Anthony Doesburg: Solar edges closer to fulfilling its potential

Over-exposure to developments in electricity generation could leave you thinking the world's energy crisis is all but solved. Progress with wind, marine, fuel cell and solar power might appear to suggest that removing fossil fuels from the electricity supply would be no great loss.

But for all the exciting breakthroughs, the inescapable observation is that new technologies have a long way to travel to get from the lab to the real world. Therefore, when they arrive, popping the champagne corks seems fully justified.

On that basis, as soon as this column is typed I'll uncork a bottle to celebrate taking my cellphone off the national grid. Rather than plug it into a wall socket to charge it, I can now fill it with juice harnessed from the sun's rays by a portable photovoltaic system.

Unplugging my cellphone doesn't quite signal the end for fossil fuel-burning power stations, but it's a sign that solar energy has exited the lab.

In fact, it's done much better than that, taking to the skies this month as the power source for Solar Impulse, an ungainly plane that flew for 87 minutes in Switzerland.

The next goal for Solar Impulse's developers is to show it will fly in the dark on battery power, before they eventually attempt a round-the-world flight. That will truly be a champagne achievement.

Solar power has been generating plenty of enthusiasm, if not much electricity, for years, and a number of ways have been found to convert energy from the sun into electricity.

Photovoltaics - producing an electric current from light striking a semiconductor - was first done in the lab more than 50 years ago. The decades since have been spent trying to improve efficiency, from less than 10 per cent initially, to better than 40 per cent today.

Another method of harvesting solar energy is to concentrate the sun's rays using mirrors and generating power from the heat, called concentrating solar thermal power, or CSP.

Some CSP projects have been built and others are planned for sunny parts of the world such as the Sahara and Mojave deserts, but the usual environmental and financial obstacles are holding them back.

Conservation concerns are understandable when these ventures typically involve covering thousands of hectares of land with mirrors, to heat liquid either in troughs or towers to produce steam that then drives turbines.

A number of United States projects have come into conflict with moves to protect public desert land.

Unsurprisingly, the International Energy Agency says investment in energy plunged in the past year. But in the Sahara, the Economist reports that Morocco is preparing to spend US$9 billion ($13 billion) to build five solar-power plants to produce about 40 per cent of the country's energy within a decade.

According to the IEA, CSP is generating about 1GW of power at present and projects on the go or on the drawing board amount to a further 15GW.

If the US could set aside 2.56 million hectares, it could generate all the power it needs from CSP, and the Middle East and North Africa could produce 100 times the needs of that region and Europe combined.

The problem is cost. CSP is at least twice as expensive as wind or coal generation, and photovoltaics more costly still. Yet there's plenty of cause for optimism.

The New Scientist magazine reported a fortnight ago on developments in solar cell manufacturing that use a fraction of the materials of traditional methods.

The resulting photovoltaic devices aren't a great advance in efficiency, but are much cheaper. What's more, they're flexible, and in some instances transparent, with potential to be incorporated into buildings and possibly even plastered over windows.

Muriel Watt, a photovoltaics (PV) expert at the University of New South Wales, says it's time to turn our eyes from the oil and coal in the ground to the solar power overhead as we look to meet our future energy needs.

Presenting the Institution of Professional Engineers' Pickering Lecture in Wellington last September, she said PV accounted for 15GW of electricity generation a year worldwide at the end of 2008, with about half as much again expected to go on stream last year, putting it miles ahead of CSP. And costs are steadily falling, she says.

They have a way to go, however, according to figures on the Energy Efficiency and Conservation Authority website.

PV panels to power a four-bedroom home will set you back up to $170,000, depending on consumption. Battery storage for when the sun's not out could bump that up to about $200,000. My cellphone charger is clearly just a modest contribution to the shift to solar power, but I'll drink to it anyway.

Fossil fuels rule

Where the world's electricity comes from (2007 figures)
Coal 41.4 per cent
Gas 20.8 per cent
Hydro 15.9 per cent
Nuclear 13.7 per cent
Oil 5.6 per cent
Biomass 0.96 per cent
Wind 0.87 per cent
Waste 0.34 per cent
Geothermal 0.31 per cent
Solar 0.024 per cent
Tide 0.0027 per cent

Source: International Energy Agency