|No 49 Em Português|
Economy and Energy – NGO has just finished a study about the future of the Brazilian electric system exactly when the fate of the Angra 3 nuclear power plant is (once more) discussed. Based on the hypothesis adopted in the study – to privilege hydraulic energy – thermal power plants arise from regulation needs and the inclusion of nuclear power plants seems to be the natural solution in the considered horizon.
Carlos Feu Alvim, José Israel Vargas, Othon Luiz Pinheiro da Silva, Omar Campos Ferreira, Frida Eidelman.
In order to establish a policy for the Electric System in Brazil it is necessary to foresee its future. In a predominantly hydroelectric system where thermal complementation is being introduced, a thirty-year horizon seems to be adequate for forecasting its port of destination and establishing its route to get there. The study describes the existing model, studies its regulation and projects the macroeconomic scenario, the electricity demand and the necessary generation park.
Annexes (only in Portuguese)
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The need of thermal plants to generate electricity in Brazil is not due to the exhaustion of the hydraulic potential; they are needed to regulate the system to which no approval has been granted for the construction of large multi-annual reservoirs that would regulate it. This is the conclusion of the non-governmental organization Economy and Energy – e&e that has just published a prospective study on electricity production in Brazil in the 2035 horizon, denominated “A Destination Port for the Brazilian Electric System” (available at the http://ecen.com site).
The study points out that even though the complementary role of thermal plants has already been acknowledged by the official planning the consequences of its regulating quality has not been entirely assimilated. As regulating plants, thermal plants must be ready to supply electricity during shortages and reduce the production pace or simply interrupt it in order to use surplus water that periodically occurs due to seasonal variations or annual oscillations of rainfall. The need for interruption can be prolonged for months and during that time the fuel used should be stored. Obviously this is not the case of plants using associated natural gas, which follows the pace of oil production, or of those fueled with gas imported under the take or pay system.
The capacity of energy storage in reservoirs - that was two years - has been reduced to 5.8 months in 2003. For seasonal regulation a little less than three months are necessary and to face a dry year like 2001, two additional months are necessary. This means that five months of stored hydraulic energy are necessary for the self-regulation of a hydroelectric system. The power plants that were planned to go into operation between 2004 and 2008 had a two-month accumulation/production ratio and the perspective is that this ratio tends to decrease for the set of power plants.
As an aggravating factor, the North and Center-western regions , that represent 83% of the exploitable potential, have a longer dry period and a smaller minimum affluence than the Southeast Region where presently are concentrated a larger storage and generation capacity. The study also shows that the imagined complementing role of rainfall is not corroborated by the historical flow data that show that the Brazilian regions, except for the South Region, have more or less coincident dry months.
In order to avoid growth scenarios that reflect more a governmental wish than a probable reality, e&e considers its own economic projection that takes into account the existing macroeconomic limitations. The growth scenarios are generally lower than the official ones. The average economic growth for the 2005-2010 period is estimated to be 3.7% annually and that for the 2003 to 2005, 4.7% annually.
The study uses the concept of equivalent energy for connecting the GDP to energy consumption. This treatment considers the intrinsic efficiency of each energy source by sector where it is used and makes the dependency of energy consumption and economic product much more solid. For example, much of the talked-about energy efficiency gains in Western Europe in the last decades are due to substituting mineral coal for natural gas (intrinsically more efficient).
It has also been taken into account that Brazil already presents an electricity share in the global energy consumption, measured in equivalent energy, almost like that of the developed countries. This share, that is already 33% ,will grow to 35%. The evaluation does not commit the common mistake of considering electricity growth much higher than that of the GDP in the long term (elasticity much higher than 1).
This electricity share, higher than expected, is due to the high participation of electricity-intensive products (aluminum, for example) in the Brazilian industrial park. On the other hand, there is an under consumption in other industrial sectors that are not modernized yet, in collective transport of the large cities and the large number of residences with low or zero electricity consumption. These facts guarantee electricity growth rates slightly higher than that of the GDP for a long time.
Finally, the projection of the necessary thermal capacity is carried out considering the thermal regulation need as a function of the hydraulic energy storage capacity available and forecasting, besides that, only 5% consumption of thermal energy at the base. Regarding the hydroelectric potential, it is assumed that all the estimated potential until 2003 will be confirmed, to which 100GW will be added, totaling 370GW and that 80% of the total will be exploited, which is a very high index in worldwide terms.
The nature of this complementation is also rather conservative, assuming that 70% of the total would be conventional thermal energy and that the present proportion of the nuclear share in thermal energy (30%) would be maintained. This proportion is smaller than that of the European countries (35%) and close to that of the OECD countries (28%).
All these conservative assumptions result in 85% of hydroelectric energy share in 2030 and 74% in 2035. The nuclear energy share would be 5% and 9%, respectively, and the remaining share would be of conventional thermal plants. In terms of installed power in 2035, 270 GW would be hydroelectric plants, 90 GW, conventional thermal plants and 36 GW, nuclear plants, equivalent to twenty eight 1.3 GW-plants of which 20 would be used as regulating plants and the other 8 would correspond to the exhaustion of the hydroelectric potential.
Among the conventional thermal plants there is considerable room for biomass plants (sugarcane bagasse and other vegetal residues) that could give a significant contribution to regulation because their production would be concentrated in the dry season.
It has also been studied the assumption that the generation and transport costs of hydroelectric generation would grow according to the hypothesis adopted in a previous study for the electric sector. In this hypothesis the exploitable hydroelectric potential would be limited to 140 GW. The required thermal power would be 214 GW of installed power of which 62 GW would be nuclear power.
According to the e&e study as well as other studies, there is no doubt that thermal energy is necessary to permit the growth of the hydroelectric generation park.
Regarding the discussion about the future of nuclear energy in Brazil, the authors consider that for the developed countries, in the visible horizon, there is no energy source besides the nuclear energy that could significantly give its contribution in the next 20 years. This means that Brazil – except for biomass and a larger use of hydroelectric energy – should not count on other primary energy sources, besides those considered in the present study, in the next thirty years. That is, Brazil cannot disregard the nuclear contribution.
For the other developing countries, the nuclear option may be closed because of non-proliferation allegations. Brazil – that already commercially dominates the fuel cycle of PWR reactors – has the opportunity to maintain access to this energy source. The completion of the Angra 3 plant that is inserted in the energy needs in the near future is an important step for consolidating the access to this energy source.
Certainly the introduction of nuclear energy in Brazil was due, in the past, to excessive projection of energy demand and for other reasons not connected to it. The decision of not continuing the construction of Angra 3 makes sense only if the Brazilian energy future is examined within a very limited time horizon. It is already necessary for regulating the system in 2011.
The introduction of nuclear energy in the Brazilian energy matrix may have had the “original sin” of being premature an even larger mistake would be to postpone the decision regarding the construction of Angra 3 and discard the nuclear contribution when it is really necessary.
Graphic Edition/Edição Gráfica:
Tuesday, 11 November 2008.
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