Desalination Driven by Steam-Generating Concentrating Solar Collector

Both in this country and abroad, fresh water supplies are increasingly being contested. Although large- scale desalination plants were to make fresh water widely available, for many communities, farms and industries desalination is still too expensive. Furthermore, all commercial desalination is energy intensive. It would be a sad irony if the solution to one environment problemthe need for secure supplies of clean waterexacerbated another oneenvironmental damage from the use of fossil fuels. The proposed work will address the complex interplay between energy use and water resources by developing a low-cost thermal distillation process that can be driven by atmospheric steam provided by non-tracking, concentrating solar collectors. As an integrated system, these two technologies can provide water at a life-cycle cost of under $0.50 per cubic meter $1.90 per 1,000 gallons) using only renewable energy resources. The proposed distillation process has the potential to more than double the efficiency of thermal processes now in commercial use. This gain in efficiency is achieved without the large metallic heat exchangers and vacuum vessels found in todays large-scale desalination plants. By operating at atmospheric pressure with plastic heat exchangers, the proposed process achieves very low production costs for water. Furthermore, by closely coupling the desalination unit to steam produced in non-tracking solar collectors with modest concentration factors, renewable energy becomes the primary resource driving the process. In addition to providing a secure source of freshwater to coastal locations, the proposed technology will convert the countrys large reservoirs of brackish to sources of potable water. The technology will also address possible environmental problems caused by the wastewater from oil and gas field operations.