Harmony Dairy, located in Mount Vernon, is the first farm in Western Washington to install a manure lagoon cover. 

The cover, which measures about 32,000 square feet, contains gas inside the lagoon and prevents the release of methane — a dangerous air pollutant and a greenhouse gas that traps more heat than carbon dioxide — into the atmosphere. 

By keeping the gas in place, the cover will also increase Harmony Dairy’s green energy production, allowing the farm to feed Puget Sound Energy’s Western Washington power grid with an extra 1 million kilowatt-hours of electricity, according to the Skagit Conservation District.

Harmony Dairy owner Jason Vander Kooy estimated the entire project cost about $350,000, mostly funded through a grant from the Washington State Conservation Commission and the Sustainable Farms and Fields Alternative Manure Management program, with help from the Skagit Conservation District.

Vander Kooy, who is well-known in the local farming community and is a commissioner for Dike District 1, likened the cover’s appearance to the floor of a bouncy castle, its black surface rising and falling depending on how much gas is stored inside. 

The cover was first installed in October, requiring the modification of the lagoon’s dikes to secure it in place and seal the lagoon completely. Vander Kooy estimated it will take a few more weeks to complete everything and operate the system at full capacity, though it’s already storing gas. All that is left to do is some plumbing work and the installation of a second engine in the digester. 

“Once we get back this summer to full capacity, we’ll make enough electricity to power the town of La Conner,” Vander Kooy said. 

From poop to gold

Harmony Dairy had already been turning the dung from 1,300 cows into electricity for some time before the idea of capping one of its three lagoons, which can hold up to 1.2 million gallons of manure, came to be a year ago.

The raw poo would initially flow through a digester, which simulates a cow’s stomach by using an engine to maintain an internal temperature of 100 degrees, where bacteria from the cows’ guts can thrive. The poo is mixed with waste, like grease, from local food processors, creating a mixture that the bacteria consume and break down, releasing methane gas.

The byproduct then goes through a separator, where all of the solid contents are separated from the liquids, creating a sterile and soft pile of dry dung that is stored in the lagoons. Manure loses 90% of its smell in the process and makes for good fertilizer, according to Vander Kooy. 

One of the greatest advantages from manure is that it is one of the best materials to make bedding for the cows, something that, a while ago, Harmony Dairy used to make with wood shavings from local lumber mills that cost up to $25,000 per month, he said.

Boosting energy production

Due to the digester’s limited space, any excess gas had to be flared off to prevent the methane from accumulating and causing an explosion. In order to better comply with clean air regulations and mitigate any environmental impacts, Harmony Dairy reached out to the Skagit Conservation District for help.

Now, the cover can trap any leftover methane from the treated manure and hold any diverted gas that the digester would otherwise have to burn, Vander Kooy said.

Currently, the temperature under the lid is about 70 degrees, which isn’t enough for bacteria to thrive. One of the next steps in the project is to install a second engine in the digester, which can create more heat that can then be propagated into the lagoon, producing more gas that in turn can be pumped back into the concrete structure and transformed into electricity.

“It’s kind of like a secondary digester tank,” he said.

All of the energy produced goes straight into the power grid, only for Harmony Dairy to have to buy it back because the digester alone is not able to create enough energy to consistently power the farm 24/7, especially when it undergoes maintenance and gas production is low. Additionally, the farm can’t store power, Vander Kooy said. 

“We sell electricity for about half the price that we have to buy it back to run the facility,” he said. “It’s just the way it’s set up.”

A first for the region

Ryan Gelwicks, farm planner at the Skagit Conservation District, said manure lagoon covers are new to the area although they are commonly used in the Midwest.

In rainy regions, lagoon covers can be helpful in protecting rainfall from contamination and preventing the lagoon from filling up with water and overflowing, he said. 

“Dairies especially are always combating rainfall into their lagoon systems,” he said.

Luisa Loi is a general assignment reporter for La Conner Community News.