The Office of Energy Efficiency and Renewable Energy Biomass Program includes major programs for developing and improving technology for biomass power; for making biofuels such as ethanol (from biomass residues as well as grain) and renewable diesel; and for making plastics and chemicals from renewable, biobased materials.

Benefits from Biomass

The Biomass Program is also the lead agency in the multi-agency Biomass Research and Development Initiative working to coordinate and accelerate all federal biobased products and bioenergy research and development in accordance with the Biomass Research and Development Act of 2000.

Fossil fuel combustion generates sulfur dioxide, nitrogen oxide, and other undesirable air emissions. Although BioPower is also generated through a combustion process, it produces fewer emissions than conventional sources.

Biomass can actually improve environmental quality by offsetting fossil fuel use and related emissions and by using wastes that are creating land use problems.

BioPower growth can also create new markets and employment for farmers and foresters, many of whom currently face economic hardship. It can establish new processing, distribution, and service industries in rural communities.

Today in parts of the developing world and until several decades ago in the U.S., biomass was primarily used to provide heat for cooking and comfort. Technologies have now been developed which can generate electricity from the energy in biomass fuels. The scale is small enough to be used on a farm or in remote villages, or large enough to provide power for a small city.

Biomass Power Overview

What is Biomass?

Wood is the most commonly used biomass fuel for heat and power. The most economic sources of wood fuels are usually wood residues from manufacturers, discarded wood products diverted from landfills, and non-hazardous wood debris from construction and demolition activities. Use of these materials for electricity generation can recoup the energy value in the material while avoiding landfill disposal.

In the future, fast-growing energy crops may become the biomass fuel of choice. These energy crops will be genetically tailored plants designed to be fast-growing, drought resistant, and readily harvested, allowing them to become a competitively-priced fuel. The U.S. Department of Energy is working with national labs, agricultural and forestry groups, power companies, and other governmental agencies to make energy crops a viable fuel source in the near future.

Types of biomass normally used for energy:

- forest debris and thinnings
- residues from wood products industry
- agricultural wastes
- fast-growing trees and crops
- wood and wood wastes
- animal manures
- non-hazardous, organic portion of municipal solid waste

Economics of BioPower

Today, cofiring offers power plant managers a relatively low cost and low risk route to add biomass capacity. These projects require small capital investments per unit of power generation capacity. Cofiring systems range in size from 1 to 30 MW of BioPower capacity. When low cost biomass fuels are used, cofiring systems can result in payback periods as low as 2 years.

A typical existing coal fueled power plant produces power for about 2.3 ¢/kWh. Cofiring inexpensive biomass fuels can reduce this cost to 2.1 ¢/kWh. In today’s direct-fired biomass power plants, generation costs are about 9 ¢/kWh. In the future, advanced technologies such as gasification-based systems could generate power for as little as 5 ¢/kWh. For comparison, a new combined-cycle power plant using natural gas can generate electricity for about 4 to 5 ¢/kWh at today’s gas prices.

Biomass is the second-most utilized renewable energy resource in the United States in terms of electricity generation. Approximately 7,000 MW of operating installed capacity generate around 37 billion kWh per year—the amount of electricity used by 4 million average U.S. homes combined, or the entire state of Colorado. Generating this amount of electricity requires around 60 million tons of biomass per year.

The most economic forms of biomass for generating electricity are residues. These are the organic byproducts of food, fiber, and forest production. Common examples used for power are sawdust, rice husks, and bagasse (the residue remaining after juice has been extracted from sugar cane). Low-cost biomass sources are also common near population and manufacturing centers where clean wood waste materials are available in large quantities. Examples are pallet and crate discards and woody yard trimmings.

Biomass is plentiful in various forms across the country. Woody biomass is concentrated in the Southeast, with high concentrations also in the Northeast, Pacific Northwest, and the Upper Great Lakes region. Herbaceous/grassy biomass is plentiful in the Midwest states, while cropland is concentrated in the upper Midwest, Lower Great Lakes region, and in the Mississippi delta. Research is presently underway to commercialize energy crops that are well-suited to regional climate conditions. Examples are: switchgrass in the Midwest and Southeast, willow in the Northeast, and hybrid poplars in heavily forested regions. Animal manures have reached excessive quantities in a number of rural areas throughout the country, especially on the Delmarva peninsula (an area encompassing Delaware, Maryland, and Virginia) and in areas of North Carolina, Georgia, Arkansas, Alabama, Mississippi, Minnesota, California, and Washington.

Electricity from Biomass/Technologies at Work

Most of today’s BioPower plants are direct-fired systems that are similar to most fossil-fuel fired power plants. The biomass fuel is burned in a boiler to produce high-pressure steam. This steam is introduced into a steam turbine, where it flows over a series of aerodynamic turbine blades, causing the turbine to rotate. The turbine is connected to an electric generator, so as the steam flow causes the turbine to rotate, the electric generator turns and electricity is produced.

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 100-1500 MW range. The small capacity plants tend to be lower in efficiency because of economic trade-offs; efficiency-enhancing equipment cannot pay for itself in small plants. Although techniques exist to push biomass steam generation efficiency over 40%, actual plant efficiencies are in the low 20% range.

Cofiring involves substituting biomass for a portion of coal in an existing power plant furnace. It 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, cofiring is far less expensive than building a new BioPower plant. Compared to the coal it replaces, biomass reduces sulphur dioxide (SO₂), nitrogen oxides (NOx), and other air emissions. After "tuning" 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% range) of a modern coal-fired power plant.

Frequently Asked Questions

What are some useful terms?
See our glossary

What is biomass?
Biomass is any sort of vegetation-trees, grasses, plants parts such as leaves, stems and twigs, and ocean plants. From it, we can extract a wealth of stored energy. Biomass is available from various industries—including agriculture, forest products, transportation, and construction—that dispose of large quantities of wood and plant products. Whether cultivated or growing wild, biomass represents a huge renewable energy source.

What's the difference between biomass and biofuel?
"Biofuel" is short for "biomass fuel." In practice, we tend to use different terms for different end uses—electric power or transportation. We tend to use "BioPower" for biomass power systems that produce electricity and "biofuels" for liquid fuels for transportation.

What is biomass power?
Biomass power is the use of biomass feedstocks instead of the usual fossil fuels (natural gas or coal) to produce electricity.

What type of energy do plants produce?
During photosynthesis, plants combine carbon dioxide from the air and water from the ground to form carbohydrates, which form the building blocks of biomass. The solar energy that drives photosynthesis is stored in the chemical bonds of the structural components of biomass. If we burn biomass efficiently (which extracts the energy stored in the chemical bonds), then oxygen from the atmosphere combines with the carbon in plants to produce carbon dioxide and water.

How much biomass exists right now?
If we took all the biomass available today, the energy content in that fuel would produce an estimated 2,740 Quads, with just 1 Quad equal to 1,000,000,000,000,000 Btus.

How can biomass be used?
It can produce electricity, liquid fuels, gaseous fuels, and a variety of useful chemicals, including those currently manufactured from petroleum. Because the energy in biomass is less concentrated than the energy in fossil fuels, new technologies are required to make this energy resource competitive with coal, oil, and natural gas. Industry and agriculture need superior energy crops and cost-effective conversion technologies to expand the use of renewable biomass.

How much biomass is being used as fuel?
At present, the world population uses only about 7% of the annual production of biomass. There is an abundance of biomass that we can tap.

What is the make-up of biomass?
While the actual ratio of components varies among species, biomass averages 75% carbohydrates or sugars and 25% lignin.

How much biomass is used for energy today?
Worldwide, biomass is the fourth largest energy resource after coal, oil, and natural gas. It is used for heating (such as wood stoves in homes and for process heat in bioprocessing industries), cooking (especially in many parts of the developing world), transportation (fuels such as ethanol) and, increasingly, for electric power production. There are estimates of about 35,000 MW of installed capacity using biomass worldwide, with about 7,000 of that in the United States. Most of this capacity is in the pulp and paper industry in combined heat and power systems.

Is municipal solid waste (MSW) considered biomass?
In its mixed waste form, MSW typically contains materials not suitable for use at BioPower facilities. Although a large fraction of the mass of municipal solid waste originates from plant matter the mixture with other urban wastes precludes its use in BioPower facilities. Materials recovery facilities that keep clean biomass materials (e.g. wood pallets, wood shavings and tree trimmings) segregated from other wastes are a potential source of biomass fuels. Biomass, when used in modern power systems, produces fewer emissions than conventional solid fuels used in power plants.

How is biomass used to produce power?
Biomass is one of the oldest fuels known to humanity. Although basic, the primitive campfire illustrates the nature of using biomass for power. When the biomass is burned, it produces heat. In a power plant, this heat is used to turn water into steam. The steam is then used to turn turbines, which are connected to electric generators. Gasifiers heat the biomass to convert it into a gas that can be used in high efficient power systems, such as combustion turbines or fuel cells.

What are energy crops?
Energy crops are crops that are grown for the specific purpose of producing energy (electricity or liquid fuels) from all or part of the resulting plant. Switchgrass, alfalfa, willow, poplar and eucalyptus are examples of plants that can be grown as energy crops.

What are the best biomass fuels for power systems?
Right now, wood is most widely used because wood-fired power systems have been in use for a long time and are well understood. In addition, there is an abundance of wood residue available for use in power systems from bioprocessing industries such as the wood products industry. However, the development of gasifiers may make many other biomass fuels usable for producing electricity.

Where are biomass resources located?
Virtually every part of the world has a biomass resource that can be tapped to create power.

What are biomass gasifiers?
Biomass gasifiers are reactors that heat biomass in a low-oxygen environment to produce a fuel gas that contains from one fifth to one half (depending on the process conditions) the heat content of natural gas. For biomass, this process takes place at about 850 degrees C.

What is renewable energy?
Renewable energy is any energy source that can be either replenished continuously or within a moderate timeframe. Renewable power sources include solar power, biomass power, wind power, hydropower, and geothermal power.

Is biomass really a renewable energy?
Yes. If biomass is cultivated and harvested properly, it is a renewable resource that can be used to generate power on demand, with no net additional contribution to global air emissions.