This article comes from the NOFA/Massachusetts 2020 June Issue Newsletter
By Christy Bassett, Northeast Organic Farming Association / Mass Dairy Program Coordinator
At Barstow’s Longview Farm in Hadley, MA, Denise Barstow and family have taken a slightly higher tech approach to manure management. With 350 cows and heifers in their dairy herd, they have a bountiful supply of fresh manure each day.
In the fall of 2015, the farm began a partnership with Vanguard Renewables which included the addition of an anaerobic digester. Barstow’s now has one of the largest and most modern anaerobic digestion systems in New England. The zero-waste, closed-loop, farm-powered anaerobic digester converts farm and food waste into electricity, heat, and fertilizer.
The food waste that Barstow’s receives and converts to energy comes from two sources: byproducts of food production from local factories and unsold or unusable food waste from restaurants or grocery stores. All of the food waste received is in a liquid form and arrives in tank trucks who use hoses to empty their loads.
“In Massachusetts, if your business creates more than one ton of food waste per week, it is illegal to put that waste into a landfill. Those companies need to dispose of it somehow, this is a green solution that helps sustain local agriculture at the same time.” says Barstow.
Farm waste includes all of the manure from the farm’s dairy barns, which is diverted and gravity fed into the anaerobic digester. After the manure and food waste have been digested, they are left with a liquid, chemical-free, fertilizer for use on crops and soil. Denise shares “We call it digestate. We spread digestate on the 450 acres of land that we farm between cuttings of hay and corn, so several times a year. We’ve seen increased soil health and crop yields as a result of the digestate and we have decreased our chemical fertilizer usage which saves us money and is better for the environment. We’ve outgrown our feedbunk storage silo while still farming the same number of acres. It’s visibly clear that we are getting more crops from our land thanks to better land practices and the spreading of digestate.”
The manure and food waste cycles out of the digester around every 30 days. Vanguard Renewables manages the digester load so it is as efficient as possible. The anaerobic digester is very similar to a stomach – it is important to keep it fed with the right things since the wrong stuff, or too much of something, will upset it. It’s a balancing act of sorts that involves chemistry and plenty of monitoring.
The microorganisms that break down the waste naturally occur in the cow manure, which is what was needed to get the system started. (Original digesters were designed to run solely on manure. Adding food waste to the mix made it a feasible system for small and medium sized farms to install.) “Now that it’s running and the microorganisms are thriving, the system could feasibly run on only food waste. But we have plenty of manure – and it’s better for the fertilizer – so the digester gets it all!” Barstow tells us.
“Vanguard Renewables is our partner on this project. They deal with the chemistry, the maintenance, and the food waste contracts. It’s a solution that allows us to focus on farming – milking cows, birthing calves, planting/harvesting crops – and Vanguard Renewables focuses on keeping the digester running and electricity flowing to the grid from our family farm.”
The 2,100 Mwh of electrical energy produced from the digester powers the farm and heats water to warm farm buildings and the family homes. The farm-powered anaerobic digester also provides enough energy to power 1,600 ‘average Massachusetts homes’ in the surrounding community via the Eversource grid and to the Cabot Creamery/Agri-Mark Cooperative butter plant in West Springfield, Massachusetts, to which Barstow’s also supplies milk.
The massive methane engine creates energy by cycling cold water through the engines so that they don’t overheat. Water leaves the engine heated to around 180F. This hot water travels back into the digester, which accelerates the breakdown of food and farm waste (it needs to be over 100F inside the system for the microorganisms to survive).
“The hot water produced is also used to clean the robot milkers in the barn, warm some of the barn floors in the winter, and the hot water travels to 8 homes to provide forced hot water heat in our neighborhood.” shares Denise.
In addition to the amazing renewable energy that this system creates, it also sequesters 85% of the methane produced by cows the farm. “We are currently working with a student at Smith College to calculate our total carbon hoofprint between no-till practices, cover crops, green building at the store, the digester, chemical use, milk production, best practices, etc – so that we can work our way to net 0 (and someday, net positive!)”
Barstow’s Longview Farm received the 2016 Green Pastures Award which is awarded to one outstanding dairy farm in the state. Also in 2016, Cabot Creamery Cooperative won the US Dairy Sustainability Award for Real Farm Power in connection with Barstow’s Anaerobic Digester for Outstanding Dairy Processing & Manufacturing Sustainability. Cabot Creamery Cooperative purchases the renewable energy credits from the farm, which is approximately the amount of energy it takes for them to produce Cabot butter. “Cabot sends us the byproduct of butter/whey powder production from their West Springfield plant, which we turn into electricity for their plant, fertilizer, then food for our cows, and then more milk to make award winning dairy products. It’s a closed loop system!” says Barstow.
To see a video tour of Barstow’s Longview Farm and explanation of how their anaerobic digester works, check out this video from Denise on the NOFA/Mass YouTube Channel.
Learn more about Barstow’s Longview Farm and how you can purchase milk and bakery items at https://www.barstowslongviewfarm.com/