Biogas is a renewable energy source that can be used to generate heat and electricity. It’s produced through the decomposition of organic materials from plants and animals, also known as “biomass.” Further refined through a renewable natural gas production process, biogas can be used for virtually any application where fossil natural gas is used.
There are three principal sources of biogas.
Municipal solid waste facilities are the primary source. Here, landfill gas is created by the decomposition of paper, yard trimmings, food waste, and other organic wastes.
Dairy farms and livestock operations are other sources. These often have covered holding ponds for animal waste and used animal bedding. When collected, this raw biogas can be burned to heat water or run specially modified, diesel-powered farm equipment.
A third source is anaerobic digesters, used by municipal sewage treatment plants, paper mills, and food processors, as well as large livestock operations. These digesters facilitate and speed up the decomposition process of plant, animal, and human waste.
Read part 2 of our white paper- 2021 Power Generation and Renewable Energy Trends, to explore renewable energy technology trends, both established and newer technologies including solar, wind, marine, and biogas.
As a renewable energy source, purified biogas can be used in place of traditional fossil fuels in a variety of applications, including utility-scale electrical generation, fuel for combined heat and power (CHP) plants, pipeline natural gas, and vehicle fuel. It can reduce the amount of material placed into landfills and can help contribute to the development of a circular economy.
It’s also made without combustion, and its production and refinement release much less carbon dioxide into the atmosphere than fossil fuels.
According to a 2019 report on biogas potential by the World Biogas Association, biogas produced by anaerobic digestion could help reduce global greenhouse gas emissions by 10%-13%.
Raw biogas has a methane composition of 40%-60%, according to the U.S. Energy Information Administration. The remaining components include carbon dioxide, water vapor, hydrogen sulfides, and other byproducts of the anaerobic digestion process.
Without removal of these byproducts, the raw biogas can corrode and damage the metal parts of power generation equipment, while having a reduced energy potential. Once treated, however, the 90% methane gas that remains is as pure as fossil methane. This gas, also referred to as renewable natural gas (RNG), can be used virtually anywhere fossil natural gas is used.
A variety of technologies and processes can be used to purify biogas. The exact approach chosen may depend on the condition of the biogas, the amount to be purified, or the intended use of the RNG. These technologies and processes include:
Filters to remove foams, small particles, grease, particulates, and other similar contaminants
A dehydration or dehumidification process to remove water vapor
Biofiltration to remove hydrogen sulfide, siloxanes, and volatile organic compounds (VOCs)
Chemical, pressure, or membrane processes to remove carbon dioxide
For pipeline quality gas, RNG often requires drying with an adsorption dryer down to a pressure dew point (PDP) of -58°F (-50°C) prior to injection into the natural gas grid
According to the U.S. Department of Energy, biomass gasification — which is currently being researched — could be deployed soon to produce hydrogen for fuel.
In this process, biomass is heated to temperatures more than nearly 1,300 degrees F (just greater than 700 degrees C). Steam and oxygen are added to the reaction, resulting in the production of both carbon dioxide and hydrogen. The hydrogen can then be removed using adsorbers or special membranes. Additional filters can be used to capture the carbon dioxide, resulting in minimal emission. The DOE is supporting research into ways to lower the capital costs associated with this process.
Another promising technology involves the use of biomass to produce synthetic natural gas through thermochemical conversion. In this process, biomass goes through a series of processes to create what’s known as Bio-SNG ( Bio -Synthetic Natural Gas). This gas can be used as a substitute for natural gas and is suitable for transmission in energy pipelines.
According to a 2020 report by the World Bioenergy Association the European Union is the world’s biogas leader.
In 2018, the EU’s production accounted for more than half of the global biogas industry. Asia was second, with a share of 32%. The Americas were a distant third at 14%.
In the United States, according to the EIA, biogas helped generate 11.75 kWh of electricity in 2019. This amounted to less than 0.5% of all electricity consumed in the country.
Overall biogas production currently is just a tiny portion of the world’s energy portfolio. But experts do believe it has potential for growth. This is especially so in Europe, where, according to a report by Euractiv, conservative estimates point to a tenfold increase in production by 2030.
As global energy needs grow, biogas holds great potential to grow in stature as a renewable power source. Parker offers a range of solutions to help those in the biofuel industry harness energy from biogas and biomass production processes.
To learn more about trends in the Renewable Energy industry, read our 2021 Power Generation and Renewable Energy Trends White Paper – Part 2.
This article was contributed by the Filtration and Energy Teams.
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