Energy Demand Management - DSM in Systems Based On Hydropower

DSM in Systems Based On Hydropower

Demand side management is completely applied for electric system based on thermo power plants or even for systems where renewable energy, as hydroelectricity, is predominant but with a complementary thermo generation, for instance, in Brazil.

In Brazil’s case, despite the generation of hydroelectric power corresponds to more than 80% of the consumption, to achieve a practical balance in the generation system, the energy generated by hydroelectric plants is used only to supply the part of the consumption below the peak hours. Peak generation is supplied by the use of fossil fuels power plants. In 2008, Brazilian consumers paid more than U$ 1 billion for complementary thermoelectric generation not previously programmed.

In Brazil, the consumer pays for all the investment to provide energy, even if a plant sits idle. In the case of fossil fuel thermo plants, at least for the majority of them, the consumers pay for the “fuels” and others operation costs only when these plants generate energy. The energy, per unit generated, is more expensive in thermo plants than in hydroelectric. Only some of the Brazilian’s thermoelectric use natural gas as fuel so they are polluting significantly more. In other words, the power generated to meet the peak demand has higher costs, both when the thermo plants are operating (investment plus operation cost) or not (investment only) and their pollution has an environmental cost and potentially, financial and social liability for its use. Thus, the expansion and the operation of the current system are not as efficient as they could be using demand side management. The consequence of this inefficiency issue is increase in energy tariffs passed on to the consumers.

Moreover, because electric energy is generated and consumed almost instantaneously, all the facilities, as transmission lines and distribution nets, are built for peak consumption. During the non-peak periods their full capacity is not utilized.

The reduction of peak consumption can benefit the efficiency of the electric systems, like the Brazilian system, in some senses: as deferring new investments in distribution and transmission networks, and reducing the necessity of complementary thermo power operation during peak periods, which can diminish both the payment for investment in new power plants to supply only during the peak period and the environmental impact associated with greenhouse gas emission.