Maputo — The international non-governmental organisation International Rivers has called for the effects of climate change to be taken into account when planning for new dams in sub-Saharan Africa.
In its report entitled "A Risky Climate for Southern African Hydro", International Rivers looks at the Zambezi Basin, which is home to the Kariba dam in Zimbabwe and the Cahora Bassa dam in Mozambique.
International Rivers is strongly opposed to dams in general, but the report reinforces that opposition by warning of the effects of climate change. It points out that numerous models predict that Africa's weather patterns "will become more variable and extreme weather events are expected to be more frequent and severe". It states that within the next half century an estimated 60 million to 120 million people in Southern Africa will face water stress.
The report concedes that African leaders are under pressure to achieve economic growth and improve living standards. However, it argues that sub-Saharan Africa (excluding South Africa) is sixty per cent dependent on hydropower, leaving countries exposed to drought-induced power shortages.
The Zambezi Basin is the largest in southern Africa with a total drainage area of 1.4 million square kilometres. It produces about five gigawatts of electricity, mainly from the dams at Kariba and Cahora Bassa.
According to the report a further 13 gigawatts of potential hydropower has been identified.
But the NGO warns that the basin is highly susceptible to extreme droughts and floods. It estimates that the 1991/92 drought seriously affected energy production, resulting in losses of 102 million US dollars and 3,000 jobs.
Such figures are questionable - the losses caused at Cahora Bassa were overwhelmingly due, not to drought, but to sabotage. No electricity could be exported to the dam's main client, the South African electricity company Eskom, because the transmission lines southwards had been sabotaged by the apartheid-backed Renamo rebels.
International Rivers points out that multiple studies have concluded that rainfall across the basin will decrease by between ten and fifteen per cent, with delayed rainy seasons and more intense rainfall. It estimates that the Zambezi runoff will decrease by between 26 and 40 per cent by 2050.
The report claims that the proposed dam at Mpanda Nkuwa, 60 kilometres downstream from Cahora Bassa, was designed based on historical hydrological records and has not been "evaluated for the risks associated with reduced mean annual flows and more extreme flood and drought cycles".
Among the report's recommendations are that the regional power supply pool should be diversified to reduce hydropower dependency, and that existing hydropower capacity should be improved rather than investing in new infrastructure.
Both of these assertions display ignorance about the real situation in the Mozambican power sector, where a great amount of work is under way to increase electricity production from a wide variety of sources. Whilst the country is predominantly dependent on power from the Cahora Bassa dam (it provides about 85 per cent of the power for the publicly-owned electricity company EDM), it was only in November 2007 that the government took over a majority stake in Hidroelectrica de Cahora Bassa (HCB), the company that operates the dam. Previously it had been owned by the Portuguese government, who had control over investment decisions.
Since then the Mozambican state has been investing heavily on renovating HCB equipment and is looking at ways to increase the output from the dam further, notably by building a second power station at the dam, on the north bank of the river.
Nor is Mozambique looking to Mpanda Nkuwa as the only source of additional electricity. In May the chairperson of EDM, Augusto Sousa, told a business conference that "we must implement new sources of energy, such as small scale hydropower stations, wind energy and photovoltaic systems".
He pointed out that EDM is negotiating with the National Hydrocarbon Company (ENH) to convert an obsolete thermal power station in Maputo to run on natural gas, which could generate 70 megawatts.
Meanwhile, a power station was opened in July at Ressano Garcia on the border with South Africa, using gas from the Pande and Temane fields in the southern Mozambican province of Inhambane. It is generating just under 110 megawatts of electricity which is being used by both South Africa and Mozambique.
Other gas-fired power stations are planned - a further plant in Ressano Garcia will generate 160 megawatts, and one in Chokwe, in the Limpopo Valley, is planned to produce 140 megawatts. Both could be operational in 2014.
Solar power is widely used in remote areas where the national grid has not reached. It is estimated that three million people already rely on solar power for their electricity.
Meanwhile, huge thermal power stations are being planned by mining companies in Tete province to use the low grade coal that they cannot export.
It can be expected that much of the electricity from these new power stations will be sold to neighbouring countries. But some of the power will be used in new Mozambican industries and to supply the growing domestic users' market.
Nationally, electricity consumption increased by 15 per cent in 2011. Just over a million households are now connected to the national grid, which is about 5.3 million Mozambicans, or 23 per cent of the population. If the households supplied by isolated, non-EDM power sources (mostly solar panels) are included, the percentage of Mozambicans with access to some form of electricity rises to around 36 per cent.