Solar thermal shoots for the sky  

The Climate Spectator has a look at advances in the solar thermal power industry - Solar thermal shoots for the sky.

BrightSource is currently building a 392MW solar thermal plant called Ivanpah in the Mojave Desert in California, and has just unveiled plans for a new 500MW plant just 60km to the south. Solar towers use software to control thousands of tracking mirrors, known as heliostats, to directly concentrate sunlight onto a boiler filled with water that sits atop a tower. Ivanpah will feature three towers each of 450 feet (137 metres, or the equivalent of a 33-storey building), at the centre of three modules that will each have a capacity of 130MW. Just by comparison, the solar tower research facility launched at the CSIRO’s flagship facility last month by Prime Minister Julia Gillard stands 30m high.

Last week, the company released plans for a 500MW plant at Hidden Hills, some 60km north of Ivanpah, and about the same distance west of Las Vegas, that will feature 750-foot towers (228m), the equivalent of a 55-storey building. According to the company, the extra height will enable it to pack more heliostats into a smaller area, reduce the space required, and boost the economics of the project significantly. Each of 750-foot towers will cost around 40 per cent more than the 450-foot towers, but their capacity will be doubled, and each will be able to generate 250MW, instead of 130MW at Ivanpah.

BrightSource also unveiled a molten salt storage option to go with its solar towers. Rather than aiming for energy produced 24/7, as has been achieved at the Gemasolar plant in Spain, the company says just six hours of storage would more than double the amount of output from the same plant – from 1,900 hours a year to more than 4,000 hours – and deliver a huge cost advantage. This will particularly be the case in when pushing output into the high-value evening peak, and will give it an advantage over other renewables such as wind and solar PV, where economically viable storage options are proving more elusive.

Carlos Aguilar, the head of international development for BrightSource, says the storage option will not likely be used at the Ivanpah project, because the summer peak load tends to fall in summer afternoons when Californian air conditioners are in most demand. But it will be applicable in other regions where local factors mean that peak loads occur later in the evening. “What we are trying to do is adapt to each plant’s needs,” he tells Climate Spectator in an interview. “When you have load curves that go into the evening – that affects the value of the energy.”

Aguilar has arrived in Australia for a week-long visit which will take him to most capital cities. Like other solar developers, BrightSource’s interest in Australia – which already has some of the best solar resources in the world – has been renewed by the government’s plans to introduce a carbon price, and create a new body, the Clean Energy Finance Corp – which will have up to $10 billion to invest to boost the deployment of new technologies.

“Australia is one of the most important markets, longer term, for solar thermal – without a doubt,” he said. “The solar research you have is fantastic. The other important reason is policy. There clearly is a focus on developing a regulatory environment that is favourable to this technology. The carbon price, when it comes into law, is an example. But there are many factors that will influence this. How fast it is going to develop we really don’t know. That’s the reason for me to visit.”

BrightSource and other solar developers in the US have benefited greatly from the use of loan guarantees from the US Department of Energy. Such mechanisms are also likely to be used now in Australia, both to help financing of some coal-fired power stations that may be affected by the carbon price, but also to help roll-out new technologies under the CEFC.

Australia currently has several large-scale solar thermal projects under planning or development. Two – a 250MW gas fired booster plant in Queensland using Areva’s compact linear Fresnel reflector technology, and a 150MW solar PV plant in NSW – will be sponsored by the Solar Flagships program; a 40MW plant using solar dish technology developed at the ANU will be built in Whyalla; and a 44MW solar boost plant will be added to the Kogan Creek coal-fired power station.

The second round of the Solar Flagships program will also likely support more and smaller utility-scale solar projects, and there have been calls for this to support solar tower and storage technologies. However, even without the Solar Flagships, some consortia – such as one supported by investment bank Investec – are expressing interest in developing projects, particularly in WA, where energy prices are high and there is a shortage of power in regional areas, and a particular problem with peak loads.

Australia, however, is not the only country to have a flagships program. South Africa launched the bidding process for its version lat week, while Morocco is expected to have a solar tower-specific round of grants next year. India is also preparing a new round of bids for its solar program, which aims to have 20GW installed by 2022, and the China market also looks promising. “They are very large markets, we will see how those evolve,” Aguilar says.