Wind, solar, hydro-power. We have heard the myriad ways to harness energy without releasing earth warming greenhouse gases into the atmosphere. However, one more unexpected but quite viable source of energy exists. It’s called biogas, and it’s made from poop.

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How it works

  • When microorganisms (e.g.bacteria) break down organic matter like manure and food waste anaerobically (without oxygen), biogas is released. Bio gas consists primarily of carbon dioxide and methane – one of the primary components of natural gas.
  • Farmers place animal manure, food waste and agricultural waste in an anaerobic digester with a pipe to extract the gas.
  • The solid byproduct is used as livestock bedding, soil amendments or in biodegradable planting pots, and the liquid byproduct is a nutrient-rich fertilizer.

Benefits of Biogas-based Energy

  1. Reduced greenhouse gas emissions. Biodigesters divert carbon dioxide and methane that would normally be released into the atmosphere. Greenhouse gas emissions from a dairy farm can be reduced by 35% when biogas-based electricity replaces grid-based electricity.
  2. Cost savings. On-site biodigesters help farmers save on electricity bills and fertilizer. A farmer told The Washington Post that he saved anywhere from $75,000 to $100,000 a year on electricity, heating, fertilizer, and animal bedding with a biodigester.
  3. Renewable. Biogas is generally considered renewable as it is produced by animal and plant waste and the source is not limited in quantity like coal or natural gas.

Bottom Line

  • Biogas generation is becoming increasingly popular. From 2000 to 2020, the number of operational anaerobic digesters in the United States has grown from 24 to 255.
  • Biogas is a popular mode of energy production in India and China, which have 4.54 million and 27 million biogas plants respectively.
  • As the world divests from fossil fuels, new and varied energy sources will be necessary to satisfy the energy needs of the world and biogas can help. Biogas just goes to show you that not all waste is useless. One cow’s waste is another man’s treasure.

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How biogas energy works

When microorganisms (e.g.bacteria) break down organic matter like manure and food waste anaerobically (without oxygen), biogas is released. 90% of biogas is methane and carbon dioxide; 60-65% is methane alone – one of the primary components of natural gas.

Biogas can satisfy many energy needs. Biogas can fuel on-site electricity generators or replace the propane in boilers. If processed, compressed and refined by removing contaminants, carbon dioxide and water vapor, people can use biogas as vehicle fuel, or in natural gas pipelines that supply businesses and homes.

Biogas generators are common on farms, especially dairy farms, which have abundant organic waste. Farmers place animal manure, food waste and agricultural waste in anaerobic digesters: often a large pit underground with a dome-shaped roof and a pipe to extract the gas. 

 

But the gas is not the only useful product of an anaerobic digester. Farmers use the solid matter as livestock bedding, soil amendments or in biodegradable planting pots. And the liquid byproduct is a nutrient-rich fertilizer.

Benefits of Biodigesters

Anaerobic digesters help farmers put all the organic waste matter to good use while saving money and the environment! There are three main benefits of biogas generation:

  • Reduced greenhouse gas emissions. Biodigesters harness carbon dioxide and methane that would normally release into the atmosphere from manure piles or landfills for energy. Diverting methane is especially important since methane is about 28 times more potent than carbon dioxide as a greenhouse gas. A study at the University of Wisconsin-Madison found that when biogas-based electricity replaces grid-based electricity, greenhouse gas emission from a dairy farm reduce by 35%.
  • Cost savings. On-site biodigesters help farmers save on electricity bills and fertilizer as farmers can produce their own energy and even sell surplus to local utility companies. A farmer told The Washington Post that he saved anywhere from $75,000 to $100,000 a year on electricity, heating, fertilizer, and animal bedding with a biodigester. 
  • Renewable. Many consider biogas renewable. Animal and plant waste produce biogas energy, and biogas energy is not a scarce resource like coal or natural gas. 

Nevertheless, biogas-based energy is not perfect. Although this source does not add to greenhouse gas emissions, pipeline leaks cancel out any emission reductions and the technology is expensive. But while other renewable technology develops, biogas can serve as a transitional energy source and satisfy agricultural energy demands. 

Biogas Energy in the World

Biogas generation is becoming increasingly popular. The US EPA’s AgStar Program promotes biogas generation from livestock waste farms. Many private companies like Vanguard Renewables and Dominion Energy also help fund biodigesters on livestock farms in the Southwest and California.

These investments have fueled the growth of the industry; from 2000 to 2020, the number of operational anaerobic digesters in the United States has grown from 24 to 255, with 33 currently under construction.

Between 2000 and 2019, anaerobic digesters on livestock farms have reduced direct and indirect emissions by 43.8 million metric tons of CO2 equivalent according to the EPA.

Biogas is a popular mode of energy production in other parts of the world. Since the 1970s, India and China have invested heavily in the development of biogas digesters. As a result, India has 4.54 million biogas plants and China has 27 million biogas plants as of 2012. Located in rural areas, these plants ensure the safe and sustainable disposal of human and animal manure as well as agricultural waste.

Bottom Line

As the world moves away from fossil fuels, new and varied energy sources will be necessary to satisfy the energy needs of the world because not every energy source is viable everywhere. Biogas can play a crucial role in a renewable energy future, especially on farms. It just goes to show you that not all waste is useless. One cow’s waste is another man’s treasure.

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