After an interview with Australian solar energy pioneer David Mills in October, this column previewed a Stanford University study showing that renewable sources - principally wind and solar - could meet all of our energy needs. Its co-author, Mark Jacobson - the university's professor of civil and environmental engineering and director of its atmosphere and energy program - appeared by videoconference at last weekend's Sustainable Living Festival in Melbourne.
He spoke about the findings of his study, which was the cover story in November's Scientific American magazine, which has generated plenty of debate in the United States (and some here, too).
Jacobson and Mark Delucchi, a research scientist at the University of California, compared available world renewable energy resources - wind, water, solar - with maximum forecast energy demand, including transport, of about 16.9 terawatts (1 terawatt equals a trillion watts) in 2030. Today's demand is 12.5 terawatts.
Eliminating fossil fuel and biomass combustion would reduce overall demand to 11.5 terawatts, the study found, because electric power is more efficient. Could available renewable resources meet such a prodigious energy demand? Yes, with a massive building program.
The world would need 3.8 million wind turbines, each producing 5 megawatts, to provide 51 per cent of supply. A further 40 per cent would come from: 49,000 large-scale, 300MW concentrating solar power stations; 40,000 large-scale, 300MW solar photovoltaic power stations; and 1.7 billion domestic-scale rooftop photovoltaic systems, each of 3 kilowatts. Less than 1 per cent of this wind and solar power infrastructure is in place already.
The remaining 9 per cent of the world's power supply would come from 900 hydroelectric power stations (mostly built); 5350 geothermal plants, each generating 100MW (mostly not built); plus thousands and thousands of small tidal and wave installations.
Given that wind, wave and solar are intermittent power sources, can they meet demand as it arises? Yes. First, renewable energy powerplants generally suffer less down-time. Second, with extensive interconnection between geographically dispersed sources, power from a windy or sunny place can substitute power from another.
As Jacobson and Delucchi wrote: ''Because the wind often blows during stormy conditions when the sun does not shine and the sun often shines on calm days with little wind, combining wind and solar can go a long way towards meeting demand, especially when geothermal provides a steady base and hydroelectric can be called on to fill in the gaps.''
The load-matching effect is demonstrated by the accompanying graphic, based on a separate study showing how four renewable energy sources could meet California's entire electricity demand around the clock on a typical July day.
Third, a smart grid allows demand to be shifted into off-peak periods - for example, to charge electric cars overnight when demand is lower.
The cost? The scientists estimated it would be in the order of $US100 trillion over 20 years, not including transmission. Professor Jacobson told me transmission would add about 10 per cent to the total cost - he reckons power lines last two or three generations of powerplants and are a relatively smaller part of the upfront cost per kilowatt hour generated.
That's the bill for a new, clean and efficient energy system and (if we move quickly) massively reduced bills for climate adaptation. The bill would be recouped by charging a forecast US4c-US10c a kWh, competitive with existing fossil fuel and nuclear sources, which average 7c/kWh in the US and are rising.
On Sunday, Jacobson dismissed the nuclear alternative. Based on a full life-cycle analysis, nuclear isn't clean, producing nine to 17 times the carbon dioxide equivalent per kWh generated by wind power, and is getting more expensive, not cheaper, unlike wind and solar. In a CNN debate this week, Jacobson said it would take decades to build 17,000 nuclear plants to meet worldwide demand, and uranium is scarce.
Using the same analysis, coal-fired power with carbon capture and storage produces 41 to 53 times the CO2 of wind, taking into account expected leakage of 1 to 18 per cent of sequestered CO2 over 1000 years.
It seems a rapid transition to 100 per cent renewable energy is not only possible, it may be cost-competitive with the touted ''clean coal'' and nuclear alternatives. In our national and state capitals, and probably in our boardrooms, it would be dismissed as a pipedream. In the real world - the planet we live on - it will soon enough become a necessity. Relative to the rest of the world, Jacobson describes Australia's clean energy resources as ''amazing''.
Also appearing last weekend were Philip Sutton, co-author of Climate Code Red, and Matthew Wright, executive director of Beyond Zero Emissions.
Both are working on plans to switch Australia over to renewable energy. BZE's recently released Transition Decade (or T10) plan estimates a complete switch by 2020 would cost $40 billion a year or 3 to 3.5 per cent of GDP.
The linchpin of the T10 plan is to build a dozen concentrating solar thermal sites around Australia, each generating 4000MW, to provide 60 per cent of our power needs. The technology to generate solar power, with up to 16 hours of storage so it can run overnight, exists now and is being used in Spain. Wind power would provide the remaining 40 per cent.
Wright told the audience that T10 - a plan, not the only plan - was meant to refute the ''can't do mantra'' of the fossil fuel lobby: renewable energy can't supply baseload power, is too expensive, will wreck the economy and will cost jobs. What rubbish. Wright has a ''can do'' mantra and it's what we need.
paddy.manning@fairfaxmedia.com.au
More important than the details of the agreement, however, is the acquisition of funding by Entech to build its unique brand of solar power products.
Solazyme 
eSolar, a producer of solar thermal power technology, and Ferrostaal, a power plant developer, have announced a partnership to deploy turnkey solar power plants in countries including Spain, the United Arab Emirates, and South Africa. 
Bloomberg News 
Bloomberg News 