MODELING THE GLOBAL SOCIETY-BIOSPHERE-CLIMATE SYSTEM: PART 1: MODEL DESCRIPTION AND TESTING

J. Alcamo, G.J.J. Kreileman, M.S. Krol, G. Zuidema

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2. Energy-Industry System of Models

The objective of the Energy-Industry system of models is to compute the emissions of greenhouse gases from world regions as a function of energy consumption and industrial production. The models are designed especially for investigating the effectiveness of improved energy efficiency and technological development on future emissions in each region, and can be used to assess the consequences of different policies and socio-economic trends on future emissions.

2.1 Energy Economy Model

The Energy Economy model divides the energy economy of each world region (Figure 2) into five energy sectors (Table 1) and computes the demand for end use "heat" and "electricity" in each of these sectors (six energy carriers are included, Table 1). Such an end use approach makes it easier to assess the potential of energy conservation measures in reducing overall energy consumption and, in turn, in reducing greenhouse emissions. Details of the models are given in de Vries et al. (1994).

                                   TABLE 1     
        End Use Energy Carriers and Sectors in Energy 
Economy ModelEnergy
Carriers                   Energy Sector         Corresponding
                                                        Activity Level                                                                                      
Coal                              
Industry              Value-added
                                                        industrial production 
                                                                          
Gas

Oil                     									 Transportation        Number 
of vehicles

Fuelwood                          Residential           Personal expenditures 

Other Biomass                     Commercial            Value-added commercial
                                                        services
                                                                                           
Electricity                       Other                 GNP

The end use heat and electricity is computed from elasticity functions that relate "activity levels" of each sector (Table 1) with end use energy consumption. Elasticity coefficients are derived for each world region with data from 1970 to 1990. The computation of end use energy also includes an energy conservation function which relates energy prices from 1970 to 1990 with the motivation for energy conservation during that period. The main adjustable variables in the model are the parameters of this energy conservation function, and the above elasticity coefficients, the main driving forces in the model are regional changes in population and GNP.

The computed end use electricity in each sector is converted into a required power plant capacity by taking into account an average power conversion rate for each region. The final step of calculations is to compute primary consumption of energy by specifying a region-specific fuel mix to deliver the end use heat in each sector, and to fulfill the required power plant capacity.

2.2 Energy Emissions Model

The Energy Emissions model applies emission coefficients to the energy consumed in each energy sector to compute the amount of CO2, CH4, N2O, and other greenhouse gases released from each region (Table 2). These sector-specific emission coefficients are obtained from the literature, but adjusted within their known range until good agreement is obtained between model calculations and data for global and regional emissions in 1990. In addition, the model takes into account emissions of CH4 that are related to fuel transportation/transformation such as CH4 leakage from natural gas pipelines. Because the Energy Emissions model is linked to the Energy Economy model, the model user can investigate emission control strategies related to the energy system; e.g. the feasibility of reducing emissions by altering the fuel mix in a sector, or by improving the efficiency of different technologies used to provide energy. In addition, control strategies of non-CO2 gases can be investigated by prescribing reductions of gases due to abatement technologies.

TABLE 2 Main sources of greenhouse gases accounted for in the IMAGE 2.0 model.Source Greenhouse Gas IMAGE 2.0 Submodel** Fuel combustion in end use CH,CO,CO,NO,NO,VOC EE sectors (Table 1). Energy conversion, transformation, CH,CO,CO,NO,NO,VOC EE and transportation. Industrial processes NO,VOC, halocarbons IE Cement manufacturing CO IE Wetland rice fields CH LUE Natural wetlands CH LUE Landfills CH deliver the end use heat in each sector, and to fulfill the required power plant capacity.

2.2 Energy Emissions Model

The Energy Emissions model app LUE Animal enteric fermentation CH LUE Animal waste CH, NO LUE Natural soils NO LUE Fertilized soils NO LUE Aquatic sources CH, NO LUE Biomass burning (Deforestation, CH*,CO*,CO*,NO*,NO*,VOC* LUE, TC agricultural waste burning, savanna burning) Soil Respiration CO* TC* Emissions calculated on grid-scale. Regional totals calculated for other sources. ** EE = Energy Emissions model, IE = Industrial Emissions model, LUE = Land Use Emissions model, TC = Terrestrial Carbon model.

2.3 Industrial Production and Industrial Emissions Models

The Industrial Production and Emissions models are used to compute emissions of greenhouse gases or their precursors that are not directly associated with energy combustion. (Emissions coming from the combustion of fuel by industry are taken into account in the "Industry" sector of the Energy Emissions model described above.) Examples of these emissions are: halocarbon emissions from refrigerators and industrial products, CO2 from the cement industry, and VOCs from chemical manufacturing. Because emissions are related to the level of industrial activity, future activity is computed by the Industrial Production model which uses a simple indexing method to compute future industrial output in different regions.

2.4 Linkages of Energy/Industry with the Rest of IMAGE 2.0

In the Atmospheric Composition model (see below), emissions from the Energy-Industry sub-system of IMAGE 2.0 are added to emissions of CO2 and other greenhouse gases coming from the terrestrial biosphere; the model then computes the resulting build-up of greenhouse gases in the atmosphere. The Energy-Industry sub-system is also linked to other parts of IMAGE 2.0 via the demand for fuelwood; this demand is computed in the Energy Economy model and then used by the Land Cover model (described below) to compute new deforested areas. (However, only part of the fuelwood demand is assumed to lead to deforestation). The Terrestrial Carbon model (also described below) computes the change in terrestrial carbon flux owing to fuelwood extraction. Biofuel demands computed by the Energy Economy model are also taken into account in the Land Cover model as an additional demand for land competing with the demand for land to satisfy food demand. This linkage allows the model to comprehensively evaluate the effect of using biofuels on greenhouse gas emissions. No feedbacks of global change on energy use are taken into account.

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Sources

Alcamo, Joseph (ed.). 1994. IMAGE 2.0: Integrated Modeling of Global Climate Change. Dordrecht, The Netherlands: Kluwer Academic Publishers.

Suggested Citation

Consortium for International Earth Science Information Network (CIESIN). 1995. IMAGE 2.0 Model Guide [online]. University Center, Mich.
CIESIN URL: http://sedac.ciesin.org/mva/image-2.0/image-2.0-toc.html

Acknowledgement

This work, including access to the data and technical assistance, is provided by CIESIN, with funding from the National Aeronautics and Space Administration under Contract NAS5-32632 for the Development and Operation of the Socioeconomic Data and Applications Center (SEDAC).

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