Definition. Biomass is biomaterials, usually plants and animal waste, that are harvested for their energy (oils, sugars, starches, combustible gases, etc.). Geographically, solar energy and biomass are the most evenly distributed forms of renewable energy.
Sources. Industrial biomass production comes two primary sources – dedicated crops, and by-products. Dedicated crops include corn and switchgrass (used for corn-based and cellulosic ethanol, respectively). Soybeans and rapeseed are used for biodiesel.

By-products are biomaterials left over from other industrial processes: wood chips and sawdust from lumber and paper mills, agricultural by-products like corn stover, orange peels and pulps leftover after juicing, animal manure, landfill gas, etc. Before recent advances in biomass technologies, most businesses considered these products to be waste.

A third source – that doesn’t really fit in the category of dedicated crop or by-product – is the selective harvest of biomass (such as prairie grasses, and woody plants like sumac) from lands considered marginal or inappropriate for agriculture.

Uses. The most developed biomass technology is biofuels - liquid fuels used for transportation. Biodiesel is produced from oils or fats, and it replaces diesel fuel. Ethanol is alcohol produced from fermentation, and it replaces gasoline.

Corn-based ethanol is a viable market technology with skyrocketing market penetration. Cellulosic ethanol (which does not derive from food crops) is five years or so from market production.

Biomass can also produce electric power, heat, and chemicals. Much of this technology is in research and development, but methane capture is a currently viable technology particularly compatible with agriculture.

Can help fight climate change. Biomass can help reduce global warming. Biomass does release carbon dioxide when combusted, but this release is balanced by the carbon dioxide that it sequesters during its growth cycle. By comparison, burning fossil fuels releases “new” carbon dioxide into the atmosphere from sources long ago sequestered in the earth’s crust and isolated from the carbon cycle.

Compatible with ag economy. Because growing biomass crops sequesters carbon from the atmosphere, in the emerging carbon economy these crops will qualify for various levels of carbon credits. (For example, the extensive roots systems of perennial plants like prairie grasses do better at carbon sequestration than the shallow roots of annuals like corn.)

Farmers will be able to earn money by growing or conserving biomass stocks, and also make money on the harvest.

Increases energy security and reduces dependence on foreign oil. Right now, biofuels are the only viable substitute for imported fossil fuels used for transportation.

Dispatchable power. Electrical generation from biomass is dispatchable, not intermittent, so it can help support base load.

Not necessarily carbon-friendly. Unfortunately, according to life cycle analysis, biomass and biofuels can still contribute to global warming. Their production, manufacturing, and end uses can still result in (often significant) carbon emissions. Corn-based ethanol is an example.

Environmental impacts. Some biomass combustion processes result in particulates, contaminants, and emissions. Other biomass impacts - the petroleum-based fertilizers used to grow corn for ethanol run off fields and into waterways, eventually contributing to the Dead Zone in the Gulf of Mexico. Ethanol production also uses vast amounts of water, often in agricultural areas that already must conserve their resources.

Sustainability. Figuring out how to balance the harms and benefits of biomass will take some doing. For example, while corn stover might be considered an agricultural waste suitable for cellulosic ethanol, leaving the stover on the fields helps cut down erosion.

Demand for biomass feedstock on a broad scale could be environmentally devastating if not carried out carefully. Clearcutting a rainforest to grow soy crops for biofuels, for example, is not good. A society that develops a capacity to consume every living thing in sight for fuel is also a scary thought.

Social impacts. Using arable land and traditional food crops like corn for fuel can contribute to rising food costs, which creates more food insecurity at home and abroad. Higher food prices hurt poorer people the most.