Competing with Fossil Fuels

Solar thermal power currently leads the way as the most cost-effective solar technology on a large scale. It currently beats other PV systems, and it also can beat the cost of electricity from fossil fuels such as natural gas. In terms of low-cost and high negative environmental impact, nothing competes with coal. But major solar thermal industry players such as eSolar, Brightsource, or Abengoa, have already beaten the price of photovoltaic and natural gas, and they have plans to beat the price of coal in the near future.

With an increasingly industrializing planet, the leaders in solar thermal technology have an ever-growing market. The issue is, and will always be, how to make solar thermal technology more economical. There are currently two methods for solar thermal collection. The first is line focus collection. The second is point focus collection.

Line focus is less expensive, technically less difficult, but not as efficient as point focus. The basis for this technology is a parabola-shaped mirror, which rotates on a single axis throughout the day tracking the sun. Point focus technique requires a series of mirrors surrounding a central tower, also known as a power tower. The mirrors focus the sun's rays onto a point on the tower, which then transfers the heat into more usable energy.

Point focus, though initially costlier and technically more nuanced, outshines line focus when results are concerned. The point of focus in a line focus mirror array can only reach temperatures around 250°C. That is a sufficient temperature to run a steam turbine, but when compared to the 500°C and higher temperatures that point focus can reach, the extra effort and cost is balanced out by its greater efficiency capability. High efficiency matters because it drives down both the land usage, and the effective cost per kWhr of the plant.

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> Major Solar Thermal Players

The environmental impact of coal is emphasized by this image of enormous pit mines. Considering the processes coal goes through to become electricity, there is no such thing as clean coal.

Although coal is currently the lowest cost power provider, it also has the most negative effect on the environment.

This image shows an example of point focus collection. The Solar Two project in California USA uses a field of mirrors to focus solar energy onto a central boiler to produce steam and electricity.

Point focus: The Solar Two project in California USA uses a field of mirrors to focus solar energy onto a central boiler to produce steam and electricity. (Photo courtesy NREL)

This image shows an example of line focus collection, specifically the Ausra Line Focus demonstration in Australia.

Line Focus: The Ausra Line Focus demonstration in Australia.