Fuelling the future

A five-year project at St AndrewsUniversity is creating technologies that will allow the development of a decentralised energy generation system in the UK.

Researchers, led by Prof John Irvine of the chemistry department, claim that by about 2050 cheap oil will no longer be available and Europe‘s reserves will be exhausted.

A bigger proportion of energy production is expected to come from renewables such as solar, wind, tidal and biomass, supplemented by nuclear, natural gas and coal.

New energy carriers

This will create an increased reliance on new energy carriers such as hydrogen, biogas or synfuels and liquid biofuels. The change will allow development of the decentralised electricity generation infrastructure to be powered by renewable and clean technologies with a strong fuel-cell component.

Under the present centralised power-generation system, energy is produced by large facilities then sent out to homes and businesses via the national grid. However, according to Irvine, in future renewable energy is more likely to be generated from numerous small self-contained generation nodes joined to the national grid by an umbilical. Fuel cells will provide back-up for when renewable generation is not producing at capacity – such as when winds are light. As energy will be generated closer to its point of use, the resulting system will have lower transmission losses, creating higher total energy efficiency with improved energy security.

‘The power system will be similar to Microsoft virtual networks,’ said Irvine. ‘It will create the same revolution as that did – this will literally be “power to the people”.’

The nodes will be supported by a network powered by advanced thermal or nuclear systems, hydropower, buffered wind power and fuel cell systems.

The St Andrews project involves 27 researchers working on a variety of projects. Research into an innovative fuel cell concept that uses solid carbon is already under way, (see The Engineer, 12 February).

Industry partners include Rolls-Royce, which is developing megawatt-sized fuel cells, and university spin-out St Andrews Fuel Cells, which is concentrating on kilowatt-sized systems.

Carbon has a much higher specific energy density than hydrogen, allowing users to carry less fuel, so smaller fuel cells can be developed.

Boost to local grid

While hydrogen and methane fuel cells have a theoretical efficiency of 69 per cent and 90 per cent respectively, the carbon-oxygen reaction that drives a carbon conversion fuel cell has the theoretical possibility to be 100 per cent efficient, with all the potential combustion heat being converted to power.

Such fuel cells placed within the gas central heating system of homes would contribute to the local grid. As the boiler burns biogas, a proportion of its output would be converted to electricity, while the rest heats the home. If this electricity is managed well it can create a fairly stable local grid, Irvine said.

‘The aim is not to create a fuel cell that works brilliantly at full capacity but poorly otherwise,’ said Irvine. ‘We need something that is efficient through a range of operating situations, so can provide a flexible solution to spikes in demand such as when thousands of people switch on their kettles during the advertisements in

Coronation Street

.’

The team is developing high- temperature electrochemical technologies to improve durability and stability of fuel cells. It is also working on reducing the manufacturing cost of cells in order to enable their widespread introduction.

It aims eventually to develop new materials that are fuel-flexible and can work with complex fuels ranging from natural gas and LPG through to biogas, liquid biofuels and biomass. Any materials used must be more tolerant of impurities such as sulphur, which often occur in biogas made from waste such as slurry. The team also aims to create materials capable of improving the efficiency of electrolysis to produce clean hydrogen for transport.

According to Irvine, biomass is key as it can be converted into electricity in a highly efficient manner. The government-sponsored project is due to end in August, 2011.