Hydro power is the mainstay renewable energy in Africa and one of the oldest forms of energy used. People harnessed water resources through history transforming them into motive power to carry out essential tasks for human wellbeing. For modern energy dams are a tested and relatively simple technology. Small and large reservoirs built into river beds harvest the mechanic power of water providing the largest share of total renewable generated electricity in Africa. The untapped potential in Africa concentrates mainly on the upper Nile and lower Congo River and is estimated to be 18 times higher by comparison to the electricity generated by dams in 2009.
What makes large hydropower dams so popular is that they represent the most economical form of renewable energy for investors and consumers alike. For investors large hydroelectric dams are a proven technology with a long track and a safe payback as expenses are absorbed over a long horizon of a dam’s operation. The concrete building of typical plant can for instance last 100 years while turbines converting water movement to electricity can last 20-30 years. For electricity users dams ensure low final prices as hydro generated energy is transmitted through central grids lowering total costs. Due to attractive finances and ease of deployment dams have been a preferred political choice and over 60% of all new grid supplied electricity in Africa between 1998-2008 was generated from hydrological resources.
A negative aspect of large hydropower is their high non-financial costs as dams may damage river ecosystems and cause social conflict. Small dams by contrast are less controversial being friendlier for the environment and are often better suited to areas that have small scale river resources. Electricity generated from small dams is on average more expensive than that from large hydro as they may involve considerable costs to transport electricity form the source to where it is needed. Besides providing electricity small hydro dams are popular as they serve multiple uses providing irrigation in the dry season, flood control and drinking water supply. There are currently over 500 small dams (less than 10 MW) in operation across Africa while there is still great potential for small hydro power generation using a proven technology that can provide carbon free energy in a dependable way.