How is biogas converted into energy?
Biogas can also be referred to as natural gas, it is found in deposits below the earth's surface where organic material such as fossils have broken down and as a result natural gas is produced. Biogas can also be produced in an anaerobic digester, this takes organic material and depletes it of oxygen, replicating the conditions found below the earth's surface. The microbes begin to break down the organic material, this process results in the production of biogas. Many industries have organic waste material that can be used to produce biogas. This includes landfill sites, wastewater treatment facilities, farming and agriculture. In this article we look at how biogas is converted into energy.
Burning biogas is the simplest way of converting the gas into energy. The gas contains high levels of methane which is very flammable, this means the gas burns easily and continuously. The controlled burning of biogas can be used to heat boilers which provide heating for a facility or it can be used to cook on. Many industries use the biogas produced on site to reduce energy bills. Some facilities also burn biogas on site as a way of disposing of the biogas, this is called gas flaring. To minimize the environmental impact of industries that produce biogas gas flaring should be avoided and companies should aim to use the biogas as a form of energy.
Biogas burns well on its own but to make an even more effective source of energy it should be upgraded into biomethane. The process of upgrading biogas into biomethane removes water vapor, carbon dioxide and other impurities, these gasses make the biogas less efficient. There are several methods that can be used to upgrade biogas, we have more information on biogas upgrading in our article What is biogas upgrading? Once upgraded the biogas is called biomethane, this biomethane has a very high concentration of methane, around 90%. The purity of biomethane makes it a much better source of energy than biogas as methane is the key flammable component. Biomethane can be injected back into the gas grid network to provide homes and businesses with gas for their cooking and heating. It can also be used to power vehicles or used directly where it is upgraded to provide heating and electricity.
Converting biogas into electricity
Biogas can also be converted into electrical power at a gas power station. The gas used at a gas power station is mostly the upgraded version of biogas, biomethane. Biomethane has a much higher level of methane which improves its efficiency. To convert biogas to electricity the gas is burned in a controlled environment. The process of burning the gas produces heat, this heat can be used to generate electricity by rotating an electric generator which produces electricity. Some gas power stations add in additional steps to improve the efficiency of converting the biogas to electricity; this includes burning the gas to heat up water then using the steam to power the electric generator.
Biogas can also be converted to energy in biogas fueled cars and vans, although not as popular as petrol and diesel, biogas is used in a number of vehicles. The biogas used is compressed into compressed natural gas or can be cooled until it becomes liquified natural gas. Biogas significantly reduces emissions from vehicles by up to 80% compared to petrol or diesel, providing a greener solution to transportation.
Anaerobic digestion projects
At QED we provide equipment and solutions to help with measuring and monitoring anaerobic digestion projects. To maximize the amount of methane produced the levels of oxygen need to be controlled within the anaerobic digester. At QED we can provide fixed gas analyzers and gas detectors so when managing a project you can understand the levels of methane being produced and also maintain the right level of oxygen to maximize methane production.
Our portable gas analyzers can be used to ensure the safety of your anaerobic digestion project and quickly detect any leaks or dangerous areas. Working together, fixed and portable gas analyzers keep operations safe and maximize the amount of methane the anaerobic digester is able to produce.