Wednesday, June 24, 2020

Dominion Energy invests in new form of biodigester that helps farmers turn manure and food waste into natural gas

Biodigesters aren't a new concept: Farmers put cow or pig manure in one end, let it percolate for a while, and it produces methane and carbon dioxide. The biogas gets filtered and then added to natural gas pipelines, and farmers get paid for it. Large dairies have been increasingly experimenting with them, trying to make money by tapping into carbon credit programs in California and Oregon.

Biodigesters are fiddly and many don't work well, so they haven't been widely adopted. But that may change, because one energy consultant recently realized that they work much better when farmers add food waste to them in addition to the manure, Jim Morrison reports for The Washington Post.

Consultant Bill Jorgenson theorized that adding food waste would "increase the energy output and boost the income for farmers through tipping fees from manufacturers, retailers and others looking to unload food waste," Morrison reports. "Best of all, it would use methane from the manure, instead of venting it into the atmosphere to contribute to climate change.

Five farms partnered with Jorgenson to found AGreen Energy LLC, which was snapped up by Vanguard Renewables in 2014 and expanded in New England. Now Dominion Energy, "which is now investing more than $200 million to join with Vanguard to capture manure methane from dairy farms in Colorado, Utah, New Mexico, Georgia and Nevada and convert it into natural gas," Morrison reports. "Dominion will own the projects and sell the gas. Vanguard will design, develop and operate the biodigesters. Farmers get paid for hosting the digester and benefit from the byproducts of the process, including heat for their property, livestock bedding and fertilizer."

Dominion's investment could make biodigesters much more common; there are 255 in the U.S. today. It's unclear how much biodigesters could help the environment. Cows produce methane when they burp, but that accounts for only a small percentage of the overall methane in the atmosphere. "But processing methane from farms into natural gas helps reduce the carbon footprint for companies such as Dominion, which has pledged to reach net zero emissions from methane and carbon dioxide by 2050,: Morrison reports.

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