Green Energy: What is Bioenergy?
Bioenergy is the energy which is stored in materials made with the help of living things. The everyday example of bioenergy is wood heat. Wood is produced by growing trees, and contains highly flammable substances. Wood heat is probably humanity's oldest energy source.
And other sources of bioenergy include alcohol and biogas. Alcohol is a flammable liquid made by certain yeasts, and biogas is a flammable gas similar to natural gas, made by bacteria.
The difference between getting fuel from living things such as trees and getting it from something like coal or oil is that bioenergy is one kind of renewable energy. Although fossil fuels were formed by organisms that lived eons ago, it takes so long to replace fossil fuels (millions of years) that for practical purposes, they are considered non-renewable.
Peat (a brown or black material found in bogs) is another resource that is not easily replaced, taking hundreds of thousands of years to renew itself. To be considered renewable (green), the resources must be replaceable within our lifespan. For instance, the wood used in your campfire replaces itself as the forest grows. Coal on the other hand can be taken from the earth only once, and can't be replaced. If a forest is managed properly, it will provide wood forever. It is the same with other forms of bioenergy, including biogas and alcohols.
Bioenergy includes:
1. Fibre Fuel
Most green plants have large amounts of a stiff material called cellulose. Cellulose is one of the main ingredients in wood, and is extracted for use in papermaking.
2. Ethanol and Methanol
Ethanol and methanol are alcohols and are highly flammable. They can be made from plant sugars or plant fibres.
3. Biogas
Most mammals-humans included-produce a flammable gas called "biogas" as they digest their food.
