Renewable Energy on Vermont Dairy Farms — Challenges and Opportunities

Sandy Levine | @CLFLevine

A version of this article first appeared in the Sunday July 21 edition of the Rutland Herald /Times Argus.

Helping farms and Vermont businesses thrive while cleaning up the environment is a win all around.

Conservation Law Foundation is pleased to serve on the Executive Committee to help Vermont’s homegrown Green Mountain Power Cow Power program to pave the way for cleaner air, happier farm neighbors and more successful Vermont businesses.

The program works by turning farm manure into electricity. The average cow produces more than 30 gallons of manure a day. Multiply that amount by 1,000 — the numbers of cows on a typical Cow Power farm — and you have a lot of cow manure. That means there is also a lot of methane, which can be used to create electricity.

Here is how it works. The manure is placed in a digester at the farm that converts the waste into methane gas. The gas fuels an engine that runs an electric generator.

Gases that would otherwise create a nuisance and release harmful and very potent greenhouse gases are instead captured to produce electricity.

Farms have an additional revenue source, and the rest of us have cleaner air and renewable power.

Currently GMP Cow Power farms are producing electricity for nearly 3,000 Vermont homes and businesses. With the expansion of GMP Cow Power so that it is now available to any GMP customer, there are opportunities to grow the program even further. Customers can sign up and make a voluntary 4-cent-per-kilowatt-hour payment on all or a portion of their electric bill. The contribution goes directly to support Cow Power projects to reduce pollution and produce 100 percent renewable power that gets used in Vermont.

Methane is one of the most potent greenhouse gases. Its global warming impact over a 20-year horizon is nearly 75 times more potent than carbon dioxide because methane traps radiation much more effectively. But instead of simply being released into the air, farm methane can be used to produce electricity. This reduces pollution and makes the farm methane projects some of the best fighters of climate change.

These projects don’t just create renewable energy; they effectively capture some of the most potent global warming gasses.

Twelve GMP Cow Power farms remove the equivalent of over 40,000 metric tons of carbon dioxide from the atmosphere every year, in addition to replacing 6,800 tons of carbon from other electric sources. This is equivalent to removing more than 9,000 cars from the highway each year that would have burned 5.3 million gallons of gasoline. These are big numbers — and the biggest benefit comes from removing methane.

Removing farm-generated methane is great but it comes with some real challenges. The first is financial. The equipment is expensive and requires steadfast maintenance to operate smoothly. It is not like a refrigerator you plug in and forget about, and is mostly economically viable only for our larger farms at this stage of technological development.

To be a real success, we need to make this work for smaller farms as well. A few smaller-scale applications are underway that look promising. For instance, some simpler digesters are used in other parts of the world. The ingenuity of Vermont’s farmers and engineers will undoubtedly yield a product that works well on smaller farms within the next decade, but we don’t have it yet.

One way to improve the economics is to find a way to value and pay for the many real benefits of farm methane projects. They are counted now as renewable power, but offer additional advantages as well. One approach would involve credits or payments that recognize their value in reducing methane pollution. That could make it economically feasible to operate smaller-scale projects, or even applications that use digesters alone, without producing electricity.

Another opportunity – and challenge – is expanding the materials used in the digester. Some farms now use additional organic waste in their digesters, such as waste from ice cream manufacturing or fish production. Currently only pre-consumer waste can be used on farms, and off-farm substances cannot make up more than 49 percent of the total digested waste.

New opportunities arise as Vermont moves to expand digesting for managing solid waste. Some organic wastes are very good fuel for digesters and can produce more methane per pound than manure, but the challenge is to make sure the waste is handled well from beginning to end. After digestion is complete and electricity is made, waste and nutrients still remain. We must be careful not to import or spread more nutrients than our land is capable of absorbing on our farm fields. Lake Champlain is already suffering from excess nutrients, and digesting our waste should not be allowed to make this problem worse.

Another new possibility includes expanding how the “products” made with farm digesters are used. Currently farms use the heat produced from the digesters to keep the digester warm. But this heat could also be used to support greenhouses or a new district heating project, among other possibilities. The challenge is to be as resourceful as possible and, like our farms, use as much of the output as possible. This will expand the reduce, reuse and recycle practice even further by adding “upcycling” — converting waste materials into products of better quality or with greater environmental value — while providing an additional revenue source.

Cow Power presents real, exciting opportunities and challenges. The leadership and innovation Vermont’s farms, businesses, utilities and customers have already shown are poised to take these efforts even further.  If you are a GMP customer, your participation in GMP Cow Power and your 4 cents per kilowatt-hour makes a huge difference. Sign up now at:



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