U.S. Biogas Production Is Key to Meeting COP26 Global Methane Pledge Goals

November 24, 2021

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by John Hanselman (Vanguard Renewables/Biofuels Digest) ... But monetary incentives sometimes get in the way of methane sequestration methods becoming more widespread; it is often necessary for governments to make sure economic opportunities for growth are in place. Perhaps the most substantial outcome from COP26 was a coalition of 100 countries, including the U.S. and EU, which launched the Global Methane Pledge, an agreement compelling participating countries to decrease methane emissions by 30% from 2020 levels by 2030.

Assuming current trends continue, methane emissions are projected to increase year-over-year until 2040 at the earliest. The countries signed onto the pledge comprise nearly 50% of global anthropogenic methane emissions and over two-thirds of the global GDP. If the measures in the Pledge are implemented as written, they are expected to prevent 0.2˚C of global temperature warming by 2050.

Reducing human-induced methane emissions is an effective strategy to rapidly reduce the rate of warming and benefit the public health of these nations. But what does decreasing methane emissions look like on the ground? What are the common causes of methane emissions, and are there existing solutions ready to tackle the challenge?

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Methane emissions from waste and agricultural product decomposition account for 20 and 40 percent of the total, respectively.

Waste Methane

Methane derived from waste is produced when bacteria decompose organic material in food waste or sewage. Food waste can range from inedible byproducts of food production to unconsumed food.
Population growth and income growth in regions with underdeveloped waste management systems are expected to result in an increase of about 13 Mt/yr of additional methane emissions, according to the Climate and Clean Air Coalition.

Agriculture Methane

Agricultural methane is derived from cattle, dairy, and crop production. What is it? Manure, what’s leftover in the fields after harvest?
An increase in emissions from enteric fermentation and manure management of around 6 Mt/yr is projected from increased demand for protein because of population growth.

Because food and farm waste are the major contributors to methane emissions, and are projected to increase, we need to focus on solutions to sequester the natural expulsion of methane from agriculture and waste decomposition. The most obvious and promising solution I see involves the production of biogas and renewable natural gas (RNG).

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Anaerobic codigestion of manure and food waste harnesses the methane released from food waste and converts it into a carbon-negative fuel source, RNG. Instead of allowing the decomposition of waste materials and agricultural byproducts to release methane into the atmosphere, this natural process can transform into something great in an anaerobic digester. Anaerobic digesters are large tanks or lagoons with attached gas-capturing mechanisms that harness biogas, composed of methane and carbon dioxide, that is expelled from decomposing cow manure and food and beverage waste. This process results in two products: biogas and liquid digestate. The captured biogas is then converted into RNG that can power the electrical grid. Liquid digestate provides a nutrient-rich fertilizer which enhances crop growth. Biogas and digestate capture through anaerobic digestion supports a circular pathway and economy, turning a negative into a positive force. Because anaerobic digestion process sequesters methane from emissions that normally come from the decomposition of manure and food waste, RNG yields a better GHG reduction profile than solar or wind.

Ramping Up Anaerobic Digestion Production is Key

To adhere to the Pledge, the signatories must begin looking for alternative methods to curb their methane emissions. Methane sequestration methods such as anaerobic digestion offer a viable, fast-acting solution.

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The methane emission reduction goals targeted by the Methane Pledge require anaerobic codigestion of manure and food waste. We need to ramp up anaerobic digestion across the country; the World Biogas Association (WBA) reaffirms that a prompt deployment of anaerobic digestion technology can help deliver on the Pledge’s commitment. Biogas is the future of renewable energy, and anaerobic digestion will lead the charge. READ MORE