May 2008

ON TOPIC


National biomass research conducted on all scales

Alternative energy sources are expected to play a crucial role in helping the United States reduce its reliance on imported petroleum and natural gas and in general, reduce the burning of fossil fuels to generate electricity and provide fuel for vehicles.

The U.S. Department of Energy, along with many partners, is helping to develop alternative fuel sources through funding for research and developing legislation that will help to create viable and commercial alternative energy sources.

Tom Welch, a DOE spokesman, believes that power generated from biomass is a proven commercial electricity generation option that the United States must pursue.

Question: To what extent is electricity generated by biomass contributing to the nation’s energy supply?

Answer: With about 9,733 megawatts (MW) of installed capacity in 2002, biomass is the single largest source of non-hydro renewable electricity in the United States. This includes about 5,886 MW of forest product and agricultural residues, 3,308 MW of generating capacity from municipal solid waste, and 539 MW of other capacity such as landfill gas.

Our studies show that the majority of electricity production from biomass is used as base load power in the existing electrical distribution system.

Question: In addition to pulp and paper facilities using wood products and food processing plants that use waste material to generate electricity, to what extent are other industries and companies turning to biomass as an energy source?

Answer: More than 200 companies outside the wood products and food industries generate biomass power in the United States. Where power producers have access to very low cost biomass supplies, using biomass in the fuel mix enhances their competitiveness. This is particularly true in the near term for power companies choosing to co-fire biomass with coal to save fuel costs and earn emissions credits.

It is evident that an increasing number of power marketers are starting to offer environmentally-friendly electricity, including biomass power, in response to consumer demand and regulatory requirements. This will only bolster and enhance that demand.

Many states, particularly California, are setting benchmarks for biomass and other alternative fuel sources to generate a percentage of their annual energy needs. We encourage these efforts - be they state or municipally directed initiatives.

Question: What are the limits to biomass energy production and what can be done to improve output?

Answer: There are four primary classes of biomass power systems: direct-fired, co-fired, gasification, and modular systems. Most of today’s biomass power plants are direct-fired systems that are similar to most fossil fuel-fired power plants.

While steam generation technology is very dependable and proven, its efficiency is limited. Biomass power boilers are typically in the 20-50 MW range, compared to coal-fired plants in the 100-1,500 MW range. The small capacity plants tend to be lower in efficiency because of economic trade-offs. We find that efficiency-enhancing equipment cannot pay for itself in small plants.

Although techniques exist to push biomass steam generation efficiency over the 40 percent level, actual plant efficiencies are in the low 20 percent range. Co-firing involves substituting biomass for a portion of coal in an existing power plant furnace. This is the most economic near-term option for introducing new biomass power generation. Because much of the existing power plant equipment can be used without major modifications, co-firing is far less expensive than building a new biomass power plant.

Question: To what extent is biomass power helping to reduce green house gases and other pollutants?

Answer: Compared to the coal it replaces, biomass reduces sulfur dioxide (SO2), nitrogen oxides (NOx), and other air emissions. After reconfiguring the boiler for peak performance, there is little or no loss in efficiency from adding biomass. This allows the energy in biomass to be converted to electricity with the high efficiency (in the 33-37 percent range) of a modern coal-fired power plant.

Biomass gasifiers operate by heating biomass in an environment where the solid biomass breaks down to form a flammable gas. This offers advantages over directly burning the biomass. The biogas can be cleaned and filtered to remove problem chemical compounds.

The gas can be used in more efficient power generation systems - combined-cycles, which combine gas turbines and steam turbines to produce electricity. The efficiency of these systems can reach 60 percent. We anticipate that gasification systems will be coupled with fuel cell systems for future applications.

Moreover, as the costs of fuel cells and biomass gasifiers come down, we expect these systems will proliferate.

Modular systems employ some of the same technology used in the other systems, but on a smaller scale more applicable to villages, farms and small industry. These systems would be most useful in remote areas.

Question: What is the Department of Energy doing to promote research in alternative fuels?

Answer: We are a major provider of funding for basic and applied research for converting biomass to biofuels. Via our e-center, companies can register to submit proposals and seek funding for their projects. We also conduct joint solicitations with the U.S. Department of Agriculture as part of the Biomass Research and Development Initiative. The primary focus of the Biomass Program is to dramatically increase usage by developing advanced technologies using cellulosic biomass instead of grains, for more efficient power production or for catalytic conversion to valuable products. Through the program, we foresee biorefineries converting biomass into a variety of fuels, chemicals, materials and power, much as petrochemical refineries do with oil and gas.

Question: The program has placed a focus on platform technologies, in which biomass would be converted to base platform chemicals to create a variety of products. How much progress is being made on that front?

Answer: Sugar platform technology breaks cellulose and hemicellulose (the bulk of most plant material) down into their component sugars. Those sugars can be fermented or otherwise converted to valuable fuels and chemicals, while thermochemical platform technology transforms solid biomass to gas or liquid by heating it with limited oxygen.

The intermediate synthesis gas or pyrolysis oil can be more efficiently and cleanly combusted or converted to valuable chemicals or materials. We are looking to industry to develop products from sugars, lignin, synthesis gas, pyrolysis oils, and other intermediate chemicals developed with these platform technologies.