Here comes the sun? 1st UK Solar to Fuel Symposium report

Materials World magazine
,
5 Feb 2012
sun on a leaf

Can we harvest the sun’s rays and forego fossil fuels? Eoin Redahan was at the 1st UK Solar to Fuel Symposium on 18 January to shed light on the matter.

The delegate was tired. History, it seems, is caught in an interminable loop. In the 1970s, as oil prices soared, solar fuels shuffled into the foreground. We needed alternative ways to fuel our cars, and significant progress was made. Then oil prices dropped, and solar fuel initiatives faded again.

‘We’re repeating work that was done 35 years ago,’ he said. ‘I was speaking to a former colleague recently, and he said to me: “Now, I’m famous. I’m famous for work I did 35 years ago.”’

But, as fossil fuels continue to vanish in smoky wisps, the conversion of solar power into fuel is pertinent once more. The sun’s rays can provide all the energy we need. If artificial photosynthesis and other technologies were honed, feedstocks for fertilisers would be optimised, and we could have clean, hydrogen-powered cars.

Several countries have been active. Japan maintained a programme through the 1980s and 90s. Large-scale interdisciplinary programmes have popped up in China and South Korea. According to the Solar Fuels and Artificial Photosynthesis report, compiled by the Royal Society (RS) in London, the Netherlands accounts for the largest single investment (€ 25m) in solar fuels research for biosolar cells, and the USA has committed $122m to a dedicated programme for solar fuels research. All of this bodes a pressing question: Just what is the UK doing?

The answer was explored in both the aforementioned RS report at the 1st UK Solar to Fuels Symposium, held in London.

In short, R&D is vibrant, though it is generally disparate with modest funding. Imperial College London is developing an artificial leaf programme, a SolarCAP consortium (at the universities of East Anglia, Manchester, Nottingham and York) is fabricating solar nanocells to produce solar fuels, and the Engineering and Physical Sciences Research Council is calling for applications to a new Solar Energy Research Hub, with up to £4m in funding.

Plenty of nascent technologies were also showcased at the conference. Professor Ivan Parkin and his colleagues at University College London are developing a nanocrystalline photochemical diode that could improve efficiency in the solardriven splitting of water into hydrogen and oxygen. Professor Lee Cronin and his team at the University of Glasgow are fabricating a redox active poloxometalate to catalyse the rapid oxidation of H2O to O2 in water at ambient temperature. Furthermore, researchers at the University of Cambridge are looking to integrate catalysts into nanostructured metal oxide materials to improve the water-splitting technique that reaps useful hydrogen.

However, while both the enthusiasm and ambition were palpable, the UK solar fuel industry is blighted by the same shortcomings as its global counterparts.

Many innovative technologies work well, but the materials used to create them are far too expensive. For example, the RS report is mentioned Japanese car manufacturer Honda’s development of a hydrogen station prototype in Los Angeles, before adding that it is too expensive for commercial scale-up. Similarly, academics go to great lengths to prove their method works, yet the fuel conversion efficiency is a long way short of commercial viability.

The lack of coherent global development in previous decades has stymied development. There is still considerable debate about the chemistry behind artificial photosynthesis, and doubts have also been raised about the relevance of photosynthesis to artificial systems. Identifying inexpensive catalysts for artificial photosynthesis and finding the best semi-conductor materials were among the problems cited by delegates.

The UK and many other countries could do worse than to adopt the US paradigm, where a concerted funding injection and crossdisciplinary research programme have borne fruit. Admittedly, few countries can afford to plough the sort of resources the USA has into its programme. Nevertheless, the strides the industry continues to make look promising.

The USA has launched a cross-disciplinary hub, the Joint Center for Artificial Photosynthesis, with the specific aim of getting products to industry. As Professor Raymond Orbach of the University of Texas in Austin, said, ‘In order to sell the hubs, it is important to recognise the need for an end state.’

And, the resultant end state made it all the way to President Obama’s presidential address in January 2011. He mentioned that the artificial leaf system developed at California Institute – which features a silicon solar cell with different catalytic materials bonded onto both sides – could lead to fuel that powers our cars. ‘It [the technique] only lasted a couple of hours,’ Orbach added, ‘but that didn’t make the press release’.

As important as this technological advance was, the subsequent public interest was possibly more so.

There was a consensus among delegates that public engagement would be extremely beneficial for solar fuel advancement. As the RS report underlined, there is a risk that the UK could lose some major ground on other countries if it doesn’t adopt a coherent strategy. It is a daunting, burgeoning field, but one with huge potential.

As Peter Edwards, of the University of Oxford, noted. ‘The challenges are enormous, but that’s what attracts us to all of this’.