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Floating photovoltaics may reduce the risk of hydro-dominated energy development in Africa

Nature Energy (2024)Cite this article

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Abstract

Floating photovoltaics (FPV) is fast becoming cost-competitive, but its social and environmental impacts are under debate. Meanwhile, developing economies anticipate hundreds of new dams over the next decade, with social and environmental implications for the next century. In this context, we estimate that FPV could produce 20–100% of the electricity expected from Africa’s planned hydropower depending on the scale of FPV deployment and its cost and efficiency relative to land-based photovoltaics. Here, at the system scale, we show that the same capital investment earmarked for planned dams in the Zambezi watercourse could be used more efficiently by building fewer reservoirs and substituting the energy supply with FPV. This approach yields an energy output 12% less variable and more robust to long-term hydrological changes. Our findings suggest that FPV’s potential to avoid the environmental, social and financial risks of hydro-dominated energy development may outweigh its potential impacts on existing reservoir uses.

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Fig. 1: FPV electricity production could match or exceed that of planned hydroelectric dams in Africa.
Fig. 2: OSeMOSYS-TEMBA scenarios of FPV capacity expansion and displacement of LPV and other technologies through 2050.
Fig. 3: Solutions of reservoir operation and joint hydropower–FPV capacity expansion along the Pareto tradeoff of operational savings (OPEX) and capital expenditure (CAPEX).
Fig. 4: Variability of electricity supply in hydropower–FPV capacity expansion solutions for the ZW.

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Data availability

Data for the OSeMOSYS-TEMBA model, the ZW-SAPP experiments and the post-processing scripts for developing figures are available from the open-source repository Zenodo at https://doi.org/10.5281/zenodo.10576226 (ref. 60). The historical hydrologic data on the Zambezi River Basin are protected by a nondisclosure agreement with Zambezi River Authority (ZRA). However, the climate model data used for the temperature and precipitation projections are freely available at http://www.csag.uct.ac.za/cordex-africa/ (ref. 61).

Code availability

The OSeMOSYS-TEMBA model18 is available from the open-source repository Zenodo at https://doi.org/10.5281/zenodo.7931050 (ref. 62). As the ZW reservoir operations simulation model contains sensitive hydrologic data and hydropower plant characteristics from the Zambezi River Authority (ZRA), Zambia Electricity Supply Corporation (ZESCO) and Hidroeléctrica de Cahora Bassa (HCB), it cannot be made public. The code of the HBV model for streamflow simulation is available from the open-source repository Zenodo at https://doi.org/10.5281/zenodo.5726941 (ref. 63). The PowNet model developed for the SAPP is available on GitHub at https://github.com/EILab-Polimi/ZRB-PowNet (ref. 64).

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Acknowledgements

This work was completed under the GoNexus project and funded by the European Union Horizon Programme call H2020-LC-CLA-2018-2019-2020 (grant agreement number 101003722; funding received by W.A., M.G. and A.C.).

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  1. Department of Electronics, Information and Bioengineering, Politecnico Di Milano, Milan, Italy

    Wyatt Arnold, Matteo Giuliani & Andrea Castelletti

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Contributions

W.A., M.G. and A.C. designed the research. W.A. conducted the numerical experiments, and led the data analysis and the writing of the original paper’s draft. M.G. and A.C. contributed to the analysis of results, review and editing of the paper.

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Correspondence to Andrea Castelletti.

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Nature Energy thanks AFM Kamal Chowdhury, Jordan Kern, Hamid Pouran and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Arnold, W., Giuliani, M. & Castelletti, A. Floating photovoltaics may reduce the risk of hydro-dominated energy development in Africa. Nat Energy (2024). https://doi.org/10.1038/s41560-024-01510-0

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