Clean and green ... or nuclear?

"If nuclear power is the answer, it must have been a pretty stupid question." So says Prof. Ian Lowe, an academic at Griffith University and President of the Australian Conservation Foundation.

But others disagree. A recent article in the peer-reviewed journal Energy by Australians Martin Nicholson, Tom Biegler and Barry Brook (NBB), and summarised in On Line Opinion, asks which is the cheapest of the "fit for service", low carbon, baseload electricity sources. They find that nuclear is cheaper than gas or coal (both with carbon capture and storage), and that solar thermal power with energy storage is the most expensive option.

The findings are disputed. University of NSW academic Dr Mark Diesendorf argues that the cheapest renewable energy sources - including landfill gas, onshore wind, conventional geothermal and hydro - are already cost-competitive with nuclear power. Tom Burke, a senior adviser to Rio Tinto in the UK, states: "The brutal truth is that no one has yet managed to work out a way of getting nuclear reactors to burn uranium as effectively as they burn money."

But my main beef with the NBB paper is the way they frame the question. Of course it's important to consider the cost and immediate availability of low carbon, baseload electricity sources. And of course it isn't a "stupid" question. But even if we agreed with their conclusion that nuclear is the cheapest of those options, that's not the end of the debate.

The question that needs to be asked is this: what's the best mix of electricity supply sources for Australia in the context of growing scientific and public concern about climate change?

Energy efficiency and conservation (ignored by NBB) provide the first part of the answer - they can provide large, quick, cheap greenhouse emissions reductions. Numerous studies envisage energy efficiency and conservation doing much of the "heavy lifting" to reduce greenhouse emissions. For example a 2007 Australian Bureau of Agricultural and Resource Economics study estimated that energy efficiency would account for 55% of Australia's greenhouse emissions reductions, and 58% of global emissions reductions, by 2050.

We can curb the growth in electricity demand through energy efficiency and conservation, but we also need a major restructure of the electricity sector. Too much of the literature on "clean energy" options pays too little attention to the issues stressed by NBB - cost, and the need for reliable electricity supply.

Can we meet the NBB objectives, and can we do so without nuclear power? One relevant study was written by Hugh Saddler, Richard Denniss and Mark Diesendorf (SDD) in 2004. The SDD study maps out a restructure of the Australian electricity sector to the year 2040. It makes virtually no allowance for technical innovation, although there has been innovation in the six years since the report was written and there will be much more by the year 2040.

The SDD report also makes no allowance for cost reductions for renewable energy sources, either through innovation or mass production - the main practical consequence is that the role of solar electricity is limited in the SDD plan because of its cost.

Even with those constraints, SDD map out a credible plan which would reduce greenhouse emissions from the electricity sector by 78% by 2040 compared to 2001. The electricity supply plan comprises solar 5%, hydro 7%, coal and petroleum 10%, wind 20%, bioenergy 28%, and natural gas 30%.

What's not to like about the SDD plan? The main concerns are bioenergy and gas. In the SDD plan, a large majority of the bioenergy comes from crop wastes. This addresses one of the major global problems with bioenergy - competition for productive land, and flow-on effects such as increased food prices. There are other concerns with bioenergy that would need to be carefully considered, not least whether it delivers the claimed reductions in greenhouse emissions.

Gas, a finite resource, could replace coal fired plants for no more than a period of several decades. Emissions from gas fired plants are about half those from coal fired plants, but about 10 times greater than emissions from nuclear power and most renewables.

If we were to accept the basic outline of the SDD plan, we'd need to phase out the use of gas over a period of several decades. The most promising candidates are solar thermal power with storage (e.g. in molten salts) and geothermal "hot rocks". Solar with storage is about twice as expensive as other low carbon electricity sources. It will certainly become cheaper, but we don't know how much cheaper. For geothermal hot rocks, a great deal of exploration and development is underway in Australia, but we've yet to see large scale geothermal electricity generation.

CSIRO scientist Dr John Wright has proposed a plan in which renewables generate over three-quarters of Australia' electricity by 2050: wind and geothermal both produce 19% of electricity demand, solar thermal 18%, solar photovoltaics 13%, bioenergy 5%, and hydro continues to provide a small percentage.

Siemens Ltd., a company with extensive involvement in the energy sector, has mapped out an energy plan for Australia in which the contribution of fossil fuels to electricity generation falls from 93% to around 10% by mid-century, with the remainder generated by a mix of renewables consisting mainly of solar (35%), wind (18%), and geothermal (17%).

Australian engineer Peter Seligman has proposed an energy supply system for Australia based largely on geothermal, wind and solar power. To ensure reliable electricity supply, Dr Seligman proposes the construction of a large "pumped hydro" energy storage system. When electricity is in short supply (e.g. calm, cloudy days), water from a very large dam is run downhill through turbines to generate electricity. At other times, water is pumped up hill to replenish the dam.

In a 2010 paper, provocatively titled "The Base Load Fallacy and other Fallacies disseminated by Renewable Energy Deniers", Dr Diesendorf writes: "Some sustainable energy sources and measures are at least as reliable as coal power. These include demand reduction by means of energy efficiency, energy conservation and solar hot water, and renewable electricity supply by hydro with large dams, bioenergy, solar thermal power with thermal storage and geothermal power. They can all be used to reduce the demand for base-load coal without reducing the reliability of the generating system."

Some other clean energy plans for Australia are those by Dr Diesendorf, Greenpeace and Beyond Zero Emissions.

One final question: why the objection to nuclear power? The key problem is its repeatedly demonstrated connection to the proliferation of Weapons of Mass Destruction. Former US Vice President Al Gore has summed up the dilemma: "For eight years in the White House, every weapons-proliferation problem we dealt with was connected to a civilian reactor program. And if we ever got to the point where we wanted to use nuclear reactors to back out a lot of coal … then we'd have to put them in so many places we'd run that proliferation risk right off the reasonability scale."

The connections between nuclear power and weapons have a precedent in Australia. Prime minister John Gorton had military ambitions for the power reactor he pushed to have constructed in the late 1960s at Jervis Bay on the NSW south coast. He admitted 30 years later: "We were interested in this thing because it could provide electricity to everybody and it could, if you decided later on, it could make an atomic bomb."