Could gas from sewage and landfills be the answer to global food shortages?
Methane, a natural gas, is being processed and turned into protein for animal feed – but could it be used in human food? Elliot Gardner finds out more.
With the global population continuing to grow exponentially, the world’s scientific and food manufacturing communities are under increasing pressure to find alternative food sources to feed the 9.7 billion people who will populate the Earth by 2050, according to projections by the United Nations Department of Economic and Social Affairs (DESA).
Last year it was announced that California -based biotechnology company Calysta had developed a process of turning methane into high-protein animal feed, making it cheaper and easier to rear animals. The feed has since been cleared and is being used in the EU, with US production starting soon.
Calysta isn’t the only company working on the methane-to-protein process - String Bio is a biotech firm based in Bengaluru, India that has separately developed a methane-to-protein processing method. While the protein is not currently ready for people to eat, both companies have expressed interest in ultimately getting the protein to a state where it is fit for human consumption, which has the potential to dramatically change the global agricultural landscape, especially in the poorer regions of Africa and Asia.
Food from landfills and sewage?
While it is a greenhouse gas, methane isn’t just a natural substance that’s been sitting in the earth for generations. Biogas is being produced in abundance by landfills, sewage plants, and even livestock farms, with the average cow reported to expel 100-200 litres a day. This means that methane from a variety of sources could potentially be put to use by bio-technicians such as Calysta or String Bio, though it’s admittedly uncertain how the general public would feel about tucking into a steak or burger made up of a gas from their local dump.
The process of production is similar to that of beer, with bacteria found in soil being fed a liquid containing the methane gas. A fermentation period is then triggered in the bacterium (Calysta uses Methylococcus capsulatus), releasing protein into water, which is then dried and processed into pellet form.
“It’s way better to turn methane into food than burn it,” Calysta chemist Alan Shaw told Bloomberg in September, “What better use for it than to turn it into protein and put it into the human food system, and take a lot of the pressure off?” According to String Bio co-founder Exhil Subbian, the protein has a taste similar to that of whey, a protein derived from milk.
While the amount of methane gas produced by each sewage system or tip is currently too low to process into protein, Calysta, which currently plans to use natural gas from a pipeline, hopes to scale down its production process to make use of methane in all its forms. Similarly, String Bio is confident that it will be able to build plants rendering biogas into protein in the next five years.
Using methane for food production has proved a controversial concept. The demand for agricultural land would be reduced, but until biogas from landfills and other waste sites can be harvested, fossil fuels would be needed to process the protein. With Shaw stating in 2016 that “you need millions of tonnes to have an impact”, the reliance on fossil fuels would add an environmentally unsustainable ingredient to a process that needs to be large in scale. Until production methods can be refined, methane food will have to be a careful balancing act, weighing the benefits of reduced agricultural impact against increased fossil fuel usage.