Graphical representation of the Ivanpah Power Complex.
High Voltage Transmission lines passing through BrightSource Energy's ISEGS.
Heliostats being assembled during the construction of the ISEGS.
A water-filled boiler placed on top of the tower.
Final design of the complex with Luz Power Tower 550.

The Ivanpah Solar Electric Generating System (ISEGS) is located in San Bernardino County of California’s Mojave Desert in the US. With an installed capacity of 377MW, it is the biggest solar thermal project in the world. It is the first large-scale solar thermal project in California in two decades.

The project was developed by a start-up company, BrightSource Energy. It was approved by California Energy Commission (CEC) in October 2010. The facility began commercial operations in December 2013.

A labour agreement was signed between the State Building and Construction Trades Council of California (SBCTC), the Building & Construction Trades Council of San Bernardino and Riverside counties, and Bechtel to ensure that the local workforce benefits from the project. The project is estimated to generate $650m in wages during a 30-year period. The plant is operated by NRG Energy.

Ivanpah project details

The ISEGS is spread over 3,471 acres of public land managed by the US Bureau of Land Management (BLM). It is built near the existing roads and transmission lines, next to a natural gas power plant.

The plant’s three 450ft high towers can produce 392MW of solar power at full capacity. It comprises three separate solar units, one of 126MW and two units of 133MW each.

Power generated by the three plants is enough to serve more than 140,000 homes during peak hours of the day. The project will also help curb carbon emissions by more than 400,000t of carbon dioxide a year, which is equivalent to removing 72,000 vehicles off road.

“The ISEGS is spread over 3,471 acres of public land managed by the US BLM.”

The project receives the tax credit equivalent to 30% of the project cost under the American Recovery and Reinvestment Act (ARRA).

The power generated from Units 1 and 3 is being sold to Pacific Gas & Electric, while that from Unit 2 is being sold to Southern California Edison under separate long-term power purchase agreements.


The project was financed by a mix of equity and debt. BrightSource raised more than $300m of equity. A total of $160m equity was raised in Round D in 2010 from Silicon Valley Venture Capital, Morgan Stanley, BP, Chevron and Google.

Bechtel Enterprises, the financing arm of Bechtel, also has an equity stake in the project. French power and transportation company Alstom also purchased equity worth $55m. The other major non-power participant is the California State Teachers Retirement System.

The US Department of Energy (DOE) also provided a conditional loan guarantee of $1.6bn as stimulus funding for the project.


The ISEGS project was developed by the company’s engineering, procurement and construction (EPC) partner Bechtel. Babcock Power subsidiary Riley Power supplied solar boilers and Siemens provided two Siemens SST-900 steam turbines, one of which was supplied in 2008.

Gear boxes, which enabled the heliostats to reflect sunlight into the boiler, were provided by Cone Drive, while Gestamp Renewables supplied the pre fabricated steel framing structures for the heliostats.


The project features Luz Power Tower technology (LPT) developed by the company. It uses sunlight to produce energy, instead of fossil fuel or nuclear power.

“The project features Luz Power Tower technology developed by the company.”

It is the first project to use BrightSource’s solar power tower technology. The technology includes 173,500 heliostats that follow the sun’s trajectory. A software integrates the solar field with a solar receiver steam generator. This technology creates high-temperature steam by reflecting sunlight on small mirrors called heliostats, to provide heat to a boiler on top of the tower.

The water inside the boiler is heated using solar energy to generate steam, which is connected through pipes to a conventional turbine to generate electricity.

In addition to LPT, the project also features a dry-cooling technology that reduces water consumption by 90%.

The plant uses 95% less water than other solar thermal technologies.

The boilers and LPT together produce high-temperature steam of up to 550°C.

Environmental impact

In order to reduce the environmental impacts of the project, BLM in association with federal, state and local partners reduced the project size from 4,073 acres to 3,471 acres.

BrightSource also announced plan to acquire 7,300 acres of mitigation land to conserve the desert tortoise after being tested for disease onsite. BLM assigned more than 3m acres of land for conservation of the species.