Eric Powell of Andgar Corp. said it is one of the most recent up-and-coming “green” ideas.

In 2000, Andgar partnered with GHD Anaerobic Digesters in Chilton, Wis., to build an anaerobic digester they needed for the Northwest. GHD has the patented design and Andgar builds them.

Andgar partnered with Vander Haak Dairy Farms in Lynden in 2004 and created a plug flow anaerobic digester that mixes cow manure and pre-consumed food waste, also known as substrates, to create renewable energy with the methane biogas produced.

Energy, bedding and fertilizer

The digester is 16 feet tall and “digests” about 45,000 gallons of manure and substrates a day.

Powell said the Vander Haak’s farm collect about 30 gallons of cow manure per day for the digester.

It has a central collection pit that collects the material and a pipeline from the collection tank, which is heated to 100 degrees to help “digest” the material, and creates methane biogas for energy that goes out to a tower and gets distributed to Puget Sound Energy.

Along with an energy output, the digester also helps create bedding and fertilizer.The materials go through a solids separator so the solids and liquid separate, and the farm uses the liquid for fertilizing the fields and solid bedding material that looks like peat moss or compost for their animals, as peat moss replacement or for soil amendment for landscapers and greenhouses.

Powell said Methane is 20 times more harmful to the environment than carbon dioxide. It is known as a greenhouse gas, which contributes to global warming.

So rather than that substance going into the atmosphere, it can go into the digester to create renewable energy.

“This process is very good for the environment and benefits everyone,” Powell said. “Food companies do not waste money on waste transportation and dairy farms get more money for their business.”

GHD’s website said it has provided environmental engineering for more than 17 years for reliable, proven solutions for farmers that are cost-effective, operate automatically and require low maintenance.

Western takes a tour
Western Students for Renewable Energy Club has arranged a tour of the Vander Haak Dairy Farm on Sunday, Feb. 27 to learn more about their digester system.

Club president Hilary McGowan, a Western senior, said she thinks it is important for everyone to consider renewable energy, and has been working on getting an anaerobic bio-digester on Western’s campus.

She and some students within the club are currently working on a grant proposal.

She said since it is such a huge proposal, it would take a lot of funds, they are making sure all of the research baselines are covered.

“It would take food scraps from the dining halls and convert them into methane gas for energy and then use the remaining as compost,” McGowan said.

McGowan emphasized that it will save Western a lot of money and reduce the amount of waste.

“We could just throw extra food that is not used in the digester, and it would reduce costs of throwing away the waste and at the same time give us extra energy,” McGowan said.

Club member Matt Moroney agrees that reusing any extra food waste would be beneficial and help save the environment.

“When those substances put methane into the atmosphere and pollute our water, it is about 20 to 25 times more potent than carbon dioxide,” Moroney said. “So why not collect these materials and allow us to obtain another source of revenue and creating renewable power.”

Vander Haak Dairy Farm
The Vander Haak Dairy Farm has about 750 cows they use for manure. The farm also takes in pre-consumed food waste to create renewable energy.

Pre-consumed food waste, also known as substrates, is food that kitchen or restaurant staff throws away due to overproduction, expiration, spoilage, trimming or handling issues, to create the renewable energy. 

Darryl Vander Haak said the farm has been in his family since 1974 and he has worked with Andgar for the past six years.

It has been an especially positive note for Vander Haak’s energy bill, which is usually only $4 a month because he gets to use the energy from the digester directly to his house through the power line connected to the digester that also distributes to Puget Sound Energy.

“I think this is great because it really goes with today’s ‘thinking green’ attitude and I like to be a part of it,” Vander Haak said.

Powell said if anyone around Whatcom County looks at their Puget Sound Energy power bill, they can check the box for renewable energy and they will be supporting  projects such as this.

Digester designs
There are different designs of digesters; the main ones Powell mentioned were a plug flow and complete mix digester.

In a traditional plug flow digester, material is pumped into the digester and pushes material from the days before, which  gets thinner as it goes through the digester, because it is constantly being pushed by thicker material.

A complete mix digester is mixed by a mechanical mixer, so the benefit of that is it can handle a wide range of material thickness, usually between 3 percent to 12 percent solids.

But since the mixing is mechanical it takes a lot of power and the retention time cannot be measured.

“A guaranteed retention time is important because it guarantees that we are killing bacteria in the manure so it can be safely used for bedding,” Powell said. “We make sure that we are getting the most efficient biogas production we can based on the material we are digesting.”

Powell said with a plug flow, things are moving at a steady rate and they can guarantee at 20 to 22-day cycle of material going in and then coming out.

The Vander Haak farm uses a modified plug flow digester where they incorporate a little bit of the plug flow and complete mix.

Their modified plug flow digester re-introduces a portion of the methane biogas to stimulate mixing in the digester rather than using a mechanical mixer.

“This allows us to mix without using a lot of electricity like you would with a complete mix digester and also have a Plug Flow method because material is steadily pushed, so we can guarantee retention time,” Powell said.

Powell describes Andgar as a great company to work for and enjoys being in this renewable energy research because he believes it looks toward all of the future energy resources.

“Having renewable energy resources will lift our current economy toward a green economy to strive. Think about it. What if we converted all dairy farm to use this renewable energy technology; it would provide not only cleaner water but save us tons of money, provide jobs, generate electricity and save our environment.”