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2. The RAINS 7.2 Model of Air Pollution

General Overview

The 'Regional Air Pollution INformation and Simulation' (RAINS)-model has been developed by IIASA as a tool for the integrated assessment of alternative strategies to reduce acid deposition in Europe and Asia (Alcamo et al., 1990).

The RAINS 7.2 model describes the pathways of emissions of sulfur dioxide, nitrogen oxides and ammonia and explores their impacts on acidification and eutrophication (Amann et al. 1996). The structure of the model is presented in Figure 1. The various sub-models are organized into three modules, i.e.,

• the emission-cost module (EMCO), with parts for nitrogen oxides, sulfur dioxide and ammonia,
• the acid deposition and ecosystems impact module (DEP), and
• the optimization module (OPT.)

Figure 1: The structure of the RAINS model

This version of the RAINS model is the outcome of a multi-year development process. Starting with version 1 in 1984 (pilot version for SO2 emissions developed for mainframe computers under UNIX), the model was continually further developed to incorporate additional pollutants (such as NOx and NH3), new features (e.g., the optimization module), innovative approaches for impact assessment (critical loads), geographical regions (Asia) and to keep track with the rapid progress in computer technology (PC-based operating systems, MS-DOS, Windows 3.11, etc.).

Earlier versions of the RAINS model were used for the scenario calculations of the Second Sulfur Protocol (Version 6) and focussed on South-East Asia (Version 7.1).

The main new characteristics of Version 7.2 are

• WINDOWS95 based software,
• multi-pollutant system, i.e., full implementation of all modules for SO2, NOx and NH3, including the optimization,
• multi-effect oriented (taking into account acidification and eutrophication),
• a full on-line help system,
• latest data on energy pathways, control technologies and costs, atmospheric dispersion and critical loads, fully reviewed within the framework of the Convention on Long-range Transboundary Air Pollution.

The Emission-Cost (EMCO) Module

EMCO consists of three parts, estimating current and future levels of emissions of SO2, NOx and ammonia, respectively. These estimates are based on national statistics and projections of economic activity, energy consumption levels, fuel characteristics, agricultural activities, etc., taking into account implemented and possible emission control measures. The time horizon extends from the year 1990 up to the year 2010.

Furthermore, EMCO also estimates costs for the reduction of emissions. Options and costs for controlling emissions of the various substances are represented in the model by considering the characteristic technical and economic features of the most important emission reduction options and technologies (Amann, Cofala, Klaassen, 1994). Regional and national potentials for emission control and the associated costs are estimated on the basis of detailed data on the most commonly used emission control technologies. The cost evaluation is based on international operating experience of pollution control equipment (e.g., Schaerer, 1993) by extrapolating it to the country-specific situation of application. A free and competitive market for the exchange of emission control technology is assumed. Important country-specific factors with strong impact on abatement costs are the characteristic sulfur content of fuels, plant capacity utilization regimes, boiler sizes etc.

These cost estimates for specific fuel types, economic sectors and abatement technologies are combined with the projected pattern of energy consumption. The RAINS model provides also 'national cost curves' that rank the abatement measures according to their cost-effectiveness. These cost curves are used as input for the optimization module (OPT). Due to country-specific factors such as energy use patterns and technical infrastructure, national cost curves show significant differences among countries (Amann et al., 1994).

To develop an integrated abatement strategy the user can apply specific control policies (consistent sets of control measures) to selected emission sources in individual countries. The consequences of energy conservation measures and fuel substitution can be explored by analyzing alternative energy pathways, either by selecting one of several energy-use scenarios contained in the database or by creating a new one based on individual expectations of fuel use.

User Options

The RAINS-EMCO user options are discribed in the chapter "Exploring RAINS-EMCO"
The features of EMCO Ammonia are discribed in Features in EMCO Ammonia.

The structure of the user options is graphically shown in "RAINS 7.2 User Options".

The Deposition- and Critical loads-Assessment (DEP) module

The Deposition and Critical loads Assessment (DEP) module of RAINS has three major tasks:

• Scenario analysis (i.e., calculation of deposition fields, comparison of acid deposition with critical loads) and other interfacing functions to other RAINS modules (e.g., construction of target deposition files for the RAINS optimization module). These options are located in the Model sub menu.
• Display of data for the modelling domain. DEP can be used to handle any geographical data for the EMEP grid system, which are stored in the required format (i.e., dBase format (*.dbf)), (Map submenu); and
• Manipulation of geographical data. (Calculate and Combine submenus). Data can be modified using a variety of numerical operations, combining data from different sets. In addition you can edit every single grid value.

Within the overall context of RAINS, the main function of DEP is to provide estimates of acid deposition loads throughout the region under study as a function of changing emissions and to compare them with maps of environmental sensitivities (the 'critical loads' maps). The emission data used as input to DEP can be produced with the RAINS-EMCO module. Resulting deposition fields and critical loads achievement can be used to construct target deposition levels used as input into the RAINS-OPTIMIZATION module.

Acid deposition fields are estimated using transfer matrices for the various substances. These (linear) transfer matrices are constructed from results of the EMEP long-range atmospheric transport model, providing information of the dispersion of pollutants from the various sources (countries) to the 547 land-based grid cells of the modelling domain (using the 150*150 kmEMEP-grid (polar stereographic projection, Posch et al. 1995, Appendix A). EMEP calculates transfer matrices for the meteorological conditions of 11 years (1986-1996). For the purposes of integrated assessment of long-term strategies, a matrix representing the average conditions of these 11 years is incorporated into RAINS.

Critical loads represent the maximum long-term deposition levels which can be tolerated by sensitive ecosystems without damage (Nilsson & Grennfeldt, 1988). Based on submissions of the European countries, harmonized databases on critical loads and critical levels are compiled at the Coordination Center for Effects (CCE) at the National Institute for Public Health and Environmental Protection (RIVM) in the Netherlands (Downing et al., 1993).

User Options

The DEP user options are discribed in the chapter "Exploring RAINS-DEP".
The structure of the user options is graphically shown at "RAINS 7.2 User Options".

The Optimization (OPT) Module

The optimization module identifies, for given set of regional target depositions levels (which can be derived, e.g., from critical loads), the cost-minimal allocation of measures to reduce emissions. This optimization takes into account that

• some emission sources are linked via the atmosphere to sensitive receptors more strongly than others (i.e., as reflected in the atmospheric transer matrices), and that
• some sources are cheaper to control than others (as captured by the cost curves).

Input to OPT:

The optimization module requires the following input:

• A set of target deposition levels, specified for all or selected groups of grid cells. The optimization will identify the cost-minimal allocation of emission reductions over Europe, so that deposition will be at all selected grids at or below the targets. Such targets can be specified for the deposition of single pollutants, or for combination of pollutants causing acidification and/or eutrophication (multi-pollutant/multi-effect optimization). Deposition targets can be generated using the optimization module or can be retrieved from files created with the DEP module.
• The national cost curves for a selected set of energy and agricultural scenarios for a particular target year. The optimization can vary emissions between the upper and lower bounds specified in the cost curves (i.e., between the maximum and the minimum technically feasible reductions).
• If desired, these ranges can be further limited by the user to take into account so-called policy constraints, i.e., political considerations, such as already commited reductions, or the non-reversal of current legislation.
• Furthermore, the optimization (automatically) makes use of the appropriate atmospheric transport matrices for the relevant pollutants.

Running the Optimization

After the problem is completely defined, the user can start the optimization process. To find the optimal solution the model performs the following steps:

• Problem generation: Preparing a file with the problem specific information in a specific format.
• Starting the Linear Programming optimization software (the 'solver').
• Converting the optimization results back and displaying them in a Session window.

Optimization Output

The optimization module provides tables with the following information:

• Optimal emission reductions, total costs and marginal costs for each country,
• Deposition at each grid after the optimization, shadow prices for the active deposition constraints.

User Options

The OPT user options are discribed in the chapter "Exploring RAINS-OPT".
The structure of the user options is graphically shown at "RAINS 7.2 User Options".

Model Integration

The modules described above are combined together into a microcomputer-based policy analysis model, RAINS 7.2. The model allows users to estimate costs and impacts of alternative emission control strategies in current and future years on a regional, country or sub-country basis, follow these emissions through the acid deposition processes, and assess the potential of those emissions to impact critical ecosystems.

The user can select pre-defined energy pathways, modify them to explore impacts of alternative developments or enter his own assessment of future energy consumption.

To any of these strategies the user can apply emission control policies, addressing individual

• fuel types (e.g., high sulfur hard coal),
• economic sectors (e.g., the combustion of fuels in private households),
• emission control technologies (e.g., the use of advanced flue gas cleaning techniques),
• regions or countries out of the study domain,
• or any combinations of these criteria.

The RAINS model can be operated in the 'scenario analysis' mode, i.e., following the pathways of the emissions from their sources to their environmental impacts (energy and emission abatement strategy). In this case the model provides estimates of regional costs and environmental benefits of alternative emission control strategies.
Alternatively, the (linear programming) 'optimization mode' is available to identify cost-optimal allocations of emission reductions in order to achieve specified deposition targets. Here the DEP Module may be used to determine the target depositions and the EMCO Module to create the national cost curves as input for OPT (see Figure 1).

The RAINS Implementation for Europe

The RAINS 7.2 model has been implemented for Europe to explore future trends in emission development and impacts on sensitive ecosystems in this region. This implementation uses certain aggregation levels to store and process relevant data.

Data on energy consumption, emissions and control costs are stored on a regional level using aggregates of administrational units. Currently the model considers 41 countries and sea regions (Table 5b). Some of the countries are further divided into subnational regions (Table 5c).

References

Alcamo J., (1987): Uncertainty of Forcast Sulfur Deposittion Due to Uncertain Spatial Distribiution of SO2 Emissions. Preprints of the 16th NATO/CCMS International Technical Meeting on Air Pollution Modelling and its Application, Lindau, FRG.

Alcamo J., Shaw R., and Hordijk L. (eds), (1990): The RAINS Model of Acidification. Science and Strategies in Europe. Dordrecht, Netherlands: Kluwer Academic Publishers.

Amann M. (1993) Transboundary Air Pollution: the RAINS Model. Options, Winter'93, International Institute for Applied Systems Analysis, Laxenburg, Austria.

Amann M., Bertok I., Cofala J., Klimont Z., Schöpp W., 1993: Structure of the RAINS 7.0 energy- and emissions database. IIASA Working Paper WP-93-67

Amann M., Cofala J., and Klaasen G., 1994, The SO2 Conrol Cost Module in the RAINS 7.0 Model, Working Paper, International Institute for Applied Systems Analysis, Laxenburg, Austria.

Amann M., Bertok I., Cofala J., Gyrfas F., Heyes C., Klimont Z., Schöpp W., (1996) Cost-effective Control of Acidifiaction and Ground-Level Ozone, International Institute for Applied Systems Analysis, Laxenburg, Austria.

Barrett K., Seland Ø., (eds.) (1994-96) EMEP/MSC-W Reports Oslo, Sweden.

Bhatti, N., Streets, D., and Foell, W. (1992) Acid Rain in Asia. Environmental Management, Vol. 16, pp. 541-562.

Carmichael, G. (1992) Modeling of Acid Deposition in Asia, pp. 30-45, Proceedings of the Third Annual Workshop on Acid Rain in Asia. AIT, Bangkok, Thailand.

Carmichel, G. et al., (1993): Acid Rain and Emissions Reduction in Asia: An International Collaborative Project on Acid Rain in Asia. Proceedings of the International Conference on Environment and Climate Change in East Asia, Taipei, Taiwan, November 30 - December 3, 1993.

Foell W., Green C., Wilkinson K. (1991) Policy-oriented Grid-based Energy and Emissions Model for Asia. Proceedings of the Third Annual Conference on Acid Rain and Emissions in Asia, Asian Institute of Technology, Bangkok, Thailand.

Heffer, J., 1983: Branching Atmospheric Trajectory (BAT) Model. NOAA Technical Memorandum ERL ARL-121.

Downing R.J., Hettelingh J.P., de Smet P. (eds.) (1993) Calculation and Mapping of Critical Loads for Europe. Coordination Center for Effects, Coordination Center for Effects, RIVM Report No. 259101003, Bilthoven, The Netherlands

Hordijk, L. (1991) Use of the RAINS Models in Acid Rain Negotiations in Europe. Environ. Sci. Technol., Vol. 25, No. 4, p. 596-603.

Kuylenstierna, J.C.I. and Chadwick, M.J. (1989) The relative sensitivity of ecosystems in Europe to the indirect effects of acidic depositions. In: J. Kämäri, D.F. Brakke, A. Jenkins, S.A. Norton and R.F. Wright, eds. Regional Acidification Models, Springer Verlag, Berlin.

Nilsson J., Grennfeldt P. (1988) Critical Loads for Sulphur and Nitrogen. Miljorapport 1988:16, Nordic Council of Ministers, Copenhagen, Denmark.

Posch M., de Smet P.A.M., Hettelingh J.-P., Downing R.J. (eds.) (1995), Calculation and Mapping of critical Treshold in Europe, RIVM Report No. 259101004, Bilthoven, Netherlands

Schaerer, B., (1993): Technologies to Clean Up Power Plants. Experience with a DM 21 Billion FGD and SCR Retrofit Programme in Germany, Part 1 and 2. Staub - Reinhaltung der Luft 53 (1993) 87-92, 157-160.

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