Fossil Abstinence: Desert Power Plants Worse Than PV Panels

Mirrors shining on power towers or miles of pipes in thermos bottles not only waste resources but also waste time. They look impressive and deliver electricity without dumping greenhouse gases but are a façade that give the impression we’re moving in the right direction. Solar power plants and $60,000 PV arrays on homes do reduce our need for electricity produced by burning coal, natural gas and nuclear fuel, so what is wrong?

Where I live such a PV array can deliver only 30% of the electricity I use. And since electricity is about 30% of my total household energy budget, a $60,000 system would address about 4% of my total carbon footprint. When we install large solar plants in deserts, which have more sunlight than cities, we hope to solve both peak oil and climate issues. But they do not. Those projects are way too expensive and, like PV panels, we actually use less than 14% of the sunlight. But PV panels can use much less material, and less labor, yet deliver the same electricity. Adding storage makes desert power plants even less efficient. Neither delivers any heat, or cooling.

Simply inviting solar thermal power stations into our communities and utilizing much more of the sunlight could more than double the performance of power plants that generate power with steam. Why should taxpayers pay $Millions to build inefficient and ineffective solar power plants in deserts? Big Energy makes money burning fossils in large plants and bureaucrats support only this “business as usual” approach. And future generations will have to pay these $billion bills.

Let’s consider some numbers. Solar 2 demonstrated solar power tower technology and annually delivered 7.9% of the sunlight as electricity. Similar projects soon hope to get this conversion efficiency to 13.7%, see: http://www.nrel.gov/csp/pdfs/34440.pdf .  Solar parabolic trough power plants have many more years of experience and the Solar Electric Generating Station VI annually converts 10.7% of the solar energy to electricity. Future solar power tower and trough projects hope to get conversion efficiencies to above 14%, see:http://www.solarpaces.org/CSP_Technology/docs/solar_trough.pdfand the 34440 article above. Making power in remote deserts and transmitting this clean electricity loses around 7.2% (in 1995) in transformers and power lines, see:http://climatetechnology.gov/library/2003/tech-options/tech-options-1-3-2.pdf diminishing desert solar effectiveness targets from 15% to 14%. These solar power stations generate steam and use turbines the same way as coal burning power plants. Every day, a typical fossil plant needs to burn 110 cars filled with coal. No one wants to live near plants that handle coal and spew mercury, ash particles and greenhouse gases. But trains don’t bring sunlight and solar power plants have no emissions, can be absolutely quiet, and can shade parking lots – so why not foster them in communities?

Power plants dump heat. Solar power plants convert about a third of the energy in steam into electricity and need cooling towers in much the same way as vehicles use radiators to get rid of their “waste” heat. But if an appropriately sized plant were near a hospital, government buildings, a mall, or condominiums, this solar energy could heat water and space and, using absorption air conditioning equipment common in large facilities, provide cooling.

Last week I mentioned a solar collector that had 1,000 square foot mirrors as the front end of a personal energy system. Although this 36 foot diameter dish is the size of a small roof, it would deliver enough power and heat to make a significant dent in the carbon footprints of farmhouses, rural homes, businesses and others with large backyards or room. They have to follow the sun from east to west so only very small ones can be on roofs.

A plug in hybrid electric car will diminish responsibility for oil spills (or ocean oil platform mishaps) but will require electricity. Though cheaper than gasoline, coal-fired power costs thousands of “black lung” deaths and otherwise injured miners and does not make the electric transportation option any better. But solar power can. Any area of concentrating mirrors can intensify sunlight 1,000 times so that smaller dishes say 20 feet in diameter delivering 7 kilowatts in full sun, may fit in some neighborhoods. On the other hand, since it takes a similar effort for site work and to make parts, much larger dishes, say 100 feet in diameter (175 kWe) would be most cost effective for those who use a lot of power, heat and cooling. One almost this large was built in Australia last summer, see: http://solar-thermal.anu.edu.au/2009/12/500-m²-dish-construction-highlights/

Before looking seriously at what it will take to replace the energy we get burning fossils, we should look at our carbon footprint and identify ways to live well that require less energy.