Crescent Dunes Solar Energy Project
In the vast Nevada desert, an ambitious project once promised to revolutionize solar energy: the Crescent Dunes Solar Energy Project. It was designed to capture sunlight, store its heat in molten salt, and generate electricity even after the sun set—a truly dispatchable form of solar power. But this pioneering venture faced a turbulent journey, grappling with technological hurdles, financial crises, and the immense challenge of bringing a groundbreaking concept to full-scale commercial reality. Crescent Dunes was a groundbreaking concentrated solar power plant, the first of its kind at scale to use molten salt for long-duration energy storage. Despite its innovative technology, the project faced severe design and operational issues, including a critical molten salt tank leak that led to years of underperformance and financial distress. After multiple bankruptcies and changes in ownership, the plant has attempted to find new life by specializing in night-time energy supply, showcasing the persistent challenges and potential of advanced solar thermal solutions.
AI Summary
In the vast Nevada desert, an ambitious project once promised to revolutionize solar energy: the Crescent Dunes Solar Energy Project. It was designed to capture sunlight, store its heat in molten salt, and generate electricity even after the sun set—a truly dispatchable form of solar power. But this pioneering venture faced a turbulent journey, grappling with technological hurdles, financial crises, and the immense challenge of bringing a groundbreaking concept to full-scale commercial reality.
- Crescent Dunes was a groundbreaking concentrated solar power plant, the first of its kind at scale to use molten salt for long-duration energy storage.
- Despite its innovative technology, the project faced severe design and operational issues, including a critical molten salt tank leak that led to years of underperformance and financial distress.
- After multiple bankruptcies and changes in ownership, the plant has attempted to find new life by specializing in night-time energy supply, showcasing the persistent challenges and potential of advanced solar thermal solutions.
The Desert Dream
Imagine a field of over ten thousand mirrors, each one tracking the sun, all focusing its intense energy onto a single, towering point in the desert sky. This was the vision behind the Crescent Dunes Solar Energy Project, nestled near Tonopah, Nevada. It was a pioneering concentrated solar power—or CSP—plant, ambitious in both its scale and its cutting-edge technology.
Unlike traditional photovoltaic solar panels that convert sunlight directly into electricity, Crescent Dunes harnessed the sun's heat. The plan was for this heat to be absorbed by molten salt, which could then be stored, allowing the plant to generate power not just during the day, but long into the night. This promised a truly 'dispatchable' form of solar energy, available on demand.
An Ambitious Beginning
Launched by SolarReserve, a startup with big aspirations, along with partners like US Renewables Group and United Technologies, the project's initial projected cost was under a billion dollars. A significant boost came in September 2011, when it secured a substantial $737 million loan guarantee from the U.S. Department of Energy, alongside a crucial power purchase agreement with NV Energy, promising to buy all its output for 25 years.
With funding secured and permits in hand, ground broke in September 2011. Construction proceeded, and by September 2015, Crescent Dunes began its highly anticipated operation. The world watched, eager to see if this innovative approach could deliver on its promise of reliable, round-the-clock solar power.
Molten Salt, Molten Problems
However, the plant's journey was anything but smooth. Just a year into operation, in October 2016, a critical issue arose: a leak in one of its massive molten salt storage tanks. This wasn't entirely unforeseen; internal comments from the owners dating back to March 2012 had already flagged potential flaws in the tank foundations, but those warnings went unheeded.
The leak forced the entire plant offline for many months of repairs, a costly setback that revealed fundamental design challenges. Even after it returned to operation in July 2017, Crescent Dunes struggled to meet its expected output. Its monthly production rarely exceeded half of the projected 40,000 megawatt-hours.
The Technology Behind the Tower
At the heart of Crescent Dunes' innovation were 10,347 individual mirrors, known as heliostats. Each one was a sophisticated array of 35 smaller mirror facets, giving it a vast surface area to precisely track the sun and reflect its rays onto a central receiver atop a 656-foot (200 meter) tall tower.
Inside that tower, molten salt—a mixture of sodium and potassium nitrates—flowed, heating up to nearly 600°C (1112°F) as it absorbed the concentrated sunlight. This superheated salt then circulated to enormous storage tanks, capable of holding enough thermal energy to power the plant for up to ten hours, even after sunset.
This thermal storage was key, as it meant the plant could deliver electricity when it was most needed, bridging the gap between daylight and demand, without relying on fossil fuel backups. Melting the 70 million pounds of salt initially took two months, but once molten, it was designed to remain in a liquid state for the plant's entire operational life.
A Flaw in the Design
But this groundbreaking technology also presented unique engineering challenges. Operating the molten salt storage tanks at such high temperatures—nearly 600°C—while maintaining a cold base temperature of 280°C meant extreme thermal expansion and contraction. At the large scale of Crescent Dunes, these significant temperature differences created immense compressive forces on the tank floor, leading to a high probability of structural failure under repeated stress cycles.
Financial Fallout and First Bankruptcy
The plant's inconsistent production and operational problems eventually led to its downfall. After last producing power in April 2019, its sole customer, NV Energy, terminated its 25-year contract in October 2019, citing a persistent 'failure to produce' the contracted power.
Furthermore, the electricity generated by Crescent Dunes was costing NV Energy around $135 per megawatt-hour. This was considerably more expensive than the less than $30 per MWh offered by newer photovoltaic solar farms being built in Nevada at the time. While Crescent Dunes offered dispatchable power, unlike intermittent PV, the cost difference was substantial.
In the wake of the contract termination, SolarReserve filed a lawsuit alleging a takeover attempt by the Department of Energy, and ultimately, Tonopah Solar Energy, the project's owner and operator, filed for Chapter 11 bankruptcy on July 30, 2020. This triggered complex legal proceedings and a restructuring of debt, leaving taxpayers on the hook for a significant portion of the initial loan guarantee.
A Second Chance, A New Role
Despite the severe setbacks, the story of Crescent Dunes didn't end there. During bankruptcy proceedings, hopes for a restart emerged. A reorganization plan was confirmed by the court in December 2020, which transferred operational control to Cobra Energy Investment LLC, a division of the Spanish construction giant ACS Group. This new management team aimed to revive the plant.
Remarkably, in July 2021, the project restarted production for NV Energy, albeit under new terms. Under its current owner, Vinci SA, and a renegotiated contract, Crescent Dunes now serves a very specific and crucial role: supplying solar energy at night only, drawing exclusively on the thermal energy stored each day. It's a testament to the continued belief in its unique storage capabilities.
Production Performance Over Time
The plant's operational history, marked by periods of activity and prolonged shutdowns, reflects its tumultuous journey. Initial expectations for monthly output were rarely met, and the 2016 tank failure severely disrupted its commissioning phase, which for a new thermal plant can typically take up to four years to reach full capacity.
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total 2015 1,703 1,831 0 3,534 2016 1,508 9,121 7,099 2,158 11,485 6,216 25,560 28,267 30,514 5,410 0 0 127,338 2017 0 0 0 0 0 0 9,420 9,192 13,666 9,263 488 0 42,029 2018 795 5,145 5,907 13,801 10,653 33,387 23,749 33,169 31,632 21,253 8,130 8,189 195,810 2019 12,889 14,431 20,041 2,807 Production suspended 50,168 2020 Production suspended 0 2021 Production suspended 3,974 15,445 20,796 11,929 17,489 5,088 74,721 2022 14,635 12,238 0 0 0 0 0 8,852 22,166 24,710 10,590 7,475 100,666 2023 8,437 2,086 0 0 0 0 6,649 14,563 13,784 18,060 10,590 6,067 80,236 2024 4,556 4,122 6,448 13,516 20,968 26,227 18,093 19,889 18,790 9,549 5,607 6,637 154,402 2025 0 - - - - - - - - - - - -
You can see from the production data that early 2019 showed promising improvements, even topping previous monthly records. But this progress was abruptly halted in April when the plant was shut down again due to its inability to consistently meet contractual power commitments, leading to NV Energy's final termination.
Continuing Challenges
The journey of Crescent Dunes remains a powerful lesson in the complexities of pioneering renewable energy technologies. While its initial vision was groundbreaking, the technical and financial hurdles proved immense. Its restart, albeit in a specialized night-time role, highlights the enduring value of dispatchable solar thermal power.
However, the struggles are not over. Most recently, on January 21, 2026, Tonopah Solar Energy filed for Chapter 11 bankruptcy for a second time, announcing plans to sell off its assets, including the Crescent Dunes project. The company reported still owing nearly $173 million in unpaid debt, indicating that even with a renewed purpose, the plant's financial viability remains precarious. The desert dream continues its uncertain path.
Article
Crescent Dunes Solar Energy Project
The Crescent Dunes Solar Energy Project is a solar thermal power project with an installed capacity of 110 megawatt (MW) and 1.1 gigawatt-hours of energy storage located near Tonopah, about 190 miles (310 km) northwest of Las Vegas. Crescent Dunes is the first commercial concentrated solar power (CSP) plant with a central receiver tower and advanced molten salt energy storage technology at full scale (110 MW), following the experimental Solar Two and Gemasolar in Spain at 50 MW. As of 2023, it is operated by its new owner, Vinci SA, and in a new contract with NV Energy, it now supplies solar energy at night only, drawing on thermal energy stored each day.
Startup energy venture company SolarReserve (created via seed funding), US Renewables Group, and United Technologies were the original owners of Tonopah Solar Energy LLC, the owner and operator of the Crescent Dunes plant. The Crescent Dunes project was subsequently backed by a $737 million in U.S. government loan guarantees and by Tonopah partnering with Cobra Thermosolar Plants, Inc. The overall venture had a projected cost of less than $1 billion. The plant suffered several design, construction and technical problems and, having not produced power since April 2019, its sole customer, NV Energy, subsequently terminated its contract. Bloomberg reported that NV Energy was not allowed to sever its agreement with the plant until after the DoE took over the shuttered plant in August 2019.
Since the initial failure of the Crescent Dunes project, SolarReserve took down its website and is believed to have permanently ceased operations. Upon the developer's silence as the involved parties sought legal recourse, the plant's exact status was publicly unknown for some time and was left to conjecture.
While proceeding through its subsequent bankruptcy proceedings, Tonopah Solar Energy stated that it had hopes for a restart of the Crescent Dunes plant by the end of 2020. According to court documents, Tonopah is owned by SolarReserve, Cobra Energy Investment LLC, a division of Spanish construction company ACS Group and Banco Santander, S.A. On September 11, 2020, the bankruptcy court approved Tonopah Solar Energy's disclosure statement. On December 3, 2020, the Chapter 11 bankruptcy reorganization plan was confirmed by the court. As one result of this plan's confirmation, Cobra now has operational control of the plant. In July 2021, the project restarted production for NV Energy.
History
Crescent Dunes Solar Energy Project
Workers installing heliostats at Crescent Dunes
In late September 2011 Tonopah Solar Energy received a $737 million loan guarantee from the United States Department of Energy (DOE) and the right to build on public land. The capital stack included $170,000,000 in EB-5 investment through SolarReserve/ACS Cobra partner CMB Regional Centers. Under a power purchase agreement between SolarReserve and NV Energy, all power generated by the Crescent Dunes project in the next 25 years would have been sold to NV Energy for $0.135 per kilowatt-hour.
Ground was broken on the project in September 2011. Construction terminated at the end of 2013, followed by several months of testing the plant systems. The project entered commissioning phase in February 2014 following completion of construction. It began operation in September 2015, but went off-line in October 2016 due to a leak in a molten salt tank. The owners warned the EPC about flaws in the salt tank foundations (and other matters) with formal comments lodged on the record in March 2012 progress meeting with DOE and its engineer present (the lender did not voice any objection). It returned to operation in July 2017.
The plant having last produced power in April 2019, NV Energy—the project's sole customer—terminated its contract in October 2019 on the basis of the project having "failed to produce." Alleging a takeover of Tonopah Solar Energy by the DOE, SolarReserve then raised the possibility of the project filing for bankruptcy, which subsequently happened. SolarReserve also filed a lawsuit, claiming that the Department of Energy was looking to appoint two new members to Tonopah Solar Energy's board of managers, giving the appearance of the Energy Department in complete control of Tonopah directors which comprise the entirety of the Tonopah Board of Managers. An interim outcome in this regard was that SolarReserve took down its website and was believed to have ceased operations permanently.
Tonopah Solar Energy filed for bankruptcy on July 30, 2020. Pending the approval of the bankruptcy court, a $200 million settlement with the remaining debtors — Tonopah Solar Energy LLC and ACS Cobra — for the return of taxpayer dollars was also announced at the end of July 2020. The amount is less than half of what taxpayers are owed on the outstanding $425 million of public debt. Under the settlement agreement and as a function of subsequent repairs, restoration of the plant to power production and acquisition of new long-term customers, ACS Cobra is liable for an additional $100 million in otherwise suspended debt.
On January 21, 2026, Tonopah Solar Energy filed for Chapter 11 bankruptcy for the second time with plans to sell its assets, including the Crescent Dunes solar energy project. The company claimed it still owes nearly $173 million in unpaid debt to Crescent Dunes Finance, Inc.
Technology
Crescent Dunes Solar Energy Project
Sunlight heating molten salt in the central tower
The project's EPC Contractor was ACS Cobra, which carried out the engineering design, procured the equipment and materials necessary, and then constructed and delivered the facility to Tonopah Solar Energy. The project includes 10,347 heliostats that collect and focus the sun's thermal energy to heat molten salt flowing through an approximately 656-foot (200 m) tall solar power tower. Each heliostat is made up of 35 6×6 feet (1.8 m) mirror facets, yielding a heliostat overall usable area of 1,245 square feet (115.7 m2). Total solar field aperture adds up to 12,882,015 square feet (1,196,778 m2). The molten salt circulates from the tower to a storage tank, where it is then used to produce steam and generate electricity.
Excess thermal energy is stored in the molten salt and could be used to generate power for up to ten hours, including during the evening hours and when direct sunlight is not available. The storage technology thus eliminated the need for any backup fossil fuels, such as natural gas. Melting about 70,000,000 pounds (32,000,000 kg) of salt took two months. Once melted, the salt stays melted for the life of the plant and is cycled through the receiver for reheating.
The thermal storage high-temperature salt tank buckling failure
Crescent Dunes was the first large (110 MW) tower CSP with thermal storage. While storage tanks of trough CSP operate at 400 °C (752 °F), Crescent Dunes operated the storage tank at almost 600 °C (1,112 °F), while keeping 280 °C (536 °F) as base (cold) temperature. Higher temperatures differences result in a greater expansion of the tank floor, generating greater compressive forces around the floor plate. At very large diameters, as the big tank of Crescent Dunes, that resulted in a high probability of failure under cycling loading.
Production
Crescent Dunes Solar Energy Project
Crescent Dunes began operation in September 2015, but went off-line in October 2016 due to a leak in a molten salt tank. It returned to operation in July 2017. While its average monthly production was expected to exceed 40,000 MWh, as of May 2019 it never reached that value and only exceeded half of it during 9 months.
<table><thead><tr><th>Year</th><th>Jan</th><th>Feb</th><th>Mar</th><th>Apr</th><th>May</th><th>Jun</th><th>Jul</th><th>Aug</th><th>Sep</th><th>Oct</th><th>Nov</th><th>Dec</th><th>Total</th></tr></thead><tbody><tr><td>2015</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1,703</td><td>1,831</td><td>0</td><td>3,534</td></tr><tr><td>2016</td><td>1,508</td><td>9,121</td><td>7,099</td><td>2,158</td><td>11,485</td><td>6,216</td><td>25,560</td><td>28,267</td><td>30,514</td><td>5,410</td><td>0</td><td>0</td><td>127,338</td></tr><tr><td>2017</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>9,420</td><td>9,192</td><td>13,666</td><td>9,263</td><td>488</td><td>0</td><td>42,029</td></tr><tr><td>2018</td><td>795</td><td>5,145</td><td>5,907</td><td>13,801</td><td>10,653</td><td>33,387</td><td>23,749</td><td>33,169</td><td>31,632</td><td>21,253</td><td>8,130</td><td>8,189</td><td>195,810</td></tr><tr><td>2019</td><td>12,889</td><td>14,431</td><td>20,041</td><td>2,807</td><td>Production suspended</td><td>50,168</td></tr><tr><td>2020</td><td>Production suspended</td><td>0</td></tr><tr><td>2021</td><td>Production suspended</td><td>3,974</td><td>15,445</td><td>20,796</td><td>11,929</td><td>17,489</td><td>5,088</td><td>74,721</td></tr><tr><td>2022</td><td>14,635</td><td>12,238</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>8,852</td><td>22,166</td><td>24,710</td><td>10,590</td><td>7,475</td><td>100,666</td></tr><tr><td>2023</td><td>8,437</td><td>2,086</td><td>0</td><td>0</td><td>0</td><td>0</td><td>6,649</td><td>14,563</td><td>13,784</td><td>18,060</td><td>10,590</td><td>6,067</td><td>80,236</td></tr><tr><td>2024</td><td>4,556</td><td>4,122</td><td>6,448</td><td>13,516</td><td>20,968</td><td>26,227</td><td>18,093</td><td>19,889</td><td>18,790</td><td>9,549</td><td>5,607</td><td>6,637</td><td>154,402</td></tr><tr><td>2025</td><td>0</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td></tr></tbody></table>
The commissioning of a new thermal plant requires up to four years to achieve 100% operating level, from the first grid connection to full production. As an example the Edwardsport production data, whose progression, skipping first partial year, is a 40% output the first full year, 57% the second full year, the next year the progression was stopped by a problem in October, but resumes with a 73% the fourth and next year. At Crescent Dunes, it was to be expected a similar progression, but the failure of the storage tanks in 2016 froze the commissioning. Following that, first full production year was delayed to 2018, starting with a 40% (200 over 500) output.
Shutdown
The first three months of 2019 (January, February and March) showed good progression, topping all previous monthly data, but in April the plant was shut down because the project's sole buyer, NV Energy, terminated the Power Purchase Agreement for failure to produce the contracted power production. The power generated also cost NV Energy about $135 per megawatt-hour, compared with less than $30 per MWh available from a new Nevada photovoltaic solar farm. However, the Tonopah solar project power is dispatchable while photovoltaic power is intermittent. Levelized cost comparisons must include the capacity payments for generating capacity available to supply power during peak hours. By doing so, low-to-high hourly wholesale electricity prices have been shown to vary by up to four orders of magnitude.
Gallery
Crescent Dunes Solar Energy Project
• 2012 January – The solar tower under construction as seen from a commercial airliner. The eponymous Crescent Dunes are at lower right. • 2014 December – Completed site as seen from a commercial airliner. • 2024 August - Crescent Dunes Solar Energy Project as seen from commercial airliner