In this video, you’ll see that Commissioner Walt Whitcomb, Maine’s Commissioner of Agriculture, makes a folksy but very important point: anaerobic digestion benefits from constancy, whereas other renewables, like wind and solar, do not. Sometimes it rains, and sometimes the wind doesn’t blow. But cow power is constant.

For those of you who like technical details, anaerobic digestion has a capacity factor (CF) of about 0.9, or 90%. Wind, by comparison, typically has a capacity factor of about 0.3, or 30%. Capacity factor is a ratio of actual energy produced vs. the total energy potential of a given system, over a fixed period of time. In simpler terms, think of CF as a measure of total and actual system runtime, relative to a theoretical runtime of 100%. That means anaerobic digestion delivers a much greater scale and supply capacity than what seems obvious at first glance (1MW anaerobic digestion plant = 3MW wind farm). Put another away, a 1MW anaerobic digestion plant generates the same amount of energy as a 3MW wind farm.

If an investor’s most important metric is generation output per dollar of capital invested, then the ‘steady stream’ of heat and electricity produced with anaerobic digestion becomes very attractive to investors, who crave predictability and a guaranteed result. That’s something for state and federal policy makers to think about as they write food waste legislation, and craft programs to encourage the development of renewable energy. Every day Stonyvale Farm feeds the cows, and within 24 hours the ‘guaranteed return’ is fuel for the digesters. It never stops — GUARANTEED!

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