Advances in solar thermal electricity technology

Various advanced solar thermal electricity technologies are reviewed with an emphasis on new technology and new market approaches. In single-axis tracking technology, the conventional parabolic trough collector is the mainstream established technology and is under continued development but is soon to face competition from two linear Fresnel reflector (LFR) technologies, the CLFR and Solarmundo. A Solarmundo prototype has been built in Belgium, and a CLFR prototype is awaiting presale of electricity as a commercial plant before it can be constructed in Queensland. In two-axis tracking technologies, dish/Stirling technologies are faced with high Stirling engine costs and emphasism may shift to solarised gas micro-turbines, which are adapted from the small stationary gas turbine market and will be available shortly at a price in the US$1 ppW range. ANU dish technology, in which steam is collected across the field and run through large steam turbines, has not been commercialised. Emphasis in solar thermal electricity applications in two-axis tracking systems seems to be shifting to tower technology. Two central receiver towers are planned for Spain, and one for Israel. Our own multi-tower solar array (MTSA) technology has gained Australian Research Council funding for an initial single tower prototype in Australia of approximately 150 kW(e) and will use combined microturbine and PV receivers. Non-tracking systems are described of two diverse types, Chimney and evacuated tubes. Solar chimney technology is being proposed for Australia based upon German technology. Air is heated underneath a large glass structure of about 5 km in diameter, and passes up a large chimney through a wind turbine near the base as it rises. A company Enviromission Ltd. has been listed in Australia to commercialise the concept. Evacuated tubes are growing rapidly for domestic hot water heating in Europe and organic rankine cycle engines such as the Freepower 6 kW are being considered for operation with thermal energy developed by evacuated tube and trough systems. These may replace some PV in medium sized applications as they offer potential for inexpensive pressurised water storage for 24 h operation, and backup by fuels instead of generators. In the medium term there is a clear trend to creation of smaller sized systems which can operate on a retail electricity cost offset basis near urban and industrial installations. In the longer term large low cost plants will be necessary for large scale electricity and fuels production. Retrofit central generation solar plants offer a cost effective transition market which allows increased production rates and gradual cost reduction for large solar thermal plant. In the paper the author describes current funding systems in Europe, Australia, and the USA, and makes suggestions for more effective programmes of support. (C) 2003 Published by Elsevier Ltd.