A NUMERICAL EXAMPLE

For a conventional fossil-fired power plant, one of the major pei— formance indicators is the percentage of conversion, or fuel utili­zation efficiency, e. g., in a typical modern Rankine-cycle power plant, 37% of the heat of combustion of the fuel used (the "low heating value" — the enthalpy of combustion for gaseous product water) appears as electricity output. The customary "heat rate" is an inverse value. The net conversion value (allowing for power plant in-house energy consumption, or "parasitics") should generally be specified. This is similar also for solar plants, except that here the "fuel" input is the local solar energy available for the faci­lity, specifically defined as the product of the total collectors’ aperture area by the local solar insolation (usually, the direct – normal) per unit area (e. g., 2580 kWh/m*/year).

2,322 kWh/т* /у 204,000 m*

202.3×10“ kWh(t)/y 84.244×10“ kWh(t)/y 64.47×10“ kWh(e)/y

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A hybrid plant may utilize fuel for superheating the solai—farm steam (e. g., 250°C) into a higher temperature (e. g., 400°C), and also for producing additional steam to be charged into the high – pressure end of the turbine (at 540°C). Still more fuel may be used at no-sun hours. Only overall summation data such as the following can, at best, be derived from company information for a specified year:

Now, then, what are the solar contribution and the overall solar efficiency?

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