transport system costs lll$/kWe. The heat engine includes the steam generator,and when its losses are included, it costs 182.5$/kWe. These results are shown in Tables 12 and 14. Power plants using steam and chemical energy transport are the most attractive for low system cost, high overall efficiency and low startup time after overnight shutdown. The use of water transport is a close third, but has a more significant initial startup time. Power plants using NaK and helium energy transport are too expensive to be competitive and in the case of NaK additional safety problems are introduced. When land, buildings and contractor fees are included, the direct costs of the steam and chemical central generation system increase from 1028$/kWe and 1020$/ kWe to 1150$/kWe and 1140$/kWe, respectively. Using the cost expression 0.0224I/PL, the energy cost is about 57 mills/kWh for either the steam or chemical system. 4.2.2 Impact Characteristics The central generation plants use the parabolic dish collectors with a heat transport subsystem collecting the heat to a central Rankine plant. Considering the two most attractive candidates which are steam and chemical transport, the overall system efficiency is about 26%. The ground cover ratio used was 0.4. A 150 MWe plant would cover 1.9 km2 (0.75 mi2). This is 1.25 km2(0.5 mi2 ) per 100 MWe. Based on the chemical system efficiency of 26.5%, the unused direct sunlight (waste heat) would be rejected at the rate of 423 MWt for a 150 MWe plant averaged during the day. More important than the rejected heat is the excess heat deposited. That is the heat deposited by the plant compared to the heat that would be deposited at the site if no plant were there. Rather than use MWh or 106 BTU, the average rate of heat release is used in MWt. The total direct power needed for a 150 MWe
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