Tag Archives: Saharan African

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Proposed Zambezi hydropower dams pose some risks, expert warns

Existing and proposed hydropower dams are not properly evaluated for the risks of natural hydrological variability, which is extremely high in the Zambezi river, not to mention the risks posed by climate change, says US State of Wisconsin Department of Safety and Professional Services hydrologist Dr Richard Beilfuss.

“The result could be that uneconomic dams underperform in the face of more extreme drought and more dangerous dams that have not been designed to handle increasingly damaging floods,” he notes.

Overall, Africa’s fourth-largest river will experience worse droughts and more extreme floods. Dams currently being proposed and built will be negatively affected, yet energy planning in the basin does not include the necessary steps to address these significant hydrological uncertainties, he warns.

The basin exhibits the worst potential effects of climate change among 11 major sub-Saharan African river basins. It will also experience the most substantial reduction in rainfall and runoff, according to the International Panel on Climate Change. Multiple studies estimate that rainfall across the basin will decrease by 10% to 15%.

“The basin is likely to experience significant warming and higher evaporation rates in the next century. Because large reservoirs evaporate more water than natural rivers, big dams could worsen local water deficits, resulting in less water for hydropower. Currently, more than 11% of the Zambezi’s mean annual flow is lost to evapora- tion from large hydropower dam reservoirs, which increases the risk of shortfalls in power generation and significantly impacts on downstream ecosystem functions,” he explains.

The designs for two of the larger dam projects proposed for the Zambezi, the Batoka Gorge and Mphanda Nkuwa dams, are based on historical hydrological records and have not been evalu- ated for the risks associated with reduced mean annual flows and more extreme flood and drought cycles. Under future climate scenarios, these hydropower stations, which are based on records of flows, are unlikely to deliver the expected services, says Beilfuss.

The occurrence of more frequent extreme floods threatens the stability and safe operation of large dams. Extreme flooding events, a natural feature of the Zambezi river system, have become more costly downstream since the construction of large dams. If dams are ‘underdesigned’ for larger floods, the result could be serious safety risks to millions of people living in the basin.

The Zambezi river is already highly modified by large hydropower dams, which have profoundly altered the hydrological conditions that are most important for downstream livelihoods and the preservation of biodiversity. The ecological goods and services provided by the river, which are key to enabling societies to adapt to climate change, are under grave threat.

Large-dam hydropower poses economic and adaptation risks. Africa has been referred to as the continent most at risk of being nega- tively affected by climate change. Successful adaptation will require new ways of thinking about water resources. We need to act now to protect our rivers as sources of livelihoods and food security,” says International Rivers Africa programme director Rudo Sanyanga.

“The region’s energy planners and governments must acknowledge these hydrological risks and take steps to improve planning and manage- ment of large dams in the basin. Existing and future dams should, at least, undergo a thorough analysis of climate risks,” notes Beilfuss.

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Source Article from http://www.engineeringnews.co.za/article/proposed-zambezi-hydropower-dams-risks-2012-10-12
Proposed Zambezi hydropower dams pose some risks, expert warns
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Major energy crisis predicted for Africa


Africa faces a major energy crisis and half of the sub-Saharan African population will be without power by 2030. This is according to a recent study by the World Bank’s energy unit. The report shows that of the 54 countries in Africa, almost half, 25 nations, will suffer this fate unless commitments are made to reverse this trend.

A United Nations-led environmental programme estimates that around 7 000MW of power needs to be installed every year is power supply is to be retained. Challenges faced on the continent include lack of reliability on the system. Power outages average 56 days a year which translates into an estimated loss of between six and 20% in revenue.
The cost of electricity is also an issue.

The rates on the continent are higher than those in the developed world. The rate here averages R1.04 per kilowatt hour compared to 32 to 64 cents in developed countries. The cause of this can primarily be attributed to the use of very expensive diesel generators both primary and back-up power suppliers.

In South Africa, the continent’s major and dominant producer of electricity, there are also on-going power shortages due to pressure on the existing infrastructure. Eskom has appealed to a 10% reduction in demand which translates to 3 000MW. The energy entity says that this will allow it to sustain a ramp up of maintenance and will create capacity for continued economic growth. Eskom currently has a typical available capacity in the region of 37 000MW taking into account plant maintenance and unplanned outages.

Source: esi-africa.com

Source Article from http://www.infrastructurene.ws/2012/08/22/major-energy-crisis-predicted-for-africa/
Major energy crisis predicted for Africa
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Easy access to safe drinking water: innovative bag is portable water purifier


More than a billion people around the world lack access to safe drinking water, and some 300 million of them are in Africa. Industrial design students Ryan Lynch and Marcus Triest have an interesting approach to tackling the problem in sub-Saharan African with his Solar Bag.

This design concept is both a shoulder bag-style container to transport water from a distant source, as well as a tool to purify it.

The container is made of polyethylene, which allows UV rays to pass through the clear outer layer and kill most of the bacteria in the water. It’s similar to purifying water with sunlight and bottles made of polyethylene terephthalate (PET).

A black polyethylene layer forms the back layer, and helps reflect the UV rays and heat the water, speeding up the purification process. The bag can apparently decontaminate 2.5 gallons of water in about six hours.

The Solar Bag can also be hung on a wall or laid out on the ground during the purification time, according to Lynch’s Web site.

A spigot at the bottom of the bag can be attached to a manual pump filter to enhance the purification.

The rest of the bag is made of sturdy nylon, and the materials costs could come to less than $5 if the bag is made in bulk.

A prototype of the Solar Bag has been made, but the designers are apparently looking for backers to help manufacture it in bulk. How many lives could it help if it actually works the way it should?



Source: http://atlantablackstar.com

Source Article from http://www.infrastructurene.ws/2012/08/08/easy-access-to-safe-drinking-water-innovative-bag-is-portable-water-purifier/
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