Solar all night?

Promise of homes as mini ‘power stations’ via solar PV link to hydrogen production

Scientists at the Massachusetts Institute of Technology have high hopes for their latest “breakthrough” in solar photovoltaics (PV). They envisage it not only powering our homes during the day, but ‘storing’ enough excess energy, by producing hydrogen, to keep the lights on all night – and keeping the car fuelled too.

What MIT has brought to the table is a more energy-efficient way of using solar electricity in splitting water. Their process, they say, can work at the domestic scale, whereas current industrial electrolysis takes place in highly controlled environments. “You can do it in a glass of water, at atmospheric pressure, in room temperature,” explains MIT's Daniel Nocera. He works on the Institute’s Solar Revolution Project, which aims to enable the large-scale deployment of solar energy within ten years. The key difference is the use of cobalt as a catalyst, which needs only around half as much electric charge as platinum to do the job.

MIT isn’t the only place experimenting with different minerals to do the job better – an international partnership of researchers claimed a similar breakthrough this summer with manganese. But Nocera certainly has the bigger picture in mind for his system: “All of a sudden your house has become a power station… it’s become a gas station,” he enthuses. The system could be particularly useful in developing countries, or remote areas where grid connections are limited, as it is a much more efficient way of storing energy than using batteries.

“This work is a step closer to being able to better harness sunlight,” comments James Barber, professor of biochemistry at Imperial College London. He accepts “it’s a long way from any practical device” – but it does raise his concern that the UK is not investing heavily enough in a renewable energy that, unlike wind and tidal power, could operate on a huge scale. In one hour, enough sunlight strikes the Earth to provide the entire planet’s energy needs for one year. Jeremy Leggett, chief executive of leading UK PV company Solar Century, said he was “cautiously excited” about the new technology, adding that “an integrated PV/fuel cell system would be fantastic”. – Hannah Bullock

1 October 2008

Hannah Bullock