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A pledge by Smithfield Foods, the world’s largest pork producer, to transform hog manure into a clean natural gas aims to mint hundreds of pig farms in North Carolina into renewable energy gold mines.

The scale envisioned by Smithfield aspires to go far beyond the roughly 40 hog farms in the United States that currently convert swine waste to energy. The concept has been tinkered with for several decades, but it has never taken off on a grand scale because the technology and logistics have been considered too expensive and too experimental for widespread adoption.

There’s no dispute that the science, which relies on releasing microbes to break down hog waste in an airless chamber, is capable of yielding an endless supply of energy-rich biogas. The agricultural fuel that pigs yield is interchangeable with the natural gas that’s most commonly obtained by fracking, a controversial drilling technology that requires injecting chemicals under high pressure to crack underground rock formations and release the gas trapped deep below.

Smithfield’s goal, set in cooperation with the nonprofit Energy Defense Fund, is to reduce the company’s greenhouse gas emissions by 25 percent by 2025 on hog farms in North Carolina, Missouri and Utah. One of the most potent greenhouse gases, methane is released by animal waste and other organic matter as dead stuff decomposes. At some landfills, the gas is flared off in perpetually flaming torches to keep it from entering the Earth’s atmosphere.

Smithfield, which controls most of the state’s 9 million hogs, plans to capture the methane, remove impurities, and sell the gas to bidders willing to pay a premium for clean energy. The moonshot appears within striking distance today, as new energy markets have emerged where bidders pay top dollar for biogas derived from animal waste, landfills and other biodegradable refuse.

“This model has the best chance of any that have come along so far,” said Mark Rice, the interim director of the Animal and Poultry Waste Management Center at N.C. State University, who has worked on improving hog waste treatment for two decades. “It’s a higher-than-most probability of success.”

Squeezing energy molecules from swine feces won’t solve all of the hog industry’s image problems, however. When the biogas leaves the farm, hog farmers will be left with voluminous quantities of liquid waste that will have to be sprayed on crop fields as fertilizer, just as farmers do now. Complaints of odors are not likely to dissipate either, because the primary source of the acrid stench neighbors complain about is the hog houses where the animals live, not the outdoor lagoons where the waste decomposes, Rice said.

“This isn’t a total solution,” said Maggie Monast, Environmental Defense Fund’s senior manager for economic Incentives and agricultural sustainability. “It’s good on greenhouse gases but it does not address water quality or odor concerns.”

Smithfield has said its ambitious greenhouse gas project is not a moral exhibit, but a capitalist undertaking contingent on making profit from selling the biogas. The revenue would come from selling the gas and from collecting subsidies that power companies and oil producers are required to pay for the clean fuel.