Solar thermal electricity
April 2010
Solar thermal trough technology in desert

In my last post I mentioned solar thermal energy technology. I thought I must mention how solar thermal is different to the photovoltaic solar cells that readers may be familiar with.

While photovoltaic cells directly use the sun’s light to create electricity, solar thermal installations use mirrors to concentrate the heat from the sun into a storage medium, such as molten salt. The high heat of this molten salt can then be used to turn a turbine by boiling water into steam, much like what happens in a coal, gas or nuclear power plant. The benefit of solar thermal over photovoltaics is that it can be relied upon as a baseload, 24 hour power source as heat is gradually drawn from the molten salt when required. The benefits of solar thermal over coal, gas and nuclear is that it requires no fuel inputs, and emits no pollution from its operations.

Solar thermal concentrator

I’m sure I’m not the only one excited by technology such as this. I’m fascinated by the idea of energy sources that need no fuel inputs and produce no pollution or emissions. Better yet, the cost of solar thermal is comparable to coal power plants and the technology is well-suited to Australian conditions. Bring it on.

A quote from page 87 of The Ecology of Commerce (1993) by Paul Hawken:

Solar technologies are currently more expensive than coal because they internalise their costs to the environment, but coal externalises its costs.

I think it’s great that despite this situation (the costs of coal pollution to the environment being written off as ‘free’), solar thermal is still emerging as an economic challenger to coal under these ‘old rules’. When we remember that coal is only ‘cheap’ because of the incomplete way we account for its environmental lifecycle, the choice between fossil fuels and renewables is stark. Let’s make our priority supporting clean, rapidly deployable technology such as solar thermal.