The generation of electricity to provide power for homes and businesses requires a great deal of fuel each year. Up until now, most of that fuel has been in the form of coal because it produces a great deal of heat compared to its weight and volume. However, burning coal releases carbon dioxide into the air that has been out of the carbon cycle for millions of years and leads to a buildup of greenhouse gases that has been shown to contribute to global climate changes. Simultaneous burning of biomass and coal reduces CO2 emissions by a significant amount.
Biomass is defined as the waste material of plants and animals that have recently died. In most cases, it refers to plant based material such as wood chips and grasses. Biomass is considered to be a renewable resource because it is possible to replant forests and crops to replace the material used as biomass for the generation of energy.
The burning of biomass produces CO2, just as the burning of fossil fuels. The difference is that the CO2 released by burning biomass is still an active part of the carbon cycle and is taken up by living plants at a rate that equals or exceeds the rate of release.
This means that emissions of greenhouse gases remain about the same in the short term, but over the long term, biomass yields a lower emission percentage because it is still a part of the carbon cycle. Coal fired electric plants are catching on to this fact and adding biomass into their feedstock to take advantage of a net decrease in their carbon emissions.
As research continues on the best ways to sustain biomass crops and forests so that the fuel that is burned is replaced at the same rate it is consumed, biomass will displace a growing percentage of coal and other fuel sources. As this happens, carbon emissions will continue to decline on a net basis until the buildup of greenhouse gases is halted or reversed.
At the present time, the most common form of biomass used in conjunction with coal is wood. This can be in the form of wood chips that are collected from other industries such as paper mills and lumber mills, or it can be in the form of pellets of compressed biomass that can contain as many BTUs of energy in the same volume as the coal being burned with it.
Studies have shown that rapid growing trees such as poplar can be used to create sustainable forests that replace the material used as quickly as it is harvested after a period of about 50 years. There are other fast growing trees that do well in other areas. Grasses, especially switch grass, are also being studied because of their rapid growth rates and replacement following harvest.
Current energy consumption calls for the use of the most cost effective fuel available. This means coal at present. However, new laws governing greenhouse emissions are making it necessary for many coal fired electric plants to simultaneously burn biomass and coal to get the net decrease in emissions that are called for by these laws.