Public description Fuel cells are electrochemical devices that convert energy stored in chemical bonds of fuels, such as hydrogen, into electricity (and heat) without releasing harmful pollutants such as CO, CO2, SOx and NOx into the atmosphere. When supplied with a "green" fuel such as hydrogen generated via electrolysis (water splitting) using renewable electricity they are an emissions free source of electricity which can be used to decarbonise transport and other energy applications. Invented by William Grove in 1839, fuel cells have found limited markets until now. There is a resurgent interest in fuel cells and hydrogen technologies driven by environmental concerns arising from extensive fossil fuel usage. Investments in the hydrogen supply chain is part of the co-ordinated programme to address global climate change. The widespread use of fuel cells in trucks, ships, aeroplanes and stationary power applications will prevent millions of tonnes of CO2 emissions in the coming years. Fuel cells are complex systems at the molecular level with mass transport and chemical reactions across multiple interfaces. Some of these chemical reactions can produce undesirable compounds, especially if pollutants are present in the air or fuel supplies. These undesirable side products attack vital internal components of the fuel cell and lead to device failure. Some of the chemical reactions are reversible with intervention mechanisms to recover performance, but some are irreversible and lead to catastrophic fuel cell failure. Clean Power's novel fuel cell system removes most critical degradation mechanisms associated with conventional designs - see clean-power.co.uk. For challenging applications at high elevations and altitudes the fuel cells must be able to start and operate at low temperatures. This project seeks to discover additives to Clean Power's liquid catholytes to prevent these from freezing at low temperatures (-40 deg C.). A number of candidate additives and different liquid catholyte combinations will be tested using the resources and expertise of the Materials Innovation Factory at the University of Liverpool.

**Decarbonising regional short haul aviation** The International Civil Aviation Organisation (ICAO) highlighted that, if no further action is taken, aviation's share of global CO2 emissions could rise with worldwide scrutiny on the sector set to increase. Demand for flights is rebounding after the impact of COVID travel restrictions and a recent forecast for yearly European flight by 2050 ranges from 13.2 million to 19.6 million (cf. 11 million flights in 2019) (EuroControl, 2022). Aviation represents around 2.4% of global carbon emissions (ICCT) and 12% of transport's contribution (ATAG), however, there are few signs of meaningful progress with emissions reductions or reduced demand in this sector. New climate modelling techniques indicate that aviation emissions are heating the climate at about x3 the rate of CO2 aviation emissions alone -- with NOx, SOx and other particulates like soot together with contrails implicated -- which are present even when Sustainable Aviation Fuels (SAFs) are used (EASA, 2022). Therefore, other solutions to decarbonise the aviation sector are urgently sought. Fuel cells have been proposed for aviation applications -- with hydrogen PEM fuel cells having the closest fit to the demanding requirements of this industry. Various projects are at different stages of development (HyFlyerII, H2Gear) and a number of companies investigating this challenge (ZeroAvia, Cranfield Aerospace Solutions, Rolls Royce, GKN, MTU) The Aviation Technology Institute's (ATI) FlyZero project looked at various scenarios and aircraft types. They predict that by 2050 there will be between 4,500 to 870 fuel cell powered regional aircraft by 2050\. Clean Power's novel hydrogen fuel cell technology is a strong candidate for powering these regional aircraft due to its low cost and high durability. This project will assess the fit of our current fuel cell systems to work in the challenging aviation environment. Performance tests will be conducted in partnership with WMG in a specialised aviation test chamber capable of simulating cruising at altitudes with the associated temperatures and air densities. For traditional PEM fuel cell architectures the low air densities at altitude represent a further challenge to the Oxygen Reduction Reaction (ORR) which takes place at the Cathode of the fuel cell. In Clean Power's fuel cells the ORR takes place away from the fuel cell stack and more time and surface area can be afforded to cope with the reduced air densities. This project will test the hypothesis that Clean Power's fuel cells are well suited to aviation applications.