Growing plants absorb and store atmospheric CO 2 . As these plants die and decompose, they release this carbon back into the atmosphere in the form of CO 2 and methane. Because they are releasing the CO 2 that they already absorbed, there is no net release of CO 2.
Biomass technologies use this process to generate carbon-neutral electricity. As things like food, yard clippings, wood and other organic matter decompose the gases they give off are collected and burned to create steam, which can then be used to generate electricity.
These gases can also be converted into other fuels like ethanol or biodiesel for later use.
Unlike wind and solar resources, biomass can be stored and used as needed. This enables it to provide “baseload” power on demand 24 hours a day. And because it contains much less sulfur and nitrogen than coal, when it’s co-fired with coal, emissions are lower than when coal is burned alone.
For more on biomass, check out the Renewable Energy Q&A .