From Pig Poop to Power
Industrial-scale livestock farms have made meat more accessible than ever before by lowering costs and increasing availability across the United States. Obviously, producing more meat requires more animals. But one aspect that is often overlooked is the fact that more animals means more animal feces. For example, a single pig can produce up to 13 pounds of manure a day. Now consider Duplin County. The “pork mother lode for the $14 billion meatpacking goliath Smithfield Foods” houses 2.3 million hogs which are estimated to generate twice as much waste each day as the entire city of New York. With such an immense amount of waste to deal with, farms have to institute manure management infrastructure.
The hogs are raised in climate-controlled barns with slatted barn floors through which the pig’s manure falls through to keep the animal pens clean. The fallen manure is temporarily stored in concrete pits beneath the pins until water is used flush the waste out to large manure lagoons for storage and treatment. These lagoons vary in capacity from 1.7 million to 3 million gallons. This system, called a liquid manure management system, has seen an increase in use since 1990 as dairy and swine facilities have grown in size. On most farms, the manure is broken down by naturally occurring bacteria over a period of 6 to 12 months, releasing immense amounts of biogas into the air. Biogas is produced when any organic waste is broken down and in the case of swine poop, is 60% to 65% methane. Methane emissions from manure management have risen by two-thirds between 1990 and 2018 to 2.5 million tons, due in large part to the growing livestock farms and the manure management systems they have chosen to institute. It is also estimated that the world’s livestock contributes 14.5 percent of annual global greenhouse gas emissions. Considering that methane has a warming impact at least 25 times greater, per pound, than carbon dioxide, minimizing the amount of methane outgassed should be of utmost importance. So, what can be done about the millions of pounds of livestock manure being produced daily?
Companies such as Roeslein Alternative Energy (RAE) have decided to essentially trap the biogas produced from the anaerobic digestion of swine manure before it reaches the atmosphere and to use the biogas to produce renewable natural gas. The manure lagoons, which are typically left uncovered, are blanketed by an impermeable cover that traps the biogas emitted as the anaerobic organisms break down the manure inside. The captured methane gets pumped out of the anaerobic lagoon, also called a digester, to a processing station that removes water vapor and carbon dioxide. After the processing, pure methane is left over which can be injected into natural gas lines used to generate power across the country.
Smithfield Foods has partnered with RAE to explore different ways of transforming hog manure into electricity and natural gas with the formalized goal of reducing their greenhouse gas (GHG) emissions 25 percent by 2025. Smithfield Foods has also partnered with Dominion Energy in an attempt to expand the manure digestion process to an industrial scale. The partnership will spend $500 million by 2028 on creating the necessary infrastructure to capture the methane produced at hundreds of hog farms around North Carolina. The farms will then be connected using underground pipes to collect methane to be fed into existing natural gas pipelines. The Smithfield and Dominion Energy project will capture about 105,000 metric tons of methane each year, which is equivalent to removing half a million cars from the road in terms of reducing the country’s greenhouse emissions. “Essentially what we’re doing is converting methane into carbon dioxide, which is a 25-to-1 benefit for the climate,” says CEO of Dominion Energy, Thomas Farrell. Additionally, companies will pay farmers for the methane-based fuel that is produced on their land, introducing a new revenue stream for farmers who have traditionally relied entirely on crops or livestock. Although manure digesters are an apparent win for both climate activists and farmers, there are concerns and complaints regarding the smell of the lagoons, the potential of lagoons flooding during storms, and the welfare of the animals involved.
Furthermore, how much of an impact does using biomethane renewable gas actually have on eliminating the need for fossil fuels? According to the U.S. Energy Information Administration, the most optimistic scenario for 2040 has the amount of RNG produced annually from manure yielding just over 1 percent of the amount of natural gas that conventional wells yielded in 2019. Not to mention that RNG cannot compete with low-priced ordinary natural gas because the cost of producing RNG from animal manure is 10-15 times greater than that of natural gas. Roman Kramarchuk, head of energy scenarios, policy, and technology analytics at S&P Global Platts, says, “without incentives, RNG is not economic at all.” And yet, RNG is still attracting sizable investment due in large part to the help of said subsidies and incentives.
Around the U.S., policies are beginning to acknowledge RNG’s potentially lighter environmental footprint and supplying subsidies that can make RNG a viable option. No sector has felt the impact of these subsidies more than the transport field as there are movements to replace diesel in trucks and busses with RNG produced by manure. California has instituted one of the most ambitious clean motor fuel laws in the nation called the Low Carbon Fuel Standard (LCFS). This regulation is designed to reduce greenhouse gas emissions associated with the life cycle of transportation fuels used in California and does so by generating credits of electricity produced from renewable or low-carbon intensity sources. Transportation companies in California are required to have a certain percentage of their fuel come from low-carbon intensity sources, so they will purchase these credits to fulfill their clean fuel requirements. RNG from swine operations is a very valuable commodity in the industry because of its ability to both prevent methane emissions and to displace petroleum-based diesel fuels, making it better than a carbon-neutral fuel but rather a carbon-negative fuel. This distinction of course raises the fuel’s price in the market. California’s LCFS has a set price of about $200 per ton on carbon reductions which translates into an incentive of nearly $70 per million Btu (British thermal unit) for manure-based RNG projects. Other incentive programs that mandate increasing the use of renewable fuel are available around the country and more and more continue to pop up each year. Even in states where regulations are not in place, private market selling to companies that are trying to meet internal emissions targets account for a large amount of clean fuel transactions.
Despite livestock manure accounting for such a small amount of the nation’s energy production for the foreseeable future, this technology should not be abandoned. It is estimated that between 30% and 60% of cattle and pig manure could be used to make RNG. There are more than 50,000 dairies and 60,000 pig farms in the U.S., yet only 255 farms have biogas digesters and only a few of those are connected to pipelines. This shows just how small the reach is of the emerging manure operations. But scientists and energy companies must press on and continue to develop optimized bacteria and techniques to maximize the amount of energy produced by animal waste while also minimizing the amount of destructive gases released into the atmosphere. Consuming meat and the necessity for animal farms will not be going away anytime soon, so optimizing the process for the betterment of humanity and for the planet itself should be prioritized.
Works Cited:
Bourne, Joel K. “Harnessing the Power of Poo: Pig Waste Becomes Electricity.” National Geographic, 13 July 2016, www.nationalgeographic.com/culture/food/the-plate/2016/07/pig-waste-energy-north-carolina/.
Charles, Dan. “Big Companies Bet On Cleaner Power From Pig Poop Ponds.” NPR, NPR, 22 Nov. 2019, www.npr.org/sections/thesalt/2019/11/22/781565978/big-companies-bet-on-cleaner-power-from-pig-poop-ponds.
“Low Carbon Fuel Standard (LCFS) Guidance 19-06.” California Air Resources Board, 2019, ww2.arb.ca.gov/sites/default/files/classic//fuels/lcfs/guidance/lcfsguidance_19-06.pdf.
Meyer, Gregory. “Methane from Manure Offers Green Fuel Revenue for US Farmers.” Financial Times, Financial Times, 25 June 2020, www.ft.com/content/773b8934-51a7-11ea-a1ef-da1721a0541e.
“Smithfield Foods, Inc. Meat Products: Smithfield Foods Company USA.” Smithfield Foods, Inc. Meat Products | Smithfield Foods Company USA, www.smithfieldfoods.com/turning-manure-into-energy.
“Swine Manure To Biomethane.” BioCycle, 19 June 2020, www.biocycle.net/swine-manure-biomethane/.
