The power of small plants

If their construction would be encouraged, small plants could gain space in the power matrix and help Brazil to save water in periods of drought

Small hydroelectric power plants (PCHs) correspond to 3.5 percent (4807 megawatts – MW) of Brazilian power matrix, whose total is 137,920 MW. They are the fourth source of energy in the country, below hydroelectric, fossil thermoelectric and wind energy plants. According to the Agência Nacional de Energia Elétrica (National Agency of Electric Energy - Aneel), the country has 4176 generating units operating. Hydroelectric plants correspond to 61.68 percent of the total generation, thermoelectric plants correspond to 28.47 percent and wind plants, to 4.66 percent. It is foreseen for the next years the addition of 40.5 thousand MW to the generating capacity, coming from 183 works in progress and more 674 works not yet started.

From this total of new generation, PCHs include 2 percent of works in progress and 9.6 percent of those which were not started. For the experts, this is a low figure due to the advantages offered by this alternative, such as the use of renewable sources and low environmental impact, among others.

The main potential of the PCHs is the possibility of their use to complete high-capacity systems, enlarging and diversifying the offer of power. “In spite of the low rainfall that is affecting hydraulic generation, Brazil has a huge hydroelectric potential”, says Adriano Pires, founding partner and director of the Centro Brasileiro de Infraestrutura (Brazilian Center of Infrastructure - CBIE). Defined as hydroelectric power plants with installed capacity between 1MW and 30 MW and flooded area below three square kilometers (30 soccer fields), PCHs are quick and efficient solutions to enlarge the offer of energy. “Since they are low-sized, they may be installed near the center of consumption, reducing the length of transmission lines and the energy losses”, explains Adriano Pires. PCHs may also be installed to ensure regional supply, relieving the national system mainly in drought periods.

“In the current situation of climate changes—if the trend of more serious drought periods remains—PCHs may help to transform other affluences in  energy”, remarks Roberto Pereira D’Araujo, director of the Instituto de Desenvolvimento Estratégico do Setor Elétrico (Institute of Strategic Development of the Electric Industry - Ilumina). “It is important to remark that a larger number of PCHs which are able to operate in the wet periods would collaborate to preserve the reservoirs of large hydroelectric plants, minimizing the later effects of the hydraulic crisis”, says also Adriano Pires, emphasizing the need of preventive planning.

PCHs have low construction, operating and maintenance costs and use national equipment, what prevents external dependence. In addition to its low cost, the construction of PCHs does not demand feasibility studies. After the study of inventory, Aneel selects the entrepreneur according to predetermined criteria, analyses the basic design of the plant and authorizes the construction.

Aneel gives to the entrepreneur exemption of taxes for the use of the transmission network (for those which started operation before 2003) and of the fee paid to states and municipalities due to the use of water resources.

“The first advantage of the PCHs is that they complement each other along the year and with no competition” says Ivo Augusto de Abreu, president of the Associação Brasileira de Fomento às Pequenas Centrais Hidrelétricas (Brazilian Association of Encouragement to Small Hydroelectric Plants - Abrapch). In Brazil, hydraulic, wind and biomass sources of energy alternate each other in their peak production. In the months that winds are reduced, rainfall increases. And when both are in the minimum point, cane (main fuel of biomass) harvest is at the maximum. Therefore, if a more intense use of renewable sources is stimulated by the responsible organs, thermoelectric plants (gas, oil, carbon) would be started only in emergencies. According to the experts, this would allow the country to save approximately R$ 2.7 billion per month.