Biodigesters: Say What?
Methane Biodigesters are systems that use anaerobic digestion to convert organic waste, such as dairy cow manure from Concentrated Animal Feeding Operations (CAFOs), into methane gas (CH4). Methane gas is a greenhouse gas with 28 times more heat trapping potential than carbon dioxide (CO2), however, when collected and contained it can be sold as a fuel source for various forms of energy like electricity, heat and transportation fuels. Often times, the methane produced is just ignited and burned to the atmosphere to convert methane into carbon dioxide, which has far less greenhouse heat trapping potential. This reducing of CH4 into CO2 has an apparent value because it is being marketed as “saving” our atmosphere from escaped methane, but not from escaped carbon dioxide.
While this biodigester technology has been touted in recent years as a sustainable, eco-friendly, “renewable“ energy resource and also a method for farm waste management, there are some concerns regarding the potential environmental hazards associated with toxic biodigester waste products. There are also concerns about the huge profits being made in the carbon credit market. A “carbon credit” (CC) refers to a kind of permit that represents one metric ton, or 2,204.62 lbs. of CO2 removed from the atmosphere. They can be purchased by an individual or, more commonly, a company, to make up for carbon dioxide emissions that come from industrial production, delivery vehicles or travel.
While biodigesters are intended to reduce greenhouse gas (GHG) emissions by capturing and utilizing methane, they can also emit other gases such as carbon dioxide, nitrogen oxides, hydrogen sulfide and escaped methane. These gases have been linked to air pollution, climate change, and health problems in humans and animals.
Additionally, the process of biodigestion will create an end product called digestate, which is a nutrient-rich slurry containing high amounts of nitrogen and phosphorus that can be used as fertilizer if properly administered. Digestate also contains infectious, pathogenic microorganisms that can survive the warm biodigestive process like E.coli and Salmonella. If not properly managed, digestate can become a source of pollution. If it is applied to fields in excessive amounts, it can lead to nutrient runoff, which can contaminate nearby water sources and contribute to the overgrowth of algae within those bodies of water. Overgrowth of algae can steal all of the oxygen out of the water creating “dead zones” which suffocates all oxygen breathing organisms in the zone.
Biodigesters really do not solve any of the environmental problems communities are dealing with─problems like how to reduce air and water pollution that are affecting the health of our communities. What biodigesters can do is create Biodigesters in Kewaunee County Photo by Paul Leline 9 another pathway for CAFO farmers, digester owners, business investors, and industrial developers to collect massive profits from the biodigestion of cow manure.
Here is a recount of a letter written by a former Kewanee County resident, Thomas Cretney, Engineer:
“I am retired with two engineering degrees and formally from Kewaunee County, WI, where five cows exist for every human. We have 17 CAFOs in a karst region with 30% of residential wells impacted from nitrate and other contaminants.
“I was hired in 2017 as an expert for Holland Township in Brown County to review the permit to build a $65 million digester for about 24,000 cattle. The permit was voted down, but the project was moved across the road to another township and is in the final stages of completion and ready for startup.
“The digester construction cost is supported by public funding from taxpayers and rate payers. Focus on Energy in Wisconsin granted renewable energy funding of $15 million to construct the $65 million Brown County digester. In addition, other millions of dollars are expected from Federal AG subsidies for its construction. The unknown investor(s) then funds the remaining construction costs to claim ownership.
“The investor/owner of a biodigester sells methane for fuel and/or collects carbon credits for reducing greenhouse gasses by collecting methane and burning methane (both actions keep methane out of the atmosphere). Other businesses, for example in California, that cannot so easily reduce their greenhouse emissions can purchase carbon credits from a biodigester in Wisconsin, and thus offset their excessive carbon emissions. They pay for their pollution.
“Digesters are finicky; they require temperature control, proper pH and other conditions to produce methane. The 120 lbs. of daily waste of one cow contains about 120,000 BTUs of heat energy, an amazing creature. The digester is claimed to recover about 1/3 of that energy as methane (but I have never seen proof) or about 40,000 BTUs per cow per day. The value of that energy sold to the gas pipeline is about $.20 per cow per day. The operating cost of the digester alone is estimated to be $.50 to $1.50 per cow per day. Disclosure of actual profits, subsidies for construction, and value of CCs transferred to the unknown investor/owner are not required to be on record to the public. The economic transfer of wealth to the unknown investors should be available to the public since those funds come from the public to support the carbon credit.
“Today the methane industries claim methane as renewable transportation fuel to gain more value from the public funding that supports the CC. But actually the methane production process alone requires two times more energy than is produced. Seems to be a violation of common sense to claim it as “renewable.” This claimed “renewable” natural gas is dirty, and it contaminates precision equipment and likely increases maintenance costs. (The average expected lifespan of a biodigester is about fifteen years.)
“The methane carbon credits were intended to stop absent well owners from allowing the release of methane from leaky, now abandoned oil wells located in the West. The methane carbon credit was not intended to be developed into a sustainable business model for industrial agriculture to forever produce and then burn this methane to the atmosphere to claim vast wealth from the sale of carbon credits. The carbon credit market will see the transfer of wealth from the public to the owners/investors forever. To sustain these monstrosities is atrocious and should be revealed.
“But the kicker is the CC by which massive quantities of dollars are gained by the unknown investor/owner. If Biden’s $60/carbon credit proposal is accepted, that converts to about two dollars per cow per day to the investor for burning the methane to the atmosphere. But the California CC is expected to increase to $150/ CC in the future and that converts to about $7.50 per cow per day. So for the 24,000 cows from the Brown County digester, that converts to $180,000 per day… to the investors! Those CC dollars come from public funding used to support the carbon credit market. In addition, this process does not prevent further destruction of our soils and contamination of our water resources.
“I have read that the Federal Green Energy Plan is to support the construction of 16,000 digesters across the country.”
It seems clear that methane biodigesters can produce usable energy, but they require much energy just to support its process. Biodigestion is advertised as a “renewable” resource, but when compared to wind energy, solar energy, geothermal and tidal energies, it’s a very dirty business in comparison and ultimately releases tremendous amounts of CO2, a greenhouse gas. Carbon credits were originally created to be a monetary incentive for owners to cap and prevent old abandoned oil wells from releasing methane directly into the atmosphere. How CCs transferred into the CAFO/Biodigester industry will have to be another story.
The way it is now, it is going to encourage farmers to increase herd sizes for manure not milk. Biodigesters are not the answer to cleaning up the messes created by the industrial farm model.
