Time for solar to shine

One of the biggest energy issues is whether solar power can work its way out of the shade and become a substantial supplier of electricity. Today big solar, as opposed to rooftop photovoltaics, is mostly a great photo-op for politicians. A shirt-sleeved Barack Obama rode Air Force One in to Florida last week – while voters in colder parts of the country were giving his party something of a towelling – to be seen on national (and international) TV amid acres of hi-tech panels, opening a 25MW solar plant in a little rural town. As is their want, the media simply focussed on the $US150 million cost to Florida Light & Power, one of America’s biggest utilities, of the development. However, my solar-power calculator tells me that scaling the little station up to 1,000 MW would cost $US6 billion. A modern coal-fired plant would cost $US2.8 billion and one fired by natural gas a little less. Rather more interestingly, perhaps, is the thought that, on the current back-of-the-envelope calculations for carbon capture and sequestration, a 1,000 MW coal plant might cost about $US4.7 billion. The real rub, however, is that the solar plant, at best, would deliver electricity only about 30 per cent of the time. To get to the energy output of the expensive CCS coal-burner per year, investors would need to spend about $US18 billion on the solar job. Which is why the really interesting solar action right now may be over on the other side of America – where a cleantech start-up company wants to build a demonstration plant near Palm Springs, California. SolarReserve aims to trial a system where the concentrating mirrors focus the sun’s energy on to millions of litres of molten salt, enabling the plant to deliver round-the-clock power. Even in the middle of the night the solar plant will deliver power by passing the molten salt through a steam generator to drive a turbine, with the cooled salt being returned for reheating next day. This technology is not all that new. It was first trialled using a 10MW system nearly 20 years ago, as part of the initial work on the space station project, but got lost in the research and development wash in the interim. The difference between this process and other solar systems using salt for storage – it flows like water when super-heated – is that this one does not use synthetic oil in generating steam, meaning it can operate at higher temperatures and, it is claimed, can harvest three times as much energy for the same amount of salt. Importantly, the plant will be air-cooled. Conventional solar thermal power stations are thirsty beasts, a problem when they are mostly located in arid areas. SolarReserve claim their concept, scaled up, would use one five hundredth of the water needed by a coal-burning power station. None of this, of course, amounts to a hill of beans in today’s pre-Copenhagen world with its only-a-short-time-to-save-the-planet mindset among so many pollies and greenies. But they will all get mugged by reality eventually and the idea that there may be a solar technology that can climb in time over the intermittency hurdle cost-effectively is not to be idly dismissed, especially versus the CCS options. The reason for Obama’s visit to Florida, by the way, apart from blatant politicking, was to push the large, investor-owned utilities to take on solar demonstration plants and he tossed $US200 million in economic stimulus funding FL&P’s way to make the point. (His rhetoric, as usual, was high quality – you can read it on the White House website.)