IN A RURAL valley south of Deerfield, power lines strung on new poles run along a stretch of muddy gravel between the main road and the interior of Bar-Way Farm, where hundreds of cows provide electricity along with their milk.

Manure from the cows is pumped into a massive, red, airtight tank that acts like a giant stomach where microbes consume the waste and create biogas (mostly methane) to power a one-megawatt generator—a process called anaerobic digestion. There aren’t enough cows here, or at any Massachusetts dairy, to power a system this size with manure alone, so it’s supercharged with a slurry of food waste delivered by tanker trucks a few times every day.

When the state banned commercial food waste from landfills in October 2014, anaerobic digestion advocates predicted a win, win, win—a much-needed destination for food waste, an economic lifeline to endangered dairy farms, and a new source of clean energy. But only two new digesters have started up on farms since then. (Two were in place before the organics ban and three non-farm digesters have started taking food waste since 2014.)

The large anaerobic digester tanks at Bar-Way Farm in Deerfield. (Photo courtesy of Vanguard Renewables)

Several snags have held back biogas—from the piles of cash needed to get started to the challenge of cracking into a crowded energy market. Still, proponents argue that better food waste processing and a little help from Beacon Hill could spark the promised cow-power boom.

“We are on the edge, trying to squeeze every dollar we can out of this farm,” says Dan Woodger, whose family owns Rockwood Farm in Granvillle, a tiny town of 1,500 about 25 miles west of Springfield. In addition to milk from about 350 cows, the Woodgers also sell mulch, composted manure, and potting soil. By springtime this year, they plan to add renewable energy with a 500-kilowatt anaerobic digestion system now under construction. “We’re crossing our fingers and banking on it working,” says Woodger.

Rockwood is hardly alone in its struggles. Years of low milk prices and recent droughts have sped a longer-term decline of Massachusetts dairy farms, whose ranks have plummeted 90 percent since 1970, with only 133 farms in operation today, according to the state Department of Agricultural Resources.

Anaerobic digesters make or save money in several ways. They collect tipping fees from waste haulers for accepting food waste and turn that waste (and cow manure) into renewable energy that qualifies for special state subsidies. The byproducts of the process, from the fibrous bits in the slurry which can be used for cow bedding, to the nutrient-rich “gray water” leftovers, which can be spread across fields of hay and corn as a replacement for chemical fertilizer, cut down on other costs. The handful of existing digesters took in more than 20 percent of Massachusetts’ diverted food waste in 2016, and they help the state meet its ambitious goal of cutting carbon emissions 25 percent from 1990 levels by 2020. So, why aren’t there more of them?

Partly, it’s a problem of scale. The upfront cost for a digester’s tanks, pumps, generator, controls, and grid connection can stretch into the millions of dollars.

“The farmers can’t do it on their own,” says Gerald Palano, alternative energy specialist at the Department of Agricultural Resources. The dairies need to partner with companies that specialize in financing, building, and operating farm-based digesters, such as Wellesley-based Vanguard Renewables and Ag-Grid Energy, based in Kennett Square, Pennsylvania.

But the small dairy farms that predominate in Massachusetts—the majority own fewer than 100 milking cows—are hamstrung by investors’ preference for larger systems that promise more reliable returns.

Another hurdle is a digesters’ need for uncontaminated food waste that is liquid enough to be pumped from tanker trucks into the digesters. That type of liquid food waste generally comes from food manufacturers such as Kraft Foods and Cape Cod Potato Chips, and the supply is limited.

There’s far more growth potential in food discarded from grocery stores and big institutions such as hospitals and universities. But that waste needs to be de-packaged, cleared of non-food contamination, and churned into a slurry. State grants have recently helped start up a handful of processors for this waste, and Vanguard also plans to invest in such facilities.

Finally, digesters must contend with the state’s net-metering cap—the amount of power a utility is legally obligated to “buy” from customers generating their own electricity. According to Vanguard’s executive chairman, John Hanselman, cap space is routinely “gobbled up by wind and solar projects” that have much faster permitting than anaerobic digestion.

Multiple bills are pending on Beacon Hill to exempt anaerobic digestion from net-metering caps, as is the case for other small generators, such as rooftop solar on homes. The justification would be that anaerobic digestion is tiny compared to wind and solar, and has far less growth potential. Even if every Massachusetts dairy farm miraculously installed a one-megawatt digester, the total power output would still lag the state’s current solar capacity by a factor of 10.

Even with the money to get an anaerobic digester started, the food waste to sustain it, and the market for its energy, getting to the finish line is not automatic, as evidenced by Bar-Way Farm. The digester started making gas in early March of last year, but Eversource didn’t make the final connection to the grid until December. So, for nine months, about half the gas was burned off by two large, open-air flares. The remaining gas went to the generator, but nearly all of the electricity was simply fed into a machine that dead-ended it to ground, except for a small fraction used to power the farm.

Still, there are signs that farm-based biogas may be nearing a tipping point. For starters, the state aims to divert 450,000 tons of food waste annually by 2020, a target that would be a 70-percent increase from 2016.

“We see most of the growth in capacity coming from anaerobic digestion,” says John Fischer, chief of commercial waste reduction and waste planning at the Department of Environmental Protection. In addition to Rockwood Farm, two other Massachusetts dairies are now installing digesters, and Fischer says DEP has held pre-permit meetings with several others.

Also promising is that anaerobic digester businesses are spreading into regional and national markets. In 2017, for instance, Vanguard partnered with Dairy Farmers of America, an 8,000-farm cooperative, to invest in more food waste and manure digesters across the country.

Since becoming the state’s first farm to co-digest food and manure in 2011, Jordan Dairy Farms in Rutland has been successful enough to up its generator size from 300 kilowatts to 500 kilowatts, and will soon boost it again to 800 kilowatts. Randy Jordan, who runs the fifth-generation family farm with his brother Brian, plans to add a one-megawatt system on another farm they own in nearby Spencer.

“People ask if we’re successful. And the way I describe success is that the doors are still open,” says Jordan. “We’re still making milk and we’re still making electricity.”

Chris Berdik is a freelance writer living in Milton.