LANSING, Mich. (Michigan News Source) – One of Michigan’s largest water contaminants—liquid manure—could become a major source of renewable energy for the state.
How does it work?
Manure from farms is dumped in a machine called a biodigester, which simmer the feces and urine in broth and keep it away from oxygen until it is converted to methane. This odorless gas, in turn, can be used to generate electrical power or produce useful chemicals.
By itself, methane is one of the most common manmade greenhouse gases, second in quantity only to carbon dioxide. It accounts for 16% of global emissions and is almost 30 times better than carbon dioxide at trapping heat in Earth’s atmosphere. According to the EPA, reducing methane emissions would have “a rapid and significant effect on atmospheric warming potential.”
Methane is also the cleanest-burning fossil fuel, producing more heat and light energy by mass than any other fossil fuel, including coal and gasoline. Burning methane—converting it to useful energy—virtually eliminates its environmental impact and provides a powerful source of useful energy.
About one-fifth of all methane emissions come from agriculture. Biodigesters ensure that at least part of these emissions gets put to good use, reducing the amount of methane that makes it to the atmosphere.
What are the industry developments?
Michigan is the second-largest center for manure biodigester development after California. After Governor Whitmer’s new clean energy bill mandating increased reliance on renewable energy over the coming years, renewed attention has been drawn to the biodigesters. Regulations are changing, and some state politicians worry they may impede technological progress.
A recent letter penned to the Department of Environment, Great Lakes and Energy expressed concerns that new laws treating biodigesters like wastewater facilities saddles this green energy method with unnecessary testing requirements and facility alterations.
“At a time when Michigan is progressing towards ambitious renewable energy standards, one would expect technology capable of converting waste into clean energy … to be welcomed rather than constrained,” State Representative Joey Andrews wrote in the letter to EGLE. “We strongly urge EGLE to reconsider the permitting requirements for community digestors.”
What do critics say?
Alongside methane, biodigesters produce solid digestate, which farmers apply to the ground like manure. Under Michigan’s current manure laws, which some say are outdated, runoff from both manure and digestate are the primary cause of toxic algae blooms in Lake Eerie, the Saginaw Bay, and Lake Macatawa. The practice has also resulted in groundwater contamination.
“We’re facing a dystopian future where we’ve turned animals in confinement operations into our gas stations and power plants,” Tyler Lobdell, a staff attorney at Food and Water Watch, told BridgeMI. “Factory farms are designed to be extractive and polluting facilities. That’s how they operate.”
Critics of biodigesters argue that the facilities are costly both to taxpayers and the surrounding environment with little return on investment.
What’s next for Michigan?
Many believe that despite current limitations, biodigester technology will be a powerful tool in helping Michigan make the switch to renewable energy.
“Digester technology really has a foothold and is no longer viewed as novel,” said MSU research engineer Dana Kirk. “I think it is the wave of the future, but it’s also a stepping-stone technology for the next wave, which would be improving how we manage nutrient separation that allows us to create value-added products.”
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