Climate change may impair electricity generation and economic viability of future Amazon hydropower

https://doi.org/10.1016/j.gloenvcha.2021.102383Get rights and content

Highlights

  • >350 large hydropower dams have been identified for construction in the Amazon basin.

  • Climate change will induce large-scale alterations in river hydrology basin-wide.

  • Frequency of zero hydropower generation increases and full-capacity operation decreases.

  • Mean hydropower generation decreases by ∼ 30% under worst-case climate change scenario.

  • Future Amazon hydropower’s levelized cost of electricity ($ MWh−1) increases substantially under climate change.

Abstract

Numerous hydropower facilities are under construction or planned in tropical and subtropical rivers worldwide. While dams are typically designed considering historic river discharge regimes, climate change is likely to induce large-scale alterations in river hydrology. Here we analyze how future climate change will affect river hydrology, electricity generation, and economic viability of > 350 potential hydropower dams across the Amazon, Earth’s largest river basin and a global hotspot for future hydropower development. Midcentury projections for the RCP 4.5 and 8.5 climate change scenarios show basin-wide reductions of river discharge (means, 13 and 16%, respectively) and hydropower generation (19 and 27%). Declines are sharper for dams in Brazil, which harbors 60% of the proposed projects. Climate change will cause more frequent low-discharge interruption of hydropower generation and less frequent full-capacity operation. Consequently, the minimum electricity sale price for projects to break even more than doubles at many proposed dams, rendering much of future Amazon hydropower less competitive than increasingly lower cost renewable sources such as wind and solar. Climate-smart power systems will be fundamental to support environmentally and financially sustainable energy development in hydropower-dependent regions.

Introduction

Global climate change is projected to alter water balances in many parts of the tropics and subtropics (IPCC, 2013), where much of the world’s untapped hydropower potential remains (Zarfl et al., 2015). If annual river discharges decrease or become more variable, projections based on historic flow records run the risk of overestimating both the magnitude and reliability of future hydropower production. Thus, while the global proliferation of hydropower dams can be a means for climate change mitigation depending on their location and design (Almeida et al., 2019b, Muller, 2019, Ocko and Hamburg, 2019), hydropower is paradoxically sensitive to the problem it is proposed to mitigate.

A global study of ∼ 25,000 hydropower facilities projected negative effects of climate change on hydropower generation capacity in up to 75% of existing hydropower plants worldwide by the middle of the century (van Vliet et al., 2016). Climate change-induced alterations in hydropower generation are projected to be spatially heterogeneous across the world (Turner et al., 2017). In South America, where a large fraction of future hydropower dams may be developed (Zarfl et al., 2015), greenhouse gas (GHG) emission scenarios derived from an ensemble of 25 general circulation models (GCMs) point to substantial overall reductions in precipitation and runoff by the end of the century (Brêda et al., 2020). A large proportion of the proposed hydropower production for South America will occur in the Amazon basin, Earth’s largest and most biologically diverse river system where over 350 potential hydropower dam sites with installed capacities above 1 MW have been identified (Almeida et al., 2019b). Yet, the Amazon is the region in South America where hydrologic effects of climate change tend to be most pronounced (Brêda et al., 2020).

Existing studies on the effects of climate change on Amazon hydropower have focused on Brazilian dams, and forecasted decreased hydropower production linked to overall rainfall reduction and increased frequency of prolonged droughts (Lima et al., 2014, Von Randow et al., 2019). For example, annual hydropower generation at Teles Pires—a large hydropower plant recently built in the southeastern Amazon—is expected to decrease by the end of the century across multiple climate change scenarios (Mohor et al., 2015). Reductions in discharge and consequently hydropower generation persist in the Amazon region even under basin-wide changes in land use, as has been projected for dams in Brazil’s Xingu (Stickler et al., 2013), Tocantins (Von Randow et al., 2019), and Tapajós basins (Arias et al., 2020).

In order to respond to concerns over environmental damage, most future hydropower dams in the Amazon lowlands will be operated as run-of-river (i.e., downstream outflow discharges approximately equal upstream inflow discharges) (Lima et al., 2014), making hydropower generation particularly sensitive to changes in discharge (Arias et al., 2020). Ultimately, climate change-induced shifts in electricity generation may jeopardize the financial feasibility of future Amazon hydropower projects (Mendes et al., 2017). By midcentury, annual losses in hydropower revenues in Brazil’s hydropower-dominant power system may exceed US$5bn owing to anticipated climate shifts (de Queiroz et al., 2019). Large dams require significant financial investments, and ultimately these river infrastructure projects result in tradeoffs between energy production and a suite of negative social and ecological impacts (Almeida et al., 2019b, Grumbine and Xu, 2011, Latrubesse et al., 2017, Schmitt et al., 2019). Thus, forecasts of hydropower production under changing climate are critical for achieving informed energy planning that can balance energy production with negative impacts to human and nature.

While existing studies provide relevant forecasts of changing hydropower dynamics expected at a subset of projects, a spatially extensive analysis to address the diversity of climatic and hydrologic settings across the Amazon basin is lacking. Here we combine a database on 351 proposed hydropower dams throughout the Amazon basin (Almeida et al., 2019b) with bias-corrected outputs of 25 GCMs from CMIP5 (WCRP Coupled Model Intercomparison Project Phase 5) and a continental-scale hydrologic model (Brêda et al., 2020). First, we estimate climate change-induced alterations in river discharge and hydropower generation at proposed dam sites by the middle of the century (2046–2065). Then, we examine whether projected alterations in electricity generation under climate change can affect the economic competitiveness of Amazon hydropower.

Section snippets

Amazon hydropower expansion

We use a database of 351 proposed dams with over 1 MW of installed capacity in the Amazon basin (Fig. 1A) (Almeida et al., 2019b). These dams have a combined installed capacity of nearly 92 GW—three times the installed capacity of all existing Amazon hydropower dams. Brazil has the largest number of proposed dams (2 1 2), followed by Peru (85), Ecuador (36), Bolivia (16), and Colombia (2). Proposed Peruvian dams hold the largest aggregate installed capacity (34.7 GW), followed by Brazilian (33.8

Changes in river discharge

For the Amazon as a whole, there is an overall trend of decreased midcentury discharge at proposed dam sites (median change: −13% under RCP 4.5 and − 20% under RCP 8.5) (Fig. 1B,C and Fig. 4A). However, projected changes in discharge at proposed dam sites vary widely across the basin, ranging from strongly negative in the east to slightly positive in the west (Fig. 1 and Fig. 4). In the Brazilian Amazon, projected discharge change is negative for all proposed dams under either RCP 4.5 (median

Conclusions

Our analyses depict outcomes under a scenario where no action is taken to design future hydropower projects that are resilient to changing hydrologic regimes. We find that if proposed Amazon dams are built to current specifications assuming historic discharge regimes, hydropower generation and economic viability may be seriously compromised under changing climate conditions by the middle of the century. To balance the benefits and costs of hydropower dams—the latter of which extend beyond

CRediT authorship contribution statement

Rafael M. Almeida: Conceptualization, Methodology, Formal analysis, Investigation, Data curation, Writing – original draft, Supervision, Funding acquisition. Ayan S. Fleischmann: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing - review & editing. João P.F. Brêda: Methodology, Software, Formal analysis, Data curation, Writing - review & editing, Visualization. Diego S. Cardoso: Methodology, Software, Writing - review & editing, Visualization.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by Cornell University’s Atkinson Center for Sustainability through a Postdoctoral Fellowship to R.M.A. and the Atkinson Academic Venture Fund. We thank all participants of the Amazon Dams Computational Sustainability Working group and appreciate helpful comments from the Cornell Limnology Group.

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