Backyard Biogas

As soon as I started writing this post, I realized there are a lot more than 5 F’s.

Fossil-fuel free! Biogas is renewable, clean, green, carbon-neutral. It requires no mining, fracking, or mountaintop removal. Of course, there are some fossil-fuel inputs required to build and maintain the infrastructure of a biogas plant, including plastics.

Flammable! This is the whole point, of course, but it’s also helpful to remember – especially to those of us who are experimenting with biogas in our own backyards – that biogas is flammable and that we must take appropriate safety precautions. If a leak were to occur in the system, an open flame or spark could potentially ignite the gas, causing an explosion. So we must do everything possible to avoid this, including proper construction and inspection of the gas lines, and appropriate safety equipment like a fire extinguisher and a gas leak detector.¹ Nevertheless, biogas is no more dangerous than having a propane canister for your grill in your backyard. In fact, it’s less dangerous, because unlike biogas, a propane canister is compressed, which makes explosions even more dangerous.²

Fun! Learning how to capture and store your own cooking fuel is immensely gratifying and empowering. I will always remember the first time I had brewed enough biogas to light. The blue color of a biogas flame is most easily visible at night. So one evening, after having seen my biogas bag slowly inflate over the course of a few days, I decided to try lighting it. The rush of seeing my gas light, and stay lit until the bag was empty, must have been something like what Prometheus felt when he stole fire from the gods on Mount Olympus.

Freedom! Biogas represents energy independence. The methane produced in a biogas reaction, once refined, is identical on a molecular level with the methane that is produced from fracking for “natural” gas. (When biogas is refined into 95%+ pure methane, it is referred to as biomethane). That means it can be used in any of the same applications: heating air and water, generating electricity, even fueling vehicle transportation through CNG (compressed natural gas). If we as a species can collectively increase our production and use of biogas and biomethane, it can help us break free from the fossil fuel system that plagues our lungs, our politics, and our entire planet.

Farts! Biogas is farts.

Finicky! Creating a stable, reliable supply of biogas is not easy as a home-brewer. It requires a lot of trial and error, especially because there’s a lack of standardized equipment available for home use. The microbes that produce biogas are a living ecosystem of dozens of different species, all too small to be seen by the human eye. Variations in temperature, feedstock, and timing can make a big difference in how much gas you produce, how long it takes to produce the gas, and how pure the gas is.

Flourishing! Even though biogas is still far from mainstream, there has been huge growth in the past decade, both on the home-brewing front and also at the industrial and commercial scales. The US is still far behind other countries like China (100,000 biogas plants!³) and Germany (10,000), and certain US states are more advanced than others (California currently has about 300 biogas plants⁴). We’ve got a long way to go, but the growth is real: according to the American Biogas Council (ABC), 2023 was the 3rd straight year of record growth in the US biogas industry, with 100 new projects coming online representing $1.8 billion in capital investments. Another 100 new projects are projected to go into operation in 2024.⁵

What else is biogas? Fantastic? Frustrating? Fraught? Leave your answers in the comments!

1. https://farm-energy.extension.org/anaerobic-digesters-and-biogas-safety/ ↩︎
2. https://www.nafi.org/blog/explosion-severity-propane-versus-natural-gas/ ↩︎
3. https://www.ieabioenergy.com/blog/publications/a-perspective-on-the-state-of-the-biogas-industry-from-selected-member-countries-of-iea-bioenergy-task-37/ ↩︎
4. https://americanbiogascouncil.org/resources/state-profiles/california/ ↩︎
5. https://americanbiogascouncil.org/third-year-of-record-growth-for-u-s-biogas-industry-expected-to-continue-in-2024-2/ ↩︎