India is making the case for CSP
Concentrated solar power is experiencing a remarkable resurgence. In a landmark move, India unveiled a 50% carve-out for CSP in its renewable energy tender for the first quarter of 2024.
Scaling up CSP will bridge the gap because of intermittent PV solar and wind to help power the world’s most populous country reliably, affordably, and continuously.
“Now is the right time for CSP,” said Rajan Varshney, Deputy Managing Director of NTPC—India’s largest state-owned utility company—in a recent interview. “As PV and wind capacity increases, increasingly more and more coal-based power will be required to make it firm and to supply electricity when the sun is not there. So by increasing PV, we cannot avoid coal unless we install CSP plus storage in Gujarat and Rajasthan.”
This new direction may surprise many in the solar industry, who had written off CSP as a technology of 15-20 years ago that ran into economic challenges in building and operating large-scale systems, particularly in California and Arizona
Today, however, CSP is enjoying a renaissance. And while earlier installations have all been massive, complex, custom-engineered, and not replicable, my company, 247Solar, has obtained fresh financing for a modular version that solves for these challenges.
Our version operates on superheated air at normal atmospheric pressure. It stores energy using simple materials, not molten salt. And it can be mass-produced in units of 400 kilowatts for economies of scale.
This model shows promise to greatly shorten project cycles, and resume the dramatic cost reductions in CSP that were achieved in its early years but slowed as the older tech matured.
Demand
Global demand for around-the-clock power has been growing because of economic growth in emerging economies. Demand is now accelerating due to data centers, cryptocurrency, and AI. As we move to electrify all of society with electric vehicles, heat pumps, and clean industrial heat, CSP emerges as a viable solution to address these pressing needs and provide zero-carbon power at all hours.
Grid operators continue to grapple with the variability of photovoltaic solar and wind energy. Wind, if it blows at night, can help balance daytime solar. But wind is much more variable than sunshine and requires long-distance high-voltage lines to get to market, which can add cost and time to wind farms’ deployment.
Even healthy doses of lithium-ion batteries—meant to handle morning and evening peak loads, as gas peakers did before them—are nowhere near enough to store the energy it would take to keep the grid powered through the night and during bad weather, as coal plants have.
In contrast, CSP’s levelized cost of energy has dramatically fallen by nearly 70% since 2010, in part because it offers longer and more economical energy storage than batteries.
And so, CSP is returning to projects that will pair it with solar PV to extend their power output into the night, while minimizing the overall LCOE by harnessing synergies between the two technologies.
Pioneers
Some of the high-profile early efforts at CSP got many things right, such as Abengoa Solar’s Solana plant near Phoenix, launched in 2013, or BrightSource’s Ivanpah plant in California, the world’s largest solar thermal plant at the time, back in 2013.
Initial CSP plants focused the sun’s heat on a single point, reaching temperatures over 1,000 degrees Fahrenheit. (247Solar’s system pushes that limit to 1,800 degrees Fahrenheit, about 1,000 degrees Celsius.) They also stored energy for 6 to 12 hours of operation at night.
But CSP is no longer just huge installations of pipes and mirrors in the desert or towers as high as a wind turbine.
My company, 247Solar, is seeing new interest in smaller, simpler, more flexible applications of this technology.
Our turbines generate electricity from nothing more than superheated air, so it doesn’t require a phase change of the energy from heat to steam as other CSP systems do.
Sustainable
We store the extra heat in cheap, inert materials such as sand, iron slag, or ceramic pellets. This eliminates the need for corrosive and high-maintenance molten salt, along with its chemical and physical challenges.
With proprietary thermal batteries, we provide 18-plus hours of long-duration storage for on-demand industrial-grade heat and electricity. They can produce power during bad weather, and when fully discharged, the turbines can even run on green hydrogen, natural gas or diesel (although because our solar capacity factor is 85%, that would be far less often than in a system of PV plus batteries with a 40% capacity factor).
Our turnkey solution, which we call 247Solar Plants™, is modular and factory-produced for rapid cost reduction through mass production and easy, quick on-site assembly.
Each module is 400 kW, with 120-foot towers (half the height of earlier versions of CSP). With fewer moving parts than conventional CSP, our solar thermal power plant is also easier to maintain in a hostile environment for added resiliency.
We hold over 31 patents worldwide (including a blanket patent just obtained in India) for our CSP system, as well as our proprietary solar collectors, ultra-efficient Heat2Power turbines that use ambient air pressure, and inexpensive thermal battery systems.
This hybrid approach leverages the strengths of both CSP and PV to generate uninterrupted power 24/7, with PV providing cheap electricity during the day, while CSP stores the sun’s energy as heat for use at night and during bad weather.
Others, such as Heliogen, BrightSource Energy, and Acciona, are also pushing the boundaries of CSP with advancements in AI-enabled systems, alternatives to the shortcomings of molten salt storage, or lower-cost parabolic trough technologies.
Potential applications for CSP include on-grid or off-grid combined heat and power, microgrids, ultra-heat for heavy industries, green hydrogen, green desalination, as well as baseload power 24/7/365—especially critical to fast-growing economies like India’s.
“Emerging technologies such as solar thermal and concentrated solar power are essential for India to meet its renewable energy targets,” said India’s New & Renewable Energy Secretary Bhupinder Singh Bhalla at the opening of the International Conference on Solar Thermal Technologies this February in New Delhi.
CSP is unmatched, especially when integrated with solar PV, for 24/7 dispatchability of flexible, dependable, and resilient zero-carbon power to meet the energy demands of tomorrow.