From waste to profit: changing the way agriculture sees waste

Posted: December 24, 2025

Agricultural waste has a lot of potential as a resource: It has high energy content and volatile components that can be converted into energy. But it’s often just that: waste. It’s underused and often disposed of in ways that harm the environment, such as incineration, which releases greenhouse gases.^[1]

The U.K.’s agricultural sector contributes about 10% of the U.K.’s emissions, mostly methane and nitrous oxide. Of those emissions, only 9% are CO₂, which makes it harder to decarbonize than other sectors, as it’s not just about reducing fossil fuel usage. Dr. Miller Alonso Camargo-Valero, Associate Professor of BioResource Systems at the University of Leeds, has been leading a project to investigate how to turn the 9.8 million tons of slurry, manure and other organic wastes that U.K. farms produce each year into valuable resources.^[2]

 “What we want to do is to look in a comprehensive way at how the agriculture sector can achieve net-zero and, for instance, can help to alleviate pressure on other sectors that cannot decarbonize at the same pace,” he explained.

Turning food and farm waste into biohydrogen

The H2Boost project, supported by the U.K. government’s Department for Energy Security and Net Zero, is a collaboration between industrial and academic partners. It concluded its successful demonstration-scale project this year.

At a food-waste processing facility in North Yorkshire, H2Boost had the capacity to transform 1,000 kg of organic waste a day into high-purity hydrogen suitable for the transport sector. The system enhances the role of anaerobic digesters, which use bacteria to break down organic waste into new byproducts. Traditionally, anaerobic digesters have several different reactions going on in them at once, creating methane and carbon dioxide. This biogas can be used to generate electricity and heat, and creates digestate as a byproduct, which can be used as fertilizer.

H2Boost’s novel approach instead separates the process into three separate parts, beginning with creating biohydrogen instead of methane. “We have an initial reactor, which is the dark fermentation unit, where we guarantee that the predominant bacteria species are those able to produce hydrogen gas. So that means that in the first stage we purify and produce biohydrogen,” Dr. Camargo-Valero explained. The process produces hydrogen gas mixed with CO₂, about half of each in the best-case scenario. The second part of the process uses standard anaerobic digesters to stabilize the remaining organic waste coming out of the dark fermentation unit, ensuring the process complies with waste legislation.

The resulting hydrogen is high-purity gas that can be compressed onsite and used to fuel farm vehicles such as tractors. It could also provide a potential income stream as farms could sell their hydrogen, although the U.K. currently lacks the widespread infrastructure for hydrogen-powered vehicles to be commonplace on the roads.

Microalgae: carbon-capture and green fertilizer  

While the H2Boost process produces CO₂ emissions, because the CO₂ is created from the biological conversion of organic waste, the emissions do not count toward government emissions targets. Even so, the project utilizes a carbon capture system for the final step of the process. Microalgae trap the CO₂ that is created by the hydrogen production and during the combustion of anaerobic biogas for power and heat generation onsite. This process fixes the carbon to the algae, while the microalgae grow using nutrient-rich digestate from the anaerobic digester.

The microalgae also have a secondary value—they can be used to create fertilizer for the farm’s crops, creating a truly circular and green farming economy. “We are not only capturing CO₂, but also recovering the nutrients that can help to reduce our dependency on industrial fertilizers. So we find a loop to recycle nutrients more efficiently, which can go directly into agriculture,” explained Dr. Camargo-Valero. “We create a route for the utilization of the nutrients in a way that creates an alternative way to produce fertilizer.” The resulting microalgal biomass can also be tailored to feed certain crops by serving as an alternative feedstock for organic fertilizer production.

A net-zero agricultural future   

The team hopes that its system could be retrofitted to existing anaerobic reactors—there are many, thanks to previous government incentives—to produce clean energy and renewable fertilizers, alongside the biogas they currently produce. The next step includes smoothing out small bumps in the technical process, before working with industrial partners to get the technology on working farms, including the University of Leeds’ own pig farm, which it hopes will show how effectively the system can be implemented.  

For Dr. Camargo-Valero, the possibilities are huge: “The majority of the big initiatives that we see in this country mostly address the use of fossil fuels—and we fully understand that priority because it’s the biggest gain that you can make. That’s a huge gain, but we’re going to continue demanding food. We're going to continue producing waste. That's something that is not going to go away. Agriculture is a sector that perhaps has not been prioritized. What we want to do is to take that challenge and try to see well, if we want to do something, here are the options.”

^{[1] https://www.sciencedirect.com/science/article/abs/pii/S0360319925000527
[2] https://www.leeds.ac.uk/agricultural-energy-systems/dir-record/profiles/20702/do-livestock-farms-hold-potential-as-hydrogen-generators}