Solana Solar Power Generating Station, with an output capacity of 280MW, is one of the largest concentrating solar power (CSP) plants in the world.
It is developed on agricultural land near the city of Gila Bend in the state of Arizona, US, and started generating power in October 2013.
Construction works for the massive solar power plant started in late 2010. Abengoa Solar developed the project for Arizona Public Service (APS).
The engineering, procurement and construction (EPC) contractors for the project are Teyma USA and Abener Engineering and Construction Services.
The Solana solar power plant provides clean energy to 70,000 households and reduces down carbon dioxide emissions by up to 475,000t each year.
Investment for the largest CSP project in the world was estimated at $2bn. The project generated more than 2,000 jobs during the construction phase and 85 jobs in operational phase.
The plant has a lifespan of more than 30 years.
Technology at the concentrating solar power (CSP) plant
Solana Solar Power Generating Station implements the CSP technology using a parabolic trough system which rotates with the movement of the sun and thermal storage using molten salts.
The technology involves mirrors which reflect the sunlight onto a pipe containing synthetic fuel, which is heated to temperatures of up to 700°F. The heated synthetic oil is transferred to a heat exchanger that heats water to produce steam. The steam generated is then used for spinning conventional steam turbines for generating electricity.
The technology also allows for the synthetic oil to flow into the molten salt storage tanks which retain the heat to be used occasionally when there is no sunlight. The storage tanks at the project site can store heat for six hours at a stretch.
Construction of Arizona’s solar power project
The Solana solar project site is extended in an area of 1,920 acres (777ha). Its solar field alone covers an area of 1,757 acres (711ha) and comprises of 3,200 parabolic trough collectors / mirrors. Each collector measures 400ft long, 18ft wide and 19ft high.
The plant is installed with 12 molten salt storage tanks measuring 140ft in diameter. The salt tanks stand 45ft above ground and are supported by foundations which are 18ft deep.
Construction works for the largest CSP plant utilised about 80,000t of steel. Major construction works comprised of laying the parabolic trough collectors, installing the 12 molten salt storage tanks, laying the cooling tower, construction of the substation, and laying of pipes for various facilities.
The construction works also included installation of the turbine generators, construction of cable trenches, and various other ancillary works.
Grid connection for the generation station
Power to the national grid is transmitted from the Solana Gen-Tie rising from the substation at the project site to the neighbouring Panda Substation owned by APS. The distance between the two substations is about 30km.
The Gen-Tie is made up of transmission structures, three single-circuit conductors and two overhead ground wires.
One of the two overhead ground wires holds a fibre optic cable which functions as a communication system for the power plant.
Financing APS’s Solana project
A federal loan guarantee of $1.45bn was offered to Abengoa Solar, by the Department of Energy (DOE) in July 2010 for the construction of the Solana solar project. Capital Riesgo Global, a subsidiary of Banco Santander, also invested $125m in the Solana generating station, for equity.
Contracts awarded for the CSP plant
The contract for the fabrication and installation of the pipe racks for the project was awarded to MMC Contractors. The contract, which was awarded in March 2012, is worth more than $10m.
The 12 molten salt storage tanks were supplied by Caldwell Tanks. The foundation works for the tanks, cooling towers, pipe supports, turbine generators and substation equipment were undertaken by Sundt Construction.
The company was also involved in other construction, excavation and installation works for the project.
Krohne Inor Lands was awarded the contract to supply the temperature sensors and transmitters for the project. Up to 900 OPTITEMP TT 51 temperature transmitters, including several tailored squid and multipoint sensors measuring 32m in length, were delivered.
Siemens was awarded the contract to supply the drives for the solar plant. The delivery comprised of 18 Robicon Perfect Harmony medium voltage drives, ten 4,000hp Genllle drives, two 2,000 hp Genllle drives and six 800hp GenIV drives.
Supply and installation of pipes for the solar field was undertaken by Haris Mechanical Southwest (HMSW). Rioglass Solar supplied approximately 85% of the parabolic trough mirrors for the project.
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