| dc.description.abstract |
The intertwined climate and biodiversity crises are among the most challenging threats to human well-being in the Anthropocene. The energy-supply sector (including electricity and heat production) is the largest source of greenhouse gas emissions that contribute to climate change. The global community recognizes the urgency of decarbonizing the global energy sector: The goals of Agenda 2030 include universal access to sustainable energy through a transition to renewable energy sources. Hydropower, the oldest and historically most cost-effective renewable energy, has expanded renewable capacity but at the cost of free-flowing rivers. Increasing fragmentation of rivers by dams threatens freshwater biodiversity. Solar and onshore wind power, while competitive, intensify land competition, with protected areas being frequently sacrificed to development needs. Consequently, a large part of the global population is challenged to align the decarbonization of electricity networks with the need to protect biodiversity. In Africa, where half of the population lacks basic electricity access, the renewable energy transition implies considerable capacity expansion. Simultaneously, Africa is home to the Congo forest and river systems, crucial global biodiversity centres. The aim of this thesis is to investigate the current status and future expansion of renewable electricity among African countries and its implications on ecosystems and society. The Renewable Power Plant Database (RePP) Africa presents harmonized in-depth information on the most important renewable technologies. It includes geographical coordinates, country information, construction status, and capacity (in megawatts) for 1074 hydro-, 1128 solar, and 276 wind power plant entries. The number of records surpasses corresponding information in other accessible databases and aligns closely with cumulative capacity data reported by international energy organizations, with discrepancies of less than 13% for hydro-, below 23% for wind, and below 32% for solar power plants. Building on RePP Africa, the ecological, social, and political impacts of 507 proposed hydropower plants, potentially operating with dam and reservoir storage, were systemically assessed. Selected impact indicators include River Regulation, Fragmentation, Potential Evaporation, Resettlement, Protected Area, Land Use Change, Sediment Entrapment, and affected Megafauna. A total of 104 hydropower plants were found to cause severe impacts. Surprisingly, both the ten top- and bottom-ranked projects exhibited relatively small capacity sizes (45.77 and 47.34 megawatts (MW); mean of 152.46 MW), underscoring that assessing hydropower plant impact solely on capacity size is inadequate. A sensitivity analysis demonstrated that the ranking is influenced by the number of included hydropower plants and the choice of indicators. In contrast to hydropower, solar and wind power have potential to lead sustainable renewable energy pathways in the future, while releasing the dam building pressure on freshwater ecosystems. Based on RePP Africa, 76% of Africa’s electricity needs projected for 2040 could be met by renewable energy, with a remaining technical potential of >99% each for wind and solar photovoltaic systems, and 51% for hydropower. Considering the assessed impacts of future hydropower, efficiently combining existing hydropower with wind and solar will be more sustainable than constructing hydropower plants alone. As resource potential differs among regions, transnational electricity sharing can support a more efficient resource exploitation. Further options to optimize renewable electricity exploitation cover maintenance, co-use, and replacement. Past hydropower plant failure has diminished available capacity by 24%, pointing out that plant maintenance can optimize performance (maintenance potential). Covering 40% of each existing hydropower reservoir with floating photovoltaics could provide 22,596 terawatt hours (TWh) of electricity which equals 41 times the electricity from proposed hydropower capacity (co-use potential). In general, all 36 African countries could replace proposed hydroelectricity generation by fully exploiting feasible onshore wind and solar photovoltaic potential with a mean surplus of 371 TWh per year (replacement potential). Yet, the effects of solar and wind infrastructure on environmental and social systems require improved understanding before their unhindered expansion can be promoted. In conclusion, the results of this thesis improve the evidence-based understanding on how renewable electricity generation and river conservation are linked. The findings can support discussions on future pathways to tackle the intertwined climate and biodiversity crises. In this regard, Africa possesses not just the capability to avoid an era of extensive reliance on fossil fuels by transitioning to renewable electricity generation but also to incorporate considerations of river conservation and trade-offs in renewable infrastructure into its renewable electricity planning. |
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