Rock Solid Energy

Photo: courtesy Geodynamics Limited

Harnessing an untapped energy source that has the capacity to power Australia for 6000 years will be the focus of a new centre at the University.

Queensland Premier Anna Bligh last year announced a $15 million five-year contribution to a new research and development centre for “hot rocks”, the Queensland Geothermal Energy Centre of Excellence.

Welcoming the announcement, UQ’s then Senior Deputy Vice-Chancellor, Professor Paul Greenfield, said it could lead to abundant zero-emission base load electricity.

“Geothermal energy has unique potential in that it creates no greenhouse gas and could be a reliable source of base load power, so it will satisfy industry, householders and the growing demand for ‘green’ energy,” Professor Greenfield said.

“It will become cost-competitive when the expense of mitigating greenhouse gas emissions from fossil fuels is factored in.

“This energy source is often called ‘hot rocks’ because it is based on fractured granites, heated to up to 300°C, which are at least 4km below the Earth’s surface.”

UQ Deputy Vice-Chancellor (Research), Professor David Siddle, said: “The Cooper and Eromanga Basins beneath Queensland and South Australia are believed to be among the best and hottest in the world, and hold enough water to supply the needs of a hot rocks power plant, without depleting the natural aquifer.”

Queensland’s geothermal energy resource is equivalent to that needed to supply Australia’s current demands for 6000 years.

“In the shorter term, we estimate that 4000MW of geothermal power could be generated by 2030 without any carbon dioxide emissions,” Professor Siddle said.

There would be three main steps to the process:

• water would be forced downwards through natural rock fractures, where it would be heated and then rise through other fractures to aboveground heat exchangers;

• the heat exchangers would heat a working fluid to drive a turbine-generator set, to produce electricity with no greenhouse emissions, while the water that had been thrust to the surface by the hot rocks would be recycled back into the earth to be reheated, forming a closed water circuit.

An exciting variation of this process involves the use of CO2 as the working fluid where a supercritical CO2 thermosiphon drives the geothermal heat exchange and the electrical power generation. The Centre will pursue both water- and CO2-based geothermal energy technologies.

Professor Greenfield said the Centre of Excellence was an investment in research and development, as well as in the expansion of technical expertise.

“We need these investments to make large-scale geothermal power generation a sustainable reality,” he said. “Ideally geothermal should become part of a mix of energy sources that would include clean coal and gas, and established renewables.”

In addition to the $15 million from the Queensland Government, UQ will provide in-kind contributions of $3.28 million over five years and a further $2.05 million will be raised from external sponsors.

The Centre will be the biggest of its type in the nation and will make Queensland and Australia a leading technology provider in the growing geothermal energy sector, through research and development.

UQ will work with institutions in the USA, where Massachusetts Institute of Technology will be a partner, the Central Research Industry for Electrical Power Industry in Japan, and Iceland, as well as relevant Australian collaborators.

Brisbane-based company, Geodynamics Ltd, is one of about 16 companies active in geothermal power generation in Australia. Geodynamics Ltd initiated Australia’s first underground heat exchanger in the Cooper Basin in late 2002.

Story author: Fiona Kennedy

• FUNDING: Queensland Department of Mines and Energy and Environmental Protection Agency
• RESEARCHERS: Professor Hal Gurgenci (School of Engineering), Professor Max Lu (Australian Insitute for Bioengineering and Nanotechnology), Professor Victor Rudolph (School of Engineering) and Professor Tapan Saha (School of Information Technology and Electrical Engineering)
• EMAIL: h.gurgenci@uq.edu.au
• WEB: www.uq.edu.au/geothermal

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