Biomass is one of those words often tossed about in alternative energy circles, to the point it can leave you feeling a big sheepish to even ask what exactly is meant by the term. Compounding the problem is that it is often misused and overused.
But biomass is growing in importance as the U.S. looks to various sources of feedstock for the next generation of biofuels. So what exactly is biomass? Here are five quick facts to put you in the know:
Biomass is defined as material that is derived from living organisms or organisms that were living at one time. From an energy-generating standpoint, when the term 'biomass' is used, it is usually being used to refer to plant material, but by definition, biomass can also mean material that comes from animals and animal-based material can also contribute to biomass used for energy.
Understand the carbon cycle and you'll understand biomass. Remember those nifty diagrams in elementary school, explaining how plants take the sun's energy to make food? If you ever had to draw the carbon cycle as a student, you already have a good understanding of biomass production. Carbon is absorbed from the atmosphere as CO2 by the plants, using energy from the sun just like in those elementary school diagrams. When the plants are consumed by animals, the biomass then becomes animal biomass. Plant material that is not eaten by animals is generally broken down, at which point it then releases carbon back into the atmosphere.
Though similar, fossil fuels are not the same as biomass. While fossil fuels are also derived from organic material, where fossil fuels are concerned, the material that absorbed CO2 from the atmosphere lived many millions of years ago. It's the timeline of these origins that help to differentiate fossil fuels from biomass. Biomass, on the other hand, takes carbon out of the atmosphere while it is still growing. That carbon is then returned when the plant material is burned or broken down. As the need for renewable sources of energy has grown, biomass is being managed more often on a sustainable basis with the organic material going toward energy harvested again and again as part of a replenished crop grown just for this very purpose. In this way, biomass is able to maintain a closed carbon cycle with no net increase of CO2 going into the atmosphere, as opposed to what happens when fossil fuels are burned.
Biomass can be derived from a wide range of materials.One of the reasons the term 'biomass' as it refers to energy can be confusing is because it can refer to material gotten from a broad range of materials. While biomass for energy could certainly be made from high-quality timber or high-value field crops, the reality is that these plant materials have existing strong market demands for other purposes, beyond renewable fuel. But there are plenty of lower-value plant residues, co-products and low-quality vegetation that can be channeled into biomass-derived energy production at very low cost. In addition to vegetation specifically farmed for energy purposes, organic products such as food or agriculture waste, industrial waste and related products all have potential for production of alternative energy.
Just as there are a number of sources of biomass, likewise there are a number of technologies which convert biomass into renewable energy. In some cases, the biomass itself may release energy that is directly used via electricity or heat. In other cases, biomass is converted to another form, such as liquid biofuel or biogas. Some of this converted biomass may be used for only one purpose or fuel type, while others have a number of renewable energy applications.