The biogas industry in the United Kingdom is on fire right now! As of December 2024, 756 anaerobic digestion (AD) plants are currently operational. This cutting-edge technology processes commercial food waste—including perishables like seasonal pumpkins— into renewable biogas. In doing so, it produces a renewable energy source that largely reduces emissions associated with food waste. The UK government is increasing the burden of food waste management regulations. This change would dramatically increase the opportunity for biogas as a potential energy source.
Europe is the world leader today in both installed biogas capacity and biogas production, with around 20,000 biogas plants. Germany is one of the most successful countries in terms of biogas production with an annual production reaching 87 terawatt-hours (TWh) per year. The production of biogas occurs through a four-stage process: hydrolysis, acidogenesis, acetogenesis, and methanogenesis, where microorganisms break down organic matter to yield a gas rich in methane and carbon dioxide.
In the UK, biogas production has taken off, largely due to the growing use of food waste. Seasonal celebrations such as Halloween and Christmas lead to extreme increases in food waste production. To take one statistic, 15–22 million pumpkins are purchased, carved and then thrown away every year in the UK. Redirecting this waste to AD facilities supports the country’s goal of reducing landfill emissions. It deepens our commitment to renewable energy production.
Understanding Biogas Production
Biogas is made up of 50% to 70% methane and 30% to 50% carbon dioxide. The upgrading of biogas into biomethane—separating out the carbon dioxide—produces a gas which is greater than 95% methane. This upgraded biomethane is almost indistinguishable from natural gas. As such, it is readily injected into the national grid or utilized as a renewable fuel substitute for vehicles.
Despite the established nature of the UK’s AD sector, experts assert that it has yet to reach its full potential. Hall, a prominent figure in the industry, noted, “The AD sector is well established in the UK but is far from reaching its full potential.” To capitalize on this opportunity, we must have robust federal government support. By March 2025, businesses will be required to separate food waste for collection, with households doing the same by March 2026.
The success of biogas production rests on the sensitivities of microorganisms used across AD operations. The variability in the type of food waste that is processed can have a huge impact on biogas yield. Dr. Cynthia Okoro-Shekwaga explained, “Food types react differently because different food provides different nutrients in different quantities.” Such variability requires precise balancing of feedstock wastes to maximize biogas production.
The Impact of Seasonal Food Waste
Seasonal surges in demand, such as with the Halloween holiday, can pose hurdles but serve as occasions for increased biogas production. Pumpkins seen here at the Clean Cities pumpkin carving contest. Pumpkins, though plentiful this season, aren’t a magic way to increase biogas production – their composition matters. Farryad Ishaq emphasized that “pumpkins after Halloween might seem like they would boost our intake, but in reality, they don’t create much of a spike in deliveries.” Rather, the aim should be to process a highly variable stream of food waste to produce the highest quality biogas as possible.
Dr. Okoro-Shekwaga added further insights into managing food waste in AD systems: “You wouldn’t set up a system wholly to run on seasonal plants because it wouldn’t be sustainable.” Seasonal foods require in-depth testing to determine their nutritional value. This allows us to determine the best ways to co-process them with other waste streams. Hall concurred that “typically, high-energy foods produce the most methane per kilogram,” signifying that a balanced diet within AD systems is essential for optimal performance.
When seasonal food waste is integrated into existing AD facilities, it increases biogas production. Besides its work to inform the public debate, it’s a remarkable educational experience. Hubbub points out that “seasonal events like Halloween are a high-profile, fun opportunity to put food waste in the spotlight and empower people to act.” This knowledge not only helps consumers practice good consumption habits but fuels participation in food waste recycling programs.
Government Regulations and Future Prospects
With the UK preparing for even more robust mandates around separating food waste, both businesses and home will have to follow suit. These March 2025 and March 2026 requirements require a quick transformation of our infrastructure. We need to act fast to improve our systems for collecting and processing food waste. Hall noted that “clarity on what happens next is needed as soon as possible to prevent companies delaying investment decisions,” highlighting the urgency for effective policy implementation.
The government’s push for food waste separation aligns with broader environmental goals to reduce greenhouse gas emissions from landfills, where waste decomposes and releases methane, a potent greenhouse gas. Every year, an estimated 22 million pumpkins are disposed of in landfills. By sending this wasted produce to anaerobic digestion plants, we can make the UK’s renewable energy mission more powerful and benefit the planet.