Solar-power replacement as a solution for hydropower foregone in US dam removals

Article metrics


There is a growing dam removal movement in the United States, driven in part by environmental, safety and cost considerations. These include electricity-producing hydro-dams, many of which are ageing and will require substantial maintenance or removal over the coming decades. However, hydropower has been and remains an important source of energy for the development of the United States, presently generating about 6% of the nation’s electricity while providing essential grid services. As a potential solution to the conflict between these imperatives, industrial-scale photovoltaics (PVs) could be used for replacement of the energy foregone from hydro-dam removals either by installing the PV infrastructure in the area formerly inundated by the dam reservoir or through offsite replacement. Presently, the total PV generation in the conterminous United States is 35,919 GWh yr−1, or approximately 13% of hydropower generation. On the basis of actual hydropower generation in the conterminous United States in 2016 (that is, 274,868 GWh yr−1), we estimated that 529,885 ha of PVs would be needed to replace the generation of all 2,603 hydro-dams—an area approximately equal to the land size of Delaware. PVs could replace the total annual energy produced from these dams while requiring only 13% of their existing reservoir area. If all the hydro-dams in the United States were removed and only 50% of the emergent land was used for PVs, 945,062 GWh yr−1 power could be generated, which is 3.44 times the current hydropower generation. These analyses are theoretical and do not consider costs, which would be highly site specific. Replacement by PVs without energy storage could not replicate the dispatchability and grid services provisions of existing hydropower facilities; however, improving battery storage capabilities may ameliorate this shortcoming. We suggest that PVs could replace much of the annual electricity output of hydro-dams in the United States while using substantially less land area and providing considerable environmental and ecological benefits.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Aspects of hydroelectric and PV generation.

base maps from US Census Bureau

Fig. 2: Relationship between existing hydropower and PV potential.

base map from US Census Bureau

Data availability

The data that support the findings of this study are available from the corresponding author upon request.

Code availability

The code associated with this paper is available from the corresponding author upon request.


  1. 1.

    National Inventory of Dams (US Army Corps of Engineers, accessed 22 September 2017);

  2. 2.

    Monthly Energy Review (US Energy Information Administration, 2018).

  3. 3.

    Bednarek, A. T. Undamming rivers: a review of the ecological impacts of dam removal. Environ. Manage. 27, 803–814 (2001).

  4. 4.

    McCartney, M. Living with dams: managing the environmental impacts. Water Policy 11, 121–139 (2009).

  5. 5.

    Freeman, M. C., Pringle, C. M., Greathouse, E. A. & Freeman, B. J. Ecosystem-level consequences of migratory faunal depletion caused by dams. Am. Fish. Soc. Symp. 35, 255–266 (2003).

  6. 6.

    Limburg, K. & Waldman, J. R. Dramatic declines in North Atlantic diadromous fishes. Bioscience 59, 955–965 (2009).

  7. 7.

    Brown, J. J. et al. Fish and hydropower on the U.S. Atlantic Coast: failed fisheries policies from half-way technologies. Conserv. Lett. 6, 280–286 (2013).

  8. 8.

    Dias, M. S. et al. Anthropogenic stressors and riverine fish extinctions. Ecol. Indic. 79, 37–46 (2017).

  9. 9.

    Langland, M. J. Sediment Transport and Capacity Change in Three Reservoirs, Lower Susquehanna River Basin, Pennsylvania and Maryland, 1900–2012 Open-File Report 2014–1235 (US Geological Survey, 2015).

  10. 10.

    Maheu, A., St-Hilaire, A., Caissie, D. & El-Jabi, N. Understanding the thermal regime of rivers influenced by small and medium size dams in eastern Canada. River Res. Appl. 32, 2032–2044 (2016).

  11. 11.

    Deemer, B. R. et al. Greenhouse gas emissions from reservoir water surfaces: a new global synthesis. Bioscience 66, 949–964 (2016).

  12. 12.

    2017 Infrastructure Report Card: Dams (American Society of Civil Engineers, accessed 5 October 2017);

  13. 13.

    Ho, M. et al. The future role of dams in the United States of America. Water Resour. Res. 53, 1–17 (2017).

  14. 14.

    Magilligan, F. J. et al. River restoration by dam removal: Enhancing connectivity at watershed scales. Elem. Sci. Anth. 4, 1–14 (2016).

  15. 15.

    Foley, M. M. et al. Dam removal: listening in. Water Resour. Res. 53, 5229–5246 (2017).

  16. 16.

    Lovett, R. A. Rivers on the run. Nature 511, 521–523 (2014).

  17. 17.

    McClenachan, L., Lovell, S. & Keaveney, C. Social benefits of restoring historical ecosystems and fisheries: alewives in Maine. Ecol. Soc. 20, 31 (2015).

  18. 18.

    O’Connor, J. E., Duda, J. J. & Grant, G. E. 1000 dams down and counting. Science 348, 496–497 (2015).

  19. 19.

    Quantifying the Value of Hydropower in the Electric Grid: Final Report (Electric Power Research Institute, 2013).

  20. 20.

    Hydropower Vision: A New Chapter for America’s 1st Renewable Electricity Source (US Department of Energy, 2016);

  21. 21.

    Waldman, J. Undamming rivers: a chance for new clean energy source. Yale Environment 360 (2015).

  22. 22.

    Macknick, J., Lee, C., Mosey, G., & Melius, J. Solar Development on Contaminated and Disturbed Lands Report No. TP-6A20-58485 (National Renewable Energy Laboratory, 2013).

  23. 23.

    Re-Powering America’s Land (Environmental Protection Agency, 2012).

  24. 24.

    Andorka, F. Tallahassee to move from hydro to solar. PV Magazine (2017).

  25. 25.

    Hernandez, R. R., Hoffacker, M. K. & Field, C. B. Efficient use of land to meet sustainable energy needs. Nat. Clim. Change 5, 353–358 (2015).

  26. 26.

    Walston, L. et al. Examining the potential for agricultural benefits from pollinator habitat at solar facilities in the United States. Environ. Sci. Technol. 13, 7566–7576 (2018).

  27. 27.

    Hernandez, R. R., Hoffacker, M. K., Murphy-Mariscal, M. L., Wu, G. C. & Allen, M. F. Solar energy development impacts on land cover change and protected areas. Proc. Natl Acad. Sci. USA 112, 13579–13584 (2015).

  28. 28.

    Turney, D. & Fthenakis, V. Environmental impacts from the installation and operation of large-scale solar power plants. Renew. Sust. Energ. Rev. 15, 3261–3270 (2011).

  29. 29.

    Denholm, P, Eichman, J. & Margolis, R. Evaluating the Technical and Economic Performance of PV Plus Storage Power Plants Report No. TP-6A20-68737 (National Renewable Energy Laboratory, 2017).

  30. 30.

    Denholm, P. & Trieu, M. Timescales of energy storage needed for reducing renewable energy curtailment. Renew. Energ. 130, 388–399 (2019).

  31. 31.

    System Advisor Model (National Renewable Energy Laboratory, 15 September 2017);

  32. 32.

    Ong, S., Campbell, C., Denholm, P., Margolis, R. & Heath, G. Land Use Requirement of Solar Power Plants in the United States Report No. TP-6A20-56290 (National Renewable Energy Laboratory, 2013).

  33. 33.

    Johnson, M. M., Kao, S.-C. Samu, N. M. & Uria-Martinez, R. Existing Hydropower Assets. HydroSource (Oak Ridge National Laboratory, 2019).

  34. 34.

    American Fact Finder (US Census Bureau, 2010);

Download references


We thank the JPB Foundation and the City University of New York for funding and A. Cak and C. Vörösmarty for facility support and discussions.

Author information

J.W. took the lead in conceiving and conducting the analysis and in writing the paper. S.S., S.A. and B.F. helped plan the analysis, contributed to the interpretation of the results and helped write the paper.

Correspondence to John Waldman.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Further reading