The nose-crinkling smell wafting up from Skagit County farm fields has different meanings for different people.

For farmers, it’s a reassurance that their land is being replenished with nutrients.

For city folks, it’s a signal to roll up their car windows.

To entrepreneurs Daryl and Kevin Maas, that not-so-subtle scent represents an untapped green energy source that could one day power thousands of homes throughout the county.

Electricity from cow pies?

You bet.

Using a simple process that’s been around for decades, the Mount Vernon-born siblings would like to build up to five small power plants capable of converting cow manure into usable energy.

Their company, Farm Power Northwest LLC, will construct, fund and operate the plants on land leased from area dairy farms.

The first site in south Mount Vernon, which they hope to have up and running sometime next year, will process 90,000 gallons of manure a day.

“When they hear about it, most people starting thinking of jokes,” Kevin Maas said. “And there’s quite a few.”

But turning manure into power could be serious business. At full capacity, their first site will create enough electricity to power the entire town of La Conner.

Each location will require an anaerobic manure digester, which consists of a heated concrete holding tank, where bacteria converts portions of the manure into a methane-rich gas.

Burning the gas stokes a nearby power generator, and the resulting power is sent to the grid.

The company will build the digesters near large concentrations of dairies so that manure can be pumped in from the closest ones and trucked in from others.

The brothers aren’t farmers. Daryl Maas, 29, is an Air Force veteran.

His older brother, Kevin Maas, 31, is a former high school history teacher, who recently completed a master’s degree in sustainable business from the Bainbridge Graduate Institute.

The Maas brothers are banking on the likelihood that the project will be an easy sell for local dairy farmers and power companies.

So far, so good.

Local dairy farmers, who’ve been beset in recent years by unstable milk prices, are interested because the project would mean additional revenue via manure sales.

Meanwhile, state mandates to increase green energy production have made the project enticing for Puget Sound Energy, which has already drafted an agreement to purchase power from Farm Power Northwest.

Compared to solar and wind power, methane digesters provide an uninterrupted source of energy.

“Solar only works during the day; wind only works when it’s windy,” Daryl Maas said. “This goes 24/7.”

Digesters have global warming related benefits, as well.

Normally, when cow manure is spread over a farm field as fertilizer, methane — a greenhouse gas — is released into the atmosphere. A digester captures that gas and keeps it out of the atmosphere.

Ultimately, each cow served by the digester has the same effect as removing one car from the road.

So far, only two other Washington dairies, including one in Lynden, operate digesters.

The catch? For starters, the systems aren’t cheap.

The Maas brothers’ first site will cost about $4 million.

Ned Zaugg, dairy specialist at the Washington State University Skagit Cooperative Extension, said that the economics of running a digester have kept the technology off of farms here.

Digesters are popular in the Midwest, where herds are larger. But dairy farmers in this region typically don’t have herds big enough to make a digester profitable.

Even if they did, most are saddled with too much debt to finance such a project.

Zaugg was involved in a study in Stanwood that explored the feasibility of creating a centralized digester for a collection of smaller farms.

Even then, the numbers didn’t work out.

“When you tallied everything together, it was a negative,” he said.

But when it comes to alternative energy markets, things are changing very quickly.

Shulin Chen, who directs WSU’s Agri-Environmental and Bioproducts Engineering Research Group in Pullman, believes digesters could soon be all the rage as the prices small-time power producers earn are rising.

“As energy prices go up, digesters are becoming more feasible,” he said. “I’m sure we’ll see more.”

The Maas brothers believe high energy prices and a regulatory environment favoring green energy make this the perfect time to launch their project.

Puget Sound Energy appears willing to commit to a high price for methane power for at least the next decade.

Meanwhile, the brothers’ initial proposal to sell carbon credits to the Portland, Ore.-based Climate Trust has already been accepted.

Those two income streams should generate more than half of the company’s revenues.

The remainder will come from selling the digester’s solid byproduct, which can be used as cow bedding or sawdust. The company also expects to receive federal tax credits.

The brothers launched their fledgling company in April. Since then, they’ve been shuffling back and forth between dairy farms and boardrooms in Seattle, where they’ve been meeting with lawyers, accountants and potential investors.

In the end, they hope their company can play a role in sustaining the local dairy industry.

“We like the idea of helping preserve the same farms we drove by as kids,” Daryl Maas said.

* Josh Lintereur can be reached at 360-416-2141 or at jlintereur @skagitvalleyherald.com.