World Wildlife Fund Sustainability Works

large pipes leading from a biogas tank to a processing plant

Is Biogas a “Green” Energy Source?

  • Date: 24 September 2020
  • Author: By Tim Juliani, director of corporate climate engagement, WWF; and Pete Pearson, senior director of food loss and waste, WWF

Biogas has gained popularity in recent years as a “greener” fuel. This is the methane created when anaerobic digestion breaks down organic matter, like in landfills or “digesters” that convert animal manure or food waste, which can then be used to replace conventional natural gas. But is it truly a renewable energy solution? Well, you may not be surprised to hear: it’s complicated.

When compared to virgin natural gas obtained by drilling into the earth, biogas is clearly a more sustainable option. About 80% of natural gas in the United States is extracted by fracking, a process where water, chemicals, and sand are forced deep within the ground to break up rock formations. The fracking process can cause significant damage to ecosystems and landscapes. Landfills and digesters produce a similar fuel without the environmental toll from the fracking process, utilizing material that already exists and would otherwise go to waste.

And there are additional benefits of biogas. Removing the abundant supply of animal manure and food waste from the environment prevents nitrogen pollution and runoff into water resources. Biogas also helps mitigate methane emissions that would have otherwise escaped from landfills or manure lagoons. Using this methane as a fuel dramatically reduces its climate impact by converting it into CO2, which is up to 34 times less potent as a greenhouse gas.

With the right processing, biogas can be upgraded to replace mined natural gas for use as a fuel for electricity production, ground transportation, and commercial and residential buildings. But by and large, we can and should rely on zero-carbon sources like wind and solar to generate electricity, and then electrify as many end-uses (such as ground transport and buildings) as possible.

Supermarket waste to be processed into biogas

At the same time, many important industrial processes that make the goods we demand -- from consumer products to food, steel and cement – require extremely high heat that currently only gas can provide. In fact, industrial thermal is responsible for around 11% of US emissions – more than the agricultural sector – and there simply is no path to a 1.5C degree future without addressing these emissions. Since this sector will likely require the use of natural gas for years to come, biogas can be part of the solution.

But to do so, the amount of biogas harvested in the US needs to increase dramatically.

WWF’s Renewable Thermal Collaborative (RTC) exists in part to do just that. The RTC now includes over a dozen leading commercial and industrial buyers and sellers of renewable solutions dedicated to collective action to solve the thermal dilemma. Together, we are working to overcome the multiple technology, market, and policy barriers that keep biogas and other technologies from being cost-competitive with fossil fuels and available at scale.

Biogas, also known as renewable natural gas, is “renewable” in the sense that humans and animals will keep producing waste – but we don’t want to encourage generating more waste for the sole purpose of creating more biogas. After all, though capturing and using methane is better than allowing it to escape to the atmosphere, burning the gas still has a climate impact. We could further reduce this impact by capturing and storing the CO2 from biogas combustion, but there are risks to this as well, so it is an imperfect answer.

In the end, while biogas today is a more sustainable solution than traditional natural gas, we should consider it as an important transition fuel on the road to completely decarbonizing our energy supply.