Another great tax payer funded report/paper weight, to be announced today by the retiring Liberal Victorian senator Judith Troeth, the Greens senator Christine Milne and the Independent Nick Xenophon, finds a 100 per cent renewable plan by 2020 would cost $37 billion a year, in public and private money - or 3 per cent of Gross Domestic Product.

It will be interesting reading given that the report suggests that 60 per cent of the target will come from base load solar-thermal plants, which is hard to imagine given there is not one utility scale plant built in Australia. Also the other 40 per cent is said to be generated by wind turbines that are not totally proven in the current market place.

The report is the result of a research collaboration between an environment group, Beyond Zero Emissions, and Melbourne University’s Energy Research Institute, with input from engineering firm Sinclair Knight Merz.

Beyond Zero Emission’s director, Matthew Wright, said yesterday the report only included commercially proven technologies, and therefore did not consider geothermal or wave power.

Under the plan 60 per cent of energy would come from base load solar-thermal plants built at 12 sites. The other 40 per cent would be generated by wind energy, with 8000 six-megawatt turbines at 23 sites.

Where wind and solar-thermal does not meet demand during peak times, the report recommends hydro and biomass technologies be used as a backup.

The plan generates 325 terawatt hours of electricity a year, up from the current generation of 228 terawatt hours, to meet energy growth projections to 2020. It is based on the assumption that energy use will halve by 2020 through energy-efficiency measures.

A $92 billion upgrade of the energy grid to help connect renewable projects to the grid and better regulate peak demand would also be needed. The proposed grid upgrade includes linking the country’s three energy grids to form one national grid.