A major benefit of solar thermal power is that it has little adverse environmental impact, with none of the polluting emissions or safety concerns associated with conventional generation technologies. There is hardly any pollution in the form of exhaust fumes or noise during operation. Decommissioning a system is not problematic.
Each square metre of reflector surface in a solar field is enough to avoid the annual production of 150 to 250 kilograms (kg) of carbon dioxide. Solar thermal power can therefore make a substantial contribution towards international commitments to reduce the steady increase in the level of greenhouse gases and their contribution to climate change.
Although central receiver plants are considered to be further away from commercialisation than parabolic trough systems, solar towers have good longer-term prospects for high conversion efficiencies. Projects are under construction in Spain and under preparation in South Africa. In future, central receiver plant projects will benefit from similar cost reductions to those expected from parabolic trough plants. The anticipated evolution of total electricity costs is that they will drop to 7 € cents/kWh in the medium term and to 5 € cents/kWh in the long term.
Parabolic dish systems are comparatively small units which use a dish-shaped reflector to concentrate sunlight, with superheated fluid being used to generate power in a small engine at the focal point of the reflector. Their potential lies primarily in decentralised power supply and remote, stand-alone power systems. Projects are currently planned in the United States, Australia and Europe. In terms of electricity costs, an attainable near-term goal is a figure of less than 15-20 € cents/kWh, depending on the solar resource.
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