Africa in a Changing Global Environment: Perspectives of climate change adaptation and mitigation strategies in Africa

CHAPTER 12

196 CHAPTER 12 INTRODUCTION T he world is faced with considerable risk and uncertainty about climate change. Particular attention has been paid increasingly to hydropower generation in recent years because it is renewable energy. In Africa, hydropower contributes 90 per cent of renewable energy generation.1 However hydropower is among the most vulnerable industries to changes in global and regional climate change. The uncertainties are accentuated by ever changing and increasing competing priorities on water resources. Current debates have witnessed a growing public and policy maker interest in the extent to which hydropower can meet the Africa’s future electricity and environmental demands. This chapter provides an understanding of the complexities around hydropower generation in a climate constrained world, compounded with huge competing priorities for water. The chapter acknowledges that a forward -looking energy strategy calls for a holistic approach to climate-related initiatives. Apart from climate change concerns, hydropower encompasses a highly heterogeneous set of socio-technical systems. The chapter thus adopts complexity science in the form of systems dynamics to aid in characterizing the huge complexities associated with hydropower generation. System dynamics and its principles of feedback, non-linearity and delay effects has helped many managers and policy makers/planners to think through how a strategy might or might not work, resulting in higher success potential, and what kind of consequences, both intended and unintended might emerge (to highlight points of leverage and risks of transition breakdown). The promise of complexity science has therefore been applied to define the parameters of sustainable power generation confronting the physical, socio-economic, bio-societal and technical factors that inherently cross traditional boundaries. Defining parameters for sustainable hydropower generation in the light of climate change AcasestudyofZambia’sKafueFlats Shingirirai Savious Mutanga and Nomasonto Magano DEFINING PARAMETERS FOR SUSTAINABLE HYDROPOWER GENERATION IN THE LIGHT OF CLIMATE CHANGE 197 HYDROPOWER AS AN ALTERNATIVE ENERGY SYSTEM This section defines and highlights evolving hydropower generation technologies and the role they play in ensuring energy security. The section also describes Africa’s richness in hydropower potential. It culminates by illuminating the case for both large and small hydro schemes as a promising alternative energy source. DEFINITION, TYPES AND CLASSIFICATION OF HYDROPOWER SCHEMES ‘Hydro’ comes from the Greek word hydra, meaning water. Hydro electricity is electricity produced from the energy contained in the downhill flow of water from rivers and lakes.2 Given its long history, hydropower is the most mature of the renewable energy industries. Originally, hydroelectric power stations were small and built next to waterfalls and close to towns because it was not possible to send the electrical energy over great distances. There is now large scale use of hydro electricity because improvements in electricity transmission means it can now be sent over hundreds of kilometers to where it is required.3 ■ Hydropower schemes can be can be categorized into four main schemes, namely: ■ Storage schemes: dam impounds water in a reservoir ■ Runoff schemes: use of natural flow: Wwir can enhance continuity of the flow. ■ Diverging schemes: water is channelled from river or lake. ■ Pumped storage: incorporates two rivers. The basic conversion technology for hydropower energy involves the building of big dams across flowing waters and creating reservoirs.4 Water in the reservoirs is subsequently released, in a controlled form to maximize the kinetic energy of the flow. This kinetic energy is then used to turn turbines that feed into a generator, then to a converter or inverter and finally to a transformer that converts the energy into electricity.5 ,6 This electricity is then connected to a grid and distributed. A key prerequisite for utilisation of hydropower conversion technologies is the existence of reliable natural water sources. As such, hydropower technologies are most relevant to areas that have permanent rivers.7 The amount of electricity generated from a system depends not only on its capacity (size of turbine and generator), but also on the amount of flowing water available,8 and the height of the surface of the water above the turbine. This height is called the ‘head’ and the greater the head, the more CHAPTER 12 198 energy available to spin a turbine, which in turn drives a generator that produces electricity. The greater the quantity of water, the greater the number and size of turbines that may be spun and the greater the power output of the generators.9 In times of drought, water to hydro electricity systems are limited...