083

The FCP, based on Equation 2-23, is: 5,213 Btu/kWh

1,020 Btu/cf

The CCP, based on Equations 2-22 and 2-24, is:

5.111 cf/kWhx $3.35/Mf x 1 Mcf/1,000 f+ $0.006/kWh = $0.017/kWh + $0.006/kWh = $0.023/kWh

Beyond ECP, FCP, and CCP

Absent from the above discussion of performance indicators are several essential factors that affect actual project economic performance for any prime mover application. When considering an investment in a prime mover system, the analysis is based not on the potential output and efficiency of the system, but the match of that potential output with the facility's internal requirements or ability to sell the outputs. While the CCP of a given system provides useful and compelling information, it provides only a limited perspective from which to make an investment decision.

In most cases, higher cogeneration heat recovery indicates a higher overall heat and fuel rate, even if the ECP or FCP remains the same. This is because as more input energy is converted to thermal energy, less is converted into power, and more fuel must be used per unit of power output. Depending on the available load or rejected energy sink of displaceable thermal energy, it is often better to consider a more thermally efficient power producing system with less heat recovery.

With an unlimited sink of thermal energy requirement, power generating thermal efficiency becomes less of a consideration. A relatively inefficient power system may be considered because decreased capital costs and increased thermal energy generation efficiency compensate for decreased power output. However, if there is a limited amount of thermal energy that can be used, the emphasis shifts to more thermally efficient prime movers that produce a higher percentage of shaft power and a lower percentage of recoverable thermal energy.

Each prime mover system considered will have a different heat rate and different combination of power and thermal outputs. Available temperatures and pressures of thermal outputs will also vary. There will be different emissions rates for different pollutants, different space requirement, and different expected service lives. Moreover, these performance characteristics will vary as operating conditions vary.

Additionally, each of the prime mover systems will require different levels of maintenance and operating attention, and they will have different capital costs. All of these factors will vary, even for the same equipment, depending on site conditions. Translating performance into cost and values requires a detailed analysis of the site conditions, the equipment performance under these conditions, and the interaction of all factors for each alternative.

Heat Recovery Unit

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