Beyond developing the technologies that will allow us to store solar and wind energy as effectively as we can store water in a dam or the earth stores heat in its core, we can also look at using innovative materials to generate our electricity. Trees, grasses, agricultural crops, and other biological materials are collectively known as biomass. Many people probably associate biomass with the manufacture of alternative fuels—ethanol and biodiesel. But here we’re talking about how wood waste, biogases, and even the scraps in your garbage—yard waste and paper that can’t be recycled into new paper products—potentially can be used as fuel in power plants (to make electricity) rather than taking up space in a landfill. Using biomass to produce power is called “biopower”. In the southeastern United States, as a matter of fact, biomass technology is already leading the region’s renewable power potential.
Wood is the most common form of biomass. In the United States, about 2 percent of the energy manufactured today comes from wood and wood waste, such as bark, sawdust, wood chips, and scraps, much of it from industries that use wood as a raw material and recycle the scrap to create their own energy supply. In landfills, when biomass rots, it produces methane, as does the manure at dairy and poultry farms; this gas can be collected and processed in tanks called digesters to produce power. Even your trash—known more formally as municipal solid waste (MSW)—contains food scraps, leaves, and lawn clippings that can become feedstock for power plants. But how much biomass can your lawn clippings and such really amount to? Right now, for example, the state of California produces more than 60 million tons of biomass each year. Less than 10 percent of that total is burned to make electricity, but if all 60 million tons were used, it could generate nearly 2,000 megawatts of electricity, enough to power 2 million homes!
Some studies estimate that in the entire United States there is an available biomass of 1.3 billion tons per year. 35 percent of the food purchased in Britain, and 50 percent in the United States, ends up rotting in a landfill, producing methane that contributes to global warming but that might be used for more constructive purposes.
Burning biomass is technically only one of many ways to produ ce biopower. To burn something, according to websters, it must undergo combustion. And combustion technically means a chemical reaction between oxygen an organic fuel—biomass, in this case. This reaction, as we know from watching a campfire, releases heat and light. But biomass can also be heated with limited oxygen in a process called gasification, or, can be heated in the complete absence of oxygen in a process called pyrolysis. These processes require attention and adaption to the different moisture content of different types of biomass feedstocks.
Additionally, biomass—because it’s composed of decomposing vegetation—contains carbon that it will release when it’s burned. But because the tree in your backyard, for instance, produces new carbon-eating leaves every year to replace the ones you’ve raked up and sent to the power plant, the level of carbon in the atmosphere remains ”carbon neutral” when biomass rather than coal is burned as a fuel. Furthermore, if trees are planted for the sole purpose of producing biopower, then the level of carbon in the atmosphere could be lowered to a level below what it originally was. In this case, biopower from these trees can potentially be “carbon negative”.
Source: ACORE Biomass Council and Green: Your Place in the New Energy Revolution, Palgrave Macmillan, 2008
- The environmental benefits of using landfill methane to produce electricity are equivalent to removing the annual greenhouse gas emissions from more than 19 million passenger vehicles (EPA)
- With heating oil costs rising , dealers in New Hampshire are reporting that sales of pellet stoves for home heating have increased by as much as 500 percent since last year (EESI).
A study by the Institute for Agriculture and Trade Policy (IATP) found that biomass forest harvests could decrease the incidence of forest fires while supplying biomass.
Source: EPA, EESI, IATP