Study shows greater potential for low-cost solar power plants

In a new study published in the journal Nature Climate Change, researchers from the Grantham Institute at Imperial College London, Stellenbosch University, and the International Institute for Applied Systems Analysis (IIASA) have calculated for the first time that connecting ‘concentrating solar power’ (CSP) plants could supply a significant amount of current electricity demand, alleviating concerns over the reliability and intermittency of renewable power.

CSP technology uses mirrors to reflect and concentrate light from the sun, which it converts into heat to power a turbine and produce electricity.

Results of the study have shown that in the Mediterranean region, for example, a connected CSP system could provide 70-80% of current electricity demand at costs comparable to other technologies that provide a stable power supply. This is comparable to energy production levels of a standard energy production plant, such as a nuclear plant.

Stefan Pfenninger, from Department of Civil and Environmental Engineering, who is currently working towards a PhD at the Grantham Institute at Imperial College London said: “Our results show that this solar energy system can satisfy up to 80% of our hunger for electricity, at not much more cost than traditional sources. This is the first study to systematically examine the potential of CSP to overcome the inherent variability of solar energy.”

One problem with deploying solar energy on a large scale is that the sun does not shine all the time, so the energy must be stored in some way. Storage is not possible with photovoltaic (PV) cells, as they convert sunlight directly to electricity, but with CSP, it becomes a reality. IIASA researcher Fabian Wagner, who also worked on the study, explains: “Unlike PV, CSP uses the sun’s energy to heat up a liquid that drives turbines. This means that the collected energy can be stored as heat, and converted to electricity only when needed.”

The researchers simulated the construction and operation of connected CSP systems in four regions around the world: the Mediterranean, South Africa, India and the United States of America. The simulations took account of weather variation, such as solar radiation, surface temperature and wind, as well as plant location, electricity demand and costs.

Results showed that if CSP plants are connected, they could provide up to 80 per cent of current electricity demand, at little to no extra cost. The researchers also showed that by doubling the surface area to trap the sun’s energy in each plant, connected CSP plants are able to create large enough heat reserves to compensate for times when the sun is not shining. This means that if one plant goes offline because of poor weather conditions, energy stored at another CSP plant could be used.

IIASA researcher Fabian Wagner said: “To address climate change we need to greatly expand our use of renewable energy systems. The key question, though, is how much energy renewable systems can actually deliver. Our study, which is the first to systematically assess how you would operate a fleet of CSP plants, shows that CSP offers massive potential as a reliable renewable energy source.”

To reduce greenhouse gas emissions and avoid current and future risks of climate change, many countries are committed to increasing use of renewable technologies in order to create a cleaner, greener and ‘de-carbonised’ energy supply.

Many analysts have suggested that the renewable energy source CSP could be scaled up to offer a high level of reliable power, without having to integrate different energy sources to feed demand. This study delivers strong evidence supporting the feasibility of such a plan.

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