivity of acetogenic and methanogenic microbes which prefer
calmer conditions (Friehe et al., 2010). A system of slowly rotating agitators is usually an

10
adequate compromise to suit both aspects of the mixing regime. Water is sometimes
added to the process to ease mixing.
Toxic Substances
It is impossible to deprive the digester of oxygen totally as molecules of this element are
released from the chemical reactions occurring inside the digester. Methanogenic bacteria
are completely intolerant of oxygen however their coexistence with oxygen consuming
bacteria from previous stages of the AD reaction ensure their survival (Friehe et al.,
2010).
Considering the common substrates to a digester tend to originate from farms, it
is not uncommon for pesticides or herbicides to infiltrate the system. These antibiotics
along with heavy metals can inhibit microorganism productivity, halting the biogas
process (Al Seadi et al., 2008).
Friehe et al (2010), report that a number of inhibitors such as; Ammonia,
Hydrogen Sulphide and volatile fatty acids, can arise from the fermentative process itself.
The most effective control mechanism for this parameter is careful selection and quality
assurance of feedstocks. This may require an alteration of practices upstream which in
turn calls for increased awareness throughout the supply chain.
C: N Ratio
The carbon nitrogen ratio is important to the growth and performance of the micro-
organisms involved in the AD process. Carbon acts as the energy source for the microbes
while nitrogen enhances their growth rates. Igoni et al (2008) reports that excess nitrogen
not used by the microorganisms can lead to excessive levels of ammonia gas while carbon
is consumed up to 30-35 times faster than nitrogen is converted; hence this study
calculates the optimum C:N ratio to be 30:1. Other reports suggest that in a co-digestion
scenario, C:N ratio can be ideal at a lower value of 15:1 (Zhang et al., 2013). This study
concludes that optimum C:N can vary between feedstock type and inoculum used.

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3.1.2 Feedstock Characteristics
Upon analysing the parameters of AD it quickly becomes clear that feedstock type
is the single most important factor to consider during the preliminary design phase of a
biogas project. Feedstock type will influence the technology type deployed, the size of the
reactor and the biogas potential of the facility. It is important to secure a constant and
reliable source of substrate for the biogas plant at an early stage of the planning process
as it will influence a lot of decisions further on in the project. Gavigan (2014) describes
the two main sources applicable for treatment in a biogas plant;
I. Products from agricultural:
 Animal slurries
 Harvest residues
 Grass / maize / cereals
II. Products from food processing
 Meat/fish processing waste
 Dairy waste
 Brewery grains
 Vegetable waste
 Food factory waste
 Sewage Sludge
 OFMSW
Figure 2 shows the approximate methane potential originating from a number of
feedstocks potentially available to a digester sited at UCD. The livestock wastes
highlighted in orange have significantly lower biomethane potentials per tonne of dry
matter than other feedstocks. This is partly explained by the high water content of
slurries (Asam et al., 2011) and by the fact that a significant amount of the energy content
has already been extracted from these wastes as they pass through the animal’s digestive
system. Despite their lower methane yields, these wastes are very popular in AD due to
their cheap cost to obtain and their natural content of anaerobic bacteria, minimizing the
need for expensive pre-cursors (Al Seadi et al., 2008).

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Agricultural residues arising from arable crops, highlighted in green, have slightly higher
methane yields than slurries. Nizami et al (2009) report that ensilage of such residues;
especially grass, can enhance their biomethane potential even further.
Figure 2: Benchmark methane yields of organic waste types (Preißler et al., 2007)
Flotation sludge and cooking oil, due to their concentrated nature along with their high
lipid and protein contents, tend to have the most favourable biomethane yields (Al Seadi
et al., 2008). The various types of food wastes (blue) also tend to have higher methane
yield compared to wastes of agricultural origin.
It is important to note that these are benchmark values; there are a lot of variables
which can raise or lower the biogas yield of every feedstock on this chart. Once a project
hits feasibility stage, empirical testing will have to be carried out on the actual feedstocks
available. This usually involves the use of a eudiometer, a device which measures the
change in volume of a gas mixture following a physical or chemical change.
As well as securing a sufficient amount of feedstock, it is also crucial to ensure the
quality of the feedstock coming in. This should involve legal agreements with feedstock
suppliers to ensure they take appropriate action to limit contaminants or unsuitable
materials. Certain feedstocks are subject to stringent government regulations which
require pre-treatment before being administered into the digester. The general perception
0
100
200
300
400
500
600
700
MethaneYield(m³/toDM)
Waste Type

13
among farmers in particular; is that these requirements are a hindrance and discourage
uptake of the technology (Bywater, 2011). On the contrary to this view, Zhang et al
(2014) found that some of these pre-treatment methods (listed in table 3) increase gas
yields to a level that the added revenues of such justify their inclusion in the biogas
system.
Table 3: Pre-treatment methods for feedstocks (Zhang et al., 2014)
Method Raw Substrate Results Key Mechanism
Microwave (145°C) Food waste Increased biogas
production
Increased solubilisation
Thermal (120°C for 30
min)
Food waste Increased biogas
production by 11%
Increased solubilisation
Freeze-thaw (-80°C -
55°C)
Food Waste Increased biogas
production by 23%
Cell wall disruption
Pressure-depressure (10
bar to 1 bar)
Food Waste Increased biogas
production by 35%
Cell wall disruption
3.1.3 Logistics of AD
The next most important factors in designing a biogas plant are the economics. The
simple fact is that organisations are not going to build these facilities solely for the sake of
environmental protection. In order to secure funding to finance these expensive projects,
stakeholders are going to need to see a return on their investment usually by ensuring
optimum methane production (Walla and Schneeberger, 2005). For these reasons it is
necessary to take the following measures to maximise the profitability of a biogas plant.
Uniformity of feedstock:
In order to size the digester correctly it is imperative to secure a constant, reliable and
uniform source of feedstock for the life time of the system. In order to maximise biogas
output and by extension; profits, it is in the operator’s interest to have the plant running
at full capacity for as many hours as possible throughout the year. Otherwise the
operational costs out-weigh the revenue streams and the plant operates at a loss. Al Seadi
et al (2008) stress the importance of securing long-term contracts with feedstock

14
suppliers. Of course if a potential investor manages their own waste streams, such as a
farmer or a food processing factory, this is less of an issue.
Co-Digestion
Studies have shown that the co-digestion of different wastes can have synergistic effects
on each other. Macias-Corral et al (2008) has demonstrated that co-digestion of OFMSW
and cattle manure can lead to a more favourable pH value, hence a more stable reaction
within the reactor and enhanced methane yields compared to these substrates being
digested individually. More specifically, Zhang et al (2013) have shown that co-digestion
of food waste and cattle manure at a ratio of 2:1 can improve methane yields by 41.1% in
batch reactors and 55.2% in semi-continuous reactors. At biogas enhancement rates like
this, it can prove very lucrative for a facility to practice co-digestion. Operators can also
gain additional revenue streams by charging gate fees for the treatment of particular types
of waste (Braun and Wellinger, 2002).
Minimization of transport:
Transport of feedstocks or the products of digestion is a very costly process. It is also
likely to involve use of fossil fuels, which is counter intuitive to one of the main reasons
for deployment of AD. The most logical solution here is to build the digester at the
source of the predominant waste type. However in a centralised facility or a co-digestion
scenario; some degree of transport is unavoidable.
Figure 3: Primary Energy Input/ Output ratio of AD supply chains (Pöschl et al, 2010)
Cattle Manure
Sludge
Food Residues
Grass Silage
Corn Silage
Straw
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120 140
PEIOratio(%)
Transport Distance (km)

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Figure 3 is depicted from Pöschl et al (2010) and illustrates the distances for which
transport of various feedstocks remains energy efficient. This was calculated on the basis
of primary energy input/ output ratio (PEIO); calculated on the presumption that
biomethane yields would over-compensate the fossil fuel energy input into the system. A
low PEIO ratio is indicative of a highly energy efficient system chain. Figure 3 shows that
straw and silage tend to have lower PEIO ratios meaning they can be transported great
distances whilst still maintaining the energy efficiency of the supply chain. At the other
end of the scale, with a particularly high PEIO are cattle manures. The PEIO ratio of
these feedstocks becomes negative at just 21 km hence it is not feasible to transport these
feedstocks even over short distances. According to Pöschl et al (2010), this disparity
between feedstocks is largely to do with their differing energy densities and by extension
dry matter contents.
It is possible to improve the PEIO ratio of certain substrates using pre-treatment
methods which separate feedstocks into solid and liquid fractions. Asam et al (2011),
report that this technique, can significantly improve the methane potential per unit
volume of substrate. This research provides an excellent technical basis for centralised
AD or co-digestion plants to work off.

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3.1.4 AD Technologies
Figure 4 is a simpler schematic of a typical full-scale biogas plant in Europe. It is included
here as a visual reference to accompany the technical description of a biogas plant below.
Figure 4: Schematic of a typical biogas plant with a single-stage digester (Blogspot.ie, 2013)
The process begins with the intake of feedstocks such as organic waste, animal slurries
and crop residues (a, b and c) into the pre-storage pit (d). In Ireland animal by-products
legislation (S.I. No. 187, 2014) dictates that all food waste must be pasteurised at 70°C
for one hour prior to entering the digester. These types of wastes must strictly segregated
at the reception station from regular farming activities and must also be kept separate
from non-hygienically problematic waste streams before entering the primary digester
(Postel et al., 2010). However it is reasonable to assume a facility could charge
considerable tipping fees for these waste types hence the costs of implementing
pasteurisation can be offset. This step, although not illustrated in fig. 4 would be included
at this point in the system.
Feedstocks are then fed into the digester (e) via pumps or a screw press
depending on the solids content of the feedstocks. Water may also be pumped in at this
stage to attain an optimal DM content (Knitter, 2011).

17
This schematic uses the example of a continuously stirred, single stage tank
reactor usually made from concrete or steel in an up-right cylindrical position. According
to Nagao et al (2012) 95% of all full-scale plants in Europe utilize this type of digester.
The key characteristics of this technology type are that all four micro-biological stages
outlined in figure 3-1 occur within the same, gently stirred reactor. The substrate is stirred
either mechanically by agitators or by pumping some of the biogas produced back into
the substrate. The popularity of this configuration is largely due to its cost-effectiveness
at sizes greater than 300m³ and due to the fact that it can usually be serviced without the
need of emptying the digested, minimizing downtime (Postel et al., 2010).
Two-stage reactors consist of two separate tanks in phase with one another. The
basic premise of this configuration is that the first reactor is optimised for hydrolysis and
acidogenesis while the second is optimized for the methanogenic stage (Abu-Dahrieh et
al., 2011). The key advantage of two-stage digestion is that higher organic loading rates
can be achieved due to the shortening of the rate-limiting hydrolysis stage (Nizami et al.,
2009). In a situation where a facility has an abundance of feedstock, this would be
advantageous for the overall productivity of the facility. Both this and single stage designs
are generally suited to farm or centralised scale facilities where sufficient economies of
scale can be achieved.
Another AD technology which has recently reached commercial maturity is batch-
process digestion. This system consists of placing the raw biomass inside a concrete or
metal container and sealing it air-tight (Postel et al., 2010). This type is particularly suited
to substrates with a high DM content such as maize or grass silage. There are a wide
variety of other reactor types which UCD could consider however a detailed discussion
of such is beyond the scope of this pre-feasibility study.
The AD process creates two key products; biogas (f) and a solid residue called
digestate (g). Digestate is pumped into an effluent storage tank. It is common to apply
solid/liquid separation techniques to the digestate such as belt filter presses or screw
separators (Postel et al., 2010). The liquid portion can be applied to arable land using
conventional spreading techniques while the solid portion acts as an excellent soil
conditioner.

18
The biogas can be used for a number of post-production applications. The
simplest application is to burn the gas in a modified natural gas boiler. This process, not
shown in figure 4 is most common in the developing world in subsistence digestion
systems however there are a few circumstances this method is used in the developed
world. The Camphill Community biogas facility in Co. Kilkenny had in its initial plans to
include a CHP unit to combust the gas. However following difficulty in obtaining a
power purchasing agreement from CER, the operators had no choice but to utilize biogas
boilers (SEAI, 2005).
The most efficient application is utilise a CHP unit (i). In this scenario, biogas is
combusted in a specialised engine such as a Stirling or Jensbacher engine. These engines
are robust enough to combust the biogas in its raw form and are used to run an electricity
generator while the heat is channelled for use either on-site or at nearby locations. Such
configurations can achieve efficiencies of up to 90% (Al Seadi et al., 2008).
While CHP is the most desirable end-use application, there is not always a
sufficient demand for the heat generated. As an alternative the biogas can be cleaned and
pressurized to upgrade it to biomethane (k). This involves the removal of impurities such
as hydrogen sulphide and carbon dioxide via various adsorption and scrubbing
techniques (Al Seadi et al., 2008). Once upgraded, the biomethane can be pumped into
the natural gas grid (l). Patrizio et al (2015) has shown that considerable subsidies which
are not currently in existence would be required to make this option economically viable.
In countries such as Sweden and Austria, upgraded biomethane is utilised as
vehicle fuel (k) (Murphy & Power, 2009). At Linkoping Biogas plant, Sweden biogas is
upgraded to be used in buses and cars. By 2005, 64 buses were running completely on
upgraded biomethane (IEA Bioenergy Task 37). According to the Swedish Gas
Association a three pronged approach of energy taxation regulations, electricity
certificates and investment supports for agricultural facilitated an innovative project like
this. Today there are now 47,000 vehicles running on biogas in Sweden. It should be
noted that Sweden has a number of car manufacturers such as Saab, Volvo and Scania to
build such vehicles. While Ireland is without this luxury, this is still an excellent example
that shows when the incentives are attractive; the private sector will develop a solution.

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3.2 Legislation and Policy
Given the aforementioned potential for AD to contribute to a variety of different areas, it
is also liable to adhere to a variety of different legislations. This has been highlighted as a
major barrier to the wholesale uptake of the technology as opposed to a driver, as it
breeds confusion and uncertainty into the relevant stakeholders (CRÉ, 2011). This
section reviews the legislation which is currently pertinent to the construction of a biogas
plant, with the intention of presenting it in a simplified and relevant manner.
3.2.1 National Renewable Energy Drivers
Speaking at a seminar introducing the upcoming white paper at Dublin Castle,
Minister Alex White stated the following;
“The impact of global warming demands that we put sustainability at the very centre of our energy policy”
DCENR (c), 2015
In his speech, Minister White also acknowledged the fact that gas and coal must be
replaced with renewable energy sources within 35 years and that policy must ensure
certainty, stability and affordability, in making the transition to a low carbon future.
Unfortunately this white paper isn’t due to be published until later this year so for the
purpose of this feasibility study, the previous white paper will have to suffice.
The Government White Paper – Delivering a sustainable energy future for Ireland 2007-
2020 lays down the strategies which are designed to ensure Ireland honours its
international and European commitments. This document centres around three pillars:
 Ensuring the security of the country’s energy supply,
 Promoting the sustainability of the country’s energy supply,
 Enhancement of the competitiveness of energy supply.
Section 3.4 of this document, “enhancing the diversity of fuels” highlights the
government’s disapproval of Nuclear energy being added to the energy mix meaning
hydro, wind and biomass technologies were forecasted to play a major role. Section 3.10
provides a general outline of measures to accelerate growth of the renewable energy
sector.

20
Broadly speaking, Kyoto protocol and the EU 20-20-20 targets acted as
precursors to the energy white paper. The Kyoto protocol mandated Europe with the
task of collectively reducing its GHG emissions to 5% above 1990 levels (EPA (a), 2015).
This prompted the EU to forge the 20-20-20 Policy targets which are as follows:
 20% reduction in GHG emissions to that of 1990 levels
 20% of electricity sourced from renewables
 20% improvement in European energy efficiency
It was recognised that some EU countries had a greater capacity to achieve these targets
than others. Burden-sharing agreements in which some countries aim for tougher targets
to offset those which can’t achieve their own were put forth to overcome this. Under EU
directive 2009/28/EC, Ireland has been set a specific, legally-binding target of 16% of
energy across all sectors generated from renewable energy sources by 2020. Article 3 and
4 of this directive provides a common framework to assist member states form their own
policies on the promotion of renewable energy. The National Renewable Energy Action
Plan (NREAP) was published in response to this directive. It set interim targets to
achieve and segregated renewable targets into the following sections:
 40% electricity generated from renewable energy (RES-E)
 12% heat supplied from renewable sources (RES-H)
 10% of the transport ran on renewable power. (RES-T)
The National Bioenergy Action Plan was published by DCENR around the same
time as the white paper. This document outlined the key strategies to develop the Irish
bioenergy sector. This strategy prompted the expansion of the REFIT programme to
include waste-to-energy projects such as AD. The strategy acknowledged the amount of
government departments with a stake in the bioenergy sector and envisaged the
development of a cross-agency information and education programme to facilitate
joined-up thinking on the subject. The plan put the onus of this task on the SEAI and
enterprise Ireland.

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3.2.2 Renewable Energy Feed-In Tariff (REFIT)
This legislation is currently the only major, monetary incentive for an organisation
to construct a digester in Ireland. The REFIT scheme is funded by the Public Service
Obligation (PSO) which is a levy imposed on all electricity users (DCENR(a), 2015). The
purpose of this scheme is to stimulate the development of renewable electricity and to
ensure Ireland meets it 2020 electricity targets of 40% coming from RES. The basic
premise of REFIT is that a minimum floor price for electricity is guaranteed for a period
of 15 years after a RES is energised. Different prices are offered to different forms of
generation technologies. AD comes under the REFIT 3 scheme which opened for
applications in 2012. The current rates offered for anaerobic digestion are illustrated in
table 4.
Table 4: REFIT rates applicable to AD (DCENR, 2015)
REFIT 3 2014 (€/kWh) 2015 (€/kWh)
Large AD Non CHP (>500kW) 10.48 c 10.50 c
Small AD Non CHP (<500kW) 11.53 c 11.55 c
Large AD CHP (>500kW) 13.62 c 13.65 c
Small AD CHP (<500 kW) 15.72 c 15.76 c
As illustrated in this table, higher tariffs are awarded to AD plants which include a CHP
unit and rightly so as this is a more efficient use of the biogas produced. The larger scaled
plants are awarded lower tariffs as it is estimated that economies of scale make such
installations more profitable. The closing date for new applications to the REFIT 3
scheme is the 31st of December 2015. What’s more is that applications are required to be
at an advanced stage to qualify for the scheme by this date. This essentially rules this
particular project out of the running for REFIT 3. The DCENR have indicated that a
new support scheme for renewable electricity projects will be available in 2016 however
have not yet published any detailed information on what this might be.

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3.2.3 Animal By-Products
This legislation is as complex as it is stringent. Granted the size of the Irish
agricultural export market, it is within the country’s interest to keep the sector disease
free. As AD is applicable to a vast spectrum of organic wastes there is cause for concern
that the application of digestate containing animal by-products poses a risk of spreading
disease (EPA(a), 2006). Introduced in 2002, this legislation regulates how animal by-
products are disposed of and processed. The consequences for non-compliance of these
rules are extreme, with any person found in breach of them liable to 3 months
imprisonment and/or a €250,000 fine (S.I. No. 187, 2014). Hence these regulations have
major implications for biogas plants.
Article 2 part 1(a) of this legislation gives a holistic definition of animal by-products:
“Entire bodies or parts of animals or products of animal origin referred to in Articles 4, 5
and 6 not intended for human consumption, including ova, embryos and semen”
These by-products are categorised based on the potential severity of the threat
they pose to the bio-security of the agricultural industry. Table 5 summarises the main
conditions any biogas plant commissioned at UCD must adhere to when dealing with
these wastes.
Category 1 waste is completely off limits for this project. The School of
Veterinary Medicine and the School of Chemistry and Chemical Biology are the only
locations this type of waste may arise from. These schools have their own waste
management plans hence it is unlikely that this waste would end up in any feedstock
streams for a potential AD at UCD
Category 2 wastes are expected to constitute a large proportion of the feedstock
stream for at least one of the scenarios proposed in this study; the siting of an AD at
Lyons Estate. The ABP legislation requires that waste in this category are pasteurised and
macerated to a maximum particle size prior to AD treatment. Manure and digestive tract
content are however exempt from this rule meaning an AD dealing with this feedstock is
not required to include expensive pre-treatment processes in the system.

23
Table 5: Summary of the main regulations from ABP legislation (EC No. 1774/2002)
Waste Type Minimum
Treatment
Constraints
Category 1
(Covered
under article
4)
 Animals suspected of
being infected by BSE
and their by-products.
 Animals other than
farmed animals.
 Catering waste of
international origin.
 Experimental Animals
 Incineration or
co-incineration.
 Burial
(household pets
only)
This category is
completely off limits for
inclusion in an AD
Category 2
(Covered
under article
5)
 Manure & digestive tract
content.
 Animals that die other
than being slaughtered
for human consumption
 Manure/gut
contents can be
treated by AD
or spread
directly onto
land.
 All other wastes
suitable for AD
following pre-
treatment.
 Must be
pasteurised @
60°C for 48
hours prior to
being fed into
AD.
 Must be
macerated to a
particle size of
>400mm
 Manure/
digestive tract
content
requires no pre-
treatment.
Category 3
(Covered
under article
6)
 Former foodstuffs of
animal origin.
 Domestic catering waste
 AD following
pre-treatment.
 Must be
pasteurised @
70°C for 1
hour prior to
being fed into
AD.
 Must be
macerated to a
particle size of
>12mm

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Category 3 wastes are also expected to contribute to the feedstock of the
proposed AD in all scenarios of this study. These wastes include catering waste, a
considerable amount of which is produced by UCD every year. Any digester which
processes this type of waste must include a pasteurisation and maceration process in its
design adding to the overall capital cost of the project. The inclusions of such pre-
treatment steps are usually justified by the fact that food waste has a much higher
biomethane potential (BMP) than animal slurries, hence the enhanced revenues from the
higher biogas production more than cover the added capital cost.
Article 7 of this legislation outlines how animal by-products should be collected,
transported and stored. ABP can only be transported by a license haulier. Annex II
dictates the following:
 ABP shall be transported in sealed packaging or covered by leak-proof containers.
 Reusable equipment used to facilitate the transport must be cleaned and washed
after each use and be dry before the next use.
 Appropriate temperatures must be maintained.
Conveniently for UCD, category 3 catering waste is exempt from these
conditions; however if such waste is to be transported off campus, a licensed haulier
must be used or alternatively UCD must seek the appropriate license from the DAFM to
transport the feedstock itself. S.I. No. 820/2007 sets out the legislation which must be
adhered to in order for such a licence to be granted. Offaly county council is the
administrative agency which issues these permits. This permit costs € 1000 per region
waste is collected from and must be renewed every five years at a cost of half the initial
amount paid. Processing time is estimated at 40 days.
There are also a number of rules related to plant layout outlined by DAFM (2009).
The digester receiving off farm wastes must be must be separated from other premises
on the farm by permanent, animal-proof close meshed fencing whilst also maintaining a
minimum of 5 metres from livestock. A way around these restrictions is to pasteurize
such wastes prior to reaching the farm. There might be some merit for UCD to pre-
pasteurize food waste before exporting it off campus in one of the digester scenarios
outlined in chapter 6.

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3.2.4 Nitrates Directive: Directive 91/676/EEC
This directive was conceived in an effort to minimize pollution to water courses
originating from agricultural sources. Under article 3.2, Ireland was obliged to designate
zones which are particularly vulnerable to water course pollution. Article 4 of this
directive prompted farmers to establish good agricultural practices. This prompted the
Department of Agriculture, Food and the Marine to divide the country’s agricultural land
into three zones based on rainfall, type of soil and duration of growing season. In each
zone there are different capacity requirements for the storage of manure (DAFM, 2006).
Table 6 highlights the outcomes of this directive. Farmers are required to store any slurry
produced at sensitive times of the year and are restricted. In addition to these regulations,
the National Nitrates Action Programme limited the application of over 170 kg of
nitrogen per hectare per annum.
Table 6: Fertilizer and storage capacity regulations (DAFM, 2006)
Zones Storage
Capacity
Required
Prohibited Application Periods
(Weeks) Chemical Fertilizers Organic Fertilizers Farmyard Manure
A 16 15 Sept -12 Jan 15 Oct – 12 Jan 1 Nov – 12 Jan
B 18 15 Sept -15 Jan 15 Oct – 15 Jan 1 Nov – 15 Jan
C 20 15 Sept -31 Jan 15 Oct – 31 Jan 1 Nov – 31 Jan
C* (Cavan and
Monaghan)
22 15 Sept -31 Jan 15 Oct – 31 Jan 1 Nov – 31 Jan
These regulations should in theory, complement the growth of AD. With it now being a
requirement to store slurry and other agricultural residues, it seems only logical that a
farmer should be able to heat these products and recover energy for them. What’s more
is that the spreading of digestate is safer for the environment than that of raw slurry
(Holm-Nielsen et al., 2009).

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3.2.5 National Waste Management Policy
Council directive 1991/156/EC was essentially the beginning of reform of
Europe’s waste management practices. Figure 5 outlines the hierarchy put forth by this
directive, which member states are expected to adhere to. In Ireland, this prompted the
publishing of many documents such as “Waste Management Changing Our Ways (1998)”
and “Waste Management: Taking Stock and moving forward (2004)” by the department
of Environment and Local Government. The aims of such documents were to outline
methods and strategies, to steer Ireland towards a more sustainable waste management
system, one which didn’t revolve around dumping multiple waste types in a landfill.
The council directive 1999/31/EC (known as the landfill directive) imposed strict
operational regulations on municipal waste landfills, in order to minimize the multitude
of negative effects this archaic disposal method had on the environment. This legislation
focuses on the management of the organic fraction of municipal solid waste (OFMSW).
Ireland was assigned the following targets for the diversion of biodegradable municipal
waste going to landfill.
 25% reduction of 1995 levels by 2010
Figure 5: Waste Management Hierarchy (DoELG, 2004)

27
With higher levels of OFMSW being diverted from landfill, technologies such as
composting and AD, along with thermal treatment techniques were expected to become
more prevalent. These technologies occupy a more favourable positions in the waste
hierarchy illustrated in figure 2. Anaerobic digestion sits between the recycling category
and energy recovery category on this chart. A well-managed system can extract nutrients
from the waste to facilitate nutrient recycling; whilst simultaneously recovering energy
from the same material.
Under article 5 of this legislation, member states were obliged to establish a
national strategy, with a view to achieving the landfill diversion targets. In accordance
with this rule; and probably most pertinent to the AD industry, the National Strategy on
Biodegradable Waste was published in 2006. A study carried out on behalf of the
European Commission revealed that the source separation of MSW into recyclable and
organic waste streams and subsequent treatment of these streams individually leads to the
lowest generation of GHG’s compared to other treatment scenarios (Smith et al., 2001).
Paper, metals and plastics are to be recycled while degradable wastes are to be treated by
composting or AD. Based on the findings of this repost along with an assessment of
other European country’s waste regimes, the action plan recommended Ireland adopted
the following measures to achieve the national waste targets:
 Source separation of MSW: This has been relatively successful in the Dublin
region at least, with every household subject to a 3-bin collection system (Dublin
City Council, 2012). The dry-recyclable “green bin” had been in place prior to this
repost and the brown bin for food waste followed shortly after.
 Introduction of legal measures to control waste collection and disposal
practices: S.I. No. 191/2015 has reinforced the regulations associated with the
collection and treatment of food and bio-waste. Under Part II, paragraph 4 of this
legislation, food waste may only collected by licenced hauliers and treated at
authorized AD or composting plants. Part III of this instrument extends these
regulations to householders stating that it is now an offence to place food waste
with non-biodegradable materials. According to Part IV, paragraph 14 of this
legislation, any person found in breach of these rules is liable to a maximum fine
of €500,000 and/or 3 months in prison.

28
 Landfill levy: S.I. No 194 of 2013 amended the landfill levy from €65 per tonne
to €75 per tonne from 1 July 2013 further discouraging waste collectors from
disposing waste at these facilities.
 Producer Responsibility Agreements: industries with high levels of a particular
waste develop their own waste management practices on site. Coillte for example,
stockpiles thousands of dry tonnes of biomass per year, with the intention of
supplying customers with woodchip boilers or CHP installations. This initiative
began with the view to treating waste wood in a more sustainable manner
however the company now seeks biomass from sources other than their own as
the demand for woodchip increased throughout the country (Coillte, 2015). Large
enterprises such as Coillte have sufficient access to capital in order to finance such
projects. Such ventures benefit the overall market as it stimulates interest in the
sector and creates demand and supply scenarios.
 Market Development: It is envisaged that, after implementing the
aforementioned strategies successfully, the end result will be a market where
demand for biodegradable waste is strong; and revenues are sufficient enough to
offset the costs of the collection and treatment of bio-waste. The report
recommends cooperation with authorities from Northern Ireland to facilitate the
development of synergies and cater for improved economies of scale along the
entire biomass supply chain.
Before a biological waste treatment facility can become operational, it must satisfy the
regulations set forth by the myriad of waste management acts between 1996 and 2008
along with the Protection of the Environment Act: S.I No. 27/2003. These instruments
define the standards of practice any given facility must aspire to for the sake of
minimising negative environmental impacts. This area is regulated by the EPA hence any
organisation intending to operate a waste treatment facility must apply for a waste permit.
S.I. No. 86/2008 outlines the different categories various waste treatment plants fall
under and the regulations which apply to such. The third schedule of this act outlines the
regulations with respect to a biological treatment facility such as a biogas plant; the costs
vary according to the amount of waste intake per annum as outlined in table 7.

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Table 7: Cost of waste permits for a bio-degradable waste facility
Intake per year Application fee
Class 11 (Part II) <5,000 tonnes €300
Class 8 (Part I) <10,000 tonnes €1,000
Class 10 (Part I) >10,000 tonnes €10,000
Paragraph (d) of S.I. No. 283/2012 insists that a completed Environmental Impact
Statement (EIS) must accompany any prospective applications to the EPA in search of a
waste permit. An EIA must be completed by a licenced professional hence outside
consultancy is required for any AD project in Ireland.

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3.3 Advantages of Anaerobic Digestion
It is important to realise that anaerobic digestion will never contribute to the field of
renewable energy generation as much as wind, hydro or even solar in Ireland. Even if the
a thousand 380kW AD plants were built over night, maximising the potential of the
available agricultural land space; this would equate to a contribution of only 6.5%
towards Ireland 2020 renewable energy targets (JCCENR, 2011). However what AD
lacks in energy potential, it makes up for in versatility and reliability as the following
section will show.
3.3.1 Societal Benefits
Renewable Energy Source
AD utilizes biomass, in a variety of forms as a feedstock. Producing energy from
biomass is considered an (almost) carbon neutral process as the CO₂ released during
combustion of the biogas was previously removed from the atmosphere via
photosynthesis (SEAI, 2013). The AD process also reduces methane emissions in the
sense that energy is recovered from the gas before it is release into the atmosphere during
combustion. Energy recovery offsets the use of fossil fuels improving the country’s
energy security and assisting in the attainment of 2020 targets. AD contributes not only
by electricity generation but also by heat generation when the biogas is used in a CHP
unit. Furthermore AD holds a significant advantage over the likes of wind power as
power output is relatively constant hence it acts as an excellent complimentary RES.
Energy Security
Fossil fuels accounted for 93.2% of Ireland overall energy usage in 2013, the
majority of which are imported (SEAI(b), 2014). Being on the periphery of Europe; puts
Ireland firmly at the end of a long and volatile supply chain. The country’s thirst for
Russian gas and Libyan oil is an unsustainable habit. As political tensions rise and fossil
reserves wane Ireland will be at the mercy of the markets and will have to pay exorbitant
energy prices in the near future. At present there is simply no back up plan in place. The
country needs to do everything in its power to wean itself off fossil fuel and realise the
vast potential of its natural resources. AD however minor a contribution needs to be
rolled out on a massive scale.

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Achievement of 2020 Targets
Looking at the more immediate future, Ireland is expected to fall short of its 2020
renewable energy targets by between 1-4% which could possibly result in fines of
between €140m and €600m a year to the exchequer (DPER, 2014). Wall et al (2013) has
estimated that the construction of 170 farm-scale digesters treating silage and slurry can
exceed the 10% of renewable energy supply in transport target should the gas be
upgraded into a biofuel. Whether the industry follows this path or not is irrelevant, the
simple fact is that AD can make some contribution to all three 2020 targets of electricity,
heat and transport.
Job Creation in Rural Areas
Decentralisation has long been an objective high on the government’s agenda.
The rolling out AD on a large scale is calculated to create 7800 jobs in construction,
farming and manufacturing predominantly in rural areas (JCCENR, 2011). The average
age in the agricultural sector is 54 according to a CSO agricultural census carried out in
2012 (Murphy, 2012). This is no surprise considering the mass exodus of young Irish
people to foreign countries in recent years. The implantation of AD can breathe much
needed youth into this sector.
Waste Treatment
In the AD process, waste is viewed as a resource; utilising locally produced waste
materials to generate localised power (Asam et al., 2011). Ireland has been slow to adopt a
modernised waste management system compared to its European Counterparts. Despite
the ban on landfills, 43% of Irelands waste was still going to these facilities in 2012
(Appendix 1). It’s no surprise that the best performers in waste management are also
highest achievers in the field of AD with Sweden and Denmark achieving diversion rates
of 99% and 97% respectively. Zhang et al (2014) identifies AD as the best treatment
method for biodegradable wastes due to their high water contents rendering them
inefficient for thermal treatment. In addition food wastes can boost biogas production
and lead to a more stable process when co-digested with agricultural slurries (Nizami et al,
2009).

32
3.3.2 Agronomic Benefits
Slurry Management
Under the nitrates directive, farmers are obliged to have storage capacities for
animal slurries for at least 20 weeks of the year. AD essentially carries out the same
function whilst simultaneously deriving energy from the substrates. The solid substrate
remaining after treatment is free from pathogens and has a higher nutrient content per
unit volume that of raw slurry making it safer to apply to land. Furthermore the digestate
has a lower biological oxygen demand making it less potent to aquatic environments
should it reach them due to run-off (Holm-Neilsen et al , 2009).
Odour Reduction
The AD process reportedly reduces odour by 80% (Al Seadi et al., 2008). The
resultant digestate after AD treatment has a much less pungent smell than raw slurry
hence when it is applied to land there are less nuisance odours emitted to the surrounding
countryside.
Additional Revenue Streams
When a CHP unit is deployed in conjunction with AD, electricity and heat can be
generated on site. This can act to either offset electricity and heat use on-site, resulting in
energy savings or alternatively electricity can be sold to the grid by securing a power
purchasing agreement. In some countries, incentives are provided for the sale of heat
however no such incentives exist in Ireland as of yet. It is also common practice to
charge gate fees for any organic wastes the AD receives from off site. In Ireland the
current rates are particularly lucrative with a tonne of food waste obtaining rates of
~€110.
Digestate Replacing Chemical Fertilizers
Digestate is rich in Nitrogen, Phosphorus, Potassium and other micronutrients. It
also has an improved fertilization efficiency due to the improved homogeneity and a
more favourable C:N ratio following AD.

33
3.4 Barriers to AD
3.4.1 Complex Legislation
Section 3.2 highlighted the fact that in order to get an AD project off the ground
it is necessary to engage with or seek approval from no less than six governing bodies
including, DCENR, DAFM, DoElG EPA, the local County Council and the national
waste permit office. The sheer thoughts alone of dealing with so many bureaucratic
agencies are likely to be too overwhelming for the average farmer. Every application
costs a significant amount of time and money and in some cases, after investing such
considerable amounts of time and effort; the project might not even gain approval for
planning permission (Bywater, 2011). This necessitates that the inception of any biogas
project will require consultancy from an early stage, making AD a costly affair even at
feasibility study stage.
3.4.2 Non-competitive Incentives
It has long been accepted that most if not all renewable energy systems require
government subsidies in order to gain a competitive edge on the established fossil fuel
markets. AD plants are no different; anything under the size of 1000 kW requires heavy
incentives (Patrizio et al. 2015).
Table 8: Irish feed-in tariff rates compared to the rest of Europe (Caslin, 2013)
Country Price per kWh
Germany 18-28c
Italy 22-28c
UK 18-25c
N. Ireland 22-27c
Austria 16-18c
France 16c +Capital Grant
Ireland 13-15c
Table 8 highlights the fact that Ireland has the lowest feed-in tariff rates in Europe. A
project which is marginally feasible in Dublin becomes a lucrative investment if sited a

34
few kilometres North in Co. Down. The DCENR must assign tariffs that are at least in
line with the rest of Europe.
3.4.3 Stakeholder Uncertainty
With no platform for information to be circulated the benefits of AD are not
common knowledge to many of the potential stakeholders within the sector. Reports of
excessive downtime and technical difficulties are more likely to travel as opposed to a
plant which has been operating successfully for extended periods of time.
With the market in its infancy there is a lack of experienced contractors, planners,
suppliers, maintenance companies who have worked with the technology hands on.
Tying in with the complex legislation; projects in advanced stages of the planning process
have been reported to be refused planning permission.
3.4.4 Lack of Access to Capital
AD is an expensive investment and in almost all cases requires loans in order to
finance. As a result of the banking crisis; money lenders are becoming increasingly
selective on the types of projects they award loans to.
The age profile of farmers in Ireland doesn’t help this situation. The average age of the
Irish farming sector is now set at 54 (Murphy, 2012). It is extremely difficult for this
demographic to gain access to finance because they are coming up so close on retirement
age. Excessive conditions are usually necessary such as having to put forward collateral
before a loan is granted.

35
3.5 Vision for Ireland
Ireland currently meets its energy requirements by importing in foreign oil and
gas, burning it in large centralised stations and distributing it long distances to customers
around the country. As fossil fuels become scarcer and scarcer it becomes less acceptable
to lose so much of the energy generated due to the inefficiencies of transmission. Hence
the days of the centralised grid are numbered. The future lies in a smart grid distribution
system consisting of multiple smaller generators providing energy to their immediate
surroundings. The beauty of this decentralised energy model is that excessive
transmission losses are minimized.
So how can Ireland adopt this new model and reduce its reliance on fossil fuels?
At a recent conference on sustainability Brendan Halligan, Chairman of the Institute of
International and European Affairs recommended (jokingly) that the best thing Ireland
can to in order to modernise its energy system; is to take the Danish Energy Policy,
translate it into English, and copy it down into our own legislation. (Sustainability
Gathering, 2015).
Despite the tongue in cheek tone there, appears to be a lot of merit in what Mr.
Halligan was saying. While Ireland is struggling to achieve its 2020 targets, Denmark is
well on its way to achieving their equivalent targets with renewables constituting a 28%
share of their grid mix (Eurostat, 2015). Topping this list was Sweden, with a 52% share.
In addition these countries currently sit at 33% and 19% below their 1991 CO₂ emissions
respectively (European Commission, 2014). It is worth looking at appendix 1 to see
where these countries are with respect to landfill diversion targets.
It is safe to say these two countries are the over-achievers of Europe. When it
comes to implementing a RES such as AD, one can safely say the Irish AD industry can
take a lot away from their experiences. Both countries recognised that their respective
governments had to create the appropriate economic conditions to facilitate the
introduction of AD. Both the Danish and Swedish governments stimulated interest in the
AD sector by imposing high taxes oil products and providing a fair feed in tariff rate for
CHP installations (Raven & Gregerson, 2007; Swedish Biogas Association, 2011). Once

36
the right incentives were in place, the private sector fabricated technologies to take
advantage of them. Wholesale uptake of AD was just one outcome of this.
Ireland on the other hand has increased its reliance on foreign fossil fuels in
recent times as opposed to taxing them; while the REFIT rates are among the lowest in
Europe. The government has failed to create the right environment for wholesale uptake
of RES in general. This issue was raised in the House of the Oireachtas, with experts
recommending a fair REFIT tariff of 19.5c/kWh for farm scale AD (JCAFM, 2010).
Followed by this joint council, the refit rates were adjust only up as far as 15c/kWh as
opposed to the recommended 19.5.
While it is clear the government need to offer better incentives to stimulate
investment, there are other factors which need to be addressed in order for Ireland to
embrace AD in its full capacity. Raven & Gregerson (2007) note a key to Denmark’s
success in this industry was the deployment of a “bottom-up strategy” which encouraged
the dissemination of information pertinent to AD throughout all the stakeholders
involved. They go on further to describe the success of a dedicated social network in
enabling this bottom up approach.
There are many dedicated experts conducting excellent research on this subject in
Ireland however there is no dedicated social network to facilitate the interaction of
various stakeholders. The SEAI is too broad, while the IrBEA are not very together as an
organisation with a poorly maintained website and zero presence on social media. There
is currently no institution driving this industry, no established centre of excellence.
One final factor Raven & Gregerson (2007) mentions, is the willingness of small
farmers to cooperate in small communities. Walker & Devine-Wright (2008) state that
the practice of a large utility company building a wind farm owned by private equity firm
offers no benefits to the community they are constructed in. It is no surprise that
NIMBYism is so prevalent in the Irish mind-set. If however a radical technology change
was implemented in which the community saw the direct benefits from such, attitudes
will most definitely change. AD being the versatile technology that it is, offers many
benefits to the immediate surroundings.

37
The key question is how can Ireland realise this vision of implementing AD in a
way that benefits its surrounding community? The general theme to emerge from the
JCAFM (2010) discussion in the House of the Oireachtas is that Ireland’s principal
feedstock for AD should be grass, given its relative abundance throughout Ireland. In the
short term, Wall et al (2013) recommends a scenario of 170, “380kW” digesters, co-
digesting dairy manure with grass silage in an effort to meet the RES-T target in 2020.
This vision sees the rolling out of a RES system on a large scale whist simultaneously
providing a slurry management solution to rural areas.
Putting the argument that the government needs to offer greater incentives aside
for the minute, what else is preventing uptake of AD? Bywater (2011) upon carrying out
a review of AD in the UK identified the farmer as the most important stakeholders in
AD. They are the ones taking the risks in building a digester, and they are the ones
dealing with the system on a day-to-day basis. There is a common misconception among
farmers that AD is only feasible at a large, centralised scale (Bywater, 2011). While it is
true that the economies of scale become greater the larger a facility gets, the
implementation of AD at farm scale is usually a worthwhile venture due to the multitude
of other benefits the technology provides to the surrounding communities. In order to
overcome this misconception, farmers need to be engaged and informed that AD is in
fact feasible in their situations. This is what will drive the Irish AD forward, especially
when an AD is recognised as an alternative slurry management system as well as RES.
It is at this point that the country’s research institutions can step in and
demonstrate, educate and inform farmers as well as other key stakeholders the key
benefits of this technology. It’s useful to look at Dundalk IT as an example of what this
might entail. Instead of demonstrating the key benefits of wind power in a classroom, the
college went and physically built a turbine on campus. The ethos behind this project was
that it was important for Ireland to expand its expertise in emerging renewable energy
technologies (Ryan, 2005).
With one of the most prestigious Schools of Agricultural and Food Science
departments in the country, UCD is poised to emulate the ethos of the Dundalk wind

38
project and apply it to anaerobic digestion. Such a project can allow stakeholders to gain
a direct insight into the technology.

39
CHAPTER 4
Objectives and Outcomes
The fundamental objective of this project is to determine whether it is feasible under any
scenario possible, to build an anaerobic digester at UCD. Within the AD industry the
orthodox aims of building a digester are usually to generate an additional income or to
adopt a more sustainable slurry management system. This project differs because the
principle motivation for constructing a digester is to act as a template for potential
stakeholders; in order to ease their uncertainties within the industry.
Given the fact that UCD has one of the most esteemed Schools of Agriculture
and Food Science Departments in the country, the development of a digester with which
the college has complete control over can be viewed as a valuable asset to the
department. It would not be unreasonable to suggest that UCD could become the centre
of best practice AD in Ireland; educating and promoting sustainable agricultural practices
and ensuring the industry thrives with the development of state of the art biogas plants
throughout the country.
As the proposed centre of AD excellence, UCD could offer the opportunity to all
the relevant stakeholders, particularly farmers, to learn more about the technology,
quelling the uncertainty which has so far been strangling any opportunity of the industry
taking off. As well as farmers, financiers, contractors, government officials and the

40
general public could be coaxed into engagement with this industry within the cosy
confines of the campus in Belfield.
To fulfil its objective as an exemplary technology appropriately, any proposed
development must be a cost-effective, state-of-the-art technology which engages as many
potential stakeholders as possible and utilizes most if not all of UCD’s organic waste. It is
also envisaged that such a development will pave the way for future research. In order to
determine if such a project is feasible, the financial feasibility of a number of different
scenarios will be tested for both the UCD campus and Lyons Estate. The most feasible
of each will then be presented in greater detail.

41
CHAPTER 5
Scope and Methodology
5.1 Methodology
This study was carried out in accordance with the prescribed methods
recommended by Al Seadi et al, (2008) and Fischer et al (2010). A cost-benefit analysis
formed the basis of the results for this project. This was carried out using the “Big-East
Biogas Calculation” tool. This is a relatively detailed and robust model, recommended by
the SEAI for estimating the investment costs and revenue streams of a biogas plant at
preliminary project stages. Data for the following inputs were gathered in order to run
the model. The projection for the best case scenario AD for Lyons estate is included in
appendix 2. It would be useful to follow this whilst reading this section.
5.1.1 Estimation of Investment Costs
To put an exact figure on capital costs at pre-feasibility study is next to impossible
no matter how experienced the planner and consultant. A detailed interpretation of the
literature pertinent to the construction of an AD in Ireland was carried out in order to
determine the regulations which must be applied to the project. In order to determine the
capital cost of the UCD scenarios; the approximate size of the facility required was
estimated using the “Big East” calculation tool. This gave sufficient data to allow a
comparison between the UCD scenario and one of the above case studies. Known cost

42
per kilowatt data for these case studies allowed an appropriate figure be assigned to any
given biogas scenario for UCD.
Upon assigning a figure to the overall investment, it was necessary to provide a
breakdown of these costs for the calculation of maintenance charges. Construction costs
usually make up 30-40% while machinery makes up 10-20% of overall investment costs
(SEAI, 2012). CHP was estimated at 500-1000 €/kWe (Caslin, 2013). Maintenance costs
for these inputs were estimated at 5-7% (SEAI, 2012). An explanation of the grid
connection process along with best estimates for the cost of such for an AD facility at
Lyons estate was provided by Mr. Tom Canning B. Eng, a consultant engineer who once
worked for the ESB. With respect to planning costs, Dun Laoghaire/Rathdown and
Kildare county councils were contacted initially for information on planning permission
however both were unwilling to provide assistance in the given time-frames of this
project. Expert advice was sought from a sustainability architect, a Mrs. Ann Gallagher,
M. Arch, to overcome this issue. The costs of the relevant permits were determined in
section 3.2.
5.1.2 Estimation of Biogas Input Data
Ensuring security of feedstock is generally accepted as the primary parameter that
will determine a project’s feasibility. Initially the ideal scenario considered; involved the
construction of an AD with a view to treating all the organic wastes produced by UCD.
With the assistance of Mr. Gary Smith from campus services, this data was collected by
liaising with the respective managers of each department. This included the student
sports and leisure centre, campus services, the first restaurant at the Gerard Manly
Hopkins centre, the School of Veterinary Medicine and Lyons Farm.
As the project progressed another scenario was considered in which additional
feedstocks would be imported in order to improve the projected economies of scale and
reduce payback periods. This scenario considered the possibility of building an AD under
the guise of the Higher Education authority of Ireland. Organic waste data was gathered
from Trinity College by interviewing the grounds and maintenance manager who wishes
not to be named. Organic waste data for DIT was readily available on its college website.

43
Upon compiling all this data; the results suggested that the economies of scale
could be improved even more. The possibility of importing additional feedstocks was
considered. Under this train of thought, it emerged that the collaboration between UCD
and a large food-processing company could prove extremely beneficial. One final
scenario involved testing the feasibility of Wall et al’s (2013) vision of co-digesting grass
silage with animal slurries.
5.1.3 Determination of the Cost of Biomass
Waste streams indigenous to UCD were considered as a baseline feedstock for the
potential AD hence there are no costs of procurement for this portion of feedstock.
Given their low energy density (Pöschl et al., (2010), under no circumstance would slurry
be transported in any scenario of this project. Costs associated with truck transport of
food waste were derived from Blaschek et al (2010). Current costs of grass silage were
estimated from Reidy (2015).
5.1.4 Revenue Streams and Finance Plans
REFIT tariffs used in the model were those outlined in table 4. Income from heat
produced was assigned a value recommended by the model itself as there are currently no
government incentives which this project can avail of. The exact cost to UCD or Trinity
for organic waste disposal was protected by commercial secrets. Estimates for tipping
fees for the disposal of food waste were extracted from Creedon et al (2010). The sale of
digestate was not considered in this project; it was assumed that such would be utilised by
UCD directly.
Typical Interest rates for construction loans were determined from The Central
Bank (2015) and were applied to the project financing plan. Sources of funding are
considered in chapter 7.

44
5.1.5 General Business Costs
The smaller scale scenarios, utilising indigenous wastes were considered to be
rather easy to manage and did not consider employing any administrators or operators.
Once scenarios began considering the importation of feedstocks, wages for a part-time
administrator were included. The site was assumed to be rent free given the fact the land
in both scenarios is owned by UCD. Costs for insurance were estimated on a per square
meter basis. The cost for transporting food waste, mentioned in section 5.1.3, was
included in the “other individual costs” section.
The economic feasibility of each scenario was considered first using this model.
The best case scenario for both the campus and Lyons estate were then considered in
more detail as ideal systems for implementation at UCD.
5.2 Site Selection
The selection of a suitable site was a relatively simple process given the mass
expanse of land that UCD has at its disposal. Two site scenarios were considered for
building the potential digester; one on campus at UCD and the other on the college
research farm at Lyons Estate.
5.3 Constraints
Pre-feasibility studies are generally given no funding and are usually pressed for time.
Given the nature of these studies; commercial enterprises and administrative agencies are
extremely reluctant to part with information especially that which involves cost.
Commercial entities are generally bound by commercial secrets and are reluctant to
provide detailed information to a project in its preliminary stages as they are not
guaranteed to win the contract for building the project at this stage. Administrative
agencies such as the county council require a clear and detailed plan of the proposed
development and will only meet under the circumstances of a fee-paid pre-planning
meeting. Upon contacting both Kildare and Dun Laoghaire/ Rathdown county councils;
along with a number of government departments it became clear that meeting with any
of these bodies would not be possible within the time-frame of this project.

45
5.4 Assumptions
Despite minimal correspondence from the appropriate agencies, for the most part, it was
possible to “read around” the issue and obtain as detailed information required from
similar case studies and best estimates from the consultants mentioned in section 5.1. It is
accepted that exact figures are not usually found at pre-feasibility in any circumstance
however every measure was taken to ensure the data in this study was as robust as
possible. The aim was to limit the occurrence of financial surprises to potential investors
for the project.

46
CHAPTER 6
Cost-Benefit Analysis
6.1 Rationale of Inputs
6.1.1 Investment Costs
Table 9 summarizes the capital costs of a number of biogas facilities throughout
Europe and Ireland. These facilities are ranked in order of their cost per kilowatt hour to
provide a template with which to estimate the investment costs for this study.
Topping this list is the Lintrop facility in Denmark; one of the largest centralised
AD facilities in the world. This plant treats a massive 547 tonnes of material a day. This
was only included in this table to demonstrate the effect economies of scale has on the
financial feasibility of AD. A facility of this scale will not be considered for
implementation at UCD.
Second on the list is the Ballytobin plant in Kilkenny. At first glance the
economics of this facility appear to excellent with an extremely low cost per kW despite
its relatively small scale. However the kW output is that of heat, no electricity. According
to SEAI (2005) the facility failed to secure a power purchasing agreement from CER. The
operators had no choice but to utilise the biogas in boilers for the production of heat.
This is a much less efficient and less lucrative option hence payback periods on the plant
are more excessive than they should be.

47
Table 9: Economics of biogas plants in UK, Germany, Denmark and Ireland
Facility Feedstock
(t/d)
Output
(kW)
Capital Cost
(€)
Cost per kW
(€/kW)
Source
Lintrop 547 2084 kWel 5,500,000 2639 (Monson et al,
2007)
Ballytobin 21 220 kWth 800,000 3636 (SEAI, 2005)
Pellmeyer 55 690 kWel 3,000,000 4347 (Patterson et al,
2009)
Kemble Farms 54 300 kWel 1,680,000 5600 (Bywater, 2011)
McDonnell
Farms
24 250 kWel 1,500,000 6000 (SEAI, 2014)
Greimel 34 500 kWel 3,000,000 6000 (Patterson et al,
2009 b)
Copy’s Green
Farm
14 140 kWel 1,000,000 7142 (Bywater, 2011)
UCD Campus
Scenarios
0.34-1.2 15-28 kWel 400,000 26,000-
14,000
(SEaB Energy,
2015)
UCD Lyons
Estate Scenarios
22-26 200-
250kWel
1,300,000 6500-5200
The remaining five facilities appear to follow a pattern of the greater the power
output, the more favourable the financials. The only exception to this pattern is the
Greimel facility. Monson et al (2007) attribute the facility’s poor economic performance
to complications in the construction phase, which added to the overall capital cost.
Once a figure is obtained for the overall investment cost, it is necessary to
determine how this is broken down for the model to accurately project maintenance
costs. Referring to table 10, the top four parameters of construction, maintenance, CHP
and machinery are estimated in the form of percentages recommended by the literature
and vary according to the investment cost. The bottom four parameters are relatively
constant throughout each scenario as they do not vary to the same degree according to
investment cost. These figures were provided by the architectural and engineering
consultants mentioned previously and more detail is provided on such in chapter 7.

48
Table 10: Break-down of investment costs for each scenario
Break-down Method of Estimation
Overall Capital Cost 5500-7500 €/kW Output
Construction 30-45% Capital Costs
Maintenance 5% Construction Costs; 5% Machinery
costs; 1% CHP costs
CHP 700-1000 €/kW Output
Machinery 10-20% Capital Costs
Planning 8600
Permits 3000
Consultancy 45000
Grid Connection 110,000 – 427,000
Grid Connection:
The proposed AD is anticipated to have a maximum export capacity (MEC) of
well below 500 kW hence it is eligible for connection to 110 kV network or less. This
means the project has to apply for grid connection through ESB networks. This project is
most likely to go under the sequential planning procedure. Connection costs can be
considerable depending on the proximity of the site to the nearest suitable connection
site. According to Tom Canning from ESB international, there are an abundance of
connection points at the proposed site at Lyon’s Farm while the UCD scenario will not
require a grid connection at all considering the constant high demand for both heat and
power on campus. The best estimates of €110,000- €427,000 are calculated from ESB
Networks (2015).
6.1.2 Biogas Input Data
Table 11 reveals the assumptions made related to the feedstocks available to UCD in the
various scenarios. The quantities of animal slurries were obtained directly from Lyon’s
farm based on 90 dairy cows, 200 beef, 150 pigs and 500 ewes. With the cap on the
national herd being lifted this year; the dairy herd is set to expand on the farm while the
beef herd is to be contracted.

49
Table 11: Characteristics of feedstocks considered for every scenario
Feedstock Quantity (t/a) Biogas Yield
(m³/t)
Dry Matter
Content (%)
Methane
Content (%)
Cattle/Pig
Manure
3809 28 10 58
Dairy/Sheep
Manure
4190 70 22 55
Food Waste 129- 2800 179 35 60
Grass Silage 4000 225 40 55
Three different food waste quantities are examined ranging from 129 t/a to 2800 t/a.
The importation of grass silage is considered for one scenario. The figures associated
with biogas yield, DM content and methane composition are based on estimates provided
by Al Seadi et al (2008) as well as from Fischer et al (2010).
6.1.3 Cost of Biomass
The majority of feedstocks listed in table 6-9 are collected at source hence there
are no associated costs for the procurement of such. Food waste is calculated at 12-20
€/t assuming distances are under 50km (Blaschek et al., 2010). The current costs of grass
silage are estimated at 28-32 €/tonne (Reidy, 2015).
6.1.4 Revenue Streams and Finance Plans
As illustrated in table 4, every scenario studied in this project is entitled to a
REFIT rate of 15c/kWh of electricity produced. The current lack of renewable heat
incentives in Ireland mean any revenues from thermal energy will be minimal. A default
value of 2c per kWh is assumed in this model. The current costs of disposing food waste
in Ireland are estimated at €110- €185 per tonne (Creedon et al., 2010).With the exception
of the “food processing company” scenario; the model used the conservative amount of
110€/t as a number of sources throughout the data collection process hinted at figures
close to this amount. If UCD were to go down the route of sealing a long term contract
to take waste from a processing company, it would undoubtedly have to offer a

50
competitive gate fee to entice the company into cooperation. Tipping fees were set at 80
€/t in this scenario. Digestate is assumed to generate no revenue in this study. The costs
of offsetting artificial fertilizers with such were also left outside the scope.
An interest value of 3.8% on construction loans was applied to the financing
section of this model as recommended by the Central Bank of Ireland (2015).
6.1.5 General Business Costs
The smaller scale scenarios assume no operator or administrator is required. The
larger scale scenarios include wages of €26,000 one employee assuming an
operator/administrator role. Rent for the site is assumed to be zero considering UCD
own both site being considered. Insurance is assumed at 3€/m³/yr for all scenarios based
on the default recommendation of the model. Other parameters in this section are
deemed irrelevant to the types of digesters being considered for this project.

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