In this video Dimitri describes how hydrogen from metals allows safe, compact storage of hydrogen energy, and how it could be particularly efficient when combined with high temperature power generation from solid oxide fuel cells or gas turbines.
 
Background:

My research is concerned with the production of more sustainable fuels made from energy sources and materials that can be sourced locally. Sources of energy could include renewable power like wind, tidal, solar etc., or waste (the energy content of municipal and commercial waste produced in the UK amounts to a third of that represented by our requirements for diesel and petrol).

Hydrogen can be produced from these sources of energy and these materials, for example by using current to split water into hydrogen and oxygen – a process known as'electrolysis'. From hydrogen, one can also prepare convenient carbon-based liquid fuels like synthetic petrol or diesel, provided that a source of carbon is available. Sources of carbon could include carbon dioxide recovered from power plants, brewery, cement works etc., and also synthesis gas derived from municipal solid waste or biomass. The most efficient process from the point of view of carbon and energy efficiency would combine hydrogen from electrolysis with a source of carbon.

However, hydrogen is a gas of very low density (one petrol tanker delivery would be replaced by 22 deliveries of hydrogen compressed at 200 atmospheres) and it is also hard to liquefy. This poses problems not just if the hydrogen is to be used directly as a fuel. Synthesis of most carbon-based liquid fuels like synthetic petrol or diesel requires a steady supply of hydrogen, rather than the variable feed rate that electrolysis can deliver, and where a suitable geological formation is not available costly bulk storage of very large volumes of the gas would be required to buffer the synthesis process.

One solution is to store the energy content of hydrogen rather than hydrogen itself. We react the hydrogen with metal oxide particles, which turns the oxides to metals. The resulting metal particles like this one can be stored for use later. Here the test rig where we have been doing this. When the energy is needed, reacting the metal sponge with steam regenerates the hydrogen and the metal oxide particles. This process allows safe, compact storage of hydrogen energy, for example in your garage or basement of your house, and it could be particularly efficient when combined with high temperature power generation processes like solid oxide fuel cells and gas turbines.

Find out more:

• Dr Dimitri Mignard School of Engineering profile: http://www.eng.ed.ac.uk/about/people/dr-dimitri-mignard
• Dr Dimitri Mignard on Edinburgh Research Explorer: http://www.research.ed.ac.uk/portal/dimitri