Page - 114 - in Water, Energy, and Environment - A Primer

Such a heat transfer and storage systemwas invented byDr Ruel Shinnar at the City University of NewYork (46). It uses pressurized CO2 as the heat transfer fluid flowing in a closed loop through the solar collectors and either through the power plant or the heat storage system.CompressedCO2 is one of the most effective gaseous high-temperature heat transfer fluids used in industry. Shinnar’s heat storage system would use commercially available vessels (cylindrical metal pipe) filled with a ceramic solid filler, and can be designed to operate at temperatures up to 3000°F. It incorporates a special feature, a cyclic counter-current pebble bed. Pebble-bed heat exchangers date back to the 1920s and have been used reliably for many industrial processes, Heat propagates as a sharp front: one end of the storage remains cold, the other end is hot and at constant temperature, allowing recovery of heat at the same top temperature atwhich itwas stored. 8.2.2.7 Current status What is the current status of CSTP?Despite its ability to store energy and, in some cases, provide electricity on demand, CSTP has not seen the rapid growth in recent years that has characterized PV markets. Economics has been an important constraining factor, but with costs coming down and more interest in low- or zero-carbon generating sources, CSTP has experienced a comeback. After many years of sitting at 354MW total installed capacity (the SEGS installations in California), today over 1800MWofCSTPplants operate in the United States, andmore than 5000MWglobally, led by Spain and theUS. Examples of operating plants are the Ivanpah Solar Power Facilty in the US (392MW), the Solaben Solar Power Station in Spain (200 MW), NOOR 1 in Morocco (160 MW; under construction to soon expand to 500 MW), and the Dhursar Power Station in India (125 MW). Many more CSTP plants have been announced or are under construction. Bid prices for Water,Energy, andEnvironment–APrimer114