Thermal solar power as an alternative to coal

{{#badges: Climate change |CoalSwarm}} Thermal solar power is electricity that is generated from the heat of the sun. The most common usage of solar thermal energy is for on site water and space heating. However, electrical energy has been reliably produced by concentrated solar power arrays. The concentrated solar power method of energy generation has arrays of mirrors focusing light onto pipes of water or other heat tranfer fluid. The hot water is heated to the boiling point and powers a steam turbine to generate electricity, or is preheated for use in fossil fuel based generation.

The chief resource required is large tracts of land with good sun exposure. Areas with arid land not suitable for farming could be readily cultivated as solar farms. The most profitable sites would be ones near to existing high voltage lines or to major consumption areas such as metropolitan areas or energy intensive industry.

The chief problem associated with this form of electricity generation is that it stops generating electricity when the sun is down. One solution is molten salt thermal storage. During the day, heat from the water is transferred to insulated chambers filled with molten salt, which retains the heat well. This thermal energy method of storage is more efficient than storage of electrical power. At night time, the heat batteries are used as a thermal source for power generation.

Currently, coal power is seen as cheeper to cleaner or more renewable sources of power. the Standard and Poore chart cited in"The War on Coal: Think Outside the (Coal) Pits" lists the average baseline cost for pulverized coal at 5.8 cents per kilowatt hour (c/kwh), or the more realistic cost of coal power generated from Powder River Basin (PRB) coal, a coal which usually has fewer contaminants and therefor somewhat bypasses the sulfur caps on coal fired generation, is priced at 6.8 c/kwh. By comparison, the same chart lists wind at 7.1 c/kwh (while noting shortages and energy transportation factors are not included) and concentrated solar (CSP) at between 7 and 11 c/kwh. The "The War on Coal: Think Outside the (Coal) Pits" article goes on to suggest that the price of coal fired power is going up due to a variety of reasons and is poised to do so even further, perhaps cataclysmicaly so. Further, the house and senate have been hamering out bills to reduce carbon emissions from power generation, and even energy execs expect at least a carbon cap trading system to be in place within a few years. This alone is likely, even in the more moderate estimates, to drive the cost of coal generation to be within the same range as renewables: 7.9 c/kwh for pulverized coal, 8.4 c/kwh with powder river basin coal according to the same S&P chart. Meanwhile, as renewable energy markets expand, the setup associated costs will go down as both technology becomes more available and established plants pay off their initial costs, meaning that the price for renewable power is only going to go down. (reference pending)

Articles and resources

External articles

• "A Solar Grand Plan," Ken Zweibel, James Mason and Vasilis Fthenakis, Scientific American, December 2007.
• "Tackling Climate Change in the U.S.: Potential Carbon Emissions Reductions from Energy Efficiency and Renewable Energy by 2030," American Solar Energy Society, January 2007.
• "The War on Coal: Think Outside the (Coal) Pits," Khosla Ventures, 2007 (PDF file)

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