What’s the deal with “carbon negative” biomethane?


What comes to mind when you read this statement:

“We are extremely excited to expand our joint venture with Chevron to build and operate 10 new, highly carbon-negative renewable natural gas projects on dairy farms across the country and continue to reinvent waste,” he said. said Bob Powell, CEO and Founder of Brightmark. me.

Excited to see another climate solution scaled up? Is your greenwashing alarm bell ringing? Just a big question mark?

For me, it was an “all of the above” type of situation when I read the announcement Last week. It’s time to unravel some of it.

Dairy farms can produce biogas by feeding cow manure to anaerobic digesters. Microorganisms in the oxygen-free (anaerobic) environment of the digester break down organic matter. This decomposition creates biogas which is cleaned up and turned into biomethane, a gas that can be used as fuel for trucks, buses and cars. Sometimes gas is also converted into electricity and fed into the grid. A dairy cow produces a lot of manure – approximately 112 pounds per day – which makes it a raw material with rapid and natural renewal, which means that the end product is renewable natural gas.

Why is this important?

Some are enthusiastic about producing natural gas on dairy farms because it drastically reduces methane emissions. Methane will play an important role in our climate future. It’s a short-lived and extremely powerful climate pollutant which stays in the atmosphere for about 12 years. One pound of methane heats the atmosphere 25 times more than one pound of carbon dioxide, which is why it is extremely important to reduce emissions quickly.

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Agriculture has a big role to play here. In California, for example, more than half of the state’s methane emissions come from cattle, especially cows. They mainly emit methane during burping but also when their manure decomposes in lagoons. The latter can be bypassed by turning manure into biomethane instead of storing it.

As this process avoids methane emissions that would otherwise occur on dairy farms, California considers this to be carbon-emitting technology Low carbon fuel standard (LCFS). California has invested $ 288.9 million in dairy digesters and other manure management approaches, funding for 60 new projects over the past five years.

Powell of Brightmark takes it one step further by telling me that the projects he runs in conjunction with Chevron and the farmers are “intensely” carbon negative. The fuel received a lower carbon intensity score in California’s LCFS program than solar or wind power, because production depends on much less infrastructure. The projects also help farmers supplement their income while allowing less nitrogen runoff when spreading manure on fields once it has dried as it passes through the biodigester.

So far so climate-friendly?

Things get complicated here. Yes, biodigesters avoid emissions. But that doesn’t necessarily make it a clean energy source or a good use of public funds. Andrew DeCoriolis, executive director of Farm Forward, told me by email: “Like ‘clean coal’ or BP’s rebranding to ‘Beyond Petroleum’, biogas is whitewashing a polluting and inhumane industry, while financially benefiting the world’s largest meat companies. The best way to reduce the environmental impacts of factory farming is to limit [their] growth and support alternative methods of food production. ”

Biomethane helps fossil fuel companies postpone their own emission reductions by making their fuel mix greener.

What is behind this statement? First, whether dairy-based biogas is carbon negative depends on where the boundary of the assessment is drawn. Captured methane is only a small fraction of the overall emissions produced by large dairies – after all, most of a cow’s methane comes in the form of burping, not excretion. Depending on the same animal and the same farms, this larger fraction of global emissions is necessarily part of the overall life cycle of the product. Second, since the extra income makes dairy farms more profitable, it can lead to farm expansion and therefore ultimately to more emissions overall.

Another more indirect consequence critics have pointed out in the past is that biomethane helps fossil fuel companies postpone their own emission reductions by making their fuel mix greener.

In the end, should we support it?

This brings me to a more fundamental question: Should we support effective climate approaches to reduce emissions in the short term but expand the impact and legacy of inherently unsustainable industries such as petroleum and industrial agriculture? Or should we dig deeper?

To be honest, I have a hard time coming up with a straightforward answer to this question myself. I don’t think we should create other path dependencies for these industries. Yet I am aware of the urgent need to employ all the scalable solutions at our disposal to avoid even more catastrophic global warming.

What is important to me, however, is not to use scarce public funds for industries that can and should take responsibility for their pollution themselves. Every agri-food company needs to reduce its emissions as quickly as possible and the use of technologies such as biodigesters could be part of their strategy. The cost should be built into their business models like any other expense, not outsourced to the public.

Ideally, the decarbonization of industry and the internalization of associated costs would occur simultaneously around the world to avoid supporting low-cost, heavily polluting farms elsewhere. But the change has to start somewhere. Based on its climate leadership on other issues, California may be better placed than many other regions to lead the way. In my opinion, the state would have done better to invest the $ 288.9 million in better manure management to help dairy farmers transition to an entirely different business model while supporting the growth of alternatives to herbal.

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