Overview
The Sandstone Solar Energy Project was a proposed concentrated solar power (CSP) facility located in Nevada, United States. Designed as a major renewable energy infrastructure initiative, the project was planned for construction just to the east of Tonopah, situated approximately 170 miles (270 km) northwest of Las Vegas. The development aimed to integrate advanced solar thermal technology with significant energy storage capabilities to provide dispatchable power to the regional grid.
At its maximum planned scale, the Sandstone Solar Energy Project was designed to deliver an installed capacity of 1,600 MW. The infrastructure was conceived as a complex of up to eight individual solar towers, with each unit contributing 200 MW to the total output. The technical design relied on integrated molten salt energy storage technology, a key feature intended to enhance the flexibility and reliability of the solar thermal generation. This storage system was specified to hold 16 gigawatt-hours (GWh) of energy, allowing the plant to generate power even when solar irradiance was variable or during peak evening demand periods.
The project was developed by SolarReserve and owned by the entity Sandstone Solar Energy, LLC. Financial projections for the infrastructure indicated an anticipated cost of about $5 billion. In terms of annual production, the planned energy output was estimated at 5,600 GW·h per year. Despite these detailed technical and financial plans, the Sandstone Solar Energy Project is currently classified with an operational status of cancelled. The cancellation marks the end of the development phase for this specific large-scale solar thermal initiative in the Nevada desert.
Project Specifications and Technology
The Sandstone Solar Energy Project was designed as a large-scale concentrated solar power (CSP) facility, utilizing solar thermal technology rather than photovoltaic panels. The project's primary technical specification was a maximum electrical capacity of 1,600 megawatts (MW). This capacity was intended to be generated through an array of up to eight individual solar towers, with each unit contributing approximately 200 MW to the total output.
Energy Storage System
A defining feature of the Sandstone project was its integrated energy storage capability, designed to mitigate the intermittency typical of solar generation. The system was planned to provide 16 gigawatt-hours (GWh) of stored energy. This storage was achieved using molten salt technology, a common method in CSP plants where heat is captured and held in a mixture of sodium nitrate and potassium nitrate. This allowed the plant to continue generating electricity even after the sun had set or during periods of cloud cover.
Technical Parameters
| Parameter | Value |
|---|---|
| Technology Type | Solar Thermal (Concentrated Solar Power) |
| Total Capacity | 1,600 MW |
| Number of Solar Towers | Up to 8 |
| Capacity per Tower | 200 MW |
| Energy Storage Capacity | 16 GWh |
| Storage Medium | Molten Salt |
| Planned Annual Output | 5,600 GWh/year |
The project's design aimed for a substantial annual energy output of 5,600 gigawatt-hours (GWh) per year. This output figure reflects the combined effect of the solar collection area and the efficiency of the molten salt storage system in smoothing out daily generation curves. The integration of storage was critical to the project's value proposition, allowing it to dispatch power during peak demand hours, typically in the late afternoon and early evening.
The development of the project was led by SolarReserve, with ownership held by Sandstone Solar Energy, LLC. The anticipated cost for the entire infrastructure, including the solar fields, towers, and storage systems, was estimated at about $5 billion. This capital expenditure covered the construction of the eight-tower configuration and the associated balance-of-plant infrastructure required to feed the generated power into the regional grid.
How does concentrated solar power with molten salt storage work?
Concentrated solar power (CSP) systems, such as the technology proposed for the Sandstone Solar Energy Project, utilize mirrors to focus sunlight onto a receiver to generate high-temperature heat. The Sandstone project specifically planned to employ solar tower technology, which relies on a field of thousands of flat, sun-tracking mirrors known as heliostats. These heliostats reflect and concentrate direct normal irradiance onto a central receiver located at the top of a tall tower. This concentration of solar energy creates intense thermal energy, significantly higher than that achieved by flat-plate photovoltaic panels.
Thermal Energy Conversion
In a solar tower configuration, the concentrated heat is absorbed by a heat transfer fluid circulating through the receiver. For the Sandstone project, the primary medium was molten salt. This fluid is heated to temperatures exceeding 500°C, depending on the specific salt mixture and system design. The superheated molten salt is then pumped through a heat exchanger, where it transfers its thermal energy to water, generating high-pressure steam. This steam drives a conventional turbine-generator set, converting the thermal energy into mechanical energy and subsequently into electricity. This Rankine cycle process allows CSP plants to integrate seamlessly with existing grid infrastructure, often utilizing steam turbines similar to those found in coal or nuclear power plants.
The Role of Molten Salt Storage
A defining advantage of the Sandstone Solar Energy Project’s design was its integrated energy storage capability. The project planned for 16 gigawatt-hours (GWh) of storage, which is critical for managing the intermittency of solar power. Molten salt serves a dual purpose: it acts as both the heat transfer fluid and the storage medium. When the sun is shining intensely, excess heat is stored in insulated tanks of molten salt. The Sandstone project’s storage capacity was designed to provide up to ten hours of power output, enabling the plant to dispatch energy during peak evening demand. This thermal storage mechanism distinguishes CSP from photovoltaic systems, which typically require separate battery banks or pumped hydro storage to achieve similar dispatch flexibility. The ability to store thermal energy in molten salt provides a cost-effective method for extending the operational window of the solar farm, enhancing its value to the electrical grid.
Development History and Timeline
The project was conceived as a major solar thermal power facility, designed to generate up to 1,600 MW of capacity. It was planned for a site just to the east of Tonopah, located approximately 170 miles (270 km) northwest of Las Vegas, in the United States. The project was anticipated to cost about $5 billion..
Project Structure and Technology
The design of the Sandstone Solar Energy Project involved up to eight solar towers. Each tower was planned to have a capacity of 200 MW. The technology selected for the project was solar thermal power with integrated molten salt energy storage. The total energy storage capacity was planned to be 16 gigawatt-hours. The projected energy output was 5,600 GW·h per year. These specifications were part of the initial development plans by SolarReserve..
Construction Timeline and Cycles
The development history included plans for a staggered construction schedule. The estimated construction start was set for 2022. The construction was planned to occur in staggered 24-month cycles. This approach was intended to manage the deployment of the up to eight 200 MW solar towers. The project status is currently listed as cancelled. The cancellation occurred after the planning phase and before the completion of the staggered construction cycles..
Financial and Operational Planning
The financial planning for the Sandstone Solar Energy Project included an anticipated cost of about $5 billion. This cost covered the development of the solar thermal power plant and the integrated molten salt energy storage system. The operational planning aimed for an annual energy output of 5,600 GW·h. The location near Tonopah was chosen for its solar resource potential..
Regulatory Process and Cancellation
The regulatory trajectory of the Sandstone Solar Energy Project concluded with its formal withdrawal from the U.S. Bureau of Land Management (BLM). In March 2019, the project developers initiated the process to remove the application from the BLM's review pipeline. This strategic move effectively halted the administrative proceedings for the facility, which had been planned as a major solar thermal installation with 1,600 MW of capacity and 16 gigawatt-hours of energy storage (per project planning documents). The withdrawal marked the end of the active regulatory phase for the development, which had been owned by Sandstone Solar Energy, LLC and developed by SolarReserve.
Following the March 2019 withdrawal, the BLM proceeded to formally close the administrative docket for the project in April 2019. This closure confirmed the cancellation status of the initiative, finalizing the end of its regulatory life. The project, which was anticipated to cost about $5 billion and was planned to generate 5,600 GW·h per year, was situated just to the east of Tonopah, approximately 170 miles (270 km) northwest of Las Vegas. The cancellation meant that the planned infrastructure, consisting of up to eight 200 MW solar towers with integrated molten salt energy storage technology, would not proceed to construction under the original application.
Economic and Environmental Context
The Sandstone Solar Energy Project was anticipated to cost about $5 billion, a significant capital investment for a solar thermal facility of its scale. This financial commitment underpinned the development of an up to 1,600 MW solar thermal power project with 16 gigawatt-hours of energy storage. The project was developed by SolarReserve and owned by Sandstone Solar Energy, LLC. The estimated cost reflects the complexity of integrating up to eight 200 MW solar towers with molten salt energy storage technology. Such infrastructure requires substantial upfront expenditure compared to conventional photovoltaic installations, particularly due to the thermal storage components necessary for dispatchable power generation. The project's design aimed to eliminate the need for backup fossil fuels through its integrated molten salt energy storage technology. This capability allowed the facility to store thermal energy and convert it to electricity during periods of low solar irradiance, thereby enhancing grid stability. The planned energy output was 5,600 GW·h per year, indicating a high capacity factor relative to other renewable sources. By reducing reliance on natural gas peaker plants, the project sought to lower carbon emissions in the Nevada energy grid. The elimination of backup fossil fuels represents a strategic shift toward more resilient and sustainable power generation in the region. Located just to the east of Tonopah, about 170 miles (270 km) northwest of Las Vegas, the project was positioned to serve the growing energy demands of southern Nevada. Its potential impact on the Nevada energy grid included increased renewable penetration and enhanced reliability through thermal storage. The cancellation of the project left questions about the economic viability of large-scale solar thermal investments in the region. Despite its operational status as cancelled, the Sandstone Solar Energy Project remains a notable example of ambitious solar thermal development in the United States.Why it matters
The Sandstone Solar Energy Project represented a significant benchmark in the deployment of concentrated solar power (CSP) technology in the United States. As a planned 1,600 MW facility utilizing solar thermal power with integrated molten salt energy storage, the project was designed to demonstrate the scalability of CSP beyond traditional photovoltaic dominance. The inclusion of 16 gigawatt-hours of energy storage was a critical technical feature, addressing one of the primary challenges of renewable energy integration: intermittency. By storing thermal energy in molten salt, the project aimed to provide dispatchable power, allowing for energy output of 5,600 GW·h per year, even when direct solar irradiance fluctuated or during peak evening demand.
Technological and Economic Scale
The project's architecture, consisting of up to eight 200 MW solar towers, highlighted the modular potential of tower-type CSP systems. This configuration allowed for incremental development and optimization of the heliostat fields and central receiver units. The anticipated cost of about $5 billion positioned Sandstone as a major capital investment in the renewable energy sector, reflecting the economic scale required to compete with other generation sources in the western United States. The development by SolarReserve and ownership by Sandstone Solar Energy, LLC, underscored the collaborative models often necessary for large-scale infrastructure projects involving complex thermal dynamics and land use.
Strategic Location and Grid Integration
Located just to the east of Tonopah, approximately 170 miles (270 km) northwest of Las Vegas, the project was strategically positioned within the high-irradiance desert regions of Nevada. This location offered optimal solar resources essential for the efficiency of solar thermal conversion. The proximity to the growing energy markets of the Southwest, particularly Nevada and California, suggested a role in strengthening regional grid reliability. Although the project was ultimately cancelled, its planning phase contributed to the broader understanding of CSP's viability in the US energy mix, influencing subsequent decisions on renewable energy storage and thermal power integration in arid climates.
See also
- Spent nuclear fuel storage locations and inventory: Congressional Research Service report
- Eg Hyatt Hy Powerplant: Technical Profile and Operational Context
- Spire Inc.: Corporate History and Natural Gas Operations
- Cap-and-Invest (Washington state)
- ION Geophysical: Corporate History, Seismic Technology and Bankruptcy