Low Temperature Solar Thermal Technologies in Australia

Except for solar water heating for hot water services and pools, very little research, development and demonstration of low temperature solar thermal technologies is occurring in Australia. Much of what is occurring is one off projects, such as the solar pond research at Centre for Water Resources in Western Australia, or the result of dedicated enthusiasts in areas such as solar cooking. However there are some encouraging developments;

Katrix, the developer of a new class of high efficiency fluid motors, was successful in winning a Renewable Energy Development Incentive (REDI) grant for a total of $811,252 in December 2005. The grant project is to develop a new high-efficiency micro-fluid motor/expander to enable small-scale residential and commercial solar thermal combined heat and power (CHP) systems. This core component of a solar thermal microCHP system, will become an enabler of such systems with power outputs of 1 - 10kW, with expected efficiencies greater than PV systems at a significantly reduced capital cost per kW.

A consortium of RMIT University, Geo-Eng Australia Pty Ltd and Pyramid Salt Pty Ltd has completed a project using a 3 000 square metre solar pond located at the Pyramid Hill salt works in northern Victoria to capture and store solar energy using pond water, which can reach up to 80°C (see Figure 1). Pyramid Salt uses the pond's heat in its commercial salt production but also for aquaculture, specifically producing brine shrimps for stock feed. It is planned in a subsequent stage of the project to generate electricity using the heat stored in the solar pond, thus making this local industry more energy self-sufficient. The 3 000 square metre solar pond is integrated into the pond evaporation system. The pond has heat exchangers installed and is used for delivering a continuous 60 kW energy load in the form of heat to the flake salt drying process.

A.F. Gason Pty Ltd of Ararat, Nelson Silos of Rochester and the Victorian University of Technology (with the support of a $370,000 grant under a previous government program) have collaborated to develop a new solar thermal system to cool grains to lower temperatures for improved storage (see Figure 2). During conventional in-silo aeration, the water in the air condenses and releases heat, leaving grain at a warmer temperature than the external ambient air. Removing the humidity in the silo is done by placing silica gel in channels. When cool but humid air flows at night, the silica gel absorbs moisture and gives out heat. This heat is removed from the silica gel by a second air stream that flows externally to the channels that contain the gel, removing the heat externally instead of inside the silo.