In 2019, UK farms produced 9.8 million tonnes of slurry, manure and other organic wastes. These forms of agricultural wastes are energy-rich, presenting opportunities for farmers who are under pressure to reduce the environmental impact of spreading manure and slurry on the land as fertiliser.
Can a revolution in clean energy technologies transform these high-energy farm wastes into sources of renewable energy? To accelerate development in this space, the UK Government is investing £1 billion to commercialise innovative clean technologies and processes through the Net Zero Innovation Portfolio.
Funded through the portfolio’s BECCS Hydrogen Innovation Programme, Phase 1 of the University of Leeds H2Boost project is scoping the development of commercially viable technologies to produce biohydrogen as fuel from a range of organic wastes across the UK, including farm waste.
Hydrogen as a renewable biofuel
Hydrogen is internationally recognised as an essential component of reaching Net Zero emissions by 2050. As a low-carbon fuel, it can deliver negative greenhouse gas emissions and holds promise for hard-to-treat sectors like industry and heat, where fuel is essential, and electrification presents many challenges. Progress is underway – hydrogen is already used to power some London buses, and the world’s first hydrogen dual-fuel tractor was launched in 2020.
With hydrogen typically generated from fossil fuel, H2Boost is one of 22 projects funded by the Department of Business, Energy and Industrial Strategy to investigate how to generate hydrogen as a renewable fuel from organic waste. For the H2Boost team, this includes scoping the feasibility of anaerobically digesting the vast amounts of slurry waste produced by livestock farming.
Digesting slurry to produce hydrogen
Led by Dr Miller Alonso Camargo-Valero in the School of Civil Engineering, University of Leeds, the project brings together collaborators from the Biorenewables Development Centre (BDC) at the University of York with the National Non-Food Crop Centre (NNFCC) and industry partners. Co-Investigator, BBSRC Discovery Fellow Dr Cynthia Okoro-Shekwaga, explains:
“Through H2Boost, we can start to address the big question of how to mitigate emissions from farming, so normal farm wastes like slurry and manure are seen as resources rather than problems. For many farmers, slurry disposal can be costly, and the run-off from spreading it on the land as fertiliser presents environmental risks to natural watercourses. Some farms already use anaerobic digestion (AD) technology, which involves a preceding fermentation step, to deal with slurry. So, we’re looking at how dark fermentation technology for generating hydrogen from biowastes can be adapted and retrofitted to current farm AD technologies.”
At the Phase 1 feasibility investigation, H2Boost scoped out a process of pre-treating organic wastes, including farm waste, to make it biodegrade more easily and to improve hydrogen yields. Then, through fermentation, a combination of microbes anaerobically digest organic materials in the waste to produce hydrogen gas and several organic compounds. The hydrogen can be collected and upgraded as biofuel for the UK transport sector, and the remaining solubilised material sent to the anaerobic digester to recover more bioenergy in the form of biomethane.
“This brings two benefits to farmers,” explains Dr Okoro-Shekwaga, “The hydrogen can be sold back into the energy system or used directly on the farm as biofuel. The secondary material from the AD process, a compost-like material, contains all the right basic nutrients that plants need. When spread on the land these are immediately taken up by the grass or crops. What’s neat about this system is that we can manipulate it depending on the farmer’s needs – hydrogen and biomethane production if they are interested in energy, or higher-quality fertiliser if they are interested in crop yield.”
Building a case for full-scale adoption
This form of hydrogen generation is currently limited to laboratory models, so the challenge for the H2Boost project has been to pilot the concept in a real-farm setting. The team’s vision is to see hydrogen fuel generation adopted and spread at scale across the UK agricultural sector.
To produce a final business case, the research team are considering how this form of agricultural hydrogen generation sits in the wider energy system. This includes scoping the technology in the context of policy, cost, economic benefit, and supply from farm to end-user.
After the initial feasibility study, the researchers aim to carry out a larger farm-scale trial and develop a business plan to launch the technology as a commercially available product.
For Dr Okoro-Shekwaga, even the feasibility study breaks exciting new ground:
“A project like this means we can contribute to potentially game-changing efforts that bridge the gap between lab research and real-life application, moving the concept of renewable hydrogen generation into a commercial, profitable system.”