~DLR (link below) will use heliostats = stearable mirrors to produce steam which drives turbines to make electricity~

3. Isn’t the water demand for the cooling of the solar thermal power plants and cleaning of the mirrors a problem in arid locations?

In arid regions, conventional oil, gas or coal-fired steam cycles are usually air-cooled, and CSP plants can be operated in the same way. Solar-thermal power plants can be cooled by air, and there are cleaning procedures that require very little water. Depending on the location, vaporised cooling towers and seawater cooling may be used because they are more efficient than air-cooling techniques. If saltwater from nearby coasts is used instead of drinking water for the cooling units, a 250 MW collector field may be used to operate a 200 MW turbine and 100,000 cubic neters of drinking water may be produced a day (over four million litres per hour) through the process of water desalination.

All details see AQUA-CSP study by German Aerospace Center (DLR):

www.dlr.de/tt/aqua-csp

4. Can the mirrors withstand the harsh desert conditions and sandstorms?

Solar-thermal power plants have been operating in the Mojave Desert for over 20 years and have withstood hailstorms, sandstorms and cyclones. In the event of impending danger, the mirrors, which are rotatable, can be positioned in such a manner that they are protected. Should the mirrors break nonetheless (0.4% per year), replacements are part of the operating costs. Signs of wear and tear on the mirrors in Kramer Junction have not been an issue for the last 20 years. Today, the power plants work more efficiently as operating and maintenance methods are now better than when operations began.

5. Aren’t the land areas required for the solar-thermal power plants enormous and an environmental threat?

According to a TRANS-CSP study, 17% of Europe’s energy requirements may be met by solar imports by 2050. This would involve 2,500 sq km of desert surface for the solar power plants and 3,500 sq km for the high-voltage direct-current transmission lines throughout the entire EU-MENA region (Europe – Middle East – North Africa). This total surface area of 6,000 sq km is as large as the Nasser reservoir near Aswan in Egypt. However, this reservoir provides only 3 Gigawatts (GW) of electric power, whereas the solar power plants would deliver 100 GW of electric power. Solar power is actually the most compact and efficient renewable energy source worldwide. The MENA region amounts to 12 million square kilometers, of which only 2,500 sq km (0.02% of the total area) will be required for the export power plants.

6. Aren’t the costs of power lines running over thousands of kilometers too high and their operation difficult to enforce?

Today, the electric losses incurred by high-voltage direct-current transmission lines (HVDC transmission lines) amount to 4-5% per 1,000-km of line, thereby increasing the price of the original energy source. These costs, plus capital and operating expenses for the power lines, account for around 1-2 c/kWh, depending on the length of the lines, in addition to the cost of production. However, the two- or threefold insolation in North Africa sufficiently makes up for the transportation costs to Europe. The German Aerospace Center (DLR) has estimated in its studies that the costs of producing and transporting solar-thermal power between 2020-2030 will be lower than that of the conventional power production technologies in Europe which are subject to constantly rising fuel prices and environmental costs. Planning and approval times lie in the discretion of the countries involved and could be accelerated by appropriate regulations enforced by the EU = European Union.

What is important for public acceptance: High-Voltage Direct Current (HVDC) transmission can be used both with overhead lines and with underground cables. Therefore, in contrast to AC technology, HVDC provides the possibility to use underground cables for the transmission of electrical energy even over long distances. The technical design and economic assessment of necessary grid infrastructure for power transmission to Europe is an essential part of the roll-out plan to be worked out under the DII. Furthermore, it is easier to communicate the need for the network to the general public when solar energy be used, instead of energy from coal or nuclear sources. The case is similar to that of highways: Of course, such a network is an environmental hazard that can only be justified through the substantial advantages and benefits for the environment which it creates. ~neil~