Monday, 23 November 2009

Catching some rays
November 17, 2009

Keith Lovegrove is a bit like Frankenstein's inventor. He's built something so powerful he's a little unsure how to deal with the strength of his creation.

Dr Lovegrove, the leader of the Australian National University's solar thermal group, and his team have recently finished the latest version of their solar thermal dish, the biggest in the world. Now they just have to test it.

But the mirror-covered dish - which gathers the sun's radiation and focuses it to a small point - is capable of creating extreme heat. At this early stage, the scientists are trying to measure its power before they get around to installing a steam-making system that would harness the heat and make electricity.

The technology has been picked up by a small Canberra company Wizard Power, which hopes to commercialise it. The dish, an improved version of the one that has been running on the ANU campus for 12 years, has been completely re-engineered for mass production. It is four times bigger than any other such dish in the world.

So just how powerful is it? "What we've found is that it actually has a considerably higher performance than we dreamt of and indeed the absolute peak optical concentration is something like 12,000 times normal sunlight," says Dr Lovegrove. "And that is enough to essentially melt any known ceramic. It actually presents quite some difficulties for us to measure the radiation, so we've been reduced to using the full moon, to determine the shape of the focal region."

In other words, this thing, which looks like a satellite dish, is too powerful right now for testing with normal sun rays. So they are using the moon as it tracks across the night sky. And when it is on during the day they must make sure that power glancing off the mirrors doesn't set nearby trees alight. "We have to be continually taking care with surrounding trees and things like that," he says. "And indeed it can be quite uncomfortable when you walk around on the surface of the mirrors, as we do in the late afternoon, you can find the radiation making your pants very warm indeed."

Dr Lovegrove's vision and research includes using the solar thermal dish to produce heat to convert algae into liquid fuel - essentially a replacement for petrol and diesel. This technique, he said, could see Australia use its massive solar resource to export clean fuel to countries such as Japan. "It's dead easy to make renewable energy for Australia," he says. "But what we need to do is shift the Australian economy so that we get an equivalent income from an export to what coal gives us at the moment."

Wizard Power and the ANU technology are one of a handful of players in Australia's embryonic solar thermal industry. As I wrote on Saturday, the industry is on the cusp of big things and there's no shortage of solar energy in Australia. Dr Lovegrove says you could power the country on solar thermal dishes on land measuring 168 kilometres long and 168 kilometres wide. Recently a huge Spanish plant overcame one of the sector's biggest stumbling blocks when it proved it could store solar energy overnight.

But even though large parts of Australia are blessed with some of the world's best resources of solar - much of the land north of Canberra, but especially inland Queensland - the industry says it will struggle for a decade to compete with existing generators, even when the emissions trading scheme brings in a price on carbon. Under the scheme's current design, they say, a high enough carbon price will not kick in quick enough. The industry, although happy with the Federal Government's $1.5 billion Solar Flagships program (some of which will fund solar panel technology) wants generous tariffs such as those found in Spain.

Dr Lovegrove said that while coal-fired electricity costs about five cents a kW hour to make, a solar thermal plant in Australia right now would spend about 20 cents making each kW hour. That price will come down to nine or 10 cents in a decade, he said, but it still makes it hard to compete now, he said.

Besides the dish type, there are several different kinds of solar thermal technology in power plants. There are parabolic troughs, essentially curved mirrors in lines. The technology used by Ausra - the company founded by Australian scientist David Mills, who is now based in California - is called Linear Fresnel, and uses flat, tilted mirrors that reflect light back to a central point. There are also solar towers, with mirrors laid out around the tower.

Ausra, which has a plant in California, has kept its technology much cheaper than the dish approach. In September, Ausra and the Queensland Government announced plans to build a 23 MW solar thermal plant at the 750 MW Kogan Creek coal-fired power station near Chinchilla. Ausra also has a three MW prototype plant next to New South Wales' Liddell coal fired power stations.

Wizard Power's Artur Zawadski says the company has a proposal for an 80 MW plant in Whyalla, South Australia. It is also looking at demonstrating different storage techniques there. solar energy, however, is very expensive. Wizard's proposed plant has a price tag of $355 million.

In Victoria, the state is blessed solar resources in the north, particularly around Mildura, which is why solar plants have always been proposed for that area. Unfortunately, the bulk of Victoria's generation capacity is in the Latrobe Valley which is not particularly sunny. Unlike in Queensland, solar thermal plants in Victoria are unlikely to be built next to coal-fired plants, said Dr Lovegrove. "They are just not in a sunny place," he said.