Road Hogs

How pig manure can pave our streets—and a path to cleaner energy

Hogs are big business in Missouri, home to 280 “concentrated animal-feeding operations,” and the country’s seventh-biggest pork producer last year. But the honor is a dubious one to a farm’s downwind neighbors, not to mention to environmental advocates who worry about the untreated manure in vast waste lagoons.

Enter the executives at Innoventor, a design-build firm based in St. Louis, who, with the help of almost $1 million from the Environmental Protection Agency, have created a contraption that recycles pig waste for road-paving and roofing products. The technology, which Innoventor believes has billion-dollar potential, eliminates the need for manure lagoons and could reduce reliance on fossil fuels.

Innoventor’s machinery acts like a pressure cooker: at a certain temperature and pressure, it converts solid excrement into bio-oil while reserving the wastewater. According to Rick Lux, an Innoventor engineer, the process retains the nutrients in the wastewater and results in a liquid fertilizer suitable for spraying.

Last spring, I drove with Lux to Rehmeier Farms in St. Charles County, Missouri, a landscape dotted with hobby farms with white picket fences and carpets of corn, to check out Innoventor’s Swine-Manure-to-Energy Unit in action. There was no hint of pig in the air until we were within 25 yards of a barn. “That’s one problem I don’t have,” Rick Rehmeier told me, before describing the red that’s been bleeding across his ledgers. The last several years haven’t been good for a commodity hog farmer.

But in good times or bad, Rehmeier’s 10,000 hogs produce more than 5 million gallons of excrement annually. Some of this manure can be spread as fertilizer, but the rest of it goes to—well, waste. Innoventor currently uses his barn as a test lab; as Rehmeier sees it, a future commercial partnership would cut his fertilizer costs and, most important, free up land for him to expand his herd.

Innoventor believes the application eventually can be adapted for other forms of waste—human included. The firm’s hope is to produce almost a pound of oil per pig, every day, and to supply 20 percent of the asphalt-binder market, which was worth approximately $11 billion last year, according to Poten & Partners, publishers of the Asphalt Weekly Monitor. There’s also money in the sprayable fertilizer, Lux says.

The technology passed a milestone in April, when a 300-foot stretch of test pavement went down on a busy Missouri road near a Six Flags amusement park. Lux is confident the road will hold up; he says the binder had to pass more than a dozen lab tests before transportation officials would use it. And no, he doesn’t expect drivers to raise an eyebrow. “I was out there twice on my hands and knees, putting my nose to the pavement,” he swore to me. “The road does not smell.”