/ 5 August 2011

Energy on tap

Energy On Tap

A simple device attached to water storage units could use gravity to create large amounts of energy and to power communication in rural areas.

New research published by the Water Research Commission and the University of Pretoria, showed that just 10 reservoirs in Tshwane could generate between 10GWh and 22.5GWh of electricity a year — the equivalent of the power used by between 3 700 and 7 500 middle-class households.

Although the government had identified the need for the development of renewable energy, “very little progress has been made and the goal set for 2013 — to generate 10 000 GWh — might not be met,” the study said. “Many factors, including the global economic crisis, could influence the slow progress. Access to finance, the cost benefit of feeding into the national grid and numerous regulatory requirements also hamper this initiative.”

Using water flow to create energy had major potential benefits, but hydropower contributed only 3% of current global energy consumption — a fraction of its potential. “Africa is the most underdeveloped continent with regard to hydropower generation, with only 6% of the estimated potential exploited. This is not a burden, but an opportunity. “South Africa has the potential to make a large contribution towards the lack of hydropower generation in Africa and the world,” it said.

The study focused on retrofitting hydropower generation facilities at existing dams around the country. Pilot generation units were retrofitted on several storage reservoirs. Power was generated by water passing through pressurised conduits on the supply side of the reservoirs.

Units were tested on a hydropower development at Sol Plaatjies municipality and at the Queenswood reservoir in Tshwane metropolitan district. Based on the average annual daily water demand of the reservoirs and the pressure in the pipelines, the findings were then applied to other metropoles.

The study also found that this form of hydropower generation could be used on a mini-scale to benefit rural communities where communication is a primary concern. Smaller units could be used on pico-hydro setups such as streams and rivers, rather than dams, where pipes divert some of the water flow and drop it down a gradient, before returning it back to the stream.

A pico-hydro generation model was developed to charge 12V batteries and cellphones in remote areas. “The first indications are that some energy can be generated from the low flow rate and low head tapped from the water supply. In these cases it will be possible to charge batteries and cellphones,” it concluded.

The study urged more research and development on the potential of hydropower generation from existing dams, pressurised conduits and other water infrastructures. It recommended a register of water infrastructure that has a potential for power generation be compiled, as well as a cost-benefit model for the development of future units.

“Energy is the lifeblood of worldwide economic and social development,” it said. “When considering the current status of global energy shortages and the emphasis to reduce CO2 emissions, development of alternative energygeneration methods and the growing energy consumption, it is clear that we need to change the way we create and use energy.”

The demand for energy was increasing continuously and the use of fossil fuels as an energy source was being resisted due to the dangers of global environmental impacts. “This forces our current generation to focus on the development of renewable energy. It is the way of the future and the potential for its development is of great magnitude,” the study said.