Future of CSP is looking sunny

Dr Sgouris Sgouridis, associate professor of engineering systems and management at the Masdar Institute of Science and Technology, discusses advancements in concentrated solar power.

The history of concentrated solar power (CSP) has seen a number of turning points. In the early 20th century it was proposed as a source of energy for sunny countries, with pilot plants looking very similar to a modern parabolic trough system.

But that was not to be, as the easy availability of fossil fuels took away the incentive to develop this form of renewable energy.

The oil crisis of the 1970s revived interest, but by the time the technology had been developed to the point of deployment, the high price of oil had also pushed further exploration. The new wave of large oilfields that went into production as a result, such as those in Alaska, the North Sea and Nigeria, again stymied CSP.

Fast forward to 2008, when the triple whammy of a new oil price shock, increasing fossil fuel production costs and fossil fuel-linked climate impact came together to position CSP for its second renaissance.

CSP installations were record-breaking in terms of size and output - the 527 megawatts of worldwide capacity installed in 2010 alone was more than double the amount present at the start of that year.

But its success was overshadowed by the extremely steep cost reductions and corresponding explosive growth of another renewable energy technology - solar photovoltaic (PV). By the end of this year, more than 100 gigawatts of PV capacity will have been installed worldwide.

The growth of low-cost PV has caused the cancellation of many planned CSP installations, or their conversion to PV. These factors combined to bring into question CSP's viability, leading at least one of the big players, Siemens, to sell off its CSP acquisitions. At the same time, Spain slashed the feed-in tariff system that had allowed it to become a leader in CSP deployment.

None of this, though, means CSP is not viable. There is no silver bullet in renewable energy - all the main technologies have advantages and disadvantages that vary in different regions of the world.

CSP's overwhelming advantage is its ability to offer low-cost thermal energy storage, which makes it the cheapest form of renewable energy after hydro that can be generated according to consumer demand.

Secondly, it can integrate with existing natural gas power plants, which can fill any gaps in solar power production.

Third, it can be used for direct thermal applications, such as industrial thermal processes, cooling using absorption chillers, or in some cases desalination. This skips the step of using electricity to generate heat.

Its main disadvantage is that while solar PV can use diffused light, CSP cannot - it is entirely dependent on direct sunlight. Even a moderate amount of cloud cover or haze dramatically cuts its power output.

As the Masdar Institute's UAE solar atlas project has shown, there are plenty of locations in the UAE and the wider Middle East where CSP is a great option.

We have found that combined with thermal energy storage, CSP can complement PV in meeting the typical post-sunset demand peak, and can do so economically when combined with measures to reduce electricity demand, such as better building insulation, more efficient and better-maintained air-conditioning equipment and low-power lighting and appliances.

Further studies at the Masdar Institute aim to make CSP even more useful by designing receivers that can use both scattered and direct radiation due to atmospheric conditions, as well as investigating its cooling applications and testing alternative storage mechanisms.

Opened last month, Shams 1 is the first operating CSP plant in the Middle East - and, for now, the biggest in the world, until larger plants in the United States come on line next year. It is already testing and demonstrating the technology's potential.

And the insights it is offering will support the development of larger and more cost-effective CSP plants. The 1.7GW of worldwide CSP capacity planned for completion this year may still pale relative to PV deployment, but it is a step towards pushing the technology learning curve and further establishing a valuable sustainable energy option.

- Dr Sgouris Sgouridis is associate professor of engineering systems and management at the Masdar Institute of Science and Technology.