انرژی از باگاس نیشکر در جیره بندی برق در برزیل: یک مدل تعادل عمومی قابل محاسبه
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|28649||2006||7 صفحه PDF||سفارش دهید||محاسبه نشده|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Energy Policy, Volume 34, Issue 9, June 2006, Pages 986–992
In the midst of the institutional reforms of the Brazilian electric sectors initiated in the 1990s, a serious electricity shortage crisis developed in 2001. As an alternative to blackout, the government instituted an emergency plan aimed at reducing electricity consumption. From June 2001 to February 2002, Brazilians were compelled to curtail electricity use by 20%. Since the late 1990s, but especially after the electricity crisis, energy policy in Brazil has been directed towards increasing thermoelectricity supply and promoting further gains in energy conservation. Two main issues are addressed here. Firstly, we estimate the economic impacts of constraining the supply of electric energy in Brazil. Secondly, we investigate the possible penetration of electricity generated from sugarcane bagasse. A computable general equilibrium (CGE) model is used. The traditional sector of electricity and the remainder of the economy are characterized by a stylized top-down representation as nested CES (constant elasticity of substitution) production functions. The electricity production from sugarcane bagasse is described through a bottom-up activity analysis, with a detailed representation of the required inputs based on engineering studies. The model constructed is used to study the effects of the electricity shortage in the preexisting sector through prices, production and income changes. It is shown that installing capacity to generate electricity surpluses by the sugarcane agroindustrial system could ease the economic impacts of an electric energy shortage crisis on the gross domestic product (GDP).
In the midst of the institutional reforms of the Brazilian electric sectors initiated in the 1990s, a serious electricity shortage crisis developed in 2001. Hydroelectricity represents approximately 90% of the total electricity produced in Brazil. Water in reservoirs typically attains its maximum volume at the end of the rainy season that extends from November to April. However, in May 2001, the average water level for reservoirs in the southeastern, central western and northeastern regions corresponded to about 30% of maximum storage capacity. As an alternative to blackout, the government instituted an emergency plan aimed at reducing electricity consumption. From June 2001 to February 2002, Brazilians were compelled to curtail electricity use by 20%. Severe penalties were imposed, such as 50–200% surcharges in the monthly bills and the possibility of power cuts for users exceeding mandated consumption targets. Firm energy is the electricity a hydropower plant can produce under the worst precipitation conditions. As a rule, the expansion of a hydroelectric system should be based on the supply of firm energy. Above-average levels of precipitation prevailed from 1997 to 2000. Yet, over the same period, the successive yearly curves for the average water level of important reservoirs in Brazil declined. As pointed out by the so-called Kelman report (Kelman et al., 2001), the level of energy stocks at hydropower plants in Brazil, observed in November 1999, corresponded to 20% of maximum storage capacity. At the time, the probability of an energy deficit for the year of 2000 was estimated at about 14%, well above the 5% threshold value commonly accepted for the electric sector. The persistent depletion of the water reserves demonstrates that electricity production was held above firm-energy level. Thus, it is clear that the energy deficit was caused by the lack of investments in electricity generation. In fact, as shown in Fig. 1, constructed with data readily available in (MME, 2003), in the 1990–2000 period, there was an increase of 52.3% in electricity consumption, whereas total generation capacity augmented by only 41.2%. In 1998, the gap between consumption and installed capacity reached the largest relative value of 18.1 percentage-wise. So, it is evident that the electricity system was, in fact, driven to its inevitable collapse in 2001. Full-size image (23 K) Fig. 1. Electricity consumption and installed capacity gap (1990–2000). Figure options This work analyzes the economic impacts of constraining hydroelectricity supply and the possible penetration of energy generated from sugarcane residues in Brazil. 2. Methodology Energy-planning issues relate to several aspects of the economy, such as price formation, output determination, income generation and distribution, consumption, government action, etc. Computable general equilibrium (CGE) models represent a coherent framework, capable of grasping most of these relevant aspects and, therefore, have been widely used to analyze energy policies (Bhattacharyya, 1996). A CGE model is a stylized representation of an economy involving producers, consumers and markets, among other things, and basically having prices and quantities associated with income flows as endogenous variables. Formulation consists of attributing a theoretical setting convenient for the analysis of the proposed questions to the observed data. Thus, CGE models are often referred to as theory with numbers or even numbers with theory. CGE models are typically used to simulate policies or exogenous events. A base case is constructed to reflect the observed reality. Scenarios are then built by altering some exogenous variables or parameters of the model as to reflect the intended or experienced changes. Post-shock equilibrium is computed, making it possible to quantify the overall economic impacts of the introduced modifications. Constructing a CGE model requires the combination of at least three related but distinct areas: formulation (economic theory), parameter estimation (econometrics) and numerical solution (applied mathematics). This was the motivation for developing Pegasus, a language for formulating, benchmarking and solving CGE models ( Scaramucci, 1997; Scaramucci and Bordoni, 1998; Bordoni, 2001). Solving a CGE model consists of finding fixed points for point-set correspondences. This can be a difficult mathematical problem. Some numerical methods for mixed complementarity problems are briefly discussed in the following section. The importance of the sugarcane agroindustry in Brazil has motivated a great number of economic studies on biomass energy, mainly after the implementation of the Brazilian Alcohol Program (Proalcool) in 1975. Using a CGE model, for instance, Sampaio de Souza (1984) made an economic assessment of the early stages of Proalcool. Income distribution between rural and urban sectors and the effects of Proalcool on food production were studied.
نتیجه گیری انگلیسی
To a great extent, the restructuring of the Brazilian electric sector initiated in the 1990s was limited to its distribution segment. Most of the generation and transmission sectors are still not privatized. The reforms instituted the change from mandatory to indicative planning in the coordination activities conducted by government agencies. Until 1998, the federal government could dictate the enlargement of electricity supply through investments made by state-owned generation firms. The changes introduced in 1998 caused the expansion of electricity capacity to depend on project-finance investments based on power purchase agreements (PPAs) between generation and distribution firms. By 1998, the privately owned distribution firms had already contracted enough energy to meet electricity demand up until 2000. However, generation firms had not made the investments in electricity supply needed to support the existing contracts (Kelman, 2001). The 2001 electricity crisis in Brazil resulted as a consequence. The institutional model for the Brazilian electric sector is now under revision. The events briefly outlined above suggest that it may be important now to use market-oriented instruments such as CGE models to assist in the formulation of policies for the electricity sector in Brazil. For instance, it was shown here that the full potential of sugarcane bagasse to produce electric energy could only have been implemented in 1996 if electricity prices had been above R$ 40 per MWh (see Table 2). This result could be useful for setting a reference price for electricity from bagasse in national programs aimed at promoting the use of renewable energy in Brazil, such as Proinfa5 (MME, 2004). Generating a large amount of energy from sugarcane biomass is possible in Brazil, but it would require an institutional milieu that is conducive to the effective functioning of a market for electricity. The results obtained here indicate that the effects of constraining the preexisting electric system may be significant. The possibility of generating electricity from sugarcane bagasse could be important to attenuate the resulting economic impacts. Obviously, a bagasse-based electricity sector could only have mitigated the adverse effects of the energy shortage in 2001 if it had been previously implemented. The general equilibrium changes anticipated by the counterfactual analysis conducted here do not occur instantaneously. It is important to stress that the only complement to the preexisting electric system considered here is a bagasse-based electricity sector. The introduction of a module describing the possibilities of generating electricity from natural gas would be essential to better capture the recent changes incurred in the Brazilian electric system. Thus, some caution should be exerted when interpreting the results. Nevertheless, it is interesting to observe that, from 1996 to 2000, thermoelectricity generation increased by 4586 MW—or 32.139 TWh, using a capacity factor of 0.8 (MME, 2003). As predicted by the model, it would be possible to produce 20.5 TWh of electricity from bagasse at a rationing level of 20% (see Table 2), with a corresponding GDP reduction of approximately 1% (see Fig. 3). This could explain why the estimated actual reduction in economic output caused by the electricity shortage in Brazil was no greater than 1%. The exact general equilibrium effects of a hydroelectricity shortage would depend on the composition of the electricity sector, as explained briefly in the previous section. Capital, labor and fuel requirements vary with the type of complementary electricity. For instance, the bagasse-based electricity sector considered here uses labor, capital and fuel inputs as described in Table 1. Clearly, other electricity sectors would have different input–output coefficients. Other modules describing alternative energy sources, such as solar and wind power, could also be inserted in the CGE model. An interesting idea is to consider a possible enlargement of fuel ethanol production, resulting in a greater availability of sugarcane bagasse. It is evident that in 1996 the electricity generation sector in Brazil was already under considerable strain (Fig. 1). However, the price set then by the government for generating electric energy was R$ 28.45/MWh, rendering it difficult for a bagasse-based electricity sector to fully emerge (Table 2). Yet crises represent opportunities. In 1975, the first oil shock led to the creation of the Proalcool. The recent electricity shortage crisis has promoted a rapid penetration of thermoelectricity. It is expected that the Brazilian sugarcane agroindustry assume, once and for all, the condition of an energy-producing sector, as suggested in Fig. 6. Vasconcellos (2001) believes that the energy from sugarcane biomass may constitute a basis for a national development program.