Economy
& Energy
No 28 - October - November 2001 ISSN 1518-2932
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28 emPortuguês
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Economy
& Energy |
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28 em Português |
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Energy and Emissions Matrix: Agriculture and Husbandry Sector Capital/Product Ratio in Brazil and in OECD Countries
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Energy and Emission Matrix: 5. Use of results in the Agriculture and Husbandry SectorNote
of the Editor: Our methodology uses the equivalent energy evaluation in each sector starting from the evolution of the energy/product coefficient. The distribution of the equivalent energy consumption among the different energy sources of final energy permits the projection of the final energy consumption (using the coefficients that reflect the relative efficiency of the energy sources) for each sector. The use of emission coefficients relative to the different sources of final energy and the hypothesis of primary sources distribution and of efficiency in the transformation process (mainly electricity generation) permits to obtain the emission coefficients by sector. a) Sectorial Equivalent Energy/ Product RatioIn Figure 15 the Sectorial Equivalent Energy/Product ratio of the main sectors that consume energy are given. The values are presented in kilo petroleum equivalent kEP. The reason why we use the same unit normally used to express the equivalent energy is because we don’t want to introduce a new unit as previously explained. In this case it should be understood that 1kEP = 10.8 Mcal approximately corresponds to 1.167 m3 of dry natural gas (BEN/MME equivalence) at a temperature of 20 0C and a pressure of 1 atmosphere. In Figure 15 we also present the values corresponding to the use of equivalent energy extrapolated for the sector. The projection is based on a value estimated for 2020 and is made through a second degree curve fitted to the historical behavior and the projected value is coupled to the last known data by a Poisson integrated curve. The time constant of the Poisson curve can be chosen by the scenario builder. It is possible to interfere in the intermediate years, as it will be shown in the annex to the present work. The convenience of working with constant prices becomes evident in Figures 16 and 17 where values at current prices and at constant prices are compared.[1].
The equivalent energy/product ratio of the agriculture and husbandry sector is notably “well behaved” at constant prices. This value, in spite of the deep changes that occurred in the technology and in the participation of energy sources, is practically constant along the 30 years of the series. The value at current prices does not show the same regularity in its behavior but, as we have already pointed out before, it is fundamentally due to the prices variation of the agriculture and husbandry products as compared to the remaining products that compose the GDP. Since the participation of the Agriculture and Husbandry Sector is supposed to be declining at current prices (based on the most advanced countries and Brazilian states) and the equivalent energy consumption is increasing in the sector, .the equivalent energy/product ratio is ascending at current prices. b) Projection of the Equivalent and Final Energy for the Agriculture and Husbandry SectorFrom the participation of sectors (at constant prices) in the GDP and the GDP value supplied (also at constant prices) by the macroeconomic module [M1] it is possible to obtain the product of the sector (% participation x GDP in US$ 94) projected for each year. Figure 18 shows the
values of product evolution and of equivalent energy at constant prices.
The historical values reflect an elevation of the equivalent energy/product
curve plateau, shown in Figure 16, from 1986 on. c) Energy Sources Participation in Equivalent EnergyThe participation of energy sources in Agriculture, as already mentioned, was very significant in the last 30 years. In Figure 19 we show the historical evolution of this participation, expressed in equivalent energy. For projections purposes, one should distinguish those energy sources used [M2] for heat generation (firewood, fuel oil, LPG and eventually natural gas) from those used for driving force (fundamentally diesel). Electricity is used for: generation of stationary driving force (where it tends to predominate), heat generation (depending on price and availability of clean energy) and illumination, where it is unbeatable, whenever it is available. The use equivalent energy evaluation data in other countries for the agriculture and husbandry sector can help in the task of projecting the energy distribution in the sector for 2020. Data relative to developed countries can be specially useful. However, it should be taken into account the size of the countries used for comparison since that fact conditions the production methods. We take from the energy balances the base data used for obtaining the final energy participation. The year chosen was 1996, for which we have non-aggregated data for the OECD countries. Economic data for macro-sectors are available in other sources, particularly in the annual reports of the World Bank.
The comparison of energy data of different countries published by OECD and converted to equivalent energy presents some problems in what concerns our choice for the future. The criteria for allocation to the Agriculture and Husbandry Sector should be substantially different. In Figure 20 the participation of the different energy sources for 1995 clearly show discrepancies in the criteria for electricity allocation whose use is zero in countries like the USA and Belgium. For petroleum products there are also substantial differences concerning participation which must indicate substantially different allocation criteria. In Figure 21 it is shown the extrapolation of the participation considered for the sector in this first initial “run”, where electricity reaches about 30% at the end of the period. It is assumed a reduction in biomass application and an increase of petroleum products, dominantly diesel for the next years. In order to evaluate the trend, it was used a list (shown in Table 7) supplied for each sector by the program utilized where are presented: a) the graphic; b) the historical participation in selected years and c) the minimum, maximum and average participation of each energy source, grouped by primary and origin energy (except electricity).
Table 7: Indicative and aggregated values for projection
d) Participation of Energy Sources in Final EnergyThe values in equivalent energy were converted to final energy using equivalence coefficients, based on efficiency values of the expected uses for the future, from the Useful Energy Balance of the Ministry of Mines and Energy of 1993. Based on these equivalence coefficients, the final energy consumption by energy source in the Agriculture and Husbandry Sector were obtained and they are shown in Figure 22 and Table 8.
Table 8: Projected values of Final Energy for the Agriculture and Husbandry Sector (10^6 toe)
e) Emissions Corresponding to Consumption in Final EnergyOnce the consumption projection in final energy is obtained, the final emissions can be obtained from the emission coefficients for the Sector. Emissions between 1990 and 1999 have been preliminarily evaluated by the team that is elaborating the National Inventory of Emissions (supplied by Branca Americano to the e&e staff). In the case of the Agriculture and Husbandry Sector, constant factors were considered along the period. The same factors were used for the years that followed and they are shown in Table 9 . It should be mentioned that only the emission coefficients for energy sources used in the Sector are shown and that in the present version we have not varied the set of energy sources to be used in the sector. In case of hypothesis that include other energy sources we should use default coefficients of the methodology adopted in Brazil (that of IPCC) for emissions evaluation.Table 9: Emission Coefficients in the Agriculture and Husbandry Sector CO2 Gg/10^3tEP
Source: MCT (Data used for emissions between 1990 and 1999) The application of these coefficients to the final energy data supplies the emission values indicated in the graphics for each gas considered as originating part of the greenhouse effect. The results for CO2, CO, CH4, NOx, N2O and NMVOCs (non-methane volatile organic compounds) are shown in Figures 23 to 28 and in Tables 8 to 14.
Table 10: Emissions of CO2 in Gg/year
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