is the consideration of line losses which do have a direct impact on system costs. Simplified methods have been used to evaluate an electric power collection subsystem; the results are shown in Section 3.2.2. The techniques used to achieve transmission level voltages are transformers with circuit breakers for startup and repair isolation. Capacitor banks are used for power factor correction and underground ac cables rather than de are used for power collection. 2.2 CENTRAL GENERATION The alternative approach to generating electric power with a field of parabolic dish collectors is collection of heat over the entire field and transporting the heat (or chemical energy produced by the heat) to a central energy conversion plant. The currently available steam Rankine plant is the most appropriate energy conversion device based on price and efficiency at moderate temperatures (-= 550°C). There are many energy transport techniques such as pumped water, steam, liquid metal, inert gases or chemical transport. This approach is sensitive to operating temperature since the heat leak from a widely distributed piping network must be carefully minimized. The temperature also defines the type of material required for the pipe wall and combined with the line pressure defines the required wall thickness. The major tradeoff within a particular scheme (specific heat transfer fluid, temperature range and pressure) is the balancing of the pipe diameter to control the fluid pressure drop and required pumping power against the thermal heat leak. The pipe diameter and amount of insulation are varied to find the minimum total cost.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==