Dr Okoro-Shekwaga awarded BBSRC Discovery Fellowship

Fellowship to investigate the production of low-carbon, high-grade biomethane from food waste for use as a vehicle fuel.

Dr Cynthia Okoro-Shekwaga has been awarded a prestigious BBSRC Discovery Fellowship to investigate the production of low-carbon, high-grade biomethane from food waste for use as a vehicle fuel. 

Biomethane gives cleaner vehicle emissions; using it to replace conventional vehicle fuels like petrol and diesel could reduce vehicular emissions by about 60–80%, which could help to cut the UK’s emissions by 6% by 2030. 

Carbon dioxide and methane are the primary greenhouses gases which lead to climate change.  Achieving the UK Government’s Net Zero target - to eliminate all greenhouse emissions arising from UK-based production and consumption processes by the year 2050 – will require extended research into ready-to-use clean energy processes, such as anaerobic digestion, especially within the transport sector, which is presently the largest single-source contributor to greenhouse emissions in the UK. 

Anaerobic digestion involves the breakdown of organic materials in the absence of oxygen to produce gas (biogas) composed of 50-70% methane and 30-50% carbon dioxide that is commonly used for electricity generation. While only the methane fraction of biogas can be used to produce energy, biogas can be ‘upgraded’ to contain over 95% methane (biomethane), which will further reduce the greenhouse gas footprint from biogas use and also make it a suitable replacement for conventional transport fuel such as petrol and diesel. However, the common methods used to upgrade biogas to biomethane are often associated with high energy demand, additional waste generation and the potential release of the trapped carbon dioxide, which reduces the overall energy yield and greenhouse reduction potential of biomethane. 

Dr Okoro-Shekwaga’s research will investigate a novel alternative called biomethanation, which is the enhancement of a key reaction that occurs during anaerobic digestion, aided by the addition of hydrogen to the anaerobic digestion process. In previous research Dr Okoro-Shekwaga developed evidence that in-situ biomethanation can be integrated into the anaerobic digestion of food waste with the potential of generating up to 65% and 59% increases in energy returns on investment and carbon savings respectively, compared to current biogas upgrade methods. 

However, a major drawback with the integration of this technology is the source of hydrogen. Water electrolysis using excess energy from other renewable sources such as wind and solar has been proposed as an ideal source, but because of the distance between respective renewable energy installations, the transportation of surplus energy from the source of production to the anaerobic digestion plant is still a challenge. 

The novelty of the proposed research includes the use of fungi to break down the difficult-to-digest fraction of food waste to glucose, which will allow enhanced production of hydrogen and the use of the hydrogen to support biogas upgrade to high-grade biomethane, thus avoiding dependence on the common biogas upgrade methods or external hydrogen sources. 

With the BBSRC Discovery Fellowship, working with partners including Olleco and the Biorenewables Development Centre, Dr Okoro-Shekwaga aims to fully exploit the potential of food waste anaerobic digestion to produce high-grade biomethane as a replacement for vehicle fuels. The overall aim is to recover high-grade biomethane using integrated biological approaches that will achieve higher greenhouse gas savings, energy and economic returns on investment, and zero-waste production.

Photo by Jasmin Sessler on Unsplash