The Basics: Concentrating Solar Thermal Power

This week I break down the basics of concentrating solar thermal (CST) and its impact on clean energy.  With the help of publications from the World Resources Institute (WRI), let's take a walk through the tremendous potential of CST.

On a planet undergoing major environmental degradation and climate change and in a nation of fluctuating fuel prices and energy policies, one thing remains constant - the Sun is shining.  We've heard it over and over again, including from the World Resources Institute (WRI), stating "an enormous solar energy resource remains largely untapped."

One answer to tapping that energy is concentrating solar thermal (CST) technology.  Some nerds tinkering with some mirrors in the Mojave Desert has proved useful.  Despite being brushed aside by nay-sayers as some nightmarish science fiction contraption, CST has been on the rise in the last few years. 

But what exactly is it?  WRI's full report on the topic, Juice From Concentrate: Reducing Emissions with Concentrating Solar Thermal Power, defines CST with the following:

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. 

Generate electricity on demand you say?  I'm listening. 

Concentrating solar thermal's potential

Currently there is over 500 megawatts (MW) of installed CST power located mainly in the US and Spain.  On the other hand, advocates for CST agree there is great potential to scale up that development to generate much more power.  CST also offers a good chance to reduce dependence on domestic coal production.  Overall, CST is an important option for the future and much more diverse portfolio of renewable energy technologies across the globe. 

Some key findings

WRI's report includes some key findings on CST that are reviewed below, overall noting that CST provides a large-scale option to deliver a zero-carbon electricity system.

• CST remains more expensive than coal as a generation source, but prices are expected to decline significantly as technology learning occurs.  A carbon price of approximately $115 per ton of CO₂ would be needed for CST (trough with 6 hours of storage) to become economically competitive with coal-fired power.

• Costs are expected to decline as new capacity comes online.  Key areas of cost improvement will come through research and development (R&D), particularly in improved storage materials, optical design, mirrors, heat collectors, heat fluids, and plant operation.  Several simple policy options can accelerate CST deployment and bring down costs.

• In the near term, investment will be driven in part by policy incentives.  The most generous incentives at present are provided through Spain's feed-in tariff.  This model is being taken up in some developing countries and may merit consideration in the United States.  U.S. support based on tax credits for investment and/or production has proven less effective, largely because it is subject to periodic and uncertain renewal.

WRI's Director of International Climate Policy, Rob Bradley, provides six recommendations for how Congress can help with CST:

1. Enact a price on carbon
2. Fund RD&D
3. Create a national Renewable Energy Standard (RES)
4. Push for CST in international technology partnerships
5. Improve the grid and transmission system
6. Consider alternative investment incentives

Bradley, explains more about CST:

"CST, which can provide power without increasing carbon dioxide emissions, will be an important part of the energy solution in the United States.  Congress can enact legislation that will facilitate bringing it to scale."

For more on the topic of CST, check out WRI's factsheet as well as their full report - Juice From Concentrate: Reducing Emissions with Concentrating Solar Thermal Power.  And don't forget to keep up on EnergyBoom's Solar section for the latest news.