According to the International Energy Agency, if you take large-scale hydro projects out of the equation, only about 2% of the world's electricity is currently generated through solar, wind and other renewable technologies.
The reason is simple: cost.
"Technically, you could supply all of the world's energy needs by covering 4% of the world's desert area with photo-voltaic panels," says Martin Green from the Advanced Silicon Photo-voltaics and Photonics research centre at the University of New South Wales in Sydney.
Yet according to International Energy Agency forecasts, renewables (once again excluding large-scale hydro) will make up only 6% of the world's energy economy in 2030, with solar cells contributing a small fraction.
It is an improvement on today's 2%, but hardly a ringing endorsement of their potential.
The problem is that solar cells convert only about 15% of the sunlight they receive into electricity; at these rates, it's not generally an economic technology.
Martin Green's research unit is in the vanguard of those trying to improve performance and bring down prices.
In the lab, his team can achieve sunlight-to-electricity efficiencies of 25% and intends to go higher, through using materials other than the conventional silicon wafer, or by stacking cells in layers which each absorb different components of the Sun's radiation.
Costs are tackled through investigating cheaper forms of silicon or cheaper ways of processing it; while on the horizon are organic cells, not very efficient, but cheap and easy to make.
"There's a well-demonstrated history of cost reductions in photo-voltaics; every doubling of the amount produced brings the cost down to about 80% of what it was before that doubling," he says, "and that's gone on for about 30 years.
"So if you can maintain that trend, you can work out how many systems you need to install to get them to a price where they'll be competitive with what else is there, and it's perhaps just a hundred times more we need to manufacture than what's been manufactured up to the present."
The German government certainly believes in this theory. It has instituted a whole raft of financial incentives designed to boost solar installation; more than 10% of the nation's electricity now comes from renewable sources, and the government believes that ramping-up production will bring costs down.
Ethanol production from sugar-cane in Brazil
More than 80% of new cars now sold in Brazil are equipped to use ethanol derived from sugar-cane as well as gasoline according to the Brazilian motor manufacturers' association (Anfavea).
Both fuels are available almost everywhere, and since ethanol can cost about a third less than petrol per litre at the moment (though the mileage is not quite as good), the home grown fuel is more popular than the foreign import. More than 70 new sugar-cane/ethanol mills are due to open in Brazil by 2012.
At one such mill, Grupa Carlos Lyra in Sao Miquel dos Campos, 90% of the cane is still refined into sugar, but the sticky syrup leftover is pumped into a distillery.
Yeast is added and a simple process of turning sugar into ethanol, not unlike rum, produces the fuel of the future.
It takes about three days to transform a burnt and bruised sugar-cane into the clear liquid which Brazilians can put in their tanks.
The Brazilian President, Luiz Inacio Lula da Silva, is delighted with the "energy revolution" that's taken place as Brazil has already been able to cut imports by US$400 billion by reducing its reliance on oil.
The focus now is on boosting exports say the Sao Paulo sugar-cane industry association. Japan is considering a deal to import up to six billion litres of Brazilian ethanol by 2008.
Fueling the Future:
a series of articles on meeting our energy needs
Copyright 2003-2006 Azlan Adnan Legal Notice
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