Oscillatory baffled reactor for enhanced 1C gas bioconversion for energy production and storage

Societies globally have a critical need for energy and materials with minimal environmental impact. There are many technologies such as solar PV, wind, wave and tidal generation which can produce electrical energy with minimal environmental impact, however when compared to conventional fossil fuel generation systems they are more difficult to fit supply to demand. Therefore there is increasing interest in developing energy storage. The production of green methane and carboxylic acids by combining hydrogen using renewable electricity with surplus carbon dioxide from a number of industrial processes, has the potential to integrate gas, electricity and refueling infrastructures, decarbonise energy and chemical supply, contribute towards energy security, as well as providing economic benefits through expansion of market potential. Effective conversions of hydrogen and carbon dioxide have recently been achieved using a novel patented microbial process (filed by University of South Wales) for the production of green methane and carboxylic acids, however, productivity is limited by the rate at which gases can be solubilised into the liquid phase. This project will investigate the feasibility of using innovative and patented oscillatory baffled reactor (OBR) technology (own by NiTech Solutions Ltd) to optimise the solubilisation of input gases, therefore optimising the rate of green gas or carboxylic acids production and improving the technical and economic viability of the biotechnology processes. The project proposes a programme of collaborative research to determine the feasibility of utilising the OBR technology to enhance the gaseous rate of transfer and thus increase the microbial conversion of renewable hydrogen and biogenic or fossil carbon dioxide to either green methane (for energy use) or carboxylic acids (as energy vectors and chemical intermediates). The project addresses the challenges of production of liquid / gaseous biofuels, and the production of commodity, platform and intermediate chemicals and materials from gaseous substrates. The aims of the proposed research are to investigate and demonstrate efficiency benefits that the OBR technology can bring to the biomethanation / carboxylic acids biotechnology processes, the effect from these reactors systems on microbial communities and demonstrate the overall feasibility of the processes both in terms of productivity and energy efficiency, therefore justifying additional industry investment in scale up focused research and process deployment. The ability to produce low carbon sustainable energy, chemicals and materials to meet variable societal demands, using low temperature and pressure conversions, using a biocatalyst based microbial community and inexpensive non-metal based catalysts, and reduce energy lost through curtailment of renewable energy in the UK and across the world is expected to bring sound environmental and economic benefits for future generations.

The project aims to determine the feasibility of utilising Oscillatory Baffled Reactor (OBR) technology to enhance the transfer of hydrogen and carbon dioxide gases into the liquid phase of novel bioprocesses, for conversions to green methane or carboxylic acids by microbial enriched anaerobic mixed cultures. Green methane produced for supply of heat, electricity or transport fuel from gaseous substrates sourced from curtailed renewable electricity via H2 and CO2 from a number of industrial processes will contribute towards emission savings as well as energy security. Alternatively, the conversion of these gases to carboxylic acids gives the possibility of temporary energy storage or their utilisation as platform chemicals. The solubilisation of gases in bioreactors working matrices has been found to be a limiting step in the rate of conversions from gaseous substrates, and optimising this transfer is expected to improve economic and scale up viability by reducing process footprint.

The ability to produce low carbon energy/chemicals to meet the demand from future generations, using low temp/pressure conversions and an inexpensive biocatalyst, and reduce energy lost through curtailment of renewable energy in the UK and across the world will bring sound societal environmental and economic benefits. The most significant source of renewable energy gas added to the gas grid is bioCH4 generated from anaerobic digestion. Limitations on the deployment of bioCH4 grid injection in the UK is the number of sites where viable amounts of organic substrates are present, and where there is a grid injection point with sufficient year round capacity to accommodate the bioCH4 produced. The linking in CH4 production from renewable electricity provides economic and carbon advantages to both gas grid operators and renewable energy generators and allows interoperability between gas, electricity and transport sectors. The novel biomethanation process (H2 + CO2 to CH4) has significant advantages compared to biogas upgrading/metal catalytic conversions i.e. lower engineering complexity and capex, greater ramping capability for intermittent operation and system modularity/mobility and economic viability at small scale. The production of green CH4 may require some form of storage, which is more effective than storing electricity. Alternatively, the option of storing energy in the form of liquid carboxylic acids has the potential to greatly expand the number of viable locations for grid injection. Efficiencies in the biomethanation carboxylic acid production processes are currently limited by gas transfer rates and not by microbial density/rate of metabolism, and therefore access to gaseous substrates is the rate limiting step. Innovative OBR technology (NiTech patented) has the potential to optimise the H2 and CO2 gas-liquid transfer. This integration can potentially lead to significantly reduced footprint infrastructures. USW current continuous reactor system (filed patent) with a zero CH4 slip, no replenishment of trace elements/nutrients/microbes post the initial media/inoculation, has delivered a 200 L gas influent/Lreactor.d throughput with 99% CH4 product, but the aim is to achieve at least a 4x increase in productivity maintaining a high quality product to increase industrially competitiveness. The OBR technology is expected to increase the rate of gas transfer and reduce the shear/disturbance of the microbial floc structures, and allow the development of key process efficiencies. For carboxylic acids production, the rate of gas transfer to the liquid based microbial matrix is equally important; in addition the gas partial pressures in the liquid matrix is expected to be critical in determining the speciation of the carboxylic acids. Exploitable outcomes from this feasibility are likely to include improved biotech processes for green methane/carboxylic acids, as well as new international markets for the integration of OBR technology. The market in the UK is forecast to grow >27GW by 2020 for wind energy, with an associated grid balancing requirements >6GW, capable of generating up to 2400 tonnes of H2. Equally the solar energy in the UK is also expected to grow exponentially by 2020 creating unprecedented issues with the electrical grid capacity and management. The UK is forecasting 7 TWh of bioCH4 in 2020 and 15 TWh in 2030 (IEA Bioenergy, 2014) and ADBA forescast a potential of 64 TWh of biomethane from organic resources and an additional 32 TWh via green CH4 (biomethanation) (>35% of the UK's domestic gas demand). EU markets have less stringent limits on the composition and quality of natural gas used in their networks which improves further the costs of production and opens up export potential for UK system developers and manufacturers. The project will seek to develop opportunities to stimulate a new UK-based supply chain capable of securing a market lead in these technologies.