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Input/Output analysis - Shortcuts to life cycle data?

7. NAMEAs and Physical IO-Tables for Denmark

Ole Gravgård Pedersen, Statistics Denmark

In relation to physical flows of resources, residuals, and products two types of accounting frameworks can be distinguished: National accounting matrices including environmental accounts (NAMEA) and physical input-output tables (PIOT). The two frameworks are connected, but differ with respect to detail and extent.

7.1 NAMEA

A NAMEA is a so-called satellite account related to the traditional national accounts. This means that the starting point is a matrix representation of parts of the national accounts. In the Danish NAMEA this starting point is the Danish monetary IO-tables, which show, among other things, the value of products supplied from one industry to another as well as the value of products supplied from industries to final demand (i.e. private and government consumption, gross fixed capital formation, exports, etc.). The classification used in the Danish IO-tables includes 130 industries.

The main idea in the NAMEA is to supplement the economic information (NAM) with accounts on resource and environment related aspects (EA), which follows the same classifications and definitions as used in the national accounts. This way, it is possible to analyse the information on resources and environment in relation to the economic information.

The Danish environmental accounts included in the NAMEA deals with the use of 40 types of energy (in various physical units as well as DKK), the reserves of natural gas and oil in the North Sea (physical units), emissions to air of eight types of substances, and transboundary flows of these substances to and from Denmark.

NAMEAs including these accounts are published on a yearly basis from Statistics Denmark. Under development are accounts for water extraction, water use, the value of reserves of natural gas and oil in the North Sea as well as accounts for environment related taxes and subsidies.

The structure of the basic flow accounts in the Danish NAMEA is shown in Figure 7-1. The figure illustrates how the same classifications are used throughout the different accounts and how the IO-table has a central role to play in the system.

Figure 7.1 Look here!
Some basic Danish NAMEA matrices. 

Table 7.1, Table 7.2 and Table 7.3 give examples of the actual information included in the system in relation to energy, water and emissions to air.

Table 7.1 shows the industries' and households' use of energy. As mentioned, the system operates with 130 industries at the most detailed level. For the purpose of presentation here, these have been aggregated to 8 main groups of industries. Likewise, the 40 different types of energy have been aggregated to three types in the table. The energy use shown is actual energy use. This means that there is some redundancy double counting in the sense that both primary energy (coal, natural gas, fuel oil, etc.) and converted energy (electricity, district heating, etc.) are included. The actual energy use is a good starting point for the estimation of emissions related to the energy use (included inTable 7.3 below). However, in relation to some other analysis of energy use it is more appropriate to look at the net energy use in which the converted energy has been substituted by primary energy used for the conversion. For those kinds of analysis matrices of net energy use are also included in the NAMEA system.

Table 7.1
Use of energy 1998. All figures in Petajoule.

Note: Primary Energy includes crude oil, natural Gas, coal etc. Converted energy includes electricity and district heating.

Table 7-2 shows the use of water by main groups of industries and by households. It is seen from the table that various kinds of water has been included: Ground water, surface water, seawater, and tap water. This table too reflects a double counting in the sense that both ground water used for production of tap water and produced tap water have been included. This double counting might look confusing at first sight. However - as in the case of energy - the double counting serves a purpose in the most the detailed NAMEA accounts because it gives a picture of the conversion of ground water into tap water.

Surface water has been included in the NAMEA in order to give a full picture of the economy's dependence of water with special reference to international comparisons.

Table 7.2
Use of water 1994. All figures in Millions m³.

Table 7.3 shows the emissions of CO₂, SO₂ and NO_x to air. Included in the numbers are both energy related emissions and non-energy related emissions. In the Danish NAMEA data is also included when it comes to emissions of NH₃, NMVOC, CO, CH₄, and N₂O.

Table  7.3
Emissions to air 1998. All figures in 1000 tonnes

The accounts for air emissions associated with the combustion of energy are based on calculations of technical coefficients expressing the content of pollutant per unit of energy consumption. The numbers for energy consumption are taken from the energy part of the system.

For cars data are furthermore calculated on the basis of a breakdown of the energy use into 187 different kinds of cars in order to make the calculations for each industry and for households more precise. Besides the estimations of emissions from technical coefficients, numbers for measured emissions from power plants are included in the system. Most of the information on emissions – including information on non-energy related emissions – is obtained from the CORINAIR database managed by the National Environmental Research Institute in Denmark.

7.2 Input-output modelling

The consistent use of the same classifications and definitions in the various parts of the Danish NAMEA system makes it easy to analyse the relationship between economic activity and resource use on one side and emission on the other side.

Table 7-4 shows results of an input-output calculation of the direct and indirect CO₂-emissions linked to the categories of final demand. The effects of various groups of private consumption are included. As an example, it is seen that transport and communication created direct emissions at 4.6 mill. tonnes. These are the emissions related to e.g. use of petrol for private cars. The Danish direct and indirect emissions were 7 mill. tonnes. This number includes the 4.6 mill. tonnes of direct emissions but also all indirect emissions from Danish industries necessary to produce the output for the consumption group transport and communication.

As an example, emissions from busses and trains used for public transportation falls under the indirect emissions. So does emissions from Danish industries which indirectly delivers goods to the public transportation companies, e.g. electricity for heating in administration buildings, paper for brochures, machinery for repairs and so on.

The global direct and indirect emissions at 8.2 mill. tonnes from Danish private consumption of transportation and communication include not only the emissions in Denmark but also all indirect emissions created in other countries as a result of the production of products exported to Denmark.

The NAMEA accounts as well as results of input-output calculations of both energy use and emissions to air are published yearly by Statistics Denmark in Danish in Input-output tabeller og analyser – import, beskæftigelse og miljø.

7.3 Physical input-output tables

The NAMEAs are characterised by representing information in mixed units. For the economic information DKK is used as unit, while for resource and environment information physical units (m³, tonnes, PJ, etc.) are used. Furthermore, the NAMEAs can be said to focus mainly on the input to and output from the economy as far as the physical flows are concerned.

In contrast to this, complete physical IO-tables (PIOTs) are made up in physical units only, and they describe the flows within the economy as well as input to and output from the economy.

For the flows within the economy PIOTs corresponds exactly to the monetary IO-tables except for the fact that all flows are in tonnes and not in DKK. This means that the PIOT shows how many tonnes of materials that are supplied from one industry to another and from one industry to a category of final demand.

Table 7.4 Look here!
CO₂-emissions by final demand categories 1992.

So far, PIOTs exist for Germany and Denmark. Both are for the reference year 1990.

For Denmark PIOTs exist for all products taken together and for various groups of products individually: Animal and vegetable products; stone, gravel and building materials; energy; wood and paper; metals and machinery; and chemical products and fertilisers. Also PIOTs for packaging materials and the nitrogen content of products have been constructed.

On the basis of the PIOTs an overall material balance for the Danish economy can be extracted. This balance is shown in figure 5. The supply side includes mainly imports and Danish resource extraction, while the largest components on the use side are accumulation of materials in the economy and residuals from the economy ending up in the environment. The figure shows that the physical trade balance for Denmark is negative in the sense that imported products weighs more than the exports.

The total supply at 123.6 mill tonnes of materials entering the economy equals the total mass accumulated and leaving the economy. Thus, there is a material balance for the economy.

Table 7.5
General material balance for the Danish economy. All commodities 1990.

Note: Only water added to products is included. No industry-internal recycling is included.

As an example of detailed information for industries included in the PIOTs table 6 shows the material balance for agriculture. First of all, it is seen that the total input at 26 mill tonnes into agriculture equals the total output from agriculture.

The table shows how much that was delivered to agriculture from the various Danish industries and from abroad. Furthermore, the amount of materials/biomass extracted from nature by agriculture is represented on the input side. On the output side we find supplies from agriculture to other industries, households and exports. Besides these outputs of products there is an output of residuals in the form of carbon (included in CO₂ emissions), sulphur (included in SO₂ emissions), other energy relates residuals, and other residuals.

The physical IO-tables for Denmark are described in Ole Gravgård Pedersen: Physical input-output tables for Denmark – Products and materials 1990, Air emissions 1992. Statistics Denmark, 1999.

Table 7.6
Physical input and output in relation to agriculture, etc. 1990 - All materials. All figures in 1000 ton.

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