Our current energy resources: fossil, nuclear, hydroelectric and renewables can and should be complemented by using biomass to cofire, gasify and combust woody material, grain and fibrous biomass. As an Excelon ad in the Washington DC subway said in the summer of 2001: "If there was ever a time to rely on one energy source, it is not now. Nuclear, Coal, Natural Gas, Hydro, Solar, Wind, and Energy Conservation." Maybe by now Excelon has some biomass energy and would add it to their list.
In Year 2000, electricity generation in the US from all sources totaled approximately 3820 tera-watt-hours (TWh or billion kWh). Of this amount Fossil provided 2706 TWh, Nuclear 752 TWh, Hydro 280 and Renewables 81 TWh. The renewables portion had 37 TWh of biomass energy (57 TWh if MSW and landfill gas is added to the biomass total), and no cofiring with coal, oil or gas by utilities. Also these numbers do not include transportation and industrial uses of biomass, which are being complemented by the corn-to-ethanol programs. Corn starch to ethanol adds 0.2 quads of biomass use, versus 0.7 quads in the electricity generation sector, and produces about 1.8 billion gallons of ethanol per year, vs. the 140 billion gallons of gasoline used per year in the US.
Why we are not using biomass
Delivery of clean, 1/4" sized (say) woody ,herbaceous or grain biomass-- from fuel that is low in energy density and found in relatively small-size units- is frequently uncertain, often expensive and continues to confound any pro forma analysis (i.e. an analysis that predicts that future return on investment will pay for all investment costs). Use of biomass does not beat the discount rates used in traditional analysis because of feedstock availability issues plus handling and transportation costs. Biomass from crops must be considered seasonal and is a problem to store over the non-growing seasons, due to its low energy density per unit volume and some need to protect against water from rain or seepage into the fuel from storage on bare soil. All biomass is local and its use depends on local sources such as: acreage for energy crops devoted to its collection, handling, storage and use; short rotation woody crop(SRWC) production such as willows and hybrid poplar; sawdust collected from sawmills and wood product manufacturers; waste products from paper mills; manufacturing, food and processing plants; and municipal waste facilities. The economics must work now, and locally, and then improve from that base.
Is biomass a competent fuel?
Tests by EPRI, DOE, USDA,NREL and others-including power companies such as Allegheny Energy Supply, Northern Indiana Public Service Company, Southern Company and TVA,for example- show that biomass is an acceptable, if not always desirable, complementary fuel source for a coal burning boiler -- utility or industrial. Biorefineries can process biomass into fuel, lignin and higher valued products. Most tests in utility boilers show positive values for reductions in criteria pollutants (SOx, NOx, CO and Hg) and also for greenhouse gas reduction. Life cycle analysis done by NREL and others show positive economic results but may conflict with pro-forma analysis done by individual investors or utility companies. On the positive environmental side, for example the land-filling of biomass waste results in some anaerobic composting of the fibrous material, thereby releasing methane gas, which has a global warming potential of more than 20 times that of CO2, per unit weight; therefore burning the material avoids the release of methane. This factor may play a role in an overall analysis if Greenhouse gas reduction has economic value.
Modular Biomass units also play an important role
Small distributed or mobile digesters or combustion units can play a role in using animal wastes as well as industrial, food processing and grain wastes. Industrial, commercial and residential wastes such as MSW, paper and process wastes are important energy sources. Locating digesters and other conversion devices at the source of the waste product does provide a valuable addition to the energy needs of businesses, farms and homes. This resource can play a role in backing up the primary electric supply and adding to the reliability of service. Small modular (distributed) sources may be paid for as part of waste disposal and environmental protection i.e. costs recognized by the public as beneficial.
What's needed?
Public awareness and market strategies can help produce a stream of biomass material usable in utility, industrial and local conversion units. Another serious issue is that of ownership and private / public constituencies. Incentives and risk money subsidized initially from state / federal research and tax programs will help to provide complementary biomass energy devices initially and until these units begin to pay their way in the market. What is required is public education and awareness of the benefits and the needed public policies that help achieve these benefits. A lot more explanation is needed for people not familiar with the biomass terminology.
One major technical-economic problem
Burning corn and stover in a fossil burner is a losing operation today. One pass harvesting i.e. cutting and separating the corn from the stover is encouraging. Wet storage when used in wet processes like hydrolysis to sugars is also encouraging but not thermal processes like co-firing. A good reference that addresses this issue is http://www.afdc.doe.gov/pdfs/7241.pdf
Burning switchgrass epitomizes the harvesting, hauling, storage problems:
Switchgrass delivery cost is estimated today at almost...$4 /MBTU. This production number is based on 6400 BTU/lb at 20.
By comparison, short rotation woody crop production (SRWC) is now found in the 3 to 7 dry ton/acre/year (dt/ac/yr). A challenge for research is the need for a production rate of 12 to 20 dt/ac/yr, for woody and herbaceous biomass. To achieve such yields within 20 years is to duplicate the type of improvement that was achieved for corn production increases between 1950 and 1970.
Seems like an unnecessarily bleak picture for switchgrass. Cofiring has been done with significant success at the plant level, but the economics in all cases need help if CRP lands are allowed to be used and the owner of the process (farmers and utilities) can get tax credits or special green power prices. It would appear that an energy crop industry would need a subsidy of over $2.00/MBTU to launch a viable business. For a 1 Quad industry or 5 cofiring of this amount requires 1 quad of energy from biomass sources, or 120 million tons from switchgrass or any combination of biomass sources that are compatible with burning in utility boilers. 10 of the nations power use by 2030; increasing transportation biofuels to 40 of current usage in 2030.
Research Needs
During 2002, biomass cofiring projects continued at seven power plants: Greenridge in Dresden NY, Plant Gadsden in Alabama (AL), Ottumwa in Iowa (IA), Dunkirk near Buffalo NY, Polk near Tampa FL, Albright in West Virginia (WV), and Willow Island also in WV. This list does not include plants where biomass cofiring at very small fractions-less than 2 of the fuel mass flow. The technology at Polk is integrated coal gasification combined cycle (IGCC).
The projects during 2002 continued and confirmed the general pattern of the past ten or more years of biomass cofiring testing and research in the United States. The DOE-funded projects at Bailly, Albright and Willow Island have been built to be capable of permanent operation. The original project for a greater-than-5 of the greenhouse gasses that coal firing generates; so there is some value to cofiring with biomass.
5. Determining the relative value of the various biomass fuels as cofiring feedstocks.This comment is interesting in that local sources could provide a variety of biomass sources. Some areas may have an abundance of chicken litter for example. Answers as to the possibilities of cofiring animal wastes should also be forthcoming.
6. Additional research on gasifiers and their application for reburning and combined cycle operations. Gasification of biomass and products from biorefineries such as lignin can add to the overall values for using biomass.
7. Further work in using waste products is definitely needed. MSW, RDF,animal waste, food wastes, some industrial wastes such as paper waste, sludges, etc., all require demonstration and research to determine the impact of these "fuels" on the power station process and its environmental compliance needs and for transportation and biobased products.
Electricity generation companies may want to consider cofiring biomass in coal- or natural-gas-fired power plants because such cofiring may often be the lowest-cost form of renewable power generation and also the lowest-cost form of greenhouse gas emission reduction. Biomass Research and Development Technical Advisory (TAC) Committee
USDOE and USDA are the agencies mainly responsible for the spending the Budget allocated for Biomass. The FY 2003 and 2004 Budgets are $299 and $190 million. Most of the Budgets are for Processing and Conversion (74 to 87
" Current US capacity of coal plants could burn at least 1 Quadrillion BTU heat input from biomass. This means individual plant biomass cofiring rates of from 5 to 10 by mass input) replacing approximately 100 Tera-Watt-hours of fossil generation. This is a sizable number and tracks the goals set by the Federal Biomass Technical Advisory Committee.
" Since most biomass use is local in nature, the development of energy crops that can generate up to 20 dry-tons-per-acre should be complemented with waste biomass resources such as sawdust, scrap wood, animal wastes, food processing wastes, industrial wastes and most other wastes that have reasonable energy content.
" The industry should look carefully at new forms of biomass gasification such as the co-gasifying demonstration at theTECO Plant in Polk County , thermal depolymerization and plasma gasification being developed at the Westinghouse Plasma Corp.
" Serious site studies need to be done for siting biorefineries that are compatible with the resources available. Several different processes are available, being tested and funded in the current federal program to determine the best available processes and end products. Individual states have unique resources that will be compatible with the available biorefinery technologies.
" Federal, state and local incentives in the form of subsidies and tax credits should also be considered as projects develop ;especially encouraging new power plant designs and feedstock growing, harvesting, handling, transportation and conversion to a boiler or gasifier fuel.
" Cooperation, coordination, communication and education of all parties interested in biomass are essential to sustain a viable biomass industry after it is appropriately jump-started. All parties must be aware of the status of biomass development and the value potential for each. Such value propositions can be refined through the business planning process and through peer to peer meetings, associations such as EEI and Farm Groups, industry /farm demonstration shows, etc.
About the author:
Velimir Lackovic runs internet portal "Energetika" ( http://www.energetika.co.yu )
dedicated to renewable energy sources,oil gas and energy efficiency. Velimir has
completed gratuadte studies in power systems engineering and
has industry experiance of over 20 years in this field.
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