A column by Mike Nichols in the Milwaukee Journal Sentinel seems to present an either/or dicotomy between wind-generated electricity and digester-generated electricity. Nichols wrote:
This is something to ponder as we head into a new year – and a new era. We are developing huge wind farms in Wisconsin. People are talking about setting turbines out on our Great Lakes. Breaking wind could be the key to the future. The only question now is “What kind?”
Do we harness our skies or our pies?
The Journal Sentinel published the following response from RENEW’s executive director Michael Vickerman:
The statement that Wisconsin can generate more electricity from manure than from windpower is not supported by the numbers.
To make biogas from manure, a dairy farm operator has to keep the cows inside and under a roof at all times. Only in a confined setting is it possible to collect cow manure and break it down in an oxygen-free digester that results in methane. Of Wisconsin’s 1.3 million dairy cows, only one-eighth of them live in confined animal operations. The average dairy cow here is part of a small herd and spends a considerable amount of time in pasture.
As stated in the column, Wisconsin is well ahead of other states in capturing energy from dairy cow manure and generating electricity with it, and there is certainly room for growth. Bear in mind, however, that takes more than 2,000 dairy cows to produce enough methane to equal the output from one commercial wind turbine. Yes, Wisconsin now boasts about two dozen biogas generation systems attached to dairy farms. But compared with the output from the 251 wind turbines installed this year at four different projects, their electrical production is quite modest.
Though other locally available resources–solar, small hydro, woody fuels and biomethane—will certainly play a larger part in contributing to Wisconsin’s electricity mix, wind energy will remain the renewable energy workhorse for the foreseeable future.
Finally, the Governor’s Global Warming Task Force recommended a raft of policies to achieve a renewable energy goal of 25% by 2025, no small undertaking I can assure you. If we are serious about achieving that goal, we must accept expanded contributions from all eligible resources. We do not have the luxury of playing favorites.