Clean Energy Cost-Savings: A Study of Mexico’s Federal Electricity Commission (CFE)

Clean Energy Cost-Savings: A Study of Mexico’s Federal Electricity Commission (CFE)

Net Thermal Efficiency and Net Heat Rate The development of new wind and solar power plants reduces the use of fossil fuels for generating electricity. The extent of the reduction depends on the type of fossil fuel power plant supply that would be avoided by having clean energy available. Table 1 shows the thermal efficiency of power plants that could be potentially replaced. Although CFE’s most modern plants have higher efficiencies, the efficiencies selected for this analysis are representative of those with a higher likelihood of being replaced based in the economic dispatch process.

Table 1. Net Thermal Efficiency (High Heating Value)

Technology

Efficiency

Combined Cycle (new) Combined Cycle (average)

58% 51% 35% 34% 40%

Steam Thermal

Coal

Internal Combustion

Gas Turbine 33% Note 1. Net thermal efficiency is defined based on the fuel’s high heating value. Note 2. Turbogas’s most modern plants have higher efficiencies.

Note 3. Although Petacalco power plant has a seventh, supercritical unit with 42% thermal efficiency, this analysis considers only the average efficiencies of the six older units and the other two coal plants, (Río Escondido and Carbon II). This thermal efficiency can in turn be used to calculate the net heat rate per MWh generated, as shown in Table 2. Table 2. Net Heat Rate (Low Heating Value) Technology Natural Gas (GJ/MWh) Diesel (GJ/MWh) Fuel Oil (GJ/MWh) Coal (GJ/MWh) Combined Cycle (58%) 7.084 Combined Cycle (51%) 8.056 7.779 Steam Thermal 11.738 11.357 Coal 11.472 Internal Combustion 9.937 Gas Turbine 12.450 12.022 GJ = gigajoules Note 1. Net heat rate is expressed based on the fuel’s low heating value Note 2. Net heat rate is determined from the net thermal efficiency, the relationship between the low heating value and the high heating value for each fuel, and assuming that 3% of the energy is self-consumed.

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