As the world gradually transitions to renewable energy—with some places shifting more gradually than others—creative solutions are vying with the more mainstream renewable energy sources like wind and solar. Biogas has arisen as one of these creative solutions. Production of biogas prevents methane, a potent greenhouse gas, and some CO2 from escaping into the atmosphere while providing a renewable fuel source. This is because biogas can be made from poop.
Biogas offers an alternative to the fossil fuel natural gas. SoCalGas, a southern California natural gas utility, calls it a renewable natural gas. Like the gas that diffuses from bacteria digesting poop, natural gas is mainly methane. It comes from deep underground and is brought to Earth's surface from wells drilled deeper than a mile beneath the surface. It's now the most popular source of electricity in the U.S.
Even cooking with natural gas can produce air pollutants, and users should make sure kitchens are well ventilated.
Transitioning from fossil fuels to clean, renewable fuels is critical to reducing global warming emissions. These energy sources won't eventually run out like fossil fuels and produce little or no greenhouse gases. Scaling up clean energy has proved expensive and controversial in the past, making room for clean solutions that make use of available resources and fit into the current power grid. One such solution? Renewable natural gas.
Renewable natural gas can come from several methane-releasing sources, including dairy operations, landfills, and sewage treatment plants. No matter the sources, the production relies on the bacteria decomposing organic matter and releasing methane.
One of the United States' biggest sources of methane is cows. Their burps give off methane, and so does their decomposing waste. Usually, livestock waste sits in "lagoons" open to the air, allowing methane to diffuse into the atmosphere as bacteria break down the poop. Dairy digesters that capture the methane for biogas provide a way to both prevent methane from reaching the atmosphere and a way to power vehicles, and maybe, eventually, homes and businesses.
Some natural gas utilities are particularly excited about biogas. The infrastructure already exists to transport biogas, as the U.S. has over 2 million miles of pipelines to transport natural gas across the country. Switching to this energy source is a way for natural gas companies to stay relevant in a world looking to abandon fossil fuels.
This anaerobic digester plant near Norfolk, Great Britain, takes advantage of bacterial digestion of biomass. Photo by Evelyn Simak, CC BY-SA 2.0
Biogas can also benefit California dairy farmers. By 2030, state law says they must decrease methane emissions by 40 percent from levels in 2013. But the environmental and climate benefits of installing dairy digesters aren't straightforward. As the West Coast director for the Center for Food Safety told Civil Eats, dairies still pollute air and water, and encouraging digesters may encourage more large-scale dairy operations, reversing a movement to support more environmentally friendly, small-scale dairy producers. This concern isn't baseless. Biogas production is an expensive undertaking, which is why most systems are geared toward large-scale operations.
SoCalGas has claimed, using information from a SoCalGas-commissioned report, that biogas has a negative emissions potential, meaning biogas use could have a net negative effect on emissions. But the leakage issues that plague the natural gas supply chain would also apply to biogas. Using biogas would not prevent methane from leaking through pipelines, something SoCalGas's report seems to ignore.
Another concern voiced by Natural Resources Defense Council scientist, Merrian Borgeson, in the is if companies start growing crops specifically for methane and production, as opposed to trapping methane from byproducts of necessary processes.
Another concern voiced by Natural Resources Defense Council scientist Merrian Borgeson, in the Los Angeles Times, is if companies start growing crops specifically for methane and production, as opposed to trapping methane from byproducts of necessary processes.
So far, California's dairy digesters are only providing biogas to fuel heavy-duty trucks. Whether large-scale adoption of biogas is feasible or affordable remains to be seen.