Concentrated solar power: BrightSource Energy launches molten salt solar thermal storage

Called SolarPLUSTM, the offering combines BrightSource’s high-efficiency LPT power tower solar thermal technology with proven two-tank molten salt storage. Concentrated solar energy industry analysts have long recognized solar thermal storage and efficiency gains as two critical components of driving down the cost of solar power electricity, while also realizing the significant reliability benefits that solar thermal power provides utilities and grid operators.

SolarPLUSTM now brings these two critical components together by combining BrightSource’s market LPT solar thermal power generating technology with proven molten salt storage. The benefits of this combination include:

Extending the production of electricity into later parts of the day and after the sun sets when it is most valued by utilities

Reducing the cost of renewable power for utilities’ customers by increasing a plant’s capacity factor and offering higher efficiencies than competing solar thermal power plants

Providing utilities with greater operational flexibility to shape production to meet changing utility customer demand

Offering utilities and grid operators additional operational and market value, by providing balancing and shaping capabilities, as well as ancillary services to support a reliable grid.

“Coupling storage with BrightSource’s high-efficiency LPT solar thermal technology represents a natural and critical advancement in utility-scale solar power generation,” said Israel Kroizer, EVP of Engineering, R&D and Product Supply, BrightSource Energy and President of BrightSource Industries (Israel) Ltd. “We’re thrilled to offer a solution that can meet the low-cost and real time power needs of utility customers, while providing the ancillary services that ensure a reliable grid.”

High-Efficiency Power Generation & Storage Drive Down Costs

Adding storage to a solar thermal power plant reduces the cost of energy produced at a plant by increasing its capacity factor – how much power a plant produces – by extending the production of electricity into later parts of the day when it is most needed by utilities. The ability to increase capacity factors by adding proven storage represents a significant advantage for solar thermal over other renewable resources like photovoltaics (PV) and wind that do not yet have economical storage capabilities.

BrightSource’s SolarPLUSTM plants also have efficiency and cost advantages over competing parabolic trough solar thermal technologies because of the LPT solar thermal power generating technology’s ability to reach higher temperature and higher pressure operating levels. Today, BrightSource’s LPT solar thermal power generating technology is producing the world’s highest temperature (540 degrees Celsius) and pressure (140 Bar) steam from solar.

In contrast, parabolic trough plants are limited to approximately 400 degrees Celsius and 100 bar pressure. The ability to reach higher temperature and pressure operating levels allows for more improved economics in pure solar generation and in storage mode relative to parabolic troughs due to higher operating efficiencies.

Enhancing Grid Reliability Adds Value for Utilities and Grid Operators

BrightSource’s SolarPLUSTM solar thermal power plants represent a critical resource in helping to meet the world’s growing demand for clean energy, while avoiding the intermittency challenges that other renewable resources like PV and wind create for utilities and grid operators. In addition to producing firm and dispatchable power, storage also provides operational flexibility, balancing and shaping capabilities, and ancillary benefits to help support a reliable grid, reducing the need for additional fossil fuel units necessitated by the intermittency of PV and wind.

“Electricity markets with high penetration levels of intermittent resources are starting to place significant value on those resources that can provide clean energy as well as operational flexibility and reliability services to the grid,” said Dr. Udi Helman, Director of Economic and Pricing Analysis for BrightSource Energy. “BrightSource’s SolarPLUSTM solar thermal power plants will empower utilities with a flexible power source that meets electricity demand at peak, can be used to further lower wholesale power costs, and supports grid reliability by providing ancillary services and improved resource adequacy.”

How BrightSource’s SolarPLUSTM Works

BrightSource’s SolarPLUSTM system leverages the company’s high-efficiency LPT solar thermal technology with proven molten salt as a storage medium. The “solar salts” – composed of 60% sodium nitrate (NaNO3) and 40% potassium nitrate (KNO3) – are commonly available materials. Today, molten salt storage – “solar salts” – is used widely in solar thermal plants in Spain.

A traditional BrightSource’s LPT power tower solar thermal system uses a field of software-controlled mirrors called heliostats to reflect the sun’s energy to a boiler atop a tower to produce high temperature and high pressure steam. The steam is used to turn a conventional steam turbine to produce electricity. In a BrightSource SolarPLUSTM plant, the steam is directed to a heat exchanger, where molten salts are further heated to a higher temperature, thus efficiently storing the heat energy for future use. Later, when the energy in storage is needed, the heat stored in the molten salts is used to generate steam to run the steam turbine.

BrightSource Energy, Inc. designs, develops and sells solar thermal power systems that deliver reliable clean energy to utilities and industrial companies. The company has contracted to sell approximately 2.6 gigawatts of power to be generated using its proprietary solar thermal technology.