CHARACTERISTICS
Biomass energy utilizes the energy content of agricultural residue, wood waste, animal wastes, or energy crops.1 These materials are either combusted in boilers to produce steam and/or heat, or gasified. Direct biomass combustion technology is very similar to coal combustion technologies; it is also relatively easy to "co-fire" biomass with coal in existing boilers. Biomass can also be converted into combustible gases, much as natural gas is used to generate electricity or to fuel vehicles.
When used to offset fossil fuel use, bioenergy systems can significantly reduce or eliminate GHG emissions. While some GHG emissions may be produced through combustion of biomass for electricity, total emissions/kWh are considerably less than those produced by fossil fuels. Also, if a replacement crop is planted, equivalent to the amount of biomass used for electricity generation, the new crop absorbs the CO2 produced by the combustion process resulting in no net emissions.
In the world, over two billion people are without electric power, and another billion have less than five hours a day of electricity. Most of these three billion people live in the middle latitudes where biomass grows abundantly, and can potentially be a viable source of fuel. Advances in biomass combustion technology contribute to its increasing viability. Further development of biomass gasification technology is ongoing, with expectations that the next generation of technologies will reach efficiencies of 65-70%. Conversion technologies for power plants that co-fire biomass with coal or municipal waste are also being developed.
SIZE:
2-100 MWe, average size is ~ 20 MW
FEATURES:
Peaking power and baseload applications (>6,000 hours/year) with 15-30% efficiency; cogeneration applications can reach 60% efficiency.
COST:
Costs will vary according to local conditions, but as a guideline:
$530-600/kW for industrial units
$300/kW where fuel sources are geographically convenient.
CURRENT USAGE:
In the U.S., installed biomass capacity for electricity generation is over 6.5 GW (over 3% of U.S. energy consumption). In Finland, Sweden and Austria, 13-18% of electricity generated is fueled by biomass.
POTENTIAL USAGE:
Resource and market assessments identify an extremely broad range of potential, with the greatest potential in developing countries. By 2050, estimates indicate that biomass could provide 17% of the world's electricity and 38% of direct fuel use.
ISSUES ASSOCIATED WITH IMPLEMENTING ACTION
- A large, steady supply of biomass is required for reliable electricity generation. Biomass supply may be climate- or season-dependent.
- Land suitable for biomass development may face competition for other uses and/or there may be opposition to harvesting existing resources such as forests.
- The cost of procuring feedstock may be prohibitive where biomass must be transported long distances to a combustion site. Since biofuels have a relatively low energy content per ton, bioenergy facilities must be sited close to their fuel source in order to minimize transportation costs. However, co-firing biomass/coal may stabilize the fuel supply for such plants.
- Typically biomass contains 1-4% non-combustible ash by weight, which may require special disposal arrangements. Such ash often contains low levels of lead, barium, selenium and arsenic, which must be carefully landfilled.
CLIMATE CHANGE IMPACT
EMISSION EFFECT:
CONDITIONS FOR EMISSIONS MITIGATION:
- Biomass used to produce energy can avoid a net increase of CO2 in the atmosphere if it is replaced by new growth that absorbs an equivalent amount of CO2.
- Total emissions will vary according to the boiler/combustor system used.
EMISSION ESTIMATE:
200 MtC/MWe/year offset
COST-EFFECTIVENESS:
Estimated net cost of CO2 avoided is from $25-38/ton.
SECONDARY EFFECTS:
May produce some methane (CH4). As with carbon emissions, when biomass is used to offset fossil fuel use, bioenergy systems can significantly reduce or eliminate SO2, NOx and particulate matter.
RESOURCES
CONTACTS
American Bioenergy Association
Washington, DC
Tel: (202) 639-0384
Fax: (202) 393-5510
http://www.biomass.org
Biomass Energy Research Association
Donald Klass
President
Washington, DC
Tel: (847) 381-6320
Fax: (847) 382-5595
bera@crada.com
http://www.crada.com/bera/
European Biomass Association
Jean-Marc Jossart
Secretariat
Louvain-la-Neuve, Belgium
Tel/Fax: + 32 10 47 34 55
jossart@ecop.ucl.ac.be
http://www.ecop.ucl.ac.be/aebiom/
National BioEnergy Industries Association
Washington, DC
Tel: (202) 383-2540
Fax: (202) 383-2670
71134.1162@compuserve.com
http://www.bioenergy.org
U.S. Department of Energy
Office of Energy Efficiency and Renewable Energy
Ray Costello
Biomass Power Team Leader
Washington, DC
Tel: (202) 586-4898
Fax: (202) 586-5127
raymond.costello@hq.doe.gov
http://www.eren.doe.gov
1These include: wood, bark, agricultural residues, peat, and refuse-derived fuels (with 50% moisture). All of these can be used in their raw form or can be pelletized through drying and compressing biomass materials. When pelletized fuels are used, average efficiencies reach 70-80%.
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