UC Davis, just west of Sacramento, has started construction of a new anaerobic digester in partnership with CleanWorld, a developer of anaerobic digestion technologies. The new facility, dubbed the Renewable Energy Anaerobic Digester, is located on top of Davis’ old landfill in order to demonstrate the potential uses for closed landfills. It also allows the new digester facility to tap into the natural  bio-gas produced by the decaying trash inside the landfill. The combined use of landfill gas and the bio-gas from the digester is projected to produce nearly 1 MW of electricity, enough to power 1,000 homes.

A digester located outside of Brandenburg, Germany

A digester located outside of Bottrop, Germany

The digester works by using natural bacteria to break down organic matter. In the case of the UC Davis digester, it will primarily be accepting food waste from dormitories, dining halls, and area restaurants, as well as agricultural waste from nearby farms. The decomposition of the waste produces natural bio-gas comprised of methane and carbon dioxide. The methane is captured and burned to generate electricity, while the carbon dioxide is released into the atmosphere. However, the levels of CO2 produced through anaerobic digestion are a fraction of the levels seen in coal plants, making them nearly carbon-neutral.

The facility also yields a significant quantity of natural fertilizer and soil additives. So much in fact that it can provide enough fertilizer for over 140 acres of farmland. CleanWorld expects to sell a large portion of the plant’s fertilizer to local farmers, providing a clean and plentiful source of fertilizer for farmers around the Davis area. In total, the facility will produce 4 million gallons of fertilizer annually, as well as divert nearly 13,500 tons of waste from area landfills.

UC Davis administrators are excited for the new facility to come online, especially because one of their own designed it. Dr. Ruihong Zhang, a researcher and professor at UC Davis, developed the new system being used in the READ facility allowing it to utilize landfill gas in addition to bio-gas from organic waste.

The READ facility is expected to begin producing electricity in December, by which time many of the town’s waste dumpsters can be expected to smell a little nicer.

Source: BioMass Magazine