Analysis of 12 Technologies to Mitigate Greenhouse Gas Emissions

As from 1997, Mexico has performed several studies concerning greenhouse gas (GHG) mitigation technologies aiming at assessing their mitigation potential and costs in the main sectors of the country: energy, forestry, transport, and agriculture.

In that year, the study “Support for National Action Plan” was performed under the coordination of the Institute of Engineering of the National Autonomous University of Mexico (UNAM), and funded by the US Agency for International Development (USAID). That study was the basis for the National Plan for Climate Change, developed by the National Institute of Ecology (INE).

In the energy sector, the analysis of GHG mitigation technologies focused on the increase of energy efficiency, fuel substitution, and the implementation of standards to reduce energy consumption. In the forestry sector, studies focused on forest management, reforestation, and promotion of agro-forestry options.

Studies on GHG mitigation technologies are listed by sector as follows:

Model

Mitigation Costs

Baseline

Future CO2 Emissions

CO2 Emission Reduction Potential

Greenhouse Gas Mitigation Costs

Model

The model used in the mitigation technology analysis was developed by the Institute of Engineering and the Institute of Ecology of the National Autonomous University of Mexico (UNAM). The model simulates the energy system and its associated GHG emissions, forestry mitigation options, and carbon capture, GHG mitigation costs, and incremental cost curves.

Energy Sector

The simulation of the energy system embraces energy demand, transformation, and supply. Sectors considered in each activity and/or sector are the following:

1. 1. Demand: agriculture, residential, commercial, services, industrial, transport, and energy sector consumption.
   2. Transformation: refining, electricity generation, and gas cracking.
   3. Supply: oil (production and export), natural gas (production and import), carbon (production and import), biomass, nuclear, geothermia, and hydroelectricity.
      
      
      For each final use, the model allocates an indicator of energy intensity or of energy consumption by activity. Indicators used by the model are: Gross Domestic Product (GDP), GDP structure, number of rural and urban houses, number of inhabitants, number of passengers per km or number of tons transported per km. The equation used for energy consumption estimation is:

Where:

Ait = Level of activity in sector j in the year t

Sijkt ( j = 1, 2,... n) y k (k =1, 2,... m) = especific activity level j per unit of aggregated activity by source of energy

Ijkt= Energy intensity of especific activity j of the source of energy k
Total demand of energy is the addition of energy demand of the different sectors.

Once the energy system is modelled, it estimates greenhouse gas emissions for each activity of energy demand, transformation, and supply. Greenhouse gases calculated by the model are: CO2, CO, NOx, and CH4.3.

Forestry Sector

The model considers final use of forestry products according to economic and national population distribution. The required area is estimated with the productivity of the different forest management strategies.

The model is divided into two main categories, forest conservation and reforestation, and includes forest loss and deforestation rates of major forests in Mexico. Carbon capture in the forestry sector (St) is estimated as follows:

Where:

Cnet i = unit of long term mitigated carbon

A it = total area of mitigation option “j” in time “t”

Cnet represents the difference between captured carbon from the mitigation option and the alternative land-use without the mitigation option. Cnet includes carbon stored in vegetation (on and under the soil), in decaying matter, in soils, wood products and carbon saved by burning firewood instead of fossil fuels.

Captured carbon is annualized through the carbon balance (Cbti) of each mitigation option. Cbti represents net mitigated carbon related to each activity in a specific year (ton of carbon/year). The annual carbon balance of forestry sector (Cbt) in the year “t” is the sum of the balance associated with carbon for each mitigation activity “i”.

Mitigation Costs

The model considers investment, operation, and maintenance costs to meet forest and energy services, and it determines mitigation costs through the concept of “annualized costs ”, which annualizes the cost of net present values.

Where:

CN i = Annualized cost
VPN I = Net Present Value
d = Rate of Return
Net sequestered carbon is the diference between sequestered carbon and the baseline:

Where:

is the difference between annualized costs, between implementation costs of the mitigation option “i” and the cost of the baseline.

are the total prevented emissions of the mitigation option (i) related to the baseline.

1994 is the reference year and the rate of return is 9% for mitigation options, both forestry and energy.

Baseline

The base scenario for the energy sector considers a GDP growth of 4.5%, no–substitution of fuel, and the expansion of the electricity sector through thermoelectric power plants. The base scenario for the forestry sector considers constant deforestation rates for each type of forest in Mexico. The following tables show population and GDP data, both historical and projected, and CO2 emission levels projected for the base GDP during the period 1990–2010

Historical Data and Growth Projections for Population and GDP

CO2 Emission Projections in Relation to GDP

Future CO2 Emissions

According to the studies performed by researchers from the institute of Engineering and the Institute of Ecology of the UNAM, CO2 emissions from the energy sector will increase in 149% from 1995 to 2010, and 10.4 million hectares will be lost in the same period. Since the deforestation rate is proportional to residual forest, the annual area will diminish in the future. CO2 emissions from the energy and forestry sector are shown in million tons in the following table.

CO2 emissions as of 2010 (Million tons)

CO2 Emission Reduction Potential

One of the main barriers to assess greenhouse gas mitigation potential is the lack of information. For this reason, only some mitigation technologies were simulated. In the energy sector the following options are considered: combined cycle power plants, efficient lighting in the residential and commercial sector, water pumping, industrial engines, industrial boilers, industrial cogeneration, the expansion of the subway, and the use of buses in the Mexico City Metropolitan Area (MCMA). In the forestry sector, forest management (temperate and tropical), reforestation and agro-forestry options are included.

CO2 emission mitigation potential of the technologies appointed for 2005 is 270 million tons and 393 million tons in 2010.

CO2 Mitigation Potential (Million tons)

The above-mentioned results show that the greatest CO2 mitigation potential in the energy sector comes from combined cycle power plants, industrial cogeneration, and wind power plants. In 2010 the mitigation percentage of energy technologies regarding GHG total mitigation potential is 33.36%.

According to Mexican experts, the greatest CO2 mitigation potential originates in the forestry sector, especially in temperate forests, which by 2010 would account for 48.5% of the total CO2 mitigation potential. Figure 7.1 shows the evolution of CO2 emissions with electric energy generation through conventional power plants as a baseline, and mitigation scenarios of the energy and forestry sector with the technologies shown in the previous table.

Base and Mitigation Scenario

Greenhouse Gas Mitigation Costs

Mitigation cost comprises capital investment, operation costs, maintenance, transformation, and generation of energy activities. In the forestry sector mitigation costs encompass current costs of forest management (including the benefits from wood products) and opportunity costs of land-use.

Negative values show that the mitigation cost of the option is lower than the mitigation cost of the base scenario (conventional power plants). The following table shows mitigation costs of energy and forestry alternatives.

Costs of Mitigation Technologies

The results obtained indicate a negative cost for almost all energy alternatives in relation to the base scenario. However, it is worth noting that even alternatives with greater cost-effectiveness relationships (for example, residential lighting) demand major investments, which are larger than conventional technologies.

Incremental Cost Curve

The curve of incremental costs incorporates one by one the mitigation technologies referred to in the base scenario. The figure shows the addition of mitigation technologies for the year 2010.

Incremental Cost Curve

Prevented CO2 accumulated emissions and mitigation costs of the different technologies are shown in the following table.

Prevented Emissions (Million tons of CO2)

Support for a Climate Change National Plan for Mexico, Institute of Engineering of the UNAM, 1997. Paper prepared for the National Institute of Ecology (INE).
Ibidem.
Omar Masera and Claudia Sheinbaum, Mitigación de Emisiones de Carbono y Prioridades de Desarrollo Nacional, Instituto de Ecología e Instituto de Ingeniería, UNAM.
Ibidem.
Ibidem.