Biomass energy generation refers to the use of biological material, such as wood, human waste, farm waste, and so on, to generate power. It's usually done by burning, either directly or after using microbes to convert solid or liquid matter into flammable gas. While there are harmful ways to do this, there are also opportunities—like using sewage treatment plants to generate energy—to use matter that is already going to decompose or be burnt, thus releasing greenhouse gasses, and harnessing those to lessen the damage by replacing more damaging energy sources.
A robotic lawnmower powered by the grass it clips, and that can store the grass-power for later use.
A lot of talk about individual climate action has centered around things like conserving energy, but the real problem is where the energy we use comes from. Biogas is brilliant because it can take any organic material, from human and pet waste, to kitchen scraps, to yard waste, and turn it into fuel for cooking, heating, or even generating electricity or driving small engines! The beauty of this is that all the material used to create this gas is from the biosphere system, which means that at worst, using it releases carbon that was only recently pulled out of the atmosphere, so it doesn't add to global climate change. Sewage treatment plants, farms, and even individual homes around the world are already using this, and the technology is simple enough that you can too!
This is a demo of a biogas generator that someone built for themselves with easily available materials. The resulting setup allows them to use their kitchen waste to generate cooking gas: