The document presents a framework for conducting comparative risk assessments of various energy technologies. It analyzes hazards and accident risks across different energy sectors, establishes risk indicators, and conducts indicator-based scenario analyses to compare risks of energy systems in the EU in 2035 under various climate policy scenarios. The analysis finds that decentralized energy systems have lower risks than large centralized ones. Achieving climate goals may reduce overall accident risks as a secondary benefit, but specific stakeholder preferences could affect which low-carbon technologies are utilized.

1. Wir schaffen Wissen – heute für morgen
Paul Scherrer Institut
Peter Burgherr, Petrissa Eckle & Stefan Hirschberg
Comparative risk assessment of energy technologies in
the context of energy security and sustainability
IDRC 2012, 26-30 August 2012, Davos Switzerland

2. Content
• Objectives
• Hazards and Accident Risks in the Energy Sector
• Framework for Comparative Risk Assessment
• Risk Indicators
• Indicator-Based Scenario Analysis
• Additional Risk Aspects
• Conclusions
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

3. Objectives
• Comparison of accident risks across for a broad set of technologies and
various country groups (e.g. OECD, EU 27, non-OECD)
• Risk indicators for current and future technologies
• Scenario analysis for EU 27 to test the hypothesis that climate policy
measures not only limit CO2 emissions, but as a secondary benefit can
reduce the overall accident risk of the energy system compared to current
conditions.
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

4. Analytical Framework for Technology Assessment
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

5. Energy Security – an Umbrella Term
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

6. Energy-related Severe Accident Database (ENSAD)
CRA within the larger context of energy security
and critical infrastructure protection
Technical Risks Natural Risks Human Risks
Severe accidents NaTech Terrorist threat, vandalism,
sabotage
Comparative Risk Assessment
PSA ENSAD (*) Hybrid Approach
- Simplified level-3 PSA - Historical experience - Statistics, literature, modeling,
- Nuclear - Severity thresholds expert judgment
- Fossil chains, hydro - New renewables, hydro, CCS
- Scope and objectives
- Tailored database queries
- Geo-referencing / coupling with external data
Evaluation Data Set for Technology Comparison
- Basic statistics, aggregated consequence indicators, F-N curves (*) ENSAD:
- Economic loss estimates, external costs - Established 1998
- Geo-statistics, risk mapping
- Bayesian analysis
- 24’830 data records
- Risk indicators, decision support - Period 1970 – 2008
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

7. Severe Accident Definition and Consequence Indicators
Risk Impact Category ENSAD severity Consequence indicator
description threshold
Human health Fatalities ≥5 Fatalities per GWeyr
Injuries ≥ 10 Injured per GWeyr
Societal Evacuees ≥ 200 Evacuees per GWeyr
Food consumption ban yes Nominal scale
Environmental Release of hydrocarbons ≥ 10’000 t Tonne per GWeyr
Land/water contamination ≥ 25 km2 km2 per GWeyr
Economic Economic loss ≥ 5 Mio USD (2000) USD per GWeyr
Upstream: Downstream:
exploration Midstream: refining and distribution
and extraction transport and storage of products Power generation
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

8. Overview of Data Sources and Assumptions
Coal, Oil, Natural Gas ENSAD database PSI; severe ( ≥5 fatalities) accidents, 1970-2008
Nuclear simplified Level-3 PSA: Pressurized Water Reactor (PWR) and European
Pressurized Reactor (EPR) at an existing plant location in Switzerland
Hydro ENSAD database PSI; severe ( ≥5 fatalities) accidents; 1970-2008
Photovoltaic (PV) * Si-technologies; 2000-2008; hazardous substances (chlorine (Cl),
hydrochloric acid (HCl), Silane (SiH4), and Trichlorosilane (HSiCl3))
Wind * Windpower Death Database (Gipe, 2010) and Wind Turbine Accident
Compilation (Caithness Windfarm Information Forum, 2010); 1975-2010
Biomass & Waste Combined Heat and Power (CHP) Biogas; ENSAD Database PSI; severe
(≥5 fatalities) accidents, 1970-2008; natural gas as proxy (Loc. Distr.)
Geothermal Enhanced Geothermal Systems (EGS); ENSAD Database PSI; severe (≥5
fatalities) accidents, 1970-2008; natural oil as proxy (Exploration)
Concentrating Solar Expert judgment; EU project NEEDS
Power (CSP)
Marine (Tides, Waves, Expert judgment
Currents)
* 1 out of 100 accidents considered severe Burgherr et al. 2011
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

9. Accident Risk Indicators
Fatality risk due to severe (≥5 fatalities) accidents
• Expected Fatality Rate [Fatalities / GWeyr]
• Maximum Consequences [Fatalities]
Land contaminated due to accidents releasing radioactive isotopes
• Expected Land Contamination [km2 / GWeyr]
• Maximum Land Contamination [km2]
Accidental tanker spills of hydrocarbons to environment (≥700 t)
• Expected Oil Spill Size [t / bn t-mi]
• Maximum Oil Spill Size [t]
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

10. Scenario Analysis
• IEA World Energy Outlook 2011 scenarios for EU 27 in year 2035
- Current Policies Scenario: no change in actual government policies
- New Policies scenario: existing policies and declared intentions
- 450 scenario: constraining average global temperature increase to 2°C
• All three scenarios still dominated by fossil fuels in 2035, although their share decreases at the
expense of renewables and nuclear power from the Current Policies towards the 450 scenario.
• Scenario analysis steps:
- Extrapolation of fatality rates to 2035
- Fatality rate & maximum consequences: chain specific values were weighted by the respective fuel shares in
each scenario to obtain a combined scenario indicator.
- Oil spill and nuclear land contamination indicators are chain-specific.
- Indicator normalization by dividing all values of a specific indicator by its maximum value. To ensure that
higher values denote a better performance the scale was then inversed because for the raw indicators higher
values (e.g. fatality rate) are worse.
- Simple weighted-sum Multi-Criteria Decision Analysis (MCDA) algorithm was used to rank the different EU 27
scenario alternatives.
- Results for 5 specific stakeholder perspectives and exploratory MCDA sampling the whole preference space.
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

11. Fatality Rates & Maximum Consequences
Burgherr et al., 2011
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

12. Specific Stakeholder Weighting Profiles
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

13. MCDA Results: Specific Stakeholder Profiles
Burgherr et al., 2012
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

14. Results of Exploratory MCDA
Burgherr et al., 2012
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

15. Additional Risk Aspects Burgherr, 2011
Risk Aspect Affected Technologies
Increased production of oil - Deep offshore oil resources (Gulf of Mexico, Brazil)
resources - Oil resources in extreme environments (Arctic)
Induced seismicity, - Oil and gas production, coal mining
subsidence - Hydropower reservoirs
- Enhanced geothermal systems
- Carbon capture and storage (CCS)
Resource competition - Bioenergy (e.g. food vs. fuel; water resources)
- Hydro reservoir (electricity vs. irrigation vs. supply...)
Hazardous substances - Explosive, flammable, toxic and asphyxiant substances in PV module
production
- Spills of chemicals via hydraulic fracturing (shale gas, geothermal) can lead
to groundwater contamination
Climate effects - Large wind deployment could locally increase lower atmosphere temperature
Long-term storage (public - Disposal of nuclear waste and CCS
acceptance)
Proliferation - Nuclear energy
Geopolitics, terrorist threat - large renewable capacities in geopolitically less stable regions
- Pirate attacks on oil/gas tankers
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

16. Conclusions
• Among centralized technologies expected accident risks are lowest for hydro
and nuclear in Western countries, while fossil chains exhibit the highest risks.
• Maximum consequences are by far highest for nuclear and hydro, intermediate
for fossil chains and very small for new renewables.
• Decentralized energy systems are less sensitive to severe accidents than large
centralized ones.
• Achievement of climate policy goals can often as a secondary benefit contribute
to reductions in overall severe accident risks, however specific stakeholder
preferences may affect the portfolio of available low-carbon technologies.
• For example, risk aversion could impede the utilization of nuclear as well as
fossil fuels in combination with carbon capture and storage (CCS) systems.
• Large-scale deployment of new renewables could be affected due to various
concerns, such as landscape disturbance, noise or ecological effects for wind
power, or geopolitical aspects when large renewable capacities are installed in
less stable regions (e.g. North Africa).
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment

17. Thank you for your attention!
In several languages risk often has the double meaning of “chance, opportunity” and “danger, loss”
Probable origins of risk lie in the Greek word ριζα (rhiza), meaning “root and/or cliff”, or the Arabic word rizq
meaning “what God and fate provide for your life”.
In our everyday language we use proverbs such as “Nothing ventured, nothing gained” or “God helps the brave”.
Laboratory for Energy Systems Analysis
http://www.psi.ch/gabe
peter.burgherr@psi.ch
IDRC 2012, 26-30 August 2012, Davos Switzerland Burgherr et al.: Comparative Risk Assessment