Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/1019735
ent on oil, if you can believe it. The island is high and liing up water to 1,000 drives up the price." Adding to its costs, much of Cyanotech's supply evaporates from its sun-powered growing pools. "The company spends a lot of money on water that is lost to the atmosphere," Leonard says. Trevi Systems' goal is to beat the potable price substan - tially, and to scale up the project quickly, eventually to supply the client's entire requirement of 200,000 m3/d. As well as cost, the technol- ogy is positioned as competitive on safety grounds. "There are concerns about some of these draw solutions, it has to be very safe. Part of our test method is to introduce the draw solution into a fish tank and to check that the fish and their fry survive," Webley says. The technology has already been proven at demonstration scales, including at Masdar, the clean energy city development in the United Arab Emirates, where it ran for a year. "The 50 m3/d programme was a success; the client was demanding low energy consumption, although not system cost savings — they saw ours was a new technology," Webley says. The $2m investment from the DoE will help to build out the project, with a substantial amount needed to recondition an existing, mothballed solar array, as well as a heat storage compo - nent that will enable the process to run consistently on solar en- ergy. Approximately $1.6 million will go to the FO plant, $200,000 to the solar array, and $100,000 to testing that the water is safe to use for Cyanotech's process. While the project benefits from the relatively high com- parative cost of potable water in Hawaii, Webley is bullish about the prospects for scaling up the technology by another factor of 10 — to 5,000 or 10,000 m3/d — the sweet spot for renewable desalination. Once again, the building indus- try has been making use of this method for some time, typically locating the PCM in a cassette embedded in a ceiling tile or wall. In Sunvapor's Solar Steam on Demand process, the steam can be produced when the PCM releases its heat, and refreezes even when the sky is dark. The goal is to develop a pro - cess that can desalinate water over a 24-hour period with a levelised cost of heat of 1.5 cents per kWh. Sunvapor's green parabolic trough collector tested at Horizon Nut in Firebaugh, California. Heat collected from a field full of these is stored in a special phase- change material. TOPIC AREA 4 Analysis for solar-thermal desalination GIS-BASED GRAPHICAL USER INTERFACE TOOLS FOR ANALYZING SOLAR-THERMAL DESALINATION SYSTEMS AND HIGH-POTENTIAL IMPLEMENTATION REGIONS • Team: Columbia University Centre for Lifecycle Analysis • Location: New York, NY • DOE Award Amount: $972,797 • Awardee Cost Share: $274,481 • Principal Investigator: Vasilis Fthenakis Where is the best location for a thermal desalination plant, which technology can be used, and how can it be valued? Work by Prof Vasilis Fthenakis at Colombia University's Centre for Life Cycle Analysis will generate maps to guide technicians as they seek a site; showing levels of salt in water and amounts of sunlight. The goal is a freely-available piece of single- interface soware to integrate techno-economic models and geospatial data layers. The resulting models will be verified by data from existing thermal desalination plants and data from solar-thermal desalination pilots at Plataforma Solar de Almeria in Tabernas, Spain. Trevi Systems forward osmosis units at the Ghantoot site, Abu Dhabi, tested as part of the Masdar renewable energy desalination pilot programme, 2013 to 2017. September 2018 Water. desalination + reuse Far Site 35