A Scenario Model for the Generation of Waste 4. Coupling of waste to economic activities in ADAMAs mentioned in Chapter 2 the amount of waste from individual sources and fractions is coupled to activity variables in ADAM. In general waste from a given source is linked to the economic activity pertaining to the source, i.e.,
For a number of fractions, however, the general coupling is not followed. For instance, the amount of some waste fractions from building/construction is linked to the activity within the building and construction branch independent of source of the waste. The point is that activity within the building and construction branch is a better indicator for the waste generated than any other production or consumption variables in ADAM. For other fractions, for instance garden waste, the amount of waste is not linked to any economic activity at all. For such fractions, the amount of waste is either assumed to be constant or has to be forecasted exogenously. All ISAG fractions are included in the model. For each fraction, the present chapter gives the coupling to explanatory variables and the development in waste coefficients, i.e. the amount of waste divided by the value of the explanatory variable (waste coefficient = amount of waste/explanatory variable), which is the relevant economic activity expressed in constant prices. When interpreting the coefficients, it should be noted that the absolute size of the coefficients is not informative. The size mainly depends on the specificity of the economic activity used to explain a given amount of waste. If the explanatory variable (the divisor in the coefficient) is a small and very specific economic activity, the coefficient will be large. In contrast, if the explanatory variable is a very large aggregated economic activity such as the total private consumption, the coefficient will be small. The important feature of the coefficient is whether it is constant or changes over time. If both the amount of waste and the explanatory variable increase 10% the coefficient is constant, and the explanatory variable is considered to account for development in the amount of waste. If the amount of waste increases 10% and the explanatory variable only increases 5%, the coefficient increases about 5%. Assuming constant coefficients, the model thus accounts for about half of the increase in the amount of waste, and additional explanations are needed. Ideally therefore, the waste coefficients calculated for the years 1994 to 1996 should be constant. As will be seen, however, the coefficients vary markedly from year to year. Assuming constant coefficients, economic development thus accounts for only part of the past development, and additional explanations like changed waste collection schemes, changed statistical coverage or changed waste generation need to be identified. Although waste coefficients do not remain constant and changes are not fully accounted for, the coefficients are assumed to be constant at the 1996 level in the baseline scenarios. The model is a scenario-model accounting for changes in economic activities. For forecasts of the amount of waste generated, however, changes in the waste coefficients may be equally important. Chapter 4 concludes with a comparison of actual and model calculated amounts of waste for the years 1994-96. 4.1 Oil and chemical wasteThis fraction covers waste oil and chemicals collected for special treatment. About half of the waste is processed by the waste processing firm "Kommune Kemi A/S". Of the waste treated by "Kommune Kemi A/S" the major part is various chemicals. Most of the waste oil is treated by other firms and reprocessed for use as fuel for heating. Oil and chemical waste is collected from the sources "Households", "Trade and Services", "Manufacturing etc.", and "Building/construction". Household sources mainly generate paint and cleaning materials. These are expected to develop in parallel with the consumption of other non-durable goods. Trade and services mainly generate waste oil. This is coupled to the private consumption of petrol and oil for vehicles, which is used as an indicator for waste oil from private cars collected at garages. Manufacturing etc. accounts for the main share of oil and chemical waste, and the amount of waste has changed considerably over the years. The major part of the waste is cleaners and chemical waste, which is coupled to industrial production in general. Waste from building/construction etc. consists of various chemicals and paint, and is expected to follow the activity within the building/construction branch. As shown in the table below, the amount of waste has varied considerably over the years. About 32,000 tonnes of the waste in 1995 is accounted for by contaminated soil from a single closed factory. The different explanatory variables in ADAM are shown in Appendix 1.
1) See list of variables in Appendix 1.4.2 Various combustiblesAs mentioned in Sections 3.1 and 3.2, the fractions "Various combustibles" and "Various non-combustibles" from households contain large, heterogeneous amounts of waste that can be subdivided into categories and forecasted separately. From ISAG, the amount of waste is divided into domestic, bulky and other waste, and these categories are disaggregated further according to the analyses mentioned in Sections 3.1 and 3.2. Fraction 19: Various Combustibles Combustible domestic waste, including domestic waste in the fraction "Various non-combustibles" consists of waste bags collected from households (see Section 3.1) and is treated together. Based on the specific analyses of the content of waste bags given in Section 3.1, the contents are divided into 20 categories. Aggregated and linked to variables in ADAM, the following table shows the categories and the explanatory variables used in the model:
Food and packaging thus accounts for about 2/3 of the total. The amount of food waste is exogenous and assumed to be constant. Expenditure for food is assumed to increase mainly due to quality and not quantity, and hence the amount of waste is relatively constant. The amount of packaging is expected to increase with the food consumption, however, and hence is related to the consumption of foodstuffs. The amount of waste paper and other non-durable goods is related to the consumption of non-durable goods, while the amount of waste durable goods is related to the consumption of durable goods. Waste durable goods could be related to the purchase of goods years earlier and represent a scrapping curve for durable goods. However, the model links the present purchase to the present waste from durable goods, the assumption being that new durable goods replace old goods, which are then scrapped. Garden waste is not related to any economic activity and is forecasted exogenously. Bulky waste is mainly collected at manned container stations. Aggregating the categories in Section 3.2, the table below shows the percentage of bulky combustible waste linked to different consumption categories in ADAM. The main type of waste is furniture and electrical devices, and their packaging, which is coupled to present purchases of durable goods. An alternative would be to relate this waste to past purchases of durable goods, trying to model the scrapping of old goods. However, we do not know the average age of the scrapped goods, and a major part will be replaced by new purchases. Waste from construction and demolition is related to do-it-yourself building activities, and is coupled to consumption of durable goods. Finally, waste textiles, footwear and other non-durable goods is coupled to consumption of non-durable goods, while waste tyres and rubber is coupled to consumption of petrol and oil for vehicles (as an indicator for the mileage driven in private cars).
Combustible waste from trade and services is coupled to production within the private and public service sectors. As is seen from the table for fraction 19, the coefficient increased considerably in 1995 and slightly in 1996. Thus assuming constant waste coefficients, economic development explains about 50% of the increase in 1996, but only a minor part of the increase in 1995. Waste from manufacturing is coupled to production within industry. This is a rather rough coupling, however, as detailed analyses of which industries generate the waste are not available. The coefficient varies in parallel with the change in the amount of waste, i.e. the economic activity only explains a minor part of the development. Waste from building/construction increased considerably and is coupled to building and construction activity. In both 1995 and 1996 the economic activity explained about ¼ of the change in the amount of waste. In general part of the increase in the amount of various combustible waste that is not explicable by economic development is due to increased waste separation at source. At the source level, agents have an incentive to reduce the amount of non-combustible waste as the levy on deliveries to landfills is considerably greater than that on deliveries to waste incineration plants. As is seen in the next section, the amount of non-combustible waste has decreased with part of this decrease ending up as various combustible waste. 4.3 Various non-combustiblesAs mentioned earlier "Various non-combustibles" is a heterogeneous fraction, and waste from households is divided into domestic waste and bulky waste. Domestic waste from households is waste bags and is allocated to the fraction "Various combustibles" from households, i.e. with respect to "Various non-combustibles", domestic waste from households is considered to be zero. Bulky waste from households is coupled to the consumption of durable goods, and waste from trade and services etc. is coupled to production within the private and public service sectors. As is apparent from the table, the amount of waste has decreased.
As production has increased, the waste coefficient has decreased considerably, i.e., the development over the years 1994 to 1996 mainly reflects changes in the waste collection, which are not explained by the economic activity. One reason for this is increased separation at source and that part of the waste is being collected as "Various combustibles" and reusable fractions. The magnitude of this is unknown, however, and for a scenario model it is still reasonable to project the amount of waste in parallel with the economic development. Waste from manufacturing is linked to industrial production in general. The coupling is only rough, however, and the waste coefficient has decreased over the period. The amount of building/construction waste is coupled to activity within the building and construction industry. As for the other sources, the waste coefficient has decreased over the period. 4.4 Paper and cardboardThis fraction consists of clean paper and cardboard, including newspapers and magazines collected separately with the purpose of recycling. The fraction is collected from households, trade and services, manufacturing etc. and building/construction. The amount of waste from latter source is negligible, however, and has been allocated to other sources. Waste of this fraction from households mainly consists of newspapers and magazines, and is coupled to the consumption of non-durable goods. While the amount has varied somewhat over the three years, the coefficient was almost identical in 1994 and 1996, i.e. a substantial part of the change is explained by consumption. With regard to trade and services and manufacturing, the amount of waste increased markedly in 1995. This mainly reflects enlargement of the collection scheme and increased separation at source. Of the amount collected from trade and services, about half consists of corrugated paper while the other half is mixed paper and cardboard. The total is coupled to production within trade and the financial sectors. As is apparent from the table, both the amount and the coefficient decreased slightly in 1996. The amount generated by manufacturing is coupled to production within the branch other manufacturing industries, which includes the paper, printing and publishing industry. Both the amount and coefficient increased slightly in 1996.
4.5 Bottles and glassThis fraction comprises bottles and glass collected for reprocessing/recycling, excluding beer and soft drink bottles reused as part of the distribution system. The total amount of bottles and glass collected decreased about 10% from 1994 to 1995. This is attributable to a procedural change, where one waste management firm switched to reporting the source of the waste as secondary sources (which is not included in the table below) instead of manufacturing, i.e., the change is mainly a statistical change.
The generation of bottle and glass waste from households is coupled to the consumption of beverages and tobacco, while that from trade and services is coupled to production within other service industries, including hotels and restaurants. As is apparent from the table, the coefficients for the individual sources vary considerably. If households and trade and services are aggregated, however, the resultant coefficient is relatively constant, i.e. the data reflects problems with correct definition of sources, while the total seems reasonable. 4.6 PlasticsThis fraction mainly encompasses plastic from packaging and agricultural use collected for reprocessing, and largely derives from manufacturing, inclusive agriculture. The small amounts from households and trade and services are coupled to the consumption of durable goods and production by the wholesale and retail trade, respectively. The large amount from manufacturing is coupled to production by agriculture and industry in general. At present, agriculture only contributes about 800 tonnes, although, the potential is about 6,000 to 8,000 tonnes.
4.7 Food waste and other organic wasteThis fraction is organic waste collected with the purpose of reprocessing for animal food or composting and biogas production.
Waste of this fraction from households is mainly source-separated organic waste for composting and biogas production. The amount is coupled to the consumption of foodstuffs and has increased somewhat due to expansion of household waste separation schemes. Waste from trade and services and manufacturing etc. increased considerably in 1995 (two and four fold, respectively), mainly due to improved statistics, i.e. firms reporting for the first time in 1995. Waste from these sources is mainly used for biogas production and the production of animal food. Waste from trade and services is coupled to the production by other service industries, including hotels and restaurants, and by the public sector, including hospitals and other large kitchens. Waste from manufacturing etc. is coupled to production within the foodstuff industry. 4.8 Garden wasteThis fraction comprises branches, leaves, grass and other organic waste collected for composting and wood chips.
The amount of this waste is not linked to any economic activity, and the development has to be forecasted exogenously. Assuming unchanged gardening behaviour and collection schemes, including unchanged composting in private gardens, the amount should remain relatively constant in a baseline scenario, i.e. the production of garden waste is expected to be relatively constant. The amount of garden waste collected may increase considerably, however, as collection schemes and use of present collection schemes are expanded. The major part of garden waste comes from households, and the large increase, especially in 1996, mainly reflects expansion of municipal collection schemes and increased usage of these. 4.9 Iron and metalIron and metal scrap collected for reprocessing includes fraction 56 (iron and metal reprocessed by Danish firms) and fraction 93 (net export of iron and metal scrap from scrap dealers). Aggregating the two fractions, the total amount of iron and metal scrap collected in Denmark is about 900,000 tonnes per year. The main metal fractions are iron, aluminium, lead and copper, and each derives from numerous sources. Generation of scrap iron and metal from households is coupled to consumption of durable goods, while scrap from trade and services is linked to production by transport and other service industries. The amount of scrap iron and metal from manufacturing etc. is coupled to production by suppliers of building materials, the metals industry and other production industries, while that from building/construction is coupled to the building and construction industry.
4.10 Car tyresThis fraction covers tyres from private cars, vans and motor cycles collected for reprocessing. At present, tyres from lorries are burned and not reprocessed and hence are not included in the table below. As regards trade and services, the amount of waste has decreased considerably over the period. This is mainly a statistical problem, however, as the recycling branch for tyres comprises many small companies and the statistical coverage in ISAG has decreased over the years. According to notification by the Environmental Fund of the Tyre Branch, about 12,000 tonnes of tyres were collected for reprocessing in 1996. Adding about 4,000 tonnes to the amount recorded in ISAG for trade and services in 1996, and thereby keeping the total more or less constant would provide a more realistic picture of the development.
As a general indicator of tyre usage the amount of tyres collected is coupled to private consumption of petrol and oil for vehicles. 4.11 Concrete, Tile/bricks, Other building/construction waste, Asphalt, Wood and Earth and stoneCommon for these fractions is that the major part of the waste derives from building/construction, demolition etc. Irrespective of the actual source from which the waste is collected, the amount of waste is coupled to activity within the building and construction industry. The total amount of waste of each of the fractions and the total waste coefficients is shown in the following table.
The fractions are shown separately apportioned by source in the tables below. The major increase seen for concrete reflects not only increased building activity but mainly enlarged and improved recycling activity, and the addition of about 210,000 tonnes in 1996 from firms reporting for the first time. If the 210,000 tonnes are subtracted from the 1996 figure, the coefficient would have been about 14.0 (and not 17.9), i.e. the waste coefficient increased by 16% from 1994 to 1996, which reflects enlarged/improved recycling schemes. The increase from 14.0 to 17.9 is due to firms reporting for the first time. The increase seen for tile/bricks mirrors increased building activity and enlarged recycling schemes. About 1/3 of the increase is attributable to increased building activity and the remainder to enlarged recycling schemes. The coefficient increased 27% from 1994 to 1996. Other building/construction waste increased markedly in 1995 and decreased slightly in 1996. From 1994 to 1996 the coefficient increased by 10%. The amount of waste asphalt largely follows building and construction activity, with a slight decrease in the waste coefficient. Wood is a minor fraction and increased considerably in 1996. The amount of waste earth and stone (excluding clean soil) from building and construction increased slightly less than the building and construction activity.
4.12 Other reusable wasteThis fraction comprises heterogeneous waste for later separation and reprocessing/recycling.
4.13 Hospital wasteThis fraction covers infectious, biodegradable and low-grade radioactive waste, which either requires special treatment or is incinerated. The amount increased somewhat from 1994 to 1996. Generation of this waste fraction not linked to any economic activity, and the amount has to be forecasted exogenously.
4.14 Sieving wasteThis fraction is waste from composting and biogas production, and will increase as these processing facilities are enlarged. For the present model, this is exogenous.
4.15 Sludge and sewageWaste from waste water treatment includes fractions 68 to 71 (sludge) and fraction 92 (sewage) and is summarised in the following table. Waste of these fractions from manufacturing derives from industrial waste water treatment plants, mainly within the food producing industries. Development in the amount of this waste is thus coupled to production in the food industry. As is apparent from the table, both the amount of waste and the waste coefficient increased considerably from 1994 to 1996. Sewage from municipal sewage treatment plants and other sources is exogenous in the present model. As the upgrading of municipal sewage treatment plants under the Action Plan on the Aquatic Environment has now been completed, sewage from municipal sewage treatment plants is almost constant.
Sand and screenings comprise another part of waste from waste water treatment. In the case of manufacturing, the fraction is also coupled to production in the food industry. In contrast to the sewage fractions, the waste coefficient for sand and screenings is relatively constant. Waste from other sources is exogenous in the present model.
4.16 Slag, flyash, flue gas purification product and residuals from coal-fired power plantsSlag, flyash and flue gas purification products are coupled to coal consumption and depend on the quality of the coal used. The amount of this waste is coupled to industrial coal consumption in TJ in the case of manufacturing etc., while the amount from other sources is minor and exogenous in the model. Generation of residuals from coal-fired power plants is coupled to coal consumption by coal-fired power plants. As is apparent from the tables, the amount of waste varied considerably over the period, however, for the large amount "residuals from coal-fired power plants", the coefficient (waste in tonnes/coal consumption in TJ) is almost constant. For baseline forecasts, coal consumption by industry and power plants is predicted in the Governments energy action plans, at present Energy21.
4.17 Dusty asbestosAsbestos materials that may emit asbestos dust are collected for special depositing. This waste derives mainly from the building and construction industry, where asbestos materials have been used as building materials. The total amount of waste is thus coupled to building and construction activity, and the coefficient is fairly stable from 1994 to 1996. For long-term forecasts, however the amount may be expected to decrease as use of asbestos in new building materials is prohibited.
4.18 Beet earthThis fraction consists of earth from the cleaning of sugar beet in the production of sugar. As is apperent from the table, the amount of earth varied considerably between the years. This reflects varying harvesting conditions, with the amount of earth being greatest in wet years. As sugar production in Europe is regulated by quotas, and as the Danish quota is not expect change, Danish sugar production is expected to remain constant. However, studies show that it should be possible to reduce the present amount to about 150,000 tonnes using cleaner technology. The amount of beet earth is therefore expected to decrease in baseline scenarios.
4.19 Actual and model calculated amounts of waste, 1994-96This section compares actual data for the total amount of waste from the individual sources with model calculations assuming constant 1996 waste coefficients. Moreover, development in the amount of waste is compared with a simple model, where the total is calculated assuming a constant waste coefficient for the total amount of waste from the source, i.e. the total amount of waste from households is assumed to follow total private consumption, that for trade and services follows total production by the trade and service sector, and so forth for the other sources. For households, the development is compared excluding fraction 54, "Garden waste". The model assumes that this fraction is exogenous, and therefore implicitly assumes the amount to be constant, whereas it actually increased by 138,300 tonnes over the period 1994 to 1996. Comparing the corrected and the calculated development, the model largely describes the increase from 1995 to 1996. However, the decrease from 1994 to 1995 is not captured by the model. Comparison of the present and the simple model revealed only minor differences. This implies that for the period 1994 to 1996, changes in the composition of the private consumption were unimportant for waste generation.
In the case of trade and services, "Garden waste" is also excluded from the comparison. This is not very important, though, as the amount is minor and relatively constant. Comparing the present model and the corrected data, the increase from 1994 to 1995 was not captured by the model. About half of the increase was within the fraction "Paper and cardboard" and was partly attributable to expansion of the collection scheme. Another large increase occurred within the fraction "Various combustibles", which the model does not capture. Comparison of the present model and the simple model revealed only minor difference.
As regards manufacturing etc., the corrected data excludes beet earth, and a total of 219,000 tonnes has been added to the 1994 ISAG figure, representing firms that should have reported in 1994 but reported for the first time in 1995. Both the present model and the simple model calculates a larger increase than the corrected data show, and neither of the models are able to capture the large figure for 1995. (A major increase in 1995 and decrease in 1996 is found for iron and metal incl. net export of scrap.)
1 219,000 tonnes added to the figure in 1994 representing firms reporting for the first time in 1995.In building/construction 240,000 tonnes were added to the figures in 1994 and 1995 representing firms reporting to ISAG for the first time in 1996. Comparing the corrected data and the model calculations, the models capture the major part of the increase in the total amount of waste, with the differences between the present model and the simple model being minor.
1 240,000 tonnes are added to the figures in 1994 and 1995 representing firms reporting for the first time in 1996.With respect to waste water treatment plants, the major part of the waste derives from municipal sewage treatment plants, and these are exogenous in the present model and assumed to be constant.
As regards other sources, the major part of the waste is residuals from coal-fired power plants, which is coupled to coal consumption by the power plants. As the waste coefficient for this waste is relatively constant, while the coal consumption varies substantially, the model captures the major part of the development.
To conclude, at the aggregated level only part of the recorded development is captured by the model. However, of the developments not captured by the model a considerable part is attributable to specific changes within a few fractions. Comparing the present model and the simple model with respect to capturing the development from 1994 to 1996, the two models perform fairly identically. Thus with respect to aggregated waste generation, the composition of production and private consumption has not changed significantly. The major advantage of the present model over the simple model is that it is able to capture the effects of changes in the composition of production and consumption.
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