Hydropower plans in eastern and southern Africa increase risk of concurrent climate-related electricity supply disruption

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. 1Grantham Research Institute on Climate Change and the Environment, London School of Economics and Political Science, Houghton Street, London, UK. 2Institute for Sustainable Resources, Bartlett School of Environment, Energy and Resources, University College London, London, UK. 3Department of Geography, Geo-informatics and Meteorology, University of Pretoria, Pretoria, South Africa. 4Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK. *e-mail: [email protected] Hydropower comprises 20.2% of installed electricity production capacity in sub-Saharan Africa (SSA) and is on an upward trajectory1. Hydropower accounts for over 90% of electricity generation in the Democratic Republic of Congo, Ethiopia, Malawi, Mozambique, Namibia and Zambia. Dam building in Africa has recently entered a phase of renewed activity, through a mix of domestic and international collaborations, many with China (Fig. 1; ref. 2). Rainfall in SSA shows pronounced variability, including prolonged drying across the Sahel since the early 1970s with some recovery in the last two decades3, relative stability punctuated by extreme wet years in eastern Africa4 and high interannual and multiyear variability in southern Africa5. Rainfall variability is responsible for significant fluctuations in lake levels and river flow, creating challenges for effective management of water resources4. The threat to hydropower generation is marked, and, due to the sector’s significant and rapidly growing contribution to electricity supply in SSA, climate-induced supply insecurity represents a critical source of economic and societal risk. The significance of fluctuations in hydropower depends on its contribution to the overall electricity system. If it is complementary to other sources as in the USA and Western Europe6, then this variability may be less of a problem, although still challenging. For example, reduction in India’s hydropower of at least 15% in 2016 was associated with low reservoir levels at multiple sites7. Whilst the contribution of hydropower to total capacity in the USA has declined to 7%, the interannual variability of hydropower generation is very high. For example, a fall of 21% (59 million megawatt hours (MW h)) of the USA’s total hydropower generation occurred from 2000 to 20018. Drought in California directly impacted hydropower generation at multiple sites across the state, with an estimated equivalent of 2.8 million fewer homes powered by hydropower in 2014 as compared with a very wet year in 20119. In cases where hydropower dominates the electricity supply mix, as in Brazil, Norway and many countries in SSA, climate variability is more of a problem. In Brazil hydropower plants comprise about 80% of electricity generation10, and even though there is significant geographical dispersion of sites and integration through transmission capacity6, reservoir levels at several major sites experienced dramatic decline during drought in 2013–15, negatively affecting production. For example, in 2014 and 2015, generation by the 14 GW Itaipu hydropower plant on the Parana River was around 6 and 3.5 million MW h, respectively, below the most recent 5-year mean11. Chronic energy scarcity and episodic supply disruption are widespread in SSA. The economic cost of power outages has been estimated at 5–7% of the gross domestic product (GDP) for Malawi, South Africa and Tanzania12. Studies of specific events highlight major consequences of reductions in electricity production associated with drought; for example, in Kenya a 25% reduction in hydropower in 2000 resulted in an estimated 1.5% reduction in GDP13. Drought-associated disruption to hydropower in the Zambezi basin during 1991–92 led to an estimated US$102 million reduction in GDP and a US$36 million reduction in export earnings13. Recent conditions during the El Niño of 2015–16 highlighted the scale of concurrent hydropower disruption associated with widespread drought in SSA. Malawi, Tanzania, Zambia and Zimbabwe all experienced electricity outages (load shedding) due to low rainfall14–16. In May 2015, low water levels at the Lake Kariba reservoir contributed to a reduction in hydropower generation. That month, the country’s national power utility warned that it might cut power supplies by one-third and the Finance Minister reduced the forecast for national GDP growth to 5.8% from more than 7%, in anticipation of power rationing and reduced copper prices17. The share of hydropower in SSA is likely to grow rapidly, as major investments are ongoing and planned. The Programme for Hydropower plans in eastern and southern Africa increase risk of concurrent climate-related electricity supply disruption