Hydropower can be a source of cost-effective, reliable electricity generation. Indeed, it has been historically a source of renewable energy for the world before solar and wind power became more economical in the last decade.

Role in global electricity mix

Hydroelectricity is the largest source of renewable energy, constituting 40% of all renewable capacity followed by solar (28%) and wind (27%). In the total electricity generation worldwide, all low-carbon sources (hydro, solar, wind, nuclear and biosolids) make around 16%, with 84% coming from fossil fuels.

In the total electricity generation worldwide, all low-carbon sources (hydro, solar, wind, nuclear and biosolids) make around 37%, with 63% coming from fossil fuels. Top 5 countries with largest hydroelectric generation / installed capacity are China, Brazil, US, Canada and Russia.

Hydroelectricity makes 40% of renewable energy globally and one-third of renewables in the US. The US neighbour, Canada relies on hydel for 60% of its electricity needs. Several countries rely on hydro for more than 50% of their electricity generation – eg, Norway (over 95%), Iceland (>70%), Nepal (99%), Bhutan (>90%), Brazil (55%), Congo (>95%) and Paraguay (almost 100%).

This infographic depicts the 5 largest hydroelectric dams in the world – the largest is China’s 22.5 GW Three Gorges Dam.

Generally hydroelectric projects (especially with no or little storage, that is, run-of-the river) can have significant seasonal variations in power outputs with large water flows (and hence high power generation) from melting of glaciers in the summer. While hydel projects are capital intensive, significantly long lives and no expensive “fuel” requirements mean they can be economical sources of electricity relative to other conventional sources.

Hydroelectric dams (involving large upstream reservoirs) can also be used to monitor water flows and control flood. However, they can have adverse sustainability concerns such as disrupting wildlife, degrading water quality, causing natural disasters (eg earthquakes), disrupting natural flow of rivers (and resulting in flooding), and causing food insecurity for people living downstream.

Hydropower in the US

In the US:

Hydropower is the second largest source (wind being the largest) of renewable electricity generation in the US, accounting for 6.1% of total electricity generation in 2021.

  • Fossil fuels contributed the most (61%) to electricity generation, followed by renewables (19.8%) and nuclear (18.9%).
  • Top 30 hydropower plants account for around 50% of US hydel generation annually, and 10 of these top 30 plants are in Washington.

Climate change and hydropower

Hydropower is a great source of clean energy and a significant part of the world’s decarbonization journey to mitigate climate change and achieve net zero emission target. However, climate change can also affect hydropower as we have seen last year (2022) when drought like conditions or low water flows reduce power generation in Europe and even can make hydroelectric dams significantly less economical in California.

Dry conditions and droughts are putting hydropower generation under stress in some regions, casting doubts about its future. As of 2022, California, Nevada, Arizona, Utah, and New Mexico were among the hardest-hit states by dry conditions, which has affected both their hydropower generation and reservoir storages. See the following infographics from Visual Capitalist and commentary at https://decarbonization.visualcapitalist.com/how-droughts-threaten-the-future-of-hydropower/.

“In most drought-hit states, hydropower’s share of electricity generation has fallen over the last two decades. For instance, California’s hydropower generation dropped from 25.5 million megawatt-hours (MWh) in 2001 to 17.3 million MWh in 2022. Over that same period, hydropower’s share of California’s electricity generation fell from 13% to 8%. Besides the long-term declines in hydroelectric generation, water levels at some reservoirs are precariously low….Notably, Lake Mead (Hoover Dam) and Lake Powell (Glen Canyon Dam)—the top two largest U.S. reservoirs by capacity, respectively—have alarmingly low storage levels with less than one-third of total storage filled.”

How to mitigate the climate change risks to hydropower?

Diversifying power generation sources (preferably with solar and wind), expanding grid and interconnections to improve reliability of supply, building energy storage systems and reducing or managing the customer demands through retrofitting and energy-efficient technologies are the obvious measures to mitigate the climate change risks. Each solution will need to be assessed for its technical and economic viability and tailored to the country or region.

Here is the answer that ChatGPT offers on making our power grid more climate-resilient:

  • “Diversify Energy Sources: Relying on a single energy source for power generation can be risky in the face of climate change impacts. Diversifying energy sources such as incorporating renewable energy like solar, wind, and hydropower, along with traditional sources like natural gas and nuclear power, can help reduce vulnerability to climate-related disruptions. Renewable energy sources are often less dependent on fossil fuels, emit fewer greenhouse gases, and are generally more resilient to extreme weather events.
  • Upgrade and Harden Infrastructure: Upgrading and hardening power grid infrastructure can make it more resilient to climate-related risks. This includes improving transmission and distribution lines, substations, and transformers to better withstand extreme weather events such as hurricanes, floods, and wildfires. Ensuring that critical infrastructure is built to withstand higher temperatures, increased precipitation, and other climate-related hazards is essential to enhancing resilience.
  • Enhance Monitoring and Early Warning Systems: Investing in advanced monitoring and early warning systems can help predict and respond to climate-related risks. This includes utilizing weather forecasting technologies, remote sensing, and other monitoring tools to detect and anticipate potential disruptions. Early warning systems can provide advanced notice of extreme weather events, allowing for proactive measures to be taken to protect power grid infrastructure and minimize downtime. 
  • Improve Grid Management and Operations: Enhancing grid management and operations can improve resilience to climate change impacts. This includes investing in smart grid technologies that enable real-time monitoring and control of the grid, as well as advanced energy management systems that can optimize power generation, distribution, and storage. Improving grid management and operations can enhance the ability to respond to changing weather conditions and minimize disruptions. 
  • Establish Redundancy and Backup Systems: Building redundancy and backup systems can help ensure continuity of power supply during climate-related disruptions. This can include redundant power generation capacity, energy storage systems, and multiple transmission routes to minimize the risk of a single point of failure. Backup power sources such as diesel generators or microgrids can provide critical power supply during emergencies. 
  • Engage in Community and Stakeholder Collaboration: Collaboration with local communities, stakeholders, and other relevant parties is crucial for climate resilience. Engaging in collaborative planning, decision-making, and coordination can help identify vulnerabilities, prioritize actions, and implement appropriate measures to enhance power grid resilience. Community involvement can also help increase awareness, preparedness, and response to climate-related risks. 
  • Plan for Future Climate Scenarios: Incorporating climate change projections and scenarios into power grid planning and design can help ensure long-term resilience. Considering potential changes in temperature, precipitation, sea level rise, and extreme weather events can inform infrastructure design, location, and operational practices. Planning for future climate scenarios can help build a power grid that is resilient to changing climatic conditions. 

In conclusion, making a power grid more climate resilient requires a multi-faceted approach that involves diversifying energy sources, upgrading infrastructure, enhancing monitoring and early warning systems, improving grid management and operations, establishing redundancy and backup systems, engaging in community collaboration, and planning for future climate scenarios. Implementing these strategies can help mitigate the impacts of climate change on the power grid and ensure reliable and resilient power supply in the face of changing weather patterns.”