Sunshine dream

Researchers at Imperial College London aim to develop a renewable, cost-effective method for harvesting solar energy to produce hydrogen fuel.

The £4m project — New and Renewable Solar Routes to Hydrogen Energy — will build on recent bioscience breakthroughs in detecting the structure of the enzyme that breaks down water into hydrogen and oxygen during photosynthesis, using green algae and inorganic enzyme analogues based on titanium supports.

It will find ways to exploit these low-temperature natural biological and photocatalytic processes to produce hydrogen to power a fuel cell.

World leader

The researchers say if the project is successful, it would make an enormous impact on the viability of hydrogen as an energy carrier and allow renewable production of hydrogen to become a reality. It will also position the UK as a world leader in one of the few solutions to a truly sustainable energy future.

‘There is a lot of understanding of how water can be broken down at the molecular level but to obtain hydrogen using solar energy in a renewable way we have to scale it up,’ said Geoffrey Maitland, ICL professor of energy engineering, who will be part of the project. ‘This is why the chemistry and engineering departments will play a big role.’

The five-year, government-funded project, which starts in October, will be led by fuel cell expert Prof Nigel Brandon, executive director of ICL’s Energy Futures Lab and involve bioscientists, chemists, engineers and industry.

Shell International and Hydrogen Solar are project partners and will act as commercial sponsors as well as lending expertise and serving on an industrial advisory panel that will monitor the scheme’s development.

In the UK and abroad there is an increasing focus on developing zero-carbon emission fuels, particularly hydrogen, using renewable energy sources. Most hydrogen is produced from natural gas, a fossil fuel, or by splitting water through electrolysis, a process that consumes a lot of electricity that is often produced by using non-renewable energy.

Solar energy is the most abundant form of renewable energy available and, if harvested efficiently, can meet global energy needs for the foreseeable future.

It is estimated that solar power could provide about 6,400 times the estimated global power demand for 2020.

Much research is focused on its direct conversion to electricity in photovoltaic devices, or on its direct conversion to heat in solar thermal devices. But a barrier to all these routes is their prohibitive cost.

The project aims to develop a demonstrator consisting of a rooftop reactor on top of the college that can use sunlight to break down water on the hundreds of litres scale.

Maitland said that to achieve their aims, the group must be able to capture the solar energy in an efficient manner.

Novel design

‘We have to design ways of capturing solar energy to get efficient transfer of light energy to the molecular centres where the breakdown of water occurs,’ said Maitland. ‘This means a novel design is needed. However, there are many questions about whether we will be able to scale up the process.’

The team will then involve Brandon, who will study how the hydrogen produced can be used to power a fuel cell.

The group also hopes to identify the potential roadblocks to the process becoming commercially viable, tackling them at the different stages of development, such as during catalyst manufacture.

They will also identify whether it is best to develop the process so that it produces hydrogen and oxygen, or hydrogen and other oxidation products.

The disadvantage of the former is that it requires major separation of the atoms and so may not be as energy efficient. However, other oxidation products may not be as compatible with fuel cells, requiring a compromise between the needs of the fuel cell and the efficiency of the solar breakdown process.