Squeezing More Juice From Concentrating Solar Thermal

Concentrating solar thermal (CST) can generate electricity on demand--not just when the sun is shining.

Australia and other nations rich in solar resources should invest in concentrating solar thermal (CST), a key low-carbon technology.

Australian Prime Minister Kevin Rudd recently announced plans to build the world’s largest solar energy project.

Previously, the Rudd Government announced it would invest nearly US $3.5 billion in a Clean Energy Initiative to support the growth of clean energy generation technologies, reduce CO2 emissions, and stimulate economic activity. Under this initiative, the Rudd Government is investing US $1.2 billion in solar technologies, including US $1.1 billion in the new Solar Flagships program. The tender specifications will be announced later in 2009 and the successful bids in 2010, but based on Rudd’s outline, the Program will develop up to four solar generation plants for 1GW of generating capacity—three times the capacity of the largest operating solar project in the world. The projects can use solar photovoltaic or concentrating solar thermal power (CST).

CST uses reflective material to concentrate the sun’s rays to power steam turbines or engines. When combined with thermal storage—which enables a plant to produce power under cloud cover and after the sun has set—CST can generate electricity on demand, not just when the sun is shining.

Given Australia’s solar resources, the announcement of the Flagships program is an important step toward meeting Australia’s 20% by 2020 renewable energy target. Australia, in fact, has some of the best resources globally for CST, as shown on this map:

Global Direct Normal Solar Radiation. Source: World Bank

According to a new WRI report, Juice from Concentrate: Reducing Emissions with Concentrating Solar Thermal Power, CST, a renewable energy resource that can be dispatched on demand, offers significant potential for reducing carbon dioxide emissions from the power sector and will be an important part of the energy solution.

Reviewing the economics of CST, WRI found that there is real scope for policy to accelerate widespread deployment of CST globally. Costs are currently high relative to coal-fired power. Initiatives such as the one in Australia provide important signals of public commitment that could improve investor confidence and ultimately bring down CST costs.

However, despite the technical viability of CST with thermal energy storage, there remain significant barriers of which policy-makers and investors need to be aware.

Most importantly, the regions with the best solar resources are often arid or water-scarce. Australia is no exception. The Australian government should consider additional incentives for plants that incorporate advanced technologies that can reduce water consumption, such as dry cooling and wet/dry hybrid cooling systems (although these technologies also increase project costs).

Second, the most abundant solar resources are not evenly spread globally and often do not coincide perfectly with large energy-consuming population centers. Australia’s solar resources are strong across the country, but less suitable in and around the major population centers in the southeast. Improved transmission systems will be needed to keep pace with the growth of CST and other renewable energy generation technologies.

Managing these challenges, Australia’s investments can help accelerate global deployment of CST by bringing down costs through learning, economies of scale, and building investor confidence. The Australian government anticipates that the learning from the Flagships Program can be shared internationally through the work of the new International Renewable Energy Agency (IRENA), which Australia recently joined.

As countries seek solutions to global climate change while meeting growing energy needs, CST will be an exciting part of the transformation of the power sector to low-carbon technologies.