Energy and Emissions Matrix
Energy Matrix 1970/2000
The National Energy Balance edited by the Ministry of Mines and Energy BEN/MME is the reference document for observing the production, transformation and consumption of energy in Brazil . The association of its data with economic and population variables supplied by IBGE permits to observe the evolution of energy parameters as a function of the latter.
Energy is found in nature under the raw or primary form resulting from its extraction from the soil (like petroleum, natural gas and mineral coal) or direct capture from nature (like firewood, solar and hydraulic energy). This primary energy is directly consumed or goes through transformation centers resulting in secondary energy. For example, refineries are transformation centers that convert petroleum to gasoline, diesel oil, fuel oil and other energy forms that are called secondary. Frequently one of these secondary energies are still transformed into other energy form such as a thermoelectric power plant that produces electricity from fuel oil. The energy, primary or secondary, is transported to the consuming center in a form called final energy.
Energy balances are structured so that energy is discriminated as:
where final energy includes the fraction of primary energy of direct use and the secondary one. Figure 5 illustrates the process. In Figure 5 it is also shown that final energy has different uses that involve a type of transformation that is not computed as such. Thereby the chemical energy of gasoline is used to generate driving energy, electrical energy is transformed into luminous energy in lamps or is used to heat water in a boiler (process heat). These uses have an efficiency that is different for each type of use and each energy source.
Energy in the form it is used is called useful energy. The MME has edited some Useful Energy Balances where are listed the efficiency of each energy source used in the sector. Since it is very difficult to consider all uses in all sectors we have adopted the equivalent energy concept which had already been applied to the Energy Matrix in 1990 in which some member of e&e present staff have participated.
In the case of the 1990 Matrix we have considered for each sector and for some use types an equivalent energy source. In the Industrial Sector heat was expressed in equivalent fuel oil, considering for each one of the other energy sources the quantity (in tep) necessary to replace 1 tep of fuel oil. For other uses (driving energy, illumination, electrochemical and others) the reference energy source was electricity. In the case of transport, diesel oil was used as the reference fuel.
In the present work we have used natural gas as reference fuel for all sectors. We took advantage of the circumstance that it can be widely used to generate heat in practically all sectors. In the case of the Transport Sector, the reference fuel could be gasoline. However, the Useful Energy Balance (BEU/MME 1992) considers this fuel as having the same efficiency of gasoline used in road transport. Natural gas was also used as reference and its equivalence has been established in most sectors relative to gasoline or even passing through the efficiency of the latter relative to diesel oil. In the case of electricity, the equivalence was established with the quantity of natural gas necessary to generate the corresponding electricity. The base values for establishing the equivalence are those from the relative efficiencies expected for the next years, indicated in the 1992 BEU.
The Measurement International System unit used to express energy in its various forms is Joule (J). It is also used the calorie (1J= 4.18 cal) or mega-calories or, more often, the petroleum ton equivalent (tep). For equivalence purposes, BEN/MME adopts 1 tep=10800 Mcal. When establishing our equivalences, we have opted for maintaining the tep unit which means the quantity of energy, on the average uses of that sector, equivalent to 10800 Mcal of natural gas.
The base for practical conversion is an equivalence table, by sector, of the quantities (in tep) of the energy source that substitutes 1 tep of natural gas. Based on the specific uses of electricity and on the historical participation of electricity in the sector, in Brazil and in other countries, it is established for each sector a minimum level of electricity not subject to competition.
In principle it is maintained the possibility of substitution among the energy sources. The evolution of the historical participation of the energy sources in the sector, the percent of use of these energy sources in the same sector in other countries and the sector’s specific uses are factors taken into consideration in the projection of the future participation of the energy sources in each sector.
The fact that the energy sources are expressed in equivalent energy facilitates the hypothesis concerning the allocation of the different sources in each sector. The inertia factors inherent in the sector regarding fuel substitution were always taken into account. In the case of transport and electricity generation, there are already physical models of these sectors that consider the inertia. This is represented, in the case of transport, by the existing fleet and the models and technology available in the market; and in the case of electricity generation, by the existing generation park and the projects under development.
Figures 6a and 6b show the evolution of energy consumption by fuel, expressed in equivalent energy. The energy sources were ordained by groups: electricity; natural gas; biomass, petroleum products and NG; and mineral coal and its products. First of all to facilitate observing the evolution of the different groups and secondly to fix limits among the groups and among the energy sources so that it will be easy to distinguish substitutions.
We can see in Figure 6 that fuels having less efficiency (biomass for heat generation) present the smallest participation in equivalent energy than in the so called final energy.
Electricity does not change much its participation since BEN/MME already considers it as having a special equivalence that is three times its calorific value . Its valorization in equivalent energy in its specific uses and in driving energy is very close to that adopted by the Balance. On the other hand, the global participation in equivalent energy is slightly smaller since for heat generation it is valorized in comparison to natural gas used for the same purpose. Table 1 summarizes the participation in final and equivalent energy of the grouped energy sources.
1: Comparison among participation in Final and Equivalent Energy, for
The energy/product ratio is an usual parameter used to associate an economic growth scenario with energy consumption. Using values of the equivalent energy/product a more regular behavior in time and in accordance to the development level is expected. Actually, our studies concerning the Energy Matrix show that this ratio is more stable along time and that it does not vary considerably for different levels of development which is also an indication for its use.
It is interesting to observe that when the final energy/product ratio is used, the less developed countries show an energy intensity larger than that of the developed countries because they use energy sources that have lower yield. The final energy intensity decreases with development.
In Figure 7 we show the evolution of the final energy/GDP and of the equivalent energy/GDP. It can be verified that in the seventies the final energy/product decreased considerably while the equivalent energy/product remained relatively stable. This is in part explained by the introduction of more concentrated and naturally more efficient energy forms. Actually, the biomass participation dropped about 21 percent points in the decade (in final energy) and 13 in equivalent energy.
It should be remembered that more elaborated energy forms such as fuel alcohol used in vehicles and vegetal coal present a yield that is even higher than that of other energy sources, as final energy. In this case, it is the previous transformation process that is less efficient.
The regularity of the equivalent energy/product also offers the perspective of using this parameter in a global form for a first approximation to energy consumption. This is made easier when we have comparisons with other economies. As a matter of fact, this was the approach we have adopted for a preliminary evaluation of thermoelectric power plants emissions presented to the MCT. At that time, we have defined an evolution of the equivalent energy intensity (equivalent energy/GDP) and of electricity participation based on a comparison with other countries.
In the present run of the Energy Matrix we are dealing with the industrial sector as a whole but we are already analyzing each industrial activity. Since the uncertainties associated with economic growth are larger than those relative to energy use, sometimes a more global approach favors conclusions and makes the adopted premises more clear.
The advantage of our approach is that it permits successive approximations from the general to the particular. It also permits the use of more general parameters for a posteriori critical evaluation of analysis regarding sector or activity. The fact that less detailed projection often presents a very similar reliability degree does not discredit sectorial analysis. In practice, important economic information arise from these analyses as in the case of data concerning energy intensity by industrial branch. These data can serve the purpose of policy orientation for the specific activity and for the industrial sector as a whole. As an example, we mention the fact that our industry, metallurgy in particular, is very energy intensive. This reveals the convenience of rationalizing as far as possible the use of energy in the sector as well as to develop in the country further steps, inside or outside the specific sector, in order to aggregate more value to the product.
The mechanism for projecting the participation of sectors in the economy is the same used in other phases of the process: Brazilian historical data are analyzed (Figure 8 at constant prices), the economy of other countries is analyzed in a static or dynamic situation (Figure 9) and preferably using a consensus process, the future behavior of the variables is estimated.
The comparison with the evolution of other countries at constant and current prices shows facts similar to the drop of agricultural and industrial prices relative to that of services. Furthermore, it should be remembered that the reduction in the participation at current prices of the agricultural and industrial activities can significantly affect the energy intensity measured at current prices.
Figure 9: Participation in the GDP of OECD of the Services, Industry and Agriculture Sectors (secondary axis on the right). There are some variations regarding the availability of data at current and constant prices in the period considered for each country and the individual activities. However, the curves presented reflect the trends of the set.
 It should be noted that the expressions energy “production” and “consumption” are not appropriate in the physical sense but they prevail in the energy balance jargon by analogy with other products.
 The equivalent energy concept is in a way an extension of the equivalence adopted by BEN for electricity and hydraulic energy and in some cases for alcohol when considering its substitution value.
Graphic Edition/Edição Gráfica:
Tuesday, 11 November 2008.