Clean technology series: hydroelectric power – an overview

Continuing our series of articles relating to clean technology, hydroelectric power is a cornerstone of the global energy system. With global installed capacity exceeding 1,400 GW, hydroelectric power supplies approximately 15% of the world’s electricity, surpassing all other renewable sources combined, including wind, solar photovoltaic, bioenergy, and geothermal[i].

In this instalment of our clean technology series, we explore the hydroelectric power landscape, considering challenges and the outlook for the future.

Technology

At a high level, the generation of electricity in a hydroelectric power plant is straightforward. Flowing water passes through a turbine which in turn drives generators. Implementations of hydroelectric power plants vary substantially.

The most common implementation of hydroelectric power is in dams. The energy generated depends on the volume of water that passes through the turbine(s) and the difference in height between the water source and the outflow, often referred to as the “head”.  The Three Gorges Dam in central China is an example of such a hydroelectric power plant and is the largest power-producing facility of any kind in the world[ii].

Another common implementation is pumped storage hydropower (PSH). A PSH power plant functions as a large-scale energy storage system, essentially acting like a giant rechargeable water battery. A PSH power plant utilizes two reservoirs at different elevations. During periods of low electricity demand or abundant generation from other power sources (like wind and solar), water is pumped from the lower reservoir to the upper reservoir. When electricity demand is high, the water is released back down to the lower reservoir through turbines to generate power. As of 2023, PSH was by far the dominant form of utility-scale energy storage globally[iii].

Run-of-river hydroelectric power plants are an increasingly common implementation of hydroelectric power. Unlike more conventional hydroelectric power plants, run-of-river plants have little or no water storage. Water from a river is channelled through a canal or penstock to drive a turbine. Accordingly, although run-of-river power plants have little or no capacity for energy storage, they are relatively cheap to build and avoid many of the environmental considerations associated with the construction of large water reservoirs.

Hydroelectric power offers significant benefits. Once constructed, a hydroelectric power plant produces no direct waste and emits considerably less greenhouse gases than fossil-fuel-powered plants over their lifetime[iv]. Furthermore, hydropower is a flexible source of electricity as the power output of hydroelectric plants can be ramped up and down very quickly to adapt to changing energy demands. In some implementations, it can take less than 10 minutes to bring hydroelectric power units up to full load, quicker even than power units of almost all fossil fuel power plants[v]. This flexibility can facilitate greater use of less consistent renewable power sources like wind and solar by ensuring grid stability.

Challenges

Although hydroelectric power is a valuable renewable energy source, it comes with its own unique challenges that require careful consideration.

For example, hydroelectric power is susceptible to climate variability. 2023 saw a notable decrease in hydroelectric power generation by over 100 TWh (more than 2% of total electricity generation from hydropower) to approximately 4,250 TWh[vi]. This decline was primarily attributed to widespread drought conditions affecting major hydropower-producing countries, including China, India, Canada, the United States and Vietnam. Historically viewed as a highly reliable baseload power source due to its use of “predictable” water flows, the growing frequency and severity of droughts in key regions are increasingly challenging this perception.

As another example, the turbines used in the generation of electricity can pose a risk to fish in the water used to drive the turbines. Although there is significant variability in the mortality rate of fish that pass through the turbines, it is clear that hydroelectric turbines can represent a threat to biodiversity[vii]. Specialised fish passages have been developed to prevent fish from entering turbines. However, these come with their own challenges, only being suitable for certain varieties of fish and often expensive to implement.

Future outlook

While worldwide hydroelectric power generation is substantial and growing in absolute terms, its rate of growth has not outpaced the combined expansion of other major energy sources, including the rapid deployment of wind and solar photovoltaic generation. Although hydroelectric power is currently the preeminent renewable energy source, the expansion of other renewable energy sources suggests that hydroelectric power is likely to be dethroned in the future, perhaps even by 2030[viii].

Patenting activity data provides valuable insights into innovation trends, technological focus areas, and geographic centres of research and development within the energy sector. While hydroelectric power is mature, patenting activity continues, reflecting ongoing efforts to improve the technology to address the challenges being faced.

According to a 2024 report by WIPO, published patent applications relating to “hydro energy” constituted 11.4% of all energy-related patent applications (including solar energy, fuel cell, wind energy, geothermal energy, and hydro energy) from 2020-2022[ix]. This places hydro energy as the fourth largest category, aligning with the trend that other renewable energy sources are experiencing higher growth. China accounted for the largest share of published hydro energy patent applications globally at 39.9%, which aligns with China’s significant investment and construction activity in this sectorix.

Data from the EPO (shown in Figure 1) indicates a surge in applications relating to PSH[x], aligning with the so called “renaissance” of PSH as 214GW worth of PSH projects undergo development worldwide[xi].

Figure 1: the number of filed patent applications per year relating to pumped storage hydropower (PSH). Source: here.

Although patenting activity for hydroelectric power technology suggests that hydroelectric power is not the primary focus of renewable energy technology development, improvements are being made to make hydroelectric power more efficient and more sustainable.

For example, researchers are developing fish-friendly energy efficient turbines to help protect biodiversity. Existing hydroelectric power plants are increasingly being digitised, using sensor measurements to adjust the working conditions of hydropower turbines, thereby reducing operational costs and further reducing greenhouse gas emissions[xii]. Furthermore, AI is being used to optimise the efficiency of hydroelectric power plants, moving from reactive management to proactive management, allowing potential issues to be foreseen and operations adjusted accordingly to avoid faults and maintenance downtime[xiii].

Conclusion

Despite not exhibiting the same growth as other renewable energy sources, it is clear that hydroelectric power remains an extremely valuable asset in the journey to net zero.

For more information or advice on protecting your hydropower inventions, please get in touch with Joseph O’Leary, or your usual Venner Shipley contact.

[i] http://hydropower.org/publications/2024-world-hydropower-outlook

[ii] https://www.sterlingtt.com/2022/03/01/biggest-power-plants-world/

[iii] https://iea.blob.core.windows.net/assets/cb39c1bf-d2b3-446d-8c35-aae6b1f3a4a0/BatteriesandSecureEnergyTransitions.pdf

[iv] https://www.ren21.net/Portals/0/documents/Resources/GSR2011_FINAL.pdf

[v] https://www.eia.gov/todayinenergy/detail.php?id=45956

[vi] https://www.iea.org/energy-system/renewables/hydroelectricity

[vii] https://conbio.onlinelibrary.wiley.com/doi/10.1111/cobi.13870

[viii] https://www.iea.org/reports/hydropower-special-market-report/executive-summary

[ix] https://www.wipo.int/edocs/pubdocs/en/wipo-pub-941-2024-en-world-intellectual-property-indicators-2024.pdf

[xi]https://www.hydropower.org/factsheets/pumped-storage

[xii] https://www.waterpowermagazine.com/analysis/hydro-technology-development-8063274/?cf-view&cf-closed

[xiii] https://www.waterpowermagazine.com/analysis/harnessing-ai-to-transform-hydropower/?cf-view