Biogas from cow manure is not a solution for the energy crisis

Preface. Smil’s article about biogas sums up why it won’t contribute to energy shortages as fossils decline. Biogass doesn’t scale and is easy to muck up. Hayes (2015) also makes this case, pointing out that even if every ounce of manure was used it would only generate 3% of U.S. electricity, and electricity only provides 20% of the energy we use, yet 64% of electricity is still generated with fossil fuels.  Biogas is not renewable either, and pollutes the air and groundwater.

Biogas also has an extremely low energy return on investment (EROI) of 1.75 to 2.1 (Yazan 2017) or 1.12-1.57 (Wang 2021). Some scientists estimate an EROI of 10:1 or more  is needed to keep modern society functioning (Hall and Cleveland 1981, Mearns 2008, Lambert et al. 2014, Murphy 2014, Fizaine and Court 2016).

I summarize four articles below.

Alice Friedemann  www.energyskeptic.com Women in ecology  author of 2021 Life After Fossil Fuels: A Reality Check on Alternative Energy best price here; 2015 When Trucks Stop Running: Energy and the Future of Transportation”, Barriers to Making Algal Biofuels, & “Crunch! Whole Grain Artisan Chips and Crackers”.  Podcasts: Crazy Town, Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity

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Smil, Vaclav. 2010. Energy Myths and Realities: Bringing Science to the Energy Policy Debate. AEI Press.

Before modernization, China’s biogas digesters were unable to produce enough fuel to cook rice three times a day, still less every day for four seasons. The reasons are obvious to anyone familiar with the complexities of bacterial processes. Biogas generation, simple in principle, is a fairly demanding process to manage in practice.  Here are some of the pitfalls:

  1. The slightest leakage will destroy the anaerobic condition required by methanogenic bacteria
  2. Low temperatures (below 20°C),
  3. Improper feedstock addition,
  4. Poor mixing practices
  5. Shortages of appropriate substrates will result in low (or no) fermentation rates,
  6. Undesirable carbon-to-nitrogen ratios and pH
  7. Formation of heavy scum.

Unless assiduously managed, a biogas digester can rapidly turn into an expensive waste pit, which—unless emptied and properly restarted—will have to be abandoned, as millions were in China. Even widespread fermentation would have provided no more than 10% of rural household energy use during the early 1980s, and once the privatization of farming got underway, most of the small family digesters were abandoned.

More than half of humanity is now living in cities, and an increasing share inhabits megacities from São Paulo to Bangkok, from Cairo to Chongqing, and megalopolises, or conglomerates of megacities. How can these combinations of high population, transportation, and industrial density be powered by small-scale, decentralized, soft-energy conversions? How can the fuel for vehicles moving along eight- or twelve-lane highways be derived from crops grown locally?

How can the massive factories producing microchips or electronic gadgets for the entire planet be energized by attached biogas digesters or by tree-derived methanol? And while some small-scale renewable conversions can be truly helpful to a poor rural household or to a small village, they cannot support such basic, modern, energy-efficient industries as iron and steel making, nitrogen fertilizer synthesis by the Haber-Bosch process, and cement production.”

Hayes, Denis and Gail. 2015. Cowed: The Hidden Impact of 93 Million Cows on America’s Health, Economy, Politics, Culture, and Environment.    W.W. Norton & Company.

Digesters are more about controlling pollution than generating electricity. If every ounce of manure from 93 million cows were converted to biogas and used to generate electricity, it would produce less than 3% of the electricity Americans currently use  (Cuellar, A.D., et al. 2008. Cow Power: the energy and emissions benefits of converting manure to biogas. Environmental Research Letters 3).

Bergamin A (2021) Turning Cow Poop Into Energy Sounds Like a Good Idea — But Not Everyone Is on Board. Discover.

Methane is a potent heat-trapping gas that is prone to leaking from gas drilling sites and pipelines in addition to cow feedlots. Because the dairy industry accounts for more than half of California’s methane emissions, the state has allocated more than $180 million to digester projects as part of its California Climate Investments program. Another $26.5 million has come from SoCalGas as part of a settlement for a natural gas leak in Aliso Canyon that dumped more than 100,000 tons of methane into the atmosphere.

While biogas, as it’s known, sounds promising, its potential is limited. Fossil gas alternatives could only supply about 13 percent of current gas demand in buildings — a limitation acknowledged by insiders from both the dairy and natural gas industries, whose research provided the data for this figure.

“So-called efforts to ‘decarbonize’ the pipeline with [dairy biogas] are a pipe dream only a gas utility executive could love,” Michael Boccadoro, executive director of Dairy Cares, an advocacy group for the dairy industry, says. “It just doesn’t make good policy sense.”

Biogas also produces the same contaminants as fossil gas when it’s burned, says Julia Jordan, a policy coordinator at Leadership Counsel for Justice & Accountability, which advocates for California’s low-income and rural communities. For that reason, biogas will do little to address the health issues that stem from using gas stoves, which have been shown to generate dangerous levels of indoor pollution.

The biggest beneficiaries of biogas, advocates say, are gas utilities and dairy operations. As California cities look to replace gas heaters, stoves and ovens with electric alternatives, SoCalGas can tout biogas as a green alternative to electrification. Meanwhile, the dairy industry will profit from the CAFO system while Central Valley communities bear the burden of air and water pollution

“We’re relying on a flawed system that makes manure a money-making scheme for not just the dairies but the natural gas industry,” Jordan says. “And this industrial, animal-feedlot style of agriculture is not working for the people in the Valley.”

Beyond methane, industrial dairies also emit huge sums of ammonia, which combines with pollution from cars and trucks to form tiny particles of ammonium nitrate that irritate the lungs. The Central Valley has some of the highest rates of asthma in the state, particularly among children. While digesters curb methane and ammonia emissions, they don’t eliminate pollution from feedlots entirely.

Feedlots also contaminate water supplies. A 2019 nitrate monitoring report found elevated nitrate concentrations in groundwater at 250 well sites across dairies in the Central Valley. The report said that nitrates seeping from liquid manure lagoons play a role. Young children exposed to nitrates can develop blue baby syndrome, which starves the body of oxygen and can prove fatal. Some studies have also linked nitrates to cancer and thyroid disease.

Tulare County residents are worried that the use of biogas will encourage the growth of industrial dairies, worsening groundwater pollution, says Blanca Escobedo, a Fresno-based policy advocate with Leadership Counsel for Justice & Accountability. Escobedo’s father worked for a Tulare County dairy.

Digesters are most profitable when fed by larger herds. At least 3,000 cows are needed to make an anaerobic digester financially viable, according to a 2018 study. Dairies that have received state digester funding have an average herd size of 7,500 cattle.

“Because of the tremendous concentration of pollutants in one area, [biogas] isn’t a renewable resource when you’re using it on this scale,” says Jonathan Evans, a senior attorney and the Environmental Health Legal Director at Center for Biological Diversity. “Especially in terms of California’s water supply and the impact on adjacent communities who have to suffer the brunt of increasingly poor air quality.”

Weißbach, D., et al. April 2013. Energy intensities, EROIs, and energy payback times of electricity generating power plants. Energy 52: 210–221

Producing natural gas from maize growing, so-called biogas, is energetically expensive due to the large electricity needs for the fermentation plants, followed by the agriculture’s energy demand because of fertilizers and machines.

Biogas-fired plants, even though they need no buffering, have the problem of enormous fuel provisioning effort which brings them clearly below the economic limit with no potential of improvements in reach.

“The Maas brothers decided to set up their Farm Power plant right between the dairies, so the manure wouldn’t need to be trucked long distances to the digester, and the finished product could be piped at reasonable cost to nearby fields. With the farmers lined up, all Farm Power had to do was find $3 million to build a million-gallon tank in which to digest manure, a generator, and tanks to hold the stuff coming in and going out of the digester, which included up to 30% pre-consumer food waste—things like cow blood, dead chickens, and fish waste. Food that has not already been digested by animals contains more energy, allowing the anaerobic bacteria in the digester to pump out more methane. The facility can process 40 to 50,000 gallons of manure daily.

This generator and another, which Farm Power operates at Lynden, Washington, generate enough electricity to power 1,000 homes. The liquid material coming out of the digester is a better fertilizer than raw manure because it contains far fewer pathogens and weed seeds and doesn’t stink as much. It first flows into a pit; from there, as a more stable manure slurry, it’s piped to nearby fields where it can be pumped through an irrigation nozzle or injected into the soil. The dry residue is turned into sanitary, comfy cow bedding. After the dry matter is squeezed through a screen, it’s loaded into trucks and hauled back to the farms. In the future, Farm Power plans to pasteurize the bedding product. Kevin scooped up some finished product stored at one of the nearby dairies. He held it out, inviting Denis to examine it. The bedding was still hot, and smelled like soil and hay.

Digesters don’t solve every environmental problem. Certain antibiotics in cow manure can kill off the fermenting and methanogenic bacteria that make the process possible. The heat in digesters probably doesn’t destroy most antibiotics. New research suggests some pathogenic and antibiotic-resistant bacteria survive anaerobic digestion. Installing a scrubber to remove sulfur dioxide from the digester gas wasn’t economically feasible for the Maas brothers, so they got a permit to emit some pollution. More nitrogen, phosphorus, and potassium remain in the final product than is ideal. Carbon dioxide is also put in the air, and the trucks hauling waste and bedding burn fuel.”

References

Fizaine F, Court V (2016) Energy expenditure, economic growth, and the minimum EROI of society. Energy Policy 95: 172-186.

Hall CAS, Cleveland CJ (1981) Petroleum drilling and production in the United States: Yield per effort and net energy analysis. Science 211: 576-579.

Lambert JG, Hall CAS, Balogh S, et al (2014) Energy, EROI and quality of life. Energy Policy 64:153–167.

Mearns E (2008) The global energy crisis and its role in the pending collapse of the global economy. Presentation to the Royal Society of Chemists, Aberdeen, Scotland. http://www. theoildrum.com/node/4712

Murphy DJ (2014) The implications of the declining energy return on investment of oil production. Philosophical transactions of the Royal Society A. https://doi.org/10.1098/rsta.2013.0126

Wang C et al (2021) Energy return on investment (EROI) of biomass conversion systems in China: Meta-analysis focused on system boundary unification. Renewable and Sustainable Energy Reviews 137.

Yazan DM et al (2017) Cooperation in manure-based biogas production networks: An agent-based modeling approach. Applied Energy 212: 820-833.
see table 8 here: https://www.researchgate.net/figure/Energy-return-on-investment-EROI_tbl3_322251797

 

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