The level of the Arenal reservoir, Costa Rica's main reserve for hydroelectric generation, fell this week to its lowest point in the last 10 years. The situation is registered after months of intensive use by the Costa Rican Electricity Institute (ICE) to supply the national electricity demand.
This May 24, the height of the reservoir closed at 533.43 meters above sea level (masl), according to data from the National Electricity Control Center (Cence). The last time the liquid availability dropped this low was in June 2013, when it marked 532.70 meters above sea level (masl). A month earlier, it was at 532.96 masl.
From January to this week, the reservoir's capacity dropped 7.74 masl after starting January at 541.17 masl. The drop represents 607 million cubic meters less water in this 87 square kilometer lagoon which, when at its maximum of 546.00 meters above sea level for generation, can hold up to 1,477 million cubic meters.
The liquid has been powering the Ardesa complex (formed by the Arenal, Dengo and Sandillal hydroelectric plants), which is key to Costa Rica's electricity supply.
Ardesa contributed a little more than one fifth of the national demand so far this year with 22.6% of all the energy consumed in the country, according to Cence data.
Ardesa gathers 330 megawatts of installed capacity for generation, where the reservoir is key for being the only one in Costa Rica capable of storing water from one year to another to provide light in the dry season.
Mario Alvarado, executive director of the Costa Rican Association of Energy Producers (Acope) warned that, if there is a lower recovery of the reservoir during the rainy season this year, there will be less water production to face the summer of 2024.
"From what I see in the technical information from Cence, we are going to start the other year at a level of 537 masl. The lower the level of the reservoir, there is a substantial reduction of generation," he warned.
La Nación consulted ICE this Thursday about the situation of the reservoir.
In response, the Institute issued a press release in which it admitted that the transition to the rainy season has been delayed due to the arrival of the El Niño phenomenon.
Despite this, ICE maintained that its level is within the projected range and that to date no critical event affecting the operation has materialized.
"These phenomena do not put at risk the electricity supply of Costa Rica nor the satisfaction of the daily demand", said the entity that has been burning bunker and diesel in thermal plants in the last weeks, as it has not happened for years.
As of May 23, these petroleum derivatives already represented 12.4% of the demand. Of the 797,246 MWh consumed on that date, 98,815 MWh were generated from these fuels (2.6% with diesel and 9.8% with bunker).
Salvador López Alfaro, former director of Cence, warned this Thursday that the National Electric System (SEN) is rather going through critical conditions and questioned the performance of the Institute, since Cence is part of its structure.
"What is happening now is just a forerunner of what will happen next summer, when El Niño will become stronger and with the low levels of the Arenal reservoir, we will probably have a very limited capacity", said the former official in his Facebook account.
López Alfaro, who was in charge of Cence for 15 years and was dismissed last year, confirmed the authenticity of the publication.
In his message, he attributed ignorance to the authorities about the operation of the National Electric System (SEN). Proof of his statement, he recalled that Marco Mora Acuña, president of ICE, declared in the Legislative Assembly the previous year that he would eliminate the thermal plants because they were not being used.
"Today we are using all the thermal potential and importing up to 25 megawatts of energy," he asserted.
According to him, the mark of 533.43 masl is a low level for the season and a forecast of 537 masl after the winter is worrisome. He recalled that the reservoir needs to use eight meters of its level to back up the SEN in summer, but its minimum safe operating height is 532 meters above sea level.
If those eight meters are required, there will be a deficit of three meters at the beginning of the next dry season if the waters reach 537 meters above sea level. That difference, he said, will have to be covered with thermal generation and imports or "there would be a risk of electricity rationing".
"These are the decisions for which it is necessary to have an authority independent of political and commercial interests, to seek what is best for the country," he said.
Carlos Montenegro, executive director of the Chamber of Industries, said Thursday that for the industrial sector, the news that only in the month of May about ¢11,861 million were spent on thermal generation and imports, "is terrible news".
"Only the effect of that month alone would impact approximately 9% the generation tariff for the following quarter and 5.4% the tariffs to the final consumer. This is of concern because given the appreciation of the colon, industrial companies have suffered an increase in their electricity tariffs of up to 12% on average, in the first half of the year", he stated.