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Is It Time For A Second Look At Concentrated Solar Power?

Renewable energies may have reached parity with fossil fuels in pricing but there are still several problems associated with their power supply. For example, their supply fluctuates with time of day. They also cannot supply energy 24X7. Concentrated solar power (CSP) was touted as a possible solution but the jury is still out on whether they can be sustainable source of supply.

A recent feature on the technology from Inside Climate News certainly points to a revival in their fortunes. The piece profiles Crescent Dunes, a CSP project in Nevada operated by SolarReserve, one of the biggest companies operating in this space. It has built CSP plants in Australia and has plans to build another one in South Africa and ten more within the United States.

There are multiple types of CSP technologies. For example, the Dish/Stirling engine uses a dish-shaped parabolic to focus and concentrate heat from the sun’s rays onto a chamber filled with gas, which is then used to drive a piston. In another incarnation of the technology, parabolic troughs, which use long, curved mirrors to focus and concentrate heat onto a liquid-filled tower. Finally, revolving mirrors, also known as heliostats, can also be used to focus heat onto a tower filled with molten salt.

The rest of the process resembles the operations of a steam engine in that it the heated material heats water to produce steam, which is used to produce power. CSP is deployed in different formats throughout the world. For example, the Nevada plant uses molten salt while a plant in Morocco uses oil as an agent to invigorate combustion.

According to the article, concentrated solar power plants produce electricity at rates that are comparable to coal plants. A plant in Spain claims that energy accumulated in the towers can operate turbines for 15 hours straight. A video by the Department of Energy on Youtube claims that a single CSP plant can generate 250 MW or more. In practical terms, this translates to energy that is enough to power 90,000 homes.  

Governments around the world plan have begun testing and deploying the technology. Dubai plans to build a 1000 MW CSP plant by 2030. The first stage of that plant will produce 200 MW by 2021. The Trump administration announced a $62 million research grant into CSP last year. According to the press release accompanying the announcement, the administration’s priorities have a broader focus, including early-stage research to address solar energy’s critical challenges of grid reliability, resilience, and storage. The Department of Energy’s innovation lab ARPA-E is trying to develop a combination of PV and CSP known as Concentrated Photovoltaic Technology.

According to Grand View research, the global market for concentrated solar power is expected to reach $8.92 billion by 2025. But the technology has to overcome several problems first.

The biggest problem is the economics of owning and operating a CSP plant. The article I referenced earlier states that the SolarReserve’s Nevada plant cost as much as $1 billion. The Noor plant in Morocco, which is expected to generate 580 MW once complete, will cost $2.45 billion. According to some reports, it has already cost a billion dollars to generate 160 MW. Ivanpah, in California’s Mojave desert, is an example of the mismatch between expectations and reality. The plant, which is expected to generate 390 MW of power and had total costs of $2.2 billion, was funded with a $1.6 billion loan guarantee from the US Department of Energy (DoE) in 2014.  

But it must remembered that those costs are a function of several factors from materials used to land costs to labor costs to expected capacity. The cost to develop solar fields also varies across the type and format of technology being used. For example, using Tower and Fresnel technology can comprise 43% of total costs while using the Parabolic Trough can use up as much as 60% of overall costs. Government subsidies, which are largely responsible for growth of solar technologies, may also help concentrated solar power technologies.

There are problems with the technology itself. For example, the Ivanpah plant uses water, which cools relatively quickly as compared to molten salts, to produce electricity. As a result, it struggled to meet contractual obligations with Pacific Gas & Electric (PG&E) until earlier this year. Molten salt has also been found to freeze in the solar field piping at night. The good news is that several innovations are already being tested to overcome these problems. For example, Sandia National Laboratories has developed a thermocline system, which separates the hold and cold liquids with a filler, using a combination of molten salts and quartzite rock and sand for filler material. In Queensland Australia, the Cloncurry plant uses graphite blocks instead of solar towers. Pipes embedded in 540 tonnes of graphite produce steam, which runs turbine for 8 hours.   

CSPs also have a higher LCOE as compared to competitors. Paradoxically enough, the cost proposition of concentrated solar power plants is undercut by PV crystalline and thin film panels, which offer power for as low as $0.2 per kilowatt.  In contrast, CSP plants have an average rate of between 15 to 20 cents. There has been slow but sure progress on the cost front. The Nevada plant generates power at a cost of $0.6 per kilowatt.     

Then there are the dangers associated with such large plants. Misaligned mirrors caused a fire in Ivanpah back in 2016 resulting in scorched pipes in one of the towers. The plant has also been accused of “incinerating”  upto 6,000 birds, who fly through the concentrated rays, in 2016. The perimeter fence enclosing the plant has also trapped innocent road runners, who are eaten by coyotes later.

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