The Engineering Institution of Zambia says the current power crisis has been caused by ZESCO’s delay to implement remedial measures despite early indications of subdued water levels at the Kariba Dam.
EIZ President Bernard Chiwala said the reservoir at Kariba Dam has not reached its maximum retention level of 488.5 meters for the last five years.
Engineer Chiwala was speaking during a presentation of report findings on the cause of low water levels at the Kariba dam.
He said the investigations showed that Lake Kariba started the 2014-2015 rain season on a lower reservoir level than the previous five years with approximately 40 billion cubic meters in storage as at 30th September 2014.
Mr. Chiwala revealed that despite restrictions on water use by Zambezi River Authority, ZESCO and the Zimbabwe Power Authority (ZESA) continued to generate power way above the 500 megawatts revised threshold, leading to further reduction of water levels.
‘The issue of low inflows was identified early however there was a delay in implementing measures to forestall the ‘business as usual’ operations,’ Mr Chiwala said.
He added, ‘According to data from the Department of Meteorology, the upper reaches of the Zambezi River (upstream of Katima Mulilo) received below normal rainfall. The middle reaches had normal rainfall.’
Mr. Chiwala said the release of 19.98 billion cubic meters (an equivalent of almost one year of generation for either of the power plants) over an 87 day period in 2011.
‘Though attributed to dam safety measures, due to restrictions in the availability of spillway gates, at that time, may not have been prudent as there was no imminent danger paused by the inflows.’
He said the low reservoir levels for the 2014/15 season cannot be attributed to the poor inflows alone as the daily reservoir was 80 percent filled during the month of July.
‘There was an element of over generation at Kariba complex. The problem has been compounding over the years,’ Mr. Chiwala said.
Mr. Chiwala stated that ZESCO exceeded its water allocation by 22 percent during 2014 saying this coupled with low inflows is a contributor to low water levels being experienced.
‘The increase in economic activities over the years has led to an increase in demand for energy and has put stress on the water resource,’ he said.
Mr. Chiwala revealed that despite the end of March 2015 directive from Zambezi River Authority to the two utilities to reduce generation, this was not immediately implemented until in ZESCO’s case, August 2015. This led to further drawdown of the reservoir threatening total shutdown of the power plant.
Mr. Chiwala added that the Engineering Institution of Zambia has recommended that customers must be encouraged to switch off non-essential loads such as geysers, hot elements and swimming pool pumps.
‘Large industrial plants operating change houses such as the mines should switch to Solar Hybrid Geysers while customers should be encouraged to use energy efficient equipment such as energy efficient lamps. ZESCO should continue with the exercise of distributing free and exchanging with energy efficient lamps.’
He also recommend that Government should issue a Statutory instrument directing that all new housing estates use hybrid solar water geysers for heating water and that existing households be given a fixed period to migrate to hybrid solar geysers.