Concentrating solar power (CSP) uses mirrors to focus sunlight onto water. This produces steam that can then turn turbines and generate electricity. It differs from photovoltaics, which use solar panels to turn sunlight directly into electricity and can operate even on overcast days. CSP only works in places where there are many days with clear skies and is a proven, reliable technology.

At the end of 2008 CSP capacity was around 430MW, and worldwide investment in the technology will reach €2bn (£1.8bn) this year, according to Sven Teske of Greenpeace International and co-author of the report. He said investment could increase, under a relatively moderate scenario, to €11.1bn by 2010 and provide 7% of the world's generating capacity by 2030. By 2050 investment could reach €92.5bn, creating almost 2m jobs by 2050 and saving 2.1bn tonnes of CO2 every year.

"Due to the feed-in tariff in Spain and a few schemes in the US, this technology is actually taking off and we wanted to highlight that we have a third big technology to fight climate change — wind, photovoltaics and now CSP," said Teske.

Spain is leading the field on CSP: more than 50 solar projects in the country have been approved for construction by the government and, by 2015, it will generate more than 2GW of power from CSP, comfortably exceeding current national targets. Spanish companies are also exporting their technology around the world.