Germany is the leading producer of biogas in the developed world, with 8,700 biogas plants with 3,400 MW of installed electric generation capacity. The United States lags far behind with less than 450 plants with 175 MW of capacity. Sweden has an even smaller number of plants, less than 200, but the most per capita and most prominent national biogas program. Most Swedish cities fuel their transit bus fleets with locally generated biogas and the country is home to the world’s first biogas powered commuter train operating between Linkoping and Vastervik. But if we were to do what has never been done before and include individual household and farm scale biogas plants that are not grid-tied, China easily eclipses the rest of the world combined. 

Although China does have a growing number of large, modern biogas plants, such as the Deqingyuan Chicken Farm near Beijing, today nearly all of China’s biogas plants are residential scale biodigesters of around 10 cubic meters (2,600 gallons) underground pit-type digesters made from brick and traditional Chinese “triple concrete” at a cost around $85 USD. These plants provide home cooking energy and are often used in conjunction with 60 cu.m. (15,800 gallon) village scale plants providing electricity. Biogas use is limited to the provinces of Szechuan and Yunnan, and remains largely unheard of in the eastern and northern cities.

Unlike conventional compost, the biogas process does not create its own heat and at the domestic scale it does not make economic sense to install a boiler to heat them. Chinese biogas systems have traditionally gotten around this by being over-sized and buried underground to maintain year-round gas production. Our Hestia Home Biogas units are the world’s first production home biogas systems for cold climates, and we have access to far more sophisticated manufacturing processes and materials than rural Chinese biogas pioneers. Our above ground 2 cu.m. (525 gallon) systems have a built-in heat exchanger intended to be heated by a solar evacuated tube water heater and are of course thoroughly insulated.

Distributed small scale biogas could complement residential PV solar as well, providing year-round cooking energy and stand-by generator fuel, while PV did the heavy lifting for electric. In addition to the lower upfront cost, home biogas does not require a grid-tie or any type of energy storage, as energy is stored in gas form and used on-demand when needed. The laws of thermodynamics are only paid once.

The natural, clean burning energy produced in a home biogas digester is not the only benefit, it also produces higher quality fertilizer for gardens and landscaping than composting with less work and no odors. In January, 2014 a survey sponsored by the National Waste Recycling Association found that 72 percent people polled currently don’t compost, but 68% of them would if they had an easy way to do it. Home biogas could not be easier compared to compost — one simply dumps waste into the biodigester the same as emptying it into a recycling bin. Meat and dairy waste does not need to be separated and there is no turning to do. There are no odors or pest hazards, as odors are trapped inside the gastight environment where rodents and insects cannot get to it.

As it has done in China, home scale biogas could potentially play a major role in America’s energy future by helping meet the energy and waste recycling needs of individual families one household at a time. While the national emphasis has been on large scale solar and wind for energy, and state and city landfill diversion efforts have focused exclusively on large composting and biogas plants, an option that has not been considered before might just lie a little closer to home.