Great point. This isn't like biodiesel or ethanol, where the co2 would end up in the air anyway. A methane generator actively creates a carbon form that is significantly worse for the environment.
Steve Wing, the UNC-Chapel Hill epidemiologist, says hog operations give off ammonia, methane—a potent greenhouse gas—and hydrogen sulfide, which causes headaches and eye irritation. They also release endotoxin, an allergen, and at least a hundred volatile organic compounds, many of which contribute to the odor of hog farms.
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The result? The covers trap odors, making the operation less smelly. Rain falling on the farm isn't contaminated by lagoon waste. And the farm is transforming waste into electricity-generating enough to power 90 refrigerators.
Anaerobic digestion causes the production of (more) methane rather than co2. Methane is a 100x more potent greenhouse gas than co2 over the short term. Over hundreds of years it breaks down but even a century from now it's 30x worse.
Anaerobic digestion is great as long as leaks are kept below 1%. Doing so is tricky.
Over hundreds of years it breaks down but even a century from now it's 30x worse.
That doesn't sound right. Most sources I've seen[1] say that atmospheric methane has about a 10 year half life. I think the 30x figure you refer to actually represents the sum of methane's annual impact over 100 years. Despite the greater immediate efficacy as a greenhouse gas, the amount of methane remaining after a century should be so small that the impact in the 101st year would be extremely (likely unmeasurably) low.
I understand this doesn't affect EPA laws, but most US states exempt farm vehicles, even things like pickup trucks (that can legally drive on roads even) from state emissions testing.
They also allow exemptions to use untaxed fuel in them, etc.
Basically, there's a sort of exemption ecosystem that might have farmers thinking they are free to do whatever they want around fuel and emissions. Which is only partially true...
Yes, but enforcement is aimed at the manufacturer...that new models rolling off the line meet the requirement. I don't believe there's any enforcement locally, for the buyer of the tractor. As mentioned, US states are very lax about farm vehicles.
No. This process is 100% carbon neutral. It recycles the carbon already in the pig manure as opposed to natural gas which is a fossil fuel and adds to the carbon cycle.
Plus locally produced and consumed, so you're not using diesel trucks/ships to move it over long distances (compared to powering his tractor using diesel or gasoline or whatever tractors normally use).
Any lost methane is significantly worse than the equivalent amount of CO2. Even though it's carbon neutral, the intermediate step converts it to a much more potent greenhouse gas that is very easy to lose to atmosphere. Without a digester, the biomass will be converted to co2 instead. Energy that could have been stored as methane is converted to heat. The best case scenario is to skip biology entirely and throw it into the incinerator, where it can be used to produce heat for power and almost only co2, skipping over methane entirely.
Done right, a digester extracts a little bit more chemical energy from biomass that simply leaving it on the ground. Done wrong it weaponizes the carbon.
"Any lost methane is significantly worse than the equivalent amount of CO2."
...except that methane doesn't persist anything like as long as CO2, so while it's mean and pointy upfront, it's out of the environment faster. This is pretty basic climate science that routinely gets misrepresented by the denier industry, which is why I'm bothering to pick this nit.
It's not like he's dumping the methane in the environment though (e.g. dumping manure on a field): it's ultimately being run through a combustion engine.
Well, he is using an anaerobic bioreactor I believe, so not sure what the exact conversion figures or alternative aerobic products would be. (The methane he extracts vs equivalent farm decomposition)
Ethanol is a bad counterexample. Most ethanol comes from corn, and most energy in corn comes from fossil methane, used to synthesize ammonia fertilizer.
Fertilizer only provides the nutrients (primarily nitrogen). The actual energy in corn comes from photosynthesis trapping the sun's energy in chemical bonds.
> We believe that outside certain conditions in the tropics most ethanol EROI values are at or below the 3:1 minimum extended EROI value required for a fuel to be minimally useful to society.
Well, he burns that, he doesn't emit it, so I don't see why that matters. Once burned it seems like the same old CO₂ is emitted, so what he does is a net win... or? I'm not a chemist.
