Is Biogas a net positive or negative?

In which we put anaerobic digesters on trial:

North Carolina’s Division of Air Quality wants to hear from people in Duplin and Sampson counties about a proposed biogas facility. It’s called Align RNG. It’s a partnership between Dominion Energy and Smithfield Foods. The project involves converting manure from 19 local hog farms into renewable energy.

“The methane product that is created, it gets inserted into this natural gas pipeline that’s then used for commercial and residential use,” said Zaynab Nasif, spokesperson for the NCDAQ.

This is one of those issues that has the environmental community split into opposing camps, with each side making some pretty solid arguments. I will endeavor to cover those equally, which means I'll probably piss everybody off. We'll start with taking a look at the science involved:

Anaerobic digestion is a process through which bacteria break down organic matter—such as manure—without oxygen. As the bacteria “work,” they generate biogas. The biogas that is generated is made mostly of methane, the primary component of natural gas. The non-methane components of the biogas are removed so the methane can be used as an energy source.

Captured biogas is transported through a pipe from the digester, directly to a gas use device or to a gas treatment system. In most cases, the only treatment needed is to remove excess moisture prior to combustion. However, if the feedstock contains high concentrations of sulfur, then hydrogen sulfide is removed from the gas to prevent corrosion of the combustion device.

Biogas can be processed to pipeline quality and sold to the local gas utility. Biogas can be converted to compressed natural gas (CNG) which can be used in applications such as vehicle fuel.

Understand, hog and poultry lagoons that do not capture methane simply release that horrific greenhouse gas directly into the atmosphere. In other words, the capture process cannot increase the total amount of methane resulting from animal wastes, it can only serve to decrease it, in one fashion or another. If the containment fails (picture a popped balloon), an extremely high concentration of methane would be released, bringing the (localized) air to a dangerously toxic level. But flaring generally prevents that. note: when methane is flared, it is converted to standard carbon dioxide.

One major downside of this technology: It is only economical on large-scale farms, or concentrated animal feeding operations (CAFOs). And many environmental advocates fear it will promote more use of those cruel and polluting facilities:

At a glance, anaerobic digesters seem like the perfect solution to one of society’s many messes: They take the waste from cows, pigs, and chickens raised en masse for human consumption, and from literal shit generate energy to power our cars, homes, and electronics. What could be more renewable than manure?

To that end, last year, the New York State Energy Research and Development Authority (NYSERDA) announced $16 million in funding for new and existing on-farm anaerobic digesters, an additional windfall for a sector that has already received more than $26 million from the agency. It’s a big investment, but NYSERDA is just one government agency bankrolling the digester industry: A database of renewable energy policies and programs across the country lists 96 financial incentives for anaerobic digesters, including property tax reductions, corporate tax credits, loan programs, grant programs, and performance-based incentives.

The only reason that anaerobic digesters can be considered a “green” technology is because methane is calculated to be 25 times more potent a greenhouse gas than carbon dioxide, so burning it for fuel and releasing carbon dioxide into the atmosphere instead is still considered to be a greenhouse gas “reduction.”

This purportedly green technology has divided environmentalists into two camps: The first, which includes organizations like the World Wildlife Fund and the Environmental Defense Fund, are those who think that anaerobic digesters make the best of a bad, but inevitable, situation. The second group, which includes Food & Water Watch, says the government is greenwashing and subsidizing factory farming at the expense of sustainable producers and genuinely clean, renewable energy like wind and solar.

While I am still undecided on the net benefit issue, I do not believe the government should be investing taxpayer dollars in large (corporate) farming operations. There are other ways to incentivize the application of this technology than throwing grants at it. It's not just the inhumane aspects of factory farms to consider; Big Ag exerts way too much control over the food distribution process, making smaller, sustainable (and organic) farming incredibly difficult to break even, much less generate a modest profit. That's where the government needs to step in, to encourage a more diverse and localized food production system. Even a limited reduction in food transportation (miles traveled) would be a huge benefit in addressing climate change.

All that being said, the sheer volume of meat consumption (globally) will continue to demand large factory farms. They aren't going away anytime soon. And they will continue to produce massive amounts of animal wastes. Converting it to Biogas not only blocks much of that methane from being released, it can also cut into the fracker's market, and (maybe) further discourage the construction of interstate pipelines.

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