The production of energy from biomass is one of the
oldest sources of energy used by humans. Biomass energy basically involves
the combustion of various organic compounds. It is similar to fossil fuels
in that the basic equation is:
Organic compounds + oxygen = water + carbon dioxide
Both biomass and fossil fuels rely ultimately on plants converting the energy of
sunlight to sugars. Further biological processes change these sugars to combustible
materials. The basic process by which plants store this energy is photosynthesis;
again the basic equation is:
Sunlight (energy) + carbon dioxide + water = glucose + oxygen
Biomass includes many different sources, like wood, peat moss, field crops,
agricultural and forestry waste products, and metabolic waste.
Biomass is used in 2 major ways,
1. Direct Combustion
2. Biochemical processes
1. This involves the burning of fuels like wood to produce heat or steam to turn turbines. This is the oldest form of energy used by humans. This is however, not a very efficient process. The burning of many organics has efficiencies as low as only a few percent - in part because the combustion temperatures are relatively low. Better design of furnances or stoves can increase this efficiency, but it is still not very effective. However, it is very easy to produce wood or other organic material for combustion. Often land that is otherwise useless for agriculture can be used to grow trees or other woody stalked plants (like hemp) which can be burned. However burning organic matter does produce carbon dioxide, yet by growing the plant or tree it has absorbed an equal amount of carbon so there is no net increase. additionally there is far fewer other pollutants released when compared to fossil fuels.
2. Biochemical processes - the two major ones here are either anerobic
digestion of organics which produces methane (anerobic = no oxygen). In particular
we can use this with animal waste products.
Animal manure (from herbivores like cattle, pigs, sheep and goats in particular)
can be decomposed and releases methane. Methane is a combustible gas that can be
used to produce heat or steam for a turbine. This is more practical on a small scale,
and allows farms to use this waste that otherwise can cause disposable problems and
pollution, as an energy form. (since methane comes in a gas form, this is sometimes
referred to as 'biogas'. An average cow can produce in one year the equivalent energy
to 50 gallons of gasoline through their waste products.
The other type of biochemical process is fermentation. This changes the sugars in
organic material into either ethanol or methanol. These are both combustible
materials. This process is aerobic, meaning it uses oxygen.
Ethanol is now often added to gasoline, as it can be mixed in with normal fuel
without changing the basic combustion engine. As a result, this fuel mixture is
actually cleaner burning and burns more efficiently (usually up to 10% in normal gasoline).
Another form of biomass is garbage. Garbage does contain a large percentage of
organic material. This material is combustible. An incinerator can use this
material as fuel to produce either heat or electricity.
60 to 70% of material in normal household garbage is combustible. This is an
ample fuel source. However, in an incinerator the waste from this combustion
either as ash, or from the gases that escape are a major concern. These are
the factors that prevent municipalities from using this technology to dispose
of their waste. Household waste can contain some very toxic substances due to
the chemical processing of anything from paper to Styrofoam containers.
The Benefit is that the garbage that would normally be heading the landfill and taking up
a lot of room is reduced in size due to inceneration.
Carbon dioxide is still produced in the combustion of biomass, so it still contributes to global warming. Things like wood also do produce particulate matter.
If it is household waste that is being used as a fuel the emissions that are created are quite significant and potentially very polluting. Some people throw away oil, cleaners and various other waste that is very toxic.
Biomass is used extensively as wood and other plant matter is readily available all over the world. Its future is seemingly quite bright as it seems as though we are returning partially to the old ways. Additionally in most cases wood proves to be a very economical method of home heating. With the increases in technology and thus efficiencies we are experiencing the benefits that biomass has to offer to our society.