Additional information on calculating the emission factor of Mexico for the JCM
Summary
In order to secure net emission reductions in the methodology, the following reference
emission factors will be applied depending on the grid to which a proposed project activity
will connect in Mexico:·Table I summarises the applied reference emission factors for the PV system(s) in a
proposed project activity, which is directly connected to a regional grid, or connected to aregional grid via an internal grid not connecting to a captive power generator (PV Case1).

·Table 1 also summarises the applied reference emission factors for the PV system(s) in a
proposed project activity, which is connected to an internal grid connecting to both aregional grid and a captive power generator (PV Case 2).

·A reference emission factor of 0.533 t-CO2/MWh is applied, in the case that the PVsystem (s) in a proposed project activity is only connected to an internal grid connecting
to a captive power generator (PV Case 3).

Table 1. Reference emission factor PV Case 1, Case 2 and Case 3
Emission factor forEmission factor forEmission factor

PV Case 1

PV Case 2for PV Case 3(tCO2/MWh)(tCO2/MWh)(tCO2/MWh)

0.434

0.434

0.533

1. Current status of electric power source mix in Mexico
The Mexican electricity system consists of a National Interconnected System (SIN) which
covers most of the country and the small isolated Baja California and Baja California Sur
grids (Figure 1). The Federal Electricity Commission (CFE), a state company, carries out
generation, transmission, distribution, supply and commercialization of electric energy
through its subsidiaries. The Mexican Secretary of Energy (SENER) manages an online
energy information portal called the Energy Information System (SIE)1.

1

http://sie.energia.gob.mx

1Figure 1. Map of Mexican national electricity grid2

Mexico generates electricity using natural gas, coal, fuel oil/diesel, hydropower, nuclear,geothermal, wind, and solar power (Figure 2). The natural gas, fuel oil/diesel, and coal areused in thermal power plants that use different types of technology: steam, combined cycle,turbogas, internal combustion, and coal-fired. In addition to domestic generation, Mexico
also imports electricity from the United States and Guatemala. The proportion of total
electricity generated from hydro, nuclear, geothermal, wind, and solar power plants as well asfrom the import, defined as low cost/must run (LCMR) power sources, were 19% of total
electricity generation in 2013, 22% of total electricity generation in 2014, and 20% of total
electricity generation in 2015 (Table 2).

300
250
200
150

27.4

38.1

41.9

26.8

30.1
25.5

31.5

33.5

33.5

138.1

143.9

151.5

2013

2014

2015

1005002Natural gas

Coal

Fuel oil/Diesel Hydro

GeothermalWindSolar PV

NuclearImportApproximate figure based on Comisión Federal de Electricidad (CFE), Informe Anual 2016

2Figure 2. Gross electricity generation in Mexico by fuel type (TWh)When the share of LCMR is less than 50% of the total grid generation, the operation ofLCMR resources would not be affected by a newly installed power plant including a PV
project. Therefore, only electricity from gas-fired, coal-fired, and oil-fired power plant istaken into account for calculating the official grid emission factor of Mexico.

Table 2. Gross electricity generation by fuelGross generation by fuel (TWh)

2013

2014

2015

Total 2013-2015

Natural gas

138.1

143.9

151.5

433.50

Coal

31.5

33.5

33.5

98.50

Fuel oil/diesel

41.9

26.8

25.5

94.2

Hydro

27.4

38.1

30.1

95.60

Nuclear

11.8

9.7

11.6

33.10

Geothermal

6.1

6

6.3

18.40

Wind

1.8

2.1

2.4

6.30

Solar PV

00

0

0.00

Import

1.21

2.12

1.65

4.98

Total domestic fossil fuel

211.5

204.2

210.5

626.20Total LCMR

48.3

58.0

52.0

158.4

Total all259.81

262.22262.55784.58% LCMR

19%

22%20%

Source: Mexican Secretary of Energy (SENER), Prospectiva del Sector Electrico 2016-2026

2. Calculation of emission factor of the national grid
In order to identify the reference emission factor of the Mexican national grid in aconservative and simple manner to secure net emission reduction, the emission factors in thismethodology are established by an operating margin that is calculated using gross electricity
generation from fossil-fuel power plants for the years 2013-2015. Emission factor of naturalgas is applied to calculate the emission factor of thermal power plants in a conservative
manner.

Conservative emission factor of fossil fuel power plants are calculated using the following
equation:
Emission factor of fossil fuel power plant [tCO2/MWh]3

= (Emission factor of fuel source [kgCO2/TJ]*10-3*0.0036[TJ/MWh])/(Heat efficiency (LHV)[%]/100)

Emission factors of coal, gas, and diesel combustion are derived from the “IPCC guideline
2006, Chapter 2, stationary combustion” as 92,800 kgCO2/TJ, 54,300 kgCO2/TJ, and 72,600
kgCO2/TJ (Table 3). Default heat efficiencies of coal-fired power plants and gas-fired power
plants are applied as 45% and 57% respectively, taking into consideration the most advanced
technologies being used in currently operational power plants in Mexico.

Table 3. Constants for calculation of reference emission factor
Item

ValuesReference

Best heat efficiency of natural gas

57%

Mitsubishi Hitachi Power Systems

power plant (Agua Prieta II, 2016)(combined cycle)

catalogue3

Best heat efficiency of coal power

45%

plant (PetaCalco, 2016)(supercritical)

UNFCCC, 20154

Best heat efficiency of diesel power

JCM

ApprovedMethodologies:

49%plant
CO2

PW_AM001, MN_AM003, etc.
emissionfactorofsub92,800 kgCO2/TJ

IPCC

guidelineforNational

bituminous coal
Greenhouse Gas Inventories 2006,
CO2 emission factor of natural gas

54,300 kgCO2/TJ

CO2 emission factor of diesel

72,600 kgCO2/TJ

Chapter 2, stationary combustion5

Applying the emission factors and plant efficiencies (Table 3), the conservative emission
factors are calculated to be 0.742 tCO2/MWh for coal-fired power plants, 0.343
tCO2/MWh for gas-fired power plants and 0.533 tCO2/MWh for diesel power plants. The
conservative emission factors are applied for calculating the reference CO2 emission
factor of the grid. Using the conservative emission factors for each power source data andelectricity generation from fossil-fuel power plants, operating margin are obtained using
the following equation:

3 https://www.mhps.com/en/products/thermal_power_plant/gas_turbin/lineup/m501f.html
4 The default efficiency factor for supercritical is 45% according to UNFCCC CDM EB (2015) Tool to calculate theemission factor for an electricity system.
IPCC default values at the lower limit of the uncertainty at a 95 per cent confidence interval.

54

Where:‫ܧܧ‬ோா,௚௥௜ௗ =∑೔ ாீ೔ ×ாி೔∑೔ ாீ೔… Equation 1EFRE,grid= The reference CO2 emission factor of grid [tCO2/MWh]EFi= Conservative emission factor of power plant type i [tCO2/MWh]EGi= Gross electricity generated and delivered to grid from fossil-fuel power plant type iin grid during 2013-2015 [MWh]Applying the conservative emission factors and power generation (Figure 2) to Equation
1, the reference emission factor to be applied for solar PV in a proposed project activity
both in PV Case 1 and PV Case 2 as mentioned above (EFRE,grid) is calculated to be 0.434
tCO2/MWh.
3. Calculation of the emission factor of a captive power generator
To determine the emission factor of a captive power generator which normally uses a dieselgenerator in a conservative and simple manner, the heat efficiency of 49%, an efficiency level
which has not been achieved yet by the world’s leading diesel generator, is applied.
The emission factor of diesel power generation is calculated from the heat efficiency using
the following equation:
Emission factor of diesel power plant [t-CO2/MWh]= (Emission factor of diesel [kgCO2/TJ]*10-3*0.0036[TJ/MWh] / (Heat efficiency (LHV) [%]/100)

Applying the default value of the emission factor of diesel combustion which is 72,600
kgCO2/TJ derived from “IPCC guideline 2006, Chapter 2, stationary combustion”, together
with the heat efficiency of 49%, the emission factor for a captive power generator (EFRE,cap) iscalculated to be 0.533 tCO2/MWh.

5