Australian researchers build solar thermal system with plastic mirrors

A team of Australian scientists is using plastic mirrors in solar thermal systems. These are lighter and cheaper than mirrors made of glass, say the researchers.

The mirror consists of an aluminum-silicon dioxide coating that is vapor-deposited onto a substrate in several layers. A plastic is used as the carrier material. The entire construction is significantly lighter than one with glass mirrors, which requires a heavy infrastructure to protect the fragile mirrors, the team from the University of South Australia (UniSA) announced.

According to the developers, the plastic mirrors are significantly lighter than conventional glass mirrors and also more robust. This makes handling – packaging, transportation and assembly – easier. Another advantage: the cost of producing plastic mirrors is around 40 percent lower than that of glass mirrors.

In a pilot project, two systems with 16 solar thermal panels each are being built and installed in the Vineyard of the Future. This is a facility at Charles Sturt University where innovations for viticulture are tested.

Solar thermal systems generate electricity or process heat

A solar thermal system generates heat by directing mirrors onto a receiver. This converts the concentrated sunlight into heat, which can be used to generate steam, for example, which then drives turbines that generate electricity. Alternatively, the thermal energy can be used as process heat.

According to the UniSA team, the solar thermal system (Concentrated Solar Thermal, CST) will supply thermal energy at temperatures between 100 degrees Celsius and 400 degrees Celsius. This temperature range is ideal for various processes. In food production, for example, it could be used to dry grain and pulses or purify waste water in agricultural operations. In industry, the team sees applications in the production of chemicals, paper manufacturing, the desalination of water or the dyeing of textiles.

Industrial process heat accounts for 25 percent of global energy demand and 20 percent of carbon dioxide emissions, said project leader Marta Llusca Jane. “Unfortunately, most forms of renewable energy – such as photovoltaics – cannot meet the high-temperature requirements in these areas.” However, the technology they have developed can.

“We are seeing record prices for fossil fuels and increasing pressure on the industry to decarbonize,” said Colin Hall. “This CST solution is ideally suited to Australia's hot, dry climate and offers a viable route to zero-emission process heat.” Hall developed the plastic mirrors. These are used in the automotive industry as rearview mirrors.

(wpl)