A Renewable Energy Source You’ve Never Heard Of – Hog Waste!

Forget solar or wind power–have you ever heard of turning animal waste into energy?

In an era when innovation manifests in every area of life, from artificial intelligence in Alexa to an app for everything you could desire, it can be interesting to highlight weird and wacky technological solutions to urgent problems like climate change.

In North Carolina, there are projects to utilize swine waste as an energy source. One example is the partnership between Smithfield Foods, the world’s largest pork producer, and Dominion Energy, a large utility company. Another example of innovators in the field is a collaboration between Duke University, Google, and Duke Energy – the Loyd Ray Farm.

Two pigs

Is it gross? Maybe. But surprising? Not that much! For decades methane capture has existed in landfills as a way to reduce greenhouse gas emissions and provide a supply of a renewable natural gas. Similarly, hog waste-to-energy aims to capture the methane from hog waste and burn it in place of traditional fossil fuels.

The Swine Waste Breakdown

North Carolina has 8.9 million pigs – that’s more pigs than the number of people in Oregon and Connecticut combined! These hogs are mostly concentrated in big factory farms (also known as CAFOS, or concentrated animal feeding operations) that can each hold over 10,000 animals. Annually, the pigs produce almost 10 billion gallons of waste – the equivalent of 15,000 Olympic-size swimming pools.

This waste is diverted into outdoor “lagoons,” which are essentially open pools in the ground exposed to the elements. As the waste settles, it undergoes anaerobic respiration, which decomposes the organic matter and releases volatile compounds like ammonia, hydrogen sulfide, and methane.

The Pig Problem

These compounds, particularly ammonia and hydrogen sulfide, have incredibly noxious odors and are classified as air pollutants. Farm workers and surrounding communities may experience adverse health effects like increased respiratory dysfunction from particle inhalation, miscarriages after ingesting nitrates that might leak into groundwater, and increased instance of diseases like meningitis after pathogen exposure. Thus, activists and neighbors have long railed against disproportionate hog farm placement in low-income communities of color.

Local health effects aren’t the only negative—the escape of methane from lagoons have detrimental climate effects. Every molecule of methane has 25 times the warming potential of a molecule of carbon dioxide, and in our rapidly warming world, methane and animal agriculture play an important role in discussions about climate change.

No Wasted Opportunities

Capping hog waste lagoons with anaerobic digesters instead of leaving them exposed to the air offers a solution on many fronts. Covering the waste lagoons reduces the escape of odors and harmful pathogens – both of which negatively impact local populations. A cap would also lessen the risk of flooding from rainfall and reduce the amount of methane emissions entering the atmosphere.

Covered hog waste lagoon captures methane

The captured biogas collected from various lagoons via these digesters is then piped to a central processing plant, where it’s refined to a higher-quality natural gas, pumped into pipelines, and then burned for energy as an alternative to traditional fossil fuels like coal.

These hog waste-to-energy initiatives are particularly attractive to companies that have made commitments to be carbon-neutral or to increase the percentage of their renewable energy consumption, especially because carbon offset credits are available through the capture of methane.

Swine waste-to-energy is an example of a smart investment that fulfills the triple bottom line: it has economic benefits due to the profit available from sale of renewable biogas, social perks from the reduction of odor to surrounding communities, and environmental assets like the prevention of powerful greenhouse gas emissions into the atmosphere.

In Conclusion: We Need Creative Energy Sources

With the degree of climate change already seen today and predicted for the future, finding unique energy sources that don’t rely on fossil fuels will be crucial to a climate action plan. Repurposing a literal waste product as renewable energy is an example of the innovative thinking we need to reduce our impact, not only on the environment, but on our neighbors as well.

Image credits: Hogs (Liz West, CC); Capped lagoon (James Morrison/WUNC)