Is Hydropower The Best Renewable Energy Source?
Hydropower, or hydroelectric power, is one of the oldest and largest sources of renewable energy that uses the natural flow of water to generate electricity. Hydropower has played a major role in the world’s renewable energy portfolio for decades, providing a stable baseload power source in many regions. However, in recent years there has been an increasing debate around whether hydropower should continue to be considered a top renewable energy source given concerns around its environmental impacts.
This article explores the central question of whether hydropower is the “best” renewable energy source available today. We will examine the benefits and drawbacks of hydropower and compare it to other leading renewable sources like wind and solar. Key factors that will be analyzed include cost, scalability, reliability, sustainability, and environmental impacts. By the end, we will have a more nuanced understanding of hydropower’s strengths and weaknesses in the modern renewable energy landscape.
Background on Hydropower
Hydropower harnesses the energy of flowing or falling water to generate electricity. A hydropower plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity (Energy.gov, 2022).
Humans have been using hydropower for thousands of years, starting with the ancient Greeks using water wheels for grinding grain. In the late 19th century, hydropower plants began generating electricity. The first hydroelectric power plant opened on the Fox River in Appleton, Wisconsin in 1882 and began transmitting electricity in 1886 (Hydropower.org, n.d.).
Today, hydropower is used in over 160 countries, meeting 16% of the world’s electricity demands. China has the highest installed capacity at 352 GW, followed by Brazil, Canada, the United States, and Russia. Hydropower accounts for 71% of electricity generation in Canada, 67% in Brazil, and 57% in Switzerland (International Hydropower Association, 2019).
Advantages of Hydropower
Hydropower offers some significant advantages as a renewable energy source. Firstly, hydropower is renewable and sustainable. The fuel source, flowing water, is continuously replenished through the natural water cycle (Department of Energy, 2022). Unlike fossil fuels which are finite, hydropower can theoretically produce electricity indefinitely.
Secondly, hydropower produces no direct waste or emissions when generating electricity. The process does not involve burning fuel, so it emits no greenhouse gases or air pollutants (Enel Green Power, 2022). This makes hydropower one of the cleanest energy sources available.
Lastly, hydropower is very flexible and can meet peak electricity demands. The flow of water driving the turbines can be rapidly adjusted to produce more or less power as needed (Department of Energy, 2022). This allows hydropower to quickly ramp up during periods of high energy use.
Disadvantages of Hydropower
While hydropower can provide clean, renewable energy, there are some key disadvantages that must be considered (https://kiwienergy.us/pros-and-cons-of-hydroelectric-energy/).
One major downside is the environmental impact of dams and reservoirs associated with hydropower projects. Building dams can disrupt natural water flows and impact local wildlife ecosystems and habitats. Dams prevent fish migration and can change water temperatures and nutrient levels (https://www.envirothonpa.org/documents/19bHydropowerAdvantagesandDisadvantages.pdf).
Another disadvantage is that suitable sites for new hydropower projects are limited. Ideal sites have high water flow rates and elevation drops for maximum electricity generation. But many of these prime locations have already been utilized. Building new dams and reservoirs in remote or protected areas is difficult and costly.
The upfront financial costs for hydropower can also be prohibitive. Constructing dams and power plants requires major infrastructure investment. While costs are usually recouped over time from electricity sales, the initial capital requirements could limit adoption, especially in developing countries.
Hydropower vs. Other Renewables
When compared to other renewable energy sources like solar, wind, and geothermal, hydropower has some advantages and disadvantages.
In terms of capacity, hydropower is by far the largest renewable energy source worldwide, producing over twice as much energy as wind and over four times as much as solar (CNBC). Large-scale hydropower projects can generate thousands of megawatts of electricity. However, the scope for new large dams is limited in many developed countries due to environmental concerns and available sites.
Regarding costs, hydropower is relatively inexpensive once the initial infrastructure is built. The levelized cost of electricity from hydropower ranges from $0.02 to $0.19 per kWh, comparable or cheaper than wind and solar (DOE). However, the high upfront costs of building dams and power stations makes it less financially viable for developing countries.
In terms of sustainability, hydropower offers a renewable and reliable energy source when designed and managed properly. The fuel source of flowing water is continuously replenished by the water cycle. The lifespan of hydropower facilities can be 50 years or more. However, building dams alters river ecosystems and can impact fish migration and sediment flow.
Overall, hydropower offers significant generating capacity as part of a diversified renewable energy mix, but has some limitations around new project development. Careful planning and mitigation is needed to reduce environmental impacts.
Case Studies
Hydropower projects can provide clean, renewable energy, but they also come with environmental and social impacts. Here are some notable examples:
The Three Gorges Dam in China is the world’s largest hydropower project, with a capacity of 22,500 MW. While providing substantial renewable energy, the dam flooded towns, displaced over 1 million people, and altered the Yangtze River ecosystem (https://www.internationalrivers.org/campaigns/three-gorges-dam).
Brazil’s Itaipu Dam is the second largest hydroelectric power station, jointly run by Brazil and Paraguay. It produces over 90 TWh annually while helping conserve the endangered Atlantic Forest in the area. However, it also flooded land and displaced thousands of people when built (https://www.power-technology.com/projects/itaipu/).
India’s Tehri Dam is the tallest dam in India at 260 meters high. It provides power to several states in India. However, it was constructed despite concerns about seismic activity in the region. Protests occurred during its long 40+ year construction period over environmental impacts (https://www.internationalrivers.org/campaigns/tehri-dam-india).
Norway relies on hydropower for over 95% of its electricity through projects like the Svartisen and Rana hydropower stations. Norway’s mountains provide ideal geography, though fish populations have been impacted by its dams. The country aims to expand hydropower while working to minimize ecosystem damage (https://www.hydropower.org/country-profiles/norway).
Overall, hydropower can provide clean renewable energy at scale when planned and managed responsibly. Striking a balance between energy generation and social and environmental impacts is key for sustainable hydropower projects.
Future of Hydropower
Hydropower is projected to continue growing globally in the coming decades. According to the International Energy Agency (IEA), hydropower generation could grow by over 60% by 2040 under stated policies scenarios, with most of this growth in non-OECD countries like China and India.[1] However, more optimistic sustainable development scenarios show hydropower generation nearly doubling by 2040.[1]
The outlook for growth in hydropower depends on several key factors. Expanding hydropower requires suitable geography, water resources, and investment capital. Climate change may alter water resources in some regions, affecting future hydropower potential.[2] However, innovations and new technologies may open up new opportunities for hydropower expansion and improved operations.
Some key innovations that may change the hydropower outlook include:[3]
- Advanced turbines and materials enabling greater efficiency and flexibility
- Pumped storage innovations providing greater grid reliability
- New streamflow forecasting improving operations
- Small, low-impact hydropower installations
With the right policies, investments, and innovations, hydropower can continue expanding globally, helping meet rising electricity demand with clean, flexible, renewable power generation.
Implementing More Hydropower
Though hydropower provides many benefits, increasing hydropower capacity also comes with challenges and considerations. According to the U.S. Department of Energy, upgrading existing hydropower infrastructure can be costly and will require significant investment [1]. Building new dams and reservoirs also requires substantial funding as well as lengthy environmental impact assessments. There are concerns about hydropower projects further fragmenting river ecosystems [1].
However, steps can be taken to mitigate environmental impacts of new hydropower projects. Strategies include implementing fish passageways, maintaining minimum flows in rivers, and operating dams to accommodate fish migration and spawning [2]. Comprehensive environmental planning, use of existing infrastructure, and employing new technologies like hydrokinetic turbines can also minimize ecological disruption. Overall, increasing hydropower capacity in a sustainable way will require balancing renewable energy goals with preservation of river health.
Conclusion
While hydropower offers many benefits as a renewable energy source, determining if it is the “best” renewable option is complex. The pros of hydropower include its reliable and consistent output, low operating costs, lack of emissions, and energy storage capabilities through pumped storage. However, the cons cannot be overlooked; large hydropower projects can negatively impact the local environment and ecosystems. Though small-scale hydropower has less impact, it provides less total energy. Compared to other renewables like solar, wind, geothermal and biomass, hydropower is unique in its flexibility and storage capacity. Yet each renewable has advantages in certain contexts or geographies.
Ultimately, the “best” renewable likely utilizes a diverse mix based on availability and demand. Rather than selecting a single winner, governments and utilities should assess the optimal blend of renewables for their needs. While hydropower offers significant benefits, it alone cannot meet all energy demands. A combination of sources provides greater reliability and reduces negative impacts. With thoughtful implementation and mitigation of ecosystem harms, hydropower can play a major role in clean energy transitions, especially when combined strategically with solar, wind and other renewables.
References
Energy Information Administration. (2020). Hydropower explained. https://www.eia.gov/energyexplained/hydropower/
International Hydropower Association. (2019). 2019 Hydropower Status Report. https://www.hydropower.org/publications/2019-hydropower-status-report
World Energy Council. (2019). World Energy Resources Hydropower. https://www.worldenergy.org/assets/downloads/World_Energy_Resources_Full_report_Hydropower_2019.pdf
International Renewable Energy Agency. (2012). Renewable Energy Technologies: Cost Analysis Series. https://www.irena.org/publications/2012/Jun/Renewable-Energy-Technologies-Cost-Analysis-Series-Hydropower
