Solana Stores Solar Energy for Night; Mass. Town Generates Solar

by | Oct 10, 2013

Energy Manage SolanaAbengoa says the Solana Generating Station (pictured), located near Gila Bend, Ariz., has passed final production tests and entered commercial operation. At 280 MW (gross), the parabolic trough plant is the first solar plant in the United States with thermal energy storage allowing for electricity to be produced at night, according to Abengoa.

Solana produces electricity at full capacity for up to six hours after sunset, using concentrating solar power (CSP) technology with solar thermal storage. Solana is Abengoa’s first utility-scale solar plant in the country to begin operation. Arizona Public Service (APS) will purchase the full output from Solana. The plant’s thermal storage system will help satisfy Arizona’s peak electricity demand by storing energy that can be used by APS to produce electricity when needed by customers during the summer evenings and night time hours. The solar thermal storage also eliminates intermittency issues, providing stability to the grid.

The process begins with 2,700 parabolic trough mirrors, which follow the sun to focus its heat on a pipe containing a heat transfer fluid. This fluid, a synthetic oil, can reach a temperature of 735 degrees Fahrenheit. The heat transfer fluid then flows to steam boilers, where it heats water to create steam. The steam drives two 140-MW turbines to produce electricity, much like a traditional power plant. In addition to creating steam, the heat transfer fluid is used to heat molten salt in tanks adjacent to the steam boilers. The thermal energy storage system includes six pairs of hot and cold tanks with a capacity of 125,000 metric tons of salt, and the molten salt is kept at a minimum temperature of 530 degrees Fahrenheit. When the sun goes down, the heat transfer fluid can be heated by the molten salt to create steam by running it through the tanks instead of the field of parabolic mirrors.

The total investment of the plant is about $2 billion and during financing, Solana received a federal loan guarantee for $1.45 billion from the US Department of Energy Federal Loan Guarantee Program. This support, along with APS contracting to purchase the power, made the construction of Solana possible.

In other solar news, ConEdison Development completed a 3.5 MW ground-mounted solar facility in Groveland, Mass., comprising more than 12,670 solar panels. The solar installation is owned by Groveland Solar, a wholly owned subsidiary of Con Edison Development. Permitting and environmental expertise was provided by Cammet Engineering, and construction was performed by Gehrlicher Solar America and Mass. Electric Construction. Under a long-term power purchase agreement with Groveland Solar, the entire output of the installation is being sold to the Groveland Electric Light Department for consumption within the town.

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