Bridport farm to turn food scraps into electricity

BRIDPORT — Roughly one-third of all food produced around the world — 1.3 billion tons of it — gets thrown away, says the United Nations Environmental Program. Most of those food scraps end up in landfills where they accelerate global warming. In Vermont, more than a quarter of our trash is food scraps, according to the Department of Environmental Conservation.
Blue Spruce Farm, a large dairy farm in Bridport, has partnered with Casella Organics, a division of Casella Waste Systems of Rutland, to turn human food waste into energy using the farm’s Cow Power methane digester.
“It’s going to be everything from vegetable trimmings to plate scrapings,” said Casella Sustainability Director Abbie Webb. “It could be melon rinds or pineapple tops or pieces of cheese. There’s a whole variety of things out there.”
For a decade Blue Spruce has put cow manure and used cow bedding into its Cow Power digester, which collects methane and burns it to generate electricity. The pilot project with Casella involves collecting food scraps, breaking them down into a slurry, and putting that slurry into the digester, which will harvest methane that’s created as the organic matter decays.
Just as it does with methane from animal waste, the digester will convert methane from the food waste into electricity.
It’s just months away from putting its first kilowatts of electricity onto the power lines.
The Blue Spruce-Casella pilot is part of Vermont’s progress towards removing all food scraps from landfills by 2020, as part of the Universal Recycling Law, or Act 148, which became law in 2012.
“When Act 148 was passed in Vermont, we all were kind of saying, ‘Geez, there’s a bunch of composters in this state but not enough for all of this food waste that the state is looking for us to divert,” said Casella’s Webb. “It would be great if we could work with the Cow Power farms, as well, recognizing that they have additional capacity in those digesters and that those are a great potential resource.”
In January 2015, Casella won a $139,000 grant from the Public Service Department’s Clean Energy Development Fund to try putting food scraps into farm-based anaerobic digesters to make energy. A goal of the pilot project was to help create a new model to guide how food scraps can be used as a safe and valuable resource for farmers who operate digesters, keeping Vermont’s farmers at the forefront of renewable energy, Agriculture Secretary Chuck Ross said at the time.
Casting about for a dairy farm with a digester that it could work with on the project, Casella officials immediately thought of Blue Spruce, said Webb.
“Blue Spruce is known throughout the state as being an innovator,” she said. “They were the first to dive into this Cow Power idea. They’re a very creative and innovative group. And they’re very focused on sustainability.”
Audet has recently returned from the Innovation Center for U.S. Dairy’s Sustainability Forum in Chicago, where farmers from around the country (including spouse Eugene Audet and Bob Foster of Foster Brothers Farm in Middlebury) attended sessions on such topics as “Exploring the Food Waste Landscape” and “Money from Manure: Nutrient Progress Update.” The farm was a 2012 winner of the center’s inaugural Dairy Sustainability Awards.
In March, Audet became the first dairy farmer to serve on a panel at the South by Southwest film and technology festival in Austin, Texas. She joined representatives from Feeding America, Kroger and the Environmental Protection Agency in the panel discussion “What a Waste: 40 Percent of Food Discarded, 49 Million Go Hungry.”
Blue Spruce also fit the bill in terms of the project’s logistical needs. The Universal Recycling Law is stepped. Year to year, it requires smaller and smaller entities to divert food scraps from landfills. Starting in 2014, entities generating 104 tons of food scraps per year had to begin to recycle — rather than trash — their compostables. This year, entities that generate up to 26 tons per year must comply. By 2020 every household in Vermont will have to comply with the law.
So Casella needed a farm that was near to the right-size restaurants, resorts and other commercial entities now working toward Act 148 food scrap compliance.
“We had to find kind of the perfect storm, where we had customers who needed the service to have a compost facility to go to. We needed to find a farm that was innovative and willing to try something new. And we also needed a manager on our end who wanted to try something new and think outside the box a little bit,” Webb said. “Really that’s how the pilot landed at the West Rutland facility, where we’re doing our processing, and at the Bridport farm.”
Looking ahead to how other dairies around the country were incorporating food waste into their digesters, Blue Spruce built a receiving area for food scraps before Act 148 was even passed, said Audet. The receiving area is simply an underground, square concrete pit that connects to the digester. A look down a trap door shows typical used cow bedding-plus-manure digester slurry waiting to make its way through the system.
Blue Spruce expects to begin receiving a steady diet of food scraps from Casella in August, but right now Casella is still working out the kinks in this pioneering processing and delivery system.
One of the main challenges is churning food scraps into a clean slurry.
“We’ve done this long enough to know that as much as you train your customers, somebody’s going to throw the occasional plastic bag in there. Or maybe some forks are going to fall off the plate or rubber gloves, hairnets, things like that,” Webb said. “So what we want to be able to do is pull that stuff out before it gets to the first stage of the process, which will be a grinder.”
Audet said that quality control on the intake side of the process is critical, because Blue Spruce has to deal with what’s left over after the methane extraction process, including spreading some residue on their land.
“When they came to us and they asked us to take the food scraps we were like ‘Whoa!’ because people aren’t going to know how to throw their food away and make sure there’s not other junk in it,” she said. “This is going on our soil, and our soil is what we treasure to grow our crops for our cows.
“We don’t want any trash. We don’t want your vitamins. We don’t want anything but the food scraps,” she continued.
The process, said Webb, involves collecting the food scraps from customers, grinding it into a clean slurry with no contaminants, and then delivering it to the farm.
Casella ran a test run in December 2015, bringing around 1,500 gallons of slurry to Blue Spruce Farm. The results showed they still need to work on how to best remove contaminants, finesse what kinds of pumps work best at the West Rutland processing facility, and find the right kind of slurry tanker with a watertight seal.
Once slurry is being regularly delivered to Blue Spruce, the project will kick into its next phase of testing and monitoring how the slurry does in the farm’s digester.
Once the project proves out at Blue Spruce, Webb said, there would be opportunities for Casella to begin sending the food scrap slurry to some of the other farm-based digesters as well.
“I think what’s most important about this is that it’s all these different sectors coming together to solve the problem,” said Webb. “We’re coming from the waste side of things. You’ve got Blue Spruce coming from the agriculture side. And then you’ve got Green Mountain Power and the Clean Energy Development Fund from the renewable energy side of things. And we each have an important role to play to make this work. That’s really going to be more and more important as we try to tackle some of these environmental issues. We’re going to need all hands on deck.”
Reporter Gaen Murphree is at [email protected].

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