about the efficacy of reclamation, a coal-fired plant based on strip mining may require more or less land than the solar plant.

The materials requirements of this approach are also great. A 100-MWe solar electric plant would use, for the arrays of heliostats alone, 30,000– 40,000 tons of steel, 5000 tons of glass, and 200,000 tons of concrete, as compared with about 5000 tons of steel and 50,000 tons of concrete for the construction of equivalent capacity with nuclear power. Equivalent capacity in a coal plant would require considerably less steel and concrete.²⁸ Many of the air pollutants produced in mining and manufacturing the steel, glass, and cement for such a solar thermal plant—notably sulfur and nitrogen oxides, carbon monoxide, and particulates—would be comparable in kind and amount with 1 year’s effluents of an equivalent coal-fired plant using current control technology, except for the particulates, which would be an order of magnitude greater for the solar plant. Thus, over the (30-yr) lifetimes of the two systems, the solar plant would be an order of magnitude more benign in most pollutants. The solar plant would be somewhat worse in effluents over the lifetime of the plant than a natural-gas-fired electric generating station of equivalent capacity (with the exception of nitrogen oxide emissions and the long-term carbon dioxide hazard) and much worse than the equivalent nuclear generating capacity.

Ecological and environmental effects of this technology in a desert location would be considerable. Burrowing animals and their habitats would be destroyed during construction, and sites would have to be chosen to avoid dense wildlife populations or endangered species. The desert surface would be altered by construction, road building, off-road vehicle traffic, building of transmission lines, and so on. This would affect erosion in the region. Wind erosion would increase because the protective desert crust, or pavement, would be broken, and water erosion and runoff would also increase, especially along roads. The hydrological cycle would be affected by this and by modification of evaporation rates due to the heliostat canopy. Evaporative losses resulting from the use of wet-tower cooling or storage reservoirs would also significantly affect this cycle. Availability of cooling water (chapters 4 and 9) may restrict the deployment of this or any other electric generating option in the Southwest and elsewhere.

Central receiver electric generating plants could also alter local and regional climates by modifying the radiation balance of the natural desert. Considerable amounts of dust are likely to be introduced into the atmosphere by construction activity. The longer-term climatic effects of this would probably not be as significant as those of modifications of the radiation balance, but the temporary potential for distant effects might be