steam accounted for 80% of Oman's thermal EOR needs, could save up to half a billion cubic feet (bcf) of gas per day and contribute more than $12B in Omani GDP by 2023. History In 1983, ARCO Solar constructed a solar steam generation pilot using central tower technology in Taft, California. The system generated one megawatt of thermal energy during peak operating conditions. Though technically feasible, the system was not cost-effective and was not replicated. [4] The ARCO pilot was the first time solar steam was applied to facilitate heavy oil recovery. References External links http://www.google.com/patents/US7472548 Solar Augmented Geothermal Energy (SAGE) – US Patent 7472548 B2 Abstract An apparatus and a method is disclosed for storage of solar energy in a subsurface geologic reservoir. The method includes transferring concentrated solar thermal energy to a fluid, thereby generating a supercritical fluid. The supercritical fluid is then injected into the subsurface geologic reservoir through at least one injection well. The subsurface geologic reservoir may be a highly permeable and porous sedimentary strata, a depleted hydrocarbon field, a depleting hydrocarbon field, a depleted oil field, a depleting oil field, a depleted gas field, or a depleting gas field. Once charged with the supercritical fluid, the subsurface geologic formation forms a synthetic geothermal reservoir. Petroleum production Solar thermal energy