Arizona Public Service Corp. (APS) says its 280 MW Solana Generating Station will be producing electricity at full capacity for up to six hours after dark, due to its combination of concentrating solar power (CSP) and thermal storage technologies.
The facility, built by Abengoa, occupies a three-square-mile site near Gila Bend and incorporates 2,700 parabolic trough mirrors. The mirrors focus sunlight on pipes containing a heat-transfer fluid that boils water to make steam, which drives two 140-MW turbines to produce electricity. APS is purchasing 100% of the output from Solana, which is expected to enter commercial operation before the end of the year.
The heat-transfer fluid also heats up molten salt stored in 12 insulated tanks. These tanks provide the thermal energy storage capability that enable the facility to continue boiling water to drive the turbines after the sun goes down.
"With Solana's substantial thermal heat storage capacity, we can manage electrical output from the plant much more effectively than from other solar power sources," says Pat Dinkel, APS' vice president of resource management.
The Department of Energy's SunShot Initiative is pursuing the development of CSP technology as part of its goal of making solar energy cost-competitive with other sources of electricity without incentives.Â