The impact of water scarcity on hydropower supplies is being witnessed across various regions of the world. In August 2022, the government of Sichuan in China initiated power rationing when drought led to reductions in reservoir levels and hydropower generation, bringing production to a two-week halt in the energy-intensive industry. Whilst in Europe, hydro generation in Italy, France and Portugal fell by over 11,200GWh during the first half of the year when compared with previous years.
Recent research also shows that climate-driven changes in drought have the potential to disrupt hydro-dependent electricity systems. Focusing on the Western US, Qiu et al reported in The Proceedings of the National Academy of Sciences that reduced hydropower production during extreme drought conditions can lead to electricity generation from individual fossil fuel plants increasing up to 65%, mainly to compensate for hydro shortages.
Indeed, the US’ Pacific Northwest is described as facing unique challenges with regards to the management of its reservoirs and hydropower systems, with states such as Washington recording more rainfall when it doesn’t need it and less when it does. Such a predicament is facing the electricity company Seattle City Light. The utility’s hydropower reserves are peaking earlier in the year, widening a summer gap in resources when there’s insufficient water to generate much-needed electricity due to hotter summers driving air conditioning energy demands up.
Consequently, City Light has had to resort to sourcing power from elsewhere, which is proving to be expensive – so much so that last October it announced a 4% rate hike to customers to replenish more than $70m it had eaten up in its emergency reserves. Adaptation and diversification are now necessary, the utility says, and it is relying more heavily on wind and solar power to make up for the gaps in its summer reserves.
Despite December precipitation being 113% above normal at the end of 2023, the hydropower generation outlook across the Pacific Northwest was still described as remaining below normal in February 2024. The current water year (running from October to September) has been mostly drier and warmer than normal which hasn’t been good for building snowpack reserves. As snowpack usually peaks in April across the region, there is still hope that it can catch up.
Dalles Dam on the Columbia River is located on the Oregon and Washington borders and is described as being a barometer for hydro conditions in the region. For April- September 2024 water supplies at the dam are forecast as being 2% lower than a year ago at 79% of normal. In January 2024 inflows into the dam were 14% less month on month and almost 30% down on the past three years.
Canada powers on
In Canada, BC Hydro experienced a record year of drought in 2023, with historically low water levels at many of its reservoirs. Although the utility reported later in December that rainfall events had refilled many of its smaller hydro facilities in the Lower Mainland and on Vancouver Island, its larger reservoirs in the north and southeast of the province were still below normal levels.
However, when extremely cold temperatures spread cross the province in January 2024, driving up peak hourly electricity demand to a record high, power imports were not required, and BC Hydro also had enough generating capacity to provide support to its neighbours in Alberta and the Pacific Northwest who were experiencing demand and system challenges.
“Extreme weather events like drought and cold snaps are putting people and communities at increased risk,” said Josie Osborne, Minister of Energy, Mines and Low Carbon Innovation. “Thanks to the resiliency of our energy system and exceptional planning by BC Hydro, we are able to meet the needs of British Columbians while also delivering clean, reliable hydroelectricity to our neighbours in Alberta when they need it most.”
Although the historic drought has impacted some of BC Hydro’s largest reservoirs, it has been planning in real-time for over a year to manage these conditions. Tools it has utilised include multi-year reservoir storage, regional diversity in its generating facilities, contracts for power, and the ability to import and export power through the Western Interconnection – a network of high-voltage transmission lines that connects BC with other utilities in western North America.
“BC is fortunate to have an integrated, provincial hydroelectric system that allows us to ramp up quickly when generation is needed and scale back when it is not,” Chris O’Riley, BC Hydro’s President and CEO, said. “Our teams carefully plan and prepare for cold weather events like this to ensure our generating facilities are running at full capacity so we can deliver clean electricity to our customers when they need it the most.”
Assessing risks
In a working paper produced for the Granthan Research Institute on Climate Change and the Environment, Senni and von Jagow say that their research strengthens the evidence about the negative effects of water-related risks and changes in water availability on hydropower. Previously research has alluded to the fact that 61-74% of 24,500 global hydropower projects would be impacted by climate-driven changes in hydrology, while by 2050 risks will increase by a third for existing and projected dams located within river basins that currently have medium to high water risks.
The authors say that their current research presents statistical evidence that water-related risks are material to hydroelectricity generation and, as far as they know, is the only study that provides estimates of the effect of water scarcity on hydroelectricity generation for high-income economies.
“This is important,” they explain, “because much of the literature on economic impacts on natural resource scarcity is focused on developing economies, arguably because they have a higher dependence on their natural resource base. However, it is important to note that vulnerabilities to natural resource also exist in developed economies.”
Using data on plant location and operating capacity, hydro generation at the plant level, power plant type, water-related risks, hydro-meteorological and reservoir data, Senni and von Jagow’s final sample included 1141 power plants from 14 European countries and 47 US states, over a sample period of 2015-2021.
They believe their findings help identify research needs in three important areas:
- Understanding the future risks to hydroelectricity generation from changing water availability and how they could be addressed.
- Exploring how these risks spill over into other sectors and the financial system.
- Extending the understanding of the relationship between nature and the economy to include further ecosystem services.
Hydropower will be crucial to the transition to renewable energy but the effects of climate change on water scarcity will determine the effectiveness of such projects, the authors warn. They add that the findings of their paper can be used for planning as well as for calibrating economy-wide models that endogenise hydroelectricity generation.
Future research is still needed though and should focus on exploring heterogeneity across regions to better project future impacts due to environmental, as well as developing water availability scenarios. An analysis of spillover effects and ownership relationships would help translate water-related risks into financial losses while, the authors add, a deeper understanding of the vulnerability of individual hydropower plants and how adaptation measures can reduce it, is crucial.
This article first appeared in International Water Power magazine.
