Biomass
Biomass refers to non-fossil, organic materials which can be burned to produce energy or converted into fuels or other products. In general, two approaches to biomass exist – growing plants specifically for energy or using the residue from plants used for other things. Biomass can be used to create biofuels, biopower and biopower.Biofuels
A distinct advantage of biomass is that it can be converted into a liquid– called biofuel – that can be used as transportation fuel. The two most prevalent biofuels are ethanol and biodiesel.
Ethanol is an alcohol fuel that is made through a fermentation and distillation process that converts starch to sugar and then to alcohol. Ethanol production in the US comes from corn, grain sorghum, and wheat. New technologies are exploring the possibility of producing ethanol from other agricultural and forestry resources including corn stover (stalks and residues from harvest), grain straw, switchgrass, and certain rapid growth trees varieties. These new technologies strive to make ethanol out of the cellulose –the fibrous material that makes up the bulk of most plant matter. Cellulosic ethanol is attractive because it has greater net energy content than corn ethanol.
In the marketplace, ethanol is blended with gasoline in various quantities. Ethanol is a common replacement for methyl t-butyl ether (MTBE) – a banned octane-boosting additive found to be responsible for groundwater and soil contamination. Most commercial vehicles can run on a low blend of ethanol called E10 – a mixture of 10 percent ethanol and 90 percent gasoline. Flex-fuel vehicles have modified engines that can accept fuels with higher alcohol content. These fuels, known as E85, are a blend of 85 percent ethanol and 15 percent gasoline.
The second biofeul, known as biodiesel, is a renewable alternative fuel for diesel engines. Biodiesel is manufactured by chemically reacting vegetable oils, soybean oil, recycled cooking grease, or even animal fats with alcohol. Similar to ethanol, biodiesel is available in a variety of blends. Biodiesel can be used as an oxygenate additive in B20– a blend of 20 percent biodiesel and 80 percent diesel fuel. Biodiesel can also be used as a direct diesel substitute in B100.
Biodiesel powered bus in Nebraska.
Photo courtesy of DOE/NREL.
Biopower
Biopower – electricity from biomass – can be generated through several techniques. Most biopower plants use a direct-firing technique. In these plants, biomass is directly burned to generate steam to drive a turbine. The turbine turns a generator that produces electricity. In some applications, spent steam can be used for manufacturing process or to heat buildings. Combining heat and power systems in this manner can greatly increases the energy efficiency of a facility.
This 50-MW power plant in Burlington, Vermont uses wood as fuel.
Photo courtesy of DOE/NREL.
Co-firing, a second biopower technique, refers to substituting biomass for a portion of coal in conventional power plants. Little plant modification is required, making co-firing less expansive than a new direct-fire power plant. Co-firing is also attractive because, relative to coal, the use of biomass lowers emissions of sulfur-dioxide, nitrogen-oxide, and other air pollutants.
Biopower through Gasification systems heat biomass in oxygen-starved environments in order to generate a synthesis gas – also known as syngas – consisting of hydrogen and carbon monoxide. The synthesis gas – also known as syngas – can be converted into other fuels or products, burned in a conventional boiler, or used in natural gas turbine. Compared to other biomass applications, the benefit of synthesis gas is that it can be filtered before combustion to remove certain chemical compounds. Synthesis gas can also be used in more-efficient combined-cycle generation systems.
Modular systems incorporating the technologies described above are under development and could be deployed at smaller scales for villages or small industries. These systems could be valuable in remote locations with abundant biomass and electricity is scarce.
Bioproducts
The basic material of petroleum industry is hydrocarbons – a combination of carbon and hydrogen. Oil and natural gas can be broken into these basic materials, which in turn are used to produce an array of consumer products such as plastics, solvents, paints, adhesives and drugs.
The basic material of biomass is carbohydrates which consist of a combination of carbon, hydrogen, and oxygen. In addition to carbohydrates, biomass contains protein and plant oils. These basic materials can be used to manufacture many of the same products produced using hydrocarbons. Basic sugars in carbohydrates can be used to make, plastics, glues, artificial sweetners, gel for toothpaste, and antifreeze. Biomass can also be used to manufacture photographic films, textiles, synthetic fabrics, molded plastic, and foam insulation. As the global consumption of consumer goods expands, biomass could provide a valuable alternative to finite petroleum resources.
Additional Resources
Department of Energy – Biomass Program
Excellent source for information – contains quick links for consumers, industry professionals, policymakers, and students.
National Biodiesel Board
The National Biodiesel Board is the national trade association representing the biodiesel industry as the coordinating body for research and development in the United States.
NC Biomass Trader
This exchange service is designed to provide a marketplace for biomass materials that can be used in bio-based manufacturing, converted to energy, or used in energy generating processes or technologies.
Piedmont Biofeuls
Piedmont Biodfeuls started as small-scale biodiesel production in Pittsboro, North Carolina. After a significant expansion, the organization became one of North Carolina’s first commercial biodiesel production facilities.
Renewable Fuels Association
The national trade association for the U.S. ethanol industry promotes policies, regulations and research and development initiatives that will lead to the increased production and use of fuel ethanol.
