Calling BS on poop gas

In this episode of Unconfined, Brent Kim breaks down the pros (meh) and cons (many) of manure digesters and the expanding biogas industry, which has been billed as a climate solution, and to which Brent says, Nah.

Mo’ Poop Mo’ Profit 

By Christine Grillo                                                                                                                                                                    Subscribe to Host Notes

This episode of Unconfined should probably come with a trigger warning—something like, “If you’re already an unbearable skeptic who Bah Humbugs every new ‘technical solution’ to the world’s biggest problems, this episode will make you even less pleasant company.” 

For this one, I hung out with long-time CLF colleague Brent Kim, and we talked about new CLF research that has, sadly, increased my curmudgeon quotient. The topic at hand was a budding romance between the fossil fuel industry and the industrial livestock industry. They’re having a baby. What could possibly go wrong?  

Biogas—or poop gas, as some like to call it—seems to be a newly invigorated attempt by industrial agriculture to greenwash the dirty facts of life on mega-dairies and other concentrated animal feeding operations (CAFOs). The business is expanding, in part with the help of generous government subsidies. Some people—mostly employed by the meat or natural gas industries—love biogas, and some people are pushing back. 

Manure digesters are the technical wizardry behind poop gas. To understand how they work, you first have to imagine a “farm” with, say, 10,000 cows who spend their days eating and defecating. Their poop is captured in a cesspit—which the industry hilariously calls a “manure lagoon,” if you dare to imagine such a lagoon—that is covered in order to trap the gases that emanate from the poop. The main gas of interest in this scenario is methane, a greenhouse gas that is far more powerful than carbon dioxide. The manure digester traps that gas. The resulting "biogas" can be burned on the farm for energy, but before it can get plugged into the electricity grid, it has to go to a conditioning facility where it can be converted into something useful. The result is something similar to natural gas, which has to be piped via pipelines to a facility where it can be burned to generate electricity. So, not exactly an elegant solution. Right off the bat, this so-called “renewable” energy requires a lot of new infrastructure and effort. 

The people who love poop gas say that it keeps methane from entering the atmosphere, a win for climate change. The people who don’t love poop gas talk about the facilities’ impact on the rural communities where they’re built: most who live in them can’t afford to leave their smelly community, or don’t want to. They worry it will inspire CAFO operators to make their operations ever bigger, the better to reap profits from generating poop gas.  

Brent shared an impressive amount of information from the study, which I recommend everyone check out. (The science brief is super-helpful, and the study itself is comprehensive.) In not a lot of time—Brent is impressive at reeling off facts from memory—he manages to address the pros and cons of manure digesters across several domains relevant to public health, and to compare them to the pros and cons of regular old CAFOs without manure digesters. That means he talks about odors from manure, ammonia, the nitrates that get into soil and drinking water, the pathogens, heavy metals and other biological contaminants that can get into air, water, and soil. He talks about digestate, which—fun fact—is a slurry of both liquid and solid poop, some of which gets applied to cropland. And he talks about methane. 

And so, how do CAFOs with digesters compare to CAFOs without digesters? As my Gen Z children would say, the difference seems pretty “mid.” Brent says that the digesters are keeping some methane out of the atmosphere and reducing some odors, but they might be putting more nitrogen into the water and higher levels of ammonia into the air. There are many ambiguous trade-offs, and for these details, you should listen to the podcast or read the brief. In terms of worker safety, it might be a wash, as well. 

But the more troubling angle on this question is when we look at how this “solution” will play out in years to come. For the digesters to work, somebody has to build a lot of infrastructure—including pipelines, which can be disrupted by some extreme weather events. And where does all that new infrastructure (conditioning facilities, pipelines, roads for transport) get built? Well, definitely not in affluent communities. Then Brent reminds us to factor in the high failure rate of these facilities. And lastly, consider this: once a producer has gone to the trouble and expense of building all this infrastructure, and is maybe possibly sort of turning a small profit with the help of federal and state grants and subsidies, what will make his or her operation more profitable? The answer is more poop.  

Brent continues to wax on about the industry: Biogas operations incentivize more poop, which means they incentivize more animals. Which means that the 10,000-cow mega-dairy may now want to become an 11,000-cow mega-dairy. Brent spilled the beans on an upcoming study that will be published soon; the team researched whether CAFOs grow in herd size when digesters are added. And guess what? They do. So, in exchange for modest wins in odor reduction and escaped methane, we find ourselves with even bigger CAFOs. From this finding, we can predict that if methane digesters become more popular, industrial agriculture will become further entrenched, and any innovative vision of a better model will be more difficult to implement. 

I’ll close this essay with the Jevons paradox, which Brent introduced me to in the episode. It’s an economic theory, but it applies to many things in life. The theory is this: as technological progress increases the efficiency with which a resource is used, the total consumption of that resource tends to increase rather than decrease. We may be technical-solutioning ourselves out of bad ag models into worse ag models. I hope not.