4. Terminology - Units of Measurement Ampere: Amps - A unit in which electrical current flow is measured. Voltage: Volt - V unit in which electrical force is measured. Wattage: Watts unit in which electrical power is measured and is obtained by multiplying Voltage and Ampere. Watt Hours: Whrs is A unit in which electrical power consumption is measured and is obtained by multiplying the wattage by the number of hours of use.
5. Examples An electrical bulb burning on 220 volts draws 3 Amps. What is the Power consumption if it runs for two hours? Power consumed will be = watts x hours = volts x amps x hours = 220 x 2 x 3 = 1320 watt hours
6. Kilowatt Hour i.e. 22000 watt hours = 22 kwh 1000 You pay for your household electricity as so much $ per kilowatt hour (kwh) which is just the watt hours divided by a thousand.
24. Batteries So if a battery is rated at 24 Amp Hour Capacity we can draw -2 Amps from it for 12 hours or -12 Amps for two hours or -24 Amps for 1 hour etc. The capacity of a battery can be given in watt hours but this is very cumbersome, and since the battery voltage is always fixed we divide the watt hours by the voltage. = volts x Amps x hours Volts To get Amp hours.
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26. Invertors An invertors is an electronic device that will convert D.C. Power into A.C Power i.e. 12 volt D.C. from a battery into 220 volt A.C. Smallest practical size for our application is 150 watt. One of 10 KW is large enough to power a 3 Bedroom House. Invertors come in two basic types: True Sine wave such as EDM Delivers 50Hz Modified Sine Wave 50Hz Disadvantage: Not as efficient as true sine wave Equipment such as specialized electronic medical instruments and measuring instruments might not perform, as they should. No problem with normal household and consumer electronic products.
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30. PV systems: Strengths & Weaknesses Use of toxic materials is some PV panels The user is less effected by rising prices for other energy sources Provision for collection of batteries and facilities to recycle batteries are necessary The solar system is an easily visible sign of a high level of responsibility, environmental awareness and commitment Energy intensity of silicon production for PV solar cells Environmental impact low compared with conventional energy sources Specific training and infrastructure needs Modular nature of PV allows for a complete range of system sizes as application dictates High capital/initial investment costs No fuel required (no additional costs for fuel nor delivery logistics) Storage/back-up usually required due to fluctuating nature of sunshine levels/no power production at night Automatic operation with very low maintenance requirements Performance is dependent on sunshine levels and local weather conditions Technology is mature. It has high reliability and long lifetimes (power output warranties from PV panels now commonly for 25 years) Weaknesses Strengths
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39. Wind systems: Strengths & Weaknesses The Technology can be adapted for complete or part manufacture (e.g. the tower) in developing countries Cranage and transport access problems for installation of larger systems in remote areas Mature, well developed, technology in developed countries Potential market needs to be large enough to support expertise/equipment required for implementation Environmental impact low compared with conventional energy sources High capital / initial investment costs can impede development (especially in developing countries) No fuel required (no additional costs for fuel nor delivery logistics) Variable power produced therefore storage/back-up required. Automatic operation with low maintenance requirements Site-specific technology (requires a suitable site) Technology is relatively simple and robust with lifetimes of over 15 years without major new investment Weaknesses Strengths
60. A stand is constructed for the turbine. A union and hinge allows the turbine to be tilted back for servicing. Screw-type gate valves insures slow operation
63. A second silt trap barrel is added to improve performance
64. The battery bank and inverter are wired. The electrician installs a subpanel for the hydro loads.
65. The log house does a nice job of reducing the sound level (sounds like a sewing machine)
66. Hydropower: Strengths & Weaknesses The technology can be adapted for manufacture/use in developing countries Engineering skills required may be unavailable/expensive to obtain locally Power is available at a fairly constant rate and at all times, subject to water resource availability High capital/initial investment costs Environmental impact low compared with conventional energy sources Although power output is generally more predictable it may fall to very low levels or even zero during the dry season No fuel required (no additional costs for fuel nor delivery logistics) Droughts and changes in local water and land use can affect power output Automatic operation with low maintenance requirements For SHP systems using small streams the maximum power is limited and cannot expand if the need grows Overall costs can, in many case, undercut all other alternatives Very site-specific technology (requires a suitable site relatively close to the location where the power is needed) Technology is relatively simple and robust with lifetimes of over 30 years without major new investment Weaknesses Strengths
78. Bioenergy: Strengths & Weaknesses Likely to be uneven resource production throughout the year Resource production may be variable depending on local climatic/weather effects, i.e. drought. Environmental impact potentially low (overall no increase in carbon dioxide) compared with conventional energy sources May require complex management system to ensure constant supply of resource, which is often bulky adding complexity to handling, transport and storage Conversion can be to gaseous, liquid or solid fuel Production can have high fertiliser and water requirements Production can produce more jobs that other renewable energy systems of a comparable size Often large areas of land are required (usually low energy density) Fuel production and conversion technology indigenous in developing countries Production can create land use competition Conversion technologies available in a wide range of power levels at different levels of technological complexity Weaknesses Strengths
81. RE Applications: Summary Mini-grids usually hybrid systems (solar-wind, solar-diesel, wind-diesel, etc.). Small-scale residential and commercial electric power needs. Village-scale Grid electricity and large-scale heating. Geothermal Low-to-medium electric power needs. Process motive power for small industry. Micro and pico hydro Supplementing mains supply. Cooking and lighting, motive power for small industry and electric needs. Transport fuel and mechanical power. Bio energy Supplementing mains supply. Heating water. Cooking. Drying crops. Solar thermal – grid‑connected, water heater, cookers, dryers, cooling Supplementing mains supply. Power for low electric power needs. Water pumping. PV (solar electric) – grid- -connected, stand‑alone, pumps Supplementing mains supply. Power for low-to medium electric power needs. Occasionally mechanical power for agriculture purposes. Wind – grid‑connected & stand-alone turbines, wind pumps Energy Service/Application RE Technology
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Notas del editor
Dorset has a very good solar source. This means that a 3-4 m 2 array of solar collectors should provide at least 50% of your total annual hot water needs. Because, it is more sunny in the summer you get virtually all your needs catered for at this time but much less in the winter. In total, you should expect to save 1500-2000 kWh per year. To get the optimum solar gain the collectors should face due south at an angle of 40 ° but slight variations are also possible. North facing roofs should not be used. A solar system needs a hot water tank so integrate well with old style immersion heating systems. They can be linked with combi style boiler but will need a specially made tank which will add to the cost.
Solar water heating is the most common domestic renewable energy installation. There are three types of solar collector: unglazed are the least efficient and are typically used for swimming pool systems; flat plate systems look like Velux windows and offer good efficiency at an affordable price; evacuated tubes collectors are most efficient and require less roof space to provide the same amount of hot water but the systems are typically more expensive.
Most systems are closed and the fluid (usually antifreeze) circulates around the system and heats the water tank by a heat exchanger. Open systems circulate water which is pumped into the tank and then to your taps. This loses less energy but needs slightly more expensive piping.
Whereas solar water heating uses the suns thermal energy to heat water, photovoltaic cells produce electric current when exposed to light. The efficiency of PV panels is much less than SWH panels so you needs a lot more on your roof to produce a similar amount of energy. There are several types which can be roof mounted or integrated into the building fabric as tiles or facades. These blend in looking like normal building materials. Unlike SWH systems they need good quality light to produce the maximum amount of electricity. The pictures are PV arrays in Dorset (clockwise from top): House in Swanage Poundbury eco home Sherborne Primary School
Most PV cells are composed of silicon. Amorphous, thin film are made from a very thin layer of semiconductor atoms deposited on a glass or metal base. These panels are flexible and therefore allow a variety of shapes but the efficiency is very low (~4-7%) Polycrystalline are wafer thin slices of melted and recrystallised silicon. They are mid range in cost and efficiency (~8-12%) Monocrystalline are thin slices cut from a single crystal of silicon. These are the most expensive type with a typical efficiency of 15%
Solar cells are composed of a semi conducting material, usually silicon and tiny amounts of boron and phosphorous. A photovoltaic cell comprises two very thin layers: one, containing phosphorous, with spare electrons – the n-type (negative) the other, containing boron, with fewer electrons – the p-type (positive). Sunlight striking the PV cell is absorbed and this energy generates particles with positive or negative charge which move randomly in all directions within the cell. The electrons (-) tend to collect in the n-type semiconductor, whilst the positive charged particles move to the p-type semiconductor. When an external load, such as an electric bulb or an electric motor, is connected between the front and back electrodes, electricity flows in the cell. NB battery systems are also possible.
Nonrenewable energies come from combustion of coal, oil, and natural gas. Their creation took millions of years, and we are using it faster than it was produced and faster than it is being created. Renewable energies come from the sun. Collection is from natural occurrences. While the energy is free, it costs money to collect it. Nuclear and geothermal energies aren’t renewable but are treated that way since the quantity is so large.
Whereas solar water heating uses the suns thermal energy to heat water, photovoltaic cells produce electric current when exposed to light. The efficiency of PV panels is much less than SWH panels so you needs a lot more on your roof to produce a similar amount of energy. There are several types which can be roof mounted or integrated into the building fabric as tiles or facades. These blend in looking like normal building materials. Unlike SWH systems they need good quality light to produce the maximum amount of electricity. The pictures are PV arrays in Dorset (clockwise from top): House in Swanage Poundbury eco home Sherborne Primary School
For the consumer, energy is the most important calculation. Everyone’s electric consumption is measured in kWh. With an understanding of the wind speed, a person can gain an early picture of what their monthly energy savings would be by comparing their electric bill to the expected kWh production
Wind speed increases with height above ground, and increasing speed increases wind power exponentially. Thus, relatively small investments in increased tower height can yield very high rates of return in power production. For instance, installing a 10-kW generator on a 100-foot tower rather than a 60-foot tower involves a 10% increase in overall system cost but can result in 29% more power. Taller towers also raise blades above air turbulence, allowing the turbines to produce more power. A rule of thumb for proper and efficient operation of a wind turbine is that the bottom of the turbine’s blades should be at least 10 feet (3 meters) above the top of anything within 300 feet (about 100 meters). County ordinances that restrict tower height may adversely affect optimum economics for small wind turbines. Unless the zoning jurisdiction has established small wind turbine as a “permitted” or “conditional” use, it may be necessary to obtain a variance or special use permit to erect an adequate tower. The Federal Aviation Administration (FAA) has regulations on the height of structures, particularly those near the approach path to runways at local airports. Objects that are higher than 200 feet (61 meters) above ground level must be reported, and beacon lights may be required. If you are within 10 miles of an airport, no matter how tall your tower will be, you should contact your local FAA office to determine if you need to file for permission to erect a tower.
Whereas solar water heating uses the suns thermal energy to heat water, photovoltaic cells produce electric current when exposed to light. The efficiency of PV panels is much less than SWH panels so you needs a lot more on your roof to produce a similar amount of energy. There are several types which can be roof mounted or integrated into the building fabric as tiles or facades. These blend in looking like normal building materials. Unlike SWH systems they need good quality light to produce the maximum amount of electricity. The pictures are PV arrays in Dorset (clockwise from top): House in Swanage Poundbury eco home Sherborne Primary School
Biomass Gasification When biomass is heated with no oxygen or only about one-third the oxygen needed for efficient combustion (amount of oxygen and other conditions determine if biomass gasifies or pyrolyzes), it gasifies to a mixture of carbon monoxide and hydrogen—synthesis gas or syngas. Combustion is a function of the mixture of oxygen with the hydrocarbon fuel. Gaseous fuels mix with oxygen more easily than liquid fuels, which in turn mix more easily than solid fuels. Syngas therefore inherently burns more efficiently and cleanly than the solid biomass from which it was made. Biomass gasification can thus improve the efficiency of large-scale biomass power facilities such as those for forest industry residues and specialized facilities such as black liquor recovery boilers of the pulp and paper industry—both major sources of biomass power. Like natural gas, syngas can also be burned in gas turbines, a more efficient electrical generation technology than steam boilers to which solid biomass and fossil fuels are limited. Most electrical generation systems are relatively inefficient, losing half to two-thirds of the energy as waste heat. If that heat can be used for an industrial process, space heating, or another purpose, efficiency can be greatly increased. Small modular biopower systems are more easily used for such "cogeneration" than most large-scale electrical generation. Just as syngas mixes more readily with oxygen for combustion, it also mixes more readily with chemical catalysts than solid fuels do, greatly enhancing its ability to be converted to other valuable fuels, chemicals and materials. The Fischer-Tropsch process converts syngas to liquid fuels needed for transportation. The water-gas shift process converts syngas to more concentrated hydrogen for fuel cells. A variety of other catalytic processes can turn syngas into a myriad of chemicals or other potential fuels or products.
http://www1.eere.energy.gov/biomass/pyrolysis.html Pyrolysis and Other Thermal Processing Solid biomass can be liquefied by pyrolysis, hydrothermal liquefaction, or other thermochemical technologies. Pyrolysis and gasification are related processes of heating with limited oxygen. Conditions for producing pyrolysis oil are more likely to include virtually no oxygen. Pyrolysis oil or other thermochemically-derived biomass liquids can be used directly as fuel, but also hold great promise as platform intermediates for production of high-value chemicals and materials. Pyrolysis Fast pyrolysis is a thermal decomposition process that occurs at moderate temperatures with a high heat transfer rate to the biomass particles and a short hot vapor residence time in the reaction zone. Several reactor configurations have been shown to assure this condition and to achieve yields of liquid product as high as 75% based on the starting dry biomass weight . They include bubbling fluid beds, circulating and transported beds, cyclonic reactors, and ablative reactors. Fast pyrolysis of biomass produces a liquid product, pyrolysis oil or bio-oil that can be readily stored and transported. Pyrolysis oil is a renewable liquid fuel and can also be used for production of chemicals. Fast pyrolysis has now achieved a commercial success for production of chemicals and is being actively developed for producing liquid fuels. Pyrolysis oil has been successfully tested in engines, turbines and boilers, and been upgraded to high quality hydrocarbon fuels although at a presently unacceptable energetic and financial cost. In the 1990s several fast pyrolysis technologies reached near-commercial status. Six circulating fluidized bed plants have been constructed by Ensyn Technologies, with the largest having a nominal capacity of 50 t/day operated for Red Arrow Products Co., Inc. in Wisconsin. DynaMotive (Vancouver, Canada) demonstrated the bubbling fluidized bed process at 10 t/day of biomass and is scaling up the plant to 100 t/day. BTG (The Netherlands) operates a rotary cone reactor system at 5 t/day and is proposing to scale the plant up to 50 t/d. Fortum has a 12 t/day pilot plant in Finland. The yields and properties of the generated liquid product, bio-oil, depend on the feedstock, the process type and conditions, and the product collection efficiency. Biomass Program researchers use both vortex (cyclonic) and fluidized bed reactors for pyrolyzing biomass. The fluidized bed reactor of the Thermochemical Users Facility at the National Renewable Energy Laboratory is a 1.8 m high cylindrical vessel of 20 cm diameter in the lower (fluidization) zone, expanded to 36 cm diameter in the freeboard section. It is equipped in a perforated gas distribution plate and an internal cyclone to retain entrained bed media (typically sand). The reactor is heated electrically and can operate at temperatures up to 700°C at a throughput of 15-20 kg/h of biomass. Recently, a catalytic steam reformer was coupled to the pyrolysis/gasification system. Like the pyrolyzer, the reformer is an externally heated fluidized bed reactor that will be used to produce hydrogen from pyrolysis gas and vapors generated in the first stage of the process and to clean the gas from tars. Biomass Program micro-scale pyrolysis systems include externally heated different types reactors coupled to the molecular-beam mass-spectrometer (MBMS). These systems are very efficient tools, especially for studying mechanisms of thermal and catalytic processes and to optimize process conditions for different products from variety of feedstocks. For example, the ongoing research sponsored by Philip Morris resulted in understanding the chemical processes of biopolymer pyrolysis and oxidation leading to aromatic hydrocarbon formation.
"Biogas Platform" — Decomposing biomass with natural consortia of microorganisms in closed tanks known as anaerobic digesters produces methane (natural gas) and carbon dioxide. This methane-rich biogas can be used as fuel or as a base chemical for biobased products. Although the Biomass Program is not currently doing much research in this area, a joint Environmental Protection Agency/Department of Agriculture/Department of Energy program known as AgStar works to encourage use of existing technology for manures at animal feedlots. http://www1.eere.energy.gov/biomass/other_platforms.html
Biofuels A variety of fuels can be made from biomass resources including the liquid fuels ethanol, methanol, biodiesel, Fischer-Tropsch diesel, and gaseous fuels such as hydrogen and methane. Biofuels research and development is composed of three main areas: producing the fuels, applications and uses of the fuels, and distribution infrastructure. Biofuels are primarily used to fuel vehicles, but can also fuel engines or fuel cells for electricity generation. For information about the use of biofuels in vehicles, see the Alternative Fuel Vehicle page under Transportation. See the Transportation page for information about the biofuels distribution infrastructure. See the Hydrogen page for more information about hydrogen as a fuel. Fuels Ethanol Ethanol is made by converting the carbohydrate portion of biomass into sugar, which is then converted into ethanol in a fermentation process similar to brewing beer. Ethanol is the most widely used biofuel today with current capacity of 1.8 billion gallons per year based on starch crops such as corn. Ethanol produced from cellulosic biomass is currently the subject of extensive research, development and demonstration efforts. Biodiesel Biodiesel is produced through a process in which organically derived oils are combined with alcohol (ethanol or methanol) in the presence of a catalyst to form ethyl or methyl ester. The biomass- derived ethyl or methyl esters can be blended with conventional diesel fuel or used as a neat fuel (100% biodiesel). Biodiesel can be made from soybean or Canola (rapeseed) oils, animal fats , waste vegetable oils , or microalgae oils . Biofuels from Synthesis Gas Biomass can be gasified to produce a synthesis gas composed primarily of hydrogen and carbon monoxide, also called syngas or biosyngas. Hydrogen can be recovered from this syngas, or it can be catalytically converted to methanol . It can also be converted using Fischer-Tropsch catalyst into a liquid stream with properties similar to diesel fuel, called Fischer-Tropsch diesel. However, all of these fuels can also be produced from natural gas using a similar process. Conversion Processes Biochemical Conversion Processes Enzymes and microorganisms are frequently used as biocatalysts to convert biomass or biomass derived compounds into desirable products. Cellulase and hemicellulase enzymes break down the carbohydrate fractions of biomass to five and six carbon sugars, a process known as hydrolysis. Yeast and bacteria ferment the sugars into products such as ethanol. Biotechnology advances are expected to lead to dramatic biochemical conversion improvements. Photobiological Conversion Processes Photobiological processes use the natural photosynthetic activity of organisms to produce biofuels directly from sunlight. For example, the photosynthetic activities of bacteria and green algae have been used to produce hydrogen from water and sunlight. Thermochemical Conversion Processes Heat energy and chemical catalysts are used to break down biomass into intermediate compounds or products. In gasification , biomass is heated in an oxygen-starved environment to produce a gas composed primarily of hydrogen and carbon monoxide. In pyrolysis , biomass is exposed to high temperatures in the absence of air, causing it to decompose. Solvents, acids and bases can be used to fractionate biomass into an array of products including sugars, cellulosic fibers and lignin . http://www.eere.energy.gov/RE/bio_fuels.html