This report examines Concentrating Solar Thermal power (CST), a renewable energy resource that presents policy-makers and investors with a significant potential for reducing carbon dioxide emissions from the power sector.
Concentrated solar thermal power (CSTP or CST) is alternately referred to as concentrated solar power (CSP). This report uses the acronym CST throughout.
In a world of rising energy prices, security concerns, and climate change, the production of energy will need to change in fundamental ways. In the electricity sector, certain renewable energy sources appear ready for the mainstream, offering not just a solution to these challenges but an exciting opportunity for investment, innovation, and job creation. Many regions are deploying wind and solar energy, successfully managing their intermittency. However, these resources are innately less predictable than coal, which limits their use at high rates of market penetration and as reliable sources of power around the clock (i.e., baseload electricity). Both developed and emerging economies require reliable power supplies on demand, and many energy analysts routinely assert that there is no realistic alternative to building more coal-fired power generators.
A serious energy alternative
This report provides a rebuttal to that assertion, outlining the potential groundbreaking role of concentrating solar thermal power (CST) in providing power on the margin of the demand curve, as well as replacing coal at the core of the power mix. If catastrophic climate change is to be averted, then reducing carbon dioxide (CO2) emissions from fossil fuel combustion is critical, and displacing coal-fired generation is the preeminent challenge. Given the hurdles facing fast, large-scale deployment of other climate-friendly technologies such as carbon capture and storage (CCS) and nuclear power, large-scale uptake of renewable energy sources such as CST will be critical to the solution.
What is concentrating thermal power?
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. Globally, solar resources are abundant.Solar resources in Australia, Mexico, the Middle East, and southern and northern Africa are equally promising. Parts of Latin America, India, central Asia, and China also have great potential (see Figure 1). Other areas, such as Europe, have solar resources that are only marginally suitable for CST, particularly in Spain and Portugal. Because CST technology components are produced from readily available commodities such as steel and glass, bottlenecks to CST market growth will likely be no more problematic than other energy options. Although CST is only one part of the energy solution, it potentially offers a major supply option in some of the world’s largest economies and load centers.
Despite the technical viability of CST, there are significant barriers of which policy-makers and investors need to be aware. Costs are currently high relative to coal. Further improvements to the technology will help bring costs down, and investors and operators are still learning how to design and operate plants most efficiently. The U.S. Department of Energy (DOE) has a goal of producing baseload power from CST at competitive prices by 2020. For the time being, consistent policy support will be important to accelerate deployment and market acceptance. The regions with the best solar resources are often arid or water-scarce. Incorporating advanced technologies such as dry cooling and wet/dry hybrid cooling systems can reduce water consumption but also increase project costs. Producing zero-carbon electricity and heat for seawater desalination is an expensive option, but may be attractive in these regions as water scarcity concerns increasingly factor into decision-making.
The most abundant solar resources are not evenly spread globally and often do not coincide perfectly with large energy-consuming population centers. Improved transmission systems will need to keep pace with the growth of CST and other renewable energy generation technologies. CST has some track record, but investors are still wary of new technologies. CST is capital intensive, and at a time when financial markets are struggling, measures to increase investor confidence will be important.
A bright future
Policy-makers and investors are looking for ways to meet rising energy demand while cutting CO2 emissions from fossil fuel use. CST offers a major opportunity to meet this challenge in a way that does not increase the long-term cost of electricity. Thanks to policy support in the U.S. and Spain, in particular, the CST industry is developing into one that can deliver at scale (see Table 1). There is real scope for policy to accelerate widespread deployment of CST in the United States and in Europe at first, but also in the Middle East and North Africa, exploiting their abundant solar resources, and in major developing economies like China and India, addressing major environmental concerns. To take advantage of its potential, policies are needed to help bring down the costs of CST plants with thermal energy storage by providing predictable price support and thereby improving investor confidence, and in the longer term to improve regulation and increase investment in transmission infrastructure. The availability of CST and other renewable power options means that expanded coal use should no longer be seen as an inevitable factor in maintaining economic growth.