Bioenergy is energy created from biological sources. The umbrella of “bioenergy” encompasses four primary bioenergy applications; Biofuel, Bioheat, Bioproducts, and Biopower.
The first caveman to build a campfire was using bioheat. Bioheat is the oldest form of external energy used by man. Any biomass (i.e. wood, wood waste, manure, straw) burned directly to create energy is bioheat.
Biopower refers to the burning of biomass for purposes of generating electricity. Today it is common for biomass to be cofired with fossil fuel sources such as coal to power electricity plants.
In certain industrial applications, biomass is burned to generate electric energy while at the same time providing thermal energy for heating. This is referred to as ‘Biomass combined heat and power’.
There are four main conversion technologies for producing heat or electricity from biomass. They are:
- Direct combustion – A solid biomass feedstock is combusted to produce steam. The steam is used to produce electricity.
- Cofiring – Cofiring involves substituting a small amount of the fossil fuel used in an electricity generating combustion process with biomass such as wood waste.
- Gasification – This involves heating biomass to very high temperatures (above 700 degrees Celsius) creating syngas which can be burned to produce electricity.
- Anaerobic Digestion – This process involves the use of microorganisms in the absence of oxygen to decompose biomass and produce biogas. The methane within this gas can be captured and burned to produce electricity.
Biofuels are created when biomass is converted directly into liquid fuels. The resulting fuel, typically biodiesel or ethanol, can be used to power transportation in much the same way as gasoline. It can power cars, ships, train, and even airplanes.
Corn is a common source of ethanol. Corn ethanol is created through a fermentation process similar to that used in brewing beer. Ethanol can be used to power flexfuel vehicles that run on a gasoline mixture of up to 85% ethanol.
Methanol can be created from biomass by burning it at high temperatures. This vaporizes the biomass in a process called gasification. The hot gas is passed through a catalyst which converts it to methanol.
Biodiesel is comprised largely of methanol that has been mixed with bio-derived oils such as vegetable oils, animal fats our recycled cooking grease.
Examples of bioproducts include many of today’s consumer products such as paints, soy-based ink, food utensils and cellophane; all of which can be produced using biomass materials.
The benefits of bioenergy include:
- Energy security – Reduced dependence on foreign sources of energy promote stability of available energy and energy independence.
- Job growth – Biofuel projects are a source of economic growth and job creation.
- Environmental benefits – Bioenergy can be carbon neutral or in some cases carbon negative. When used in conjunction with carbon capture technology, the biomass used for the creation of energy could remove more CO2 during its natural growth cycle than the end use releases into the environment.
Images source: http://www.nrel.gov/