Owner: Abengoa Solar Company – Seville, Spain
Engineer/Designer: Owner engineered project – Jim Shelby, St. Louis, MO
Construction Manager: Sundt Construction
Quantity of Lightweight Aggregate: 90,000 cubic yards
When commissioned, the Solana Solar Power Plant was the largest parabolic trough plant in the world and the first U.S. solar plant with molten salt thermal energy storage, so that electricity can be supplied at night or on cloudy days. The construction costs totaled $2 billion. Ninety thousand cubic yards of 3/8” aggregate was supplied for this backfill application. The thermal properties of expanded shale, clay or slate were needed to hold the temperature of petroleum gel above 800 °F.
This plant has a total capacity of 280 megawatts (MW) gross from two 140 MW gross (125 MW net) steam turbine generators, which is enough to power 70,000 homes while avoiding around 475,000 tons of CO2 every year. Arizona Public Service (APS) has contracted to purchase 100% of the power output generated from Solana to meet the Arizona Corporation Commission’s (ACC) mandate that the state’s regulated utilities provide 15% of their electricity from renewable energy sources by 2025.
One of Sundt’s seven contracts includes building and installing foundations for the project’s twelve 140-foot-diameter salt tanks. The massive tanks extend approximately 45 feet into the air and the foundations extend 18 feet below ground, where the tanks were surrounded and secured by expanded shale lightweight aggregate.