Is Hydroelectric Better Than Nuclear?

As the world seeks cleaner forms of energy production, hydroelectric and nuclear power have emerged as two potential alternatives to fossil fuels. Both provide emissions-free electricity generation on a large scale. However, there is an ongoing debate about which source is actually better.

This analysis aims to compare hydroelectric and nuclear power across several key factors. These include cost, environmental impact, reliability, safety, growth potential and public opinion. When weighing these considerations, the evidence suggests hydroelectric power is generally preferable to nuclear. Hydroelectric boasts lower costs and reduced environmental effects in most cases. Thus, hydroelectricity should be prioritized over nuclear, where feasible.

Overview of Hydroelectric Power

Hydroelectric power captures the energy from moving water to generate electricity. According to the U.S. Geological Survey, hydroelectric power is produced when falling or fast-flowing water turns turbines connected to generators ( Dams are built to raise the level of water and increase the flow rate, creating potential energy from the height and kinetic energy from the motion. This energy is harvested through turbines, which turn generators to produce electricity that is fed into the grid.

Most hydroelectric facilities use dams on rivers to store water in reservoirs. When the water is released from the reservoir, it flows through tunnels and conduits towards the turbines. As the water strikes turbine blades, it causes the shaft to rotate at high speeds. The generator converts the mechanical energy into electricity using electromagnetic induction. The amount of electricity generated depends on the volume and flow rate of water as well as the height differential ( Larger dams with bigger reservoirs and greater water flow can generate more power.

Overview of Nuclear Power

Nuclear power plants use nuclear fission to generate electricity. In nuclear fission, atoms of uranium fuel are split apart, releasing a large amount of energy in the form of heat and radiation. The process begins inside the reactor core, where uranium rods are submerged in water. The uranium atoms split when bombarded by neutrons, creating more neutrons that cause more splits in a continuous chain reaction. Control rods absorb excess neutrons to regulate the reaction. The heat from the fission reaction turns the surrounding water into steam, which spins a turbine to generate electricity. Nuclear power plants provide consistent baseload power, operating 24/7 with high availability factors. In 2020, nuclear energy produced 20% of total U.S. electricity. According to the Department of Energy, there are 93 operating nuclear reactors in 28 states.

Cost Comparison

When it comes to cost, hydroelectric power has a clear advantage over nuclear power. Hydroelectric plants are significantly cheaper to build and operate.

The average construction cost for a hydroelectric dam in the U.S. is about $2,000 per kW of capacity, according to the US Energy Information Administration (EIA). That’s over 3 times cheaper than building a new nuclear plant, which costs around $6,600 per kW (source).

Operating costs are also far lower for hydroelectric. The EIA estimates hydroelectric costs around $30 per MWh generated, while nuclear is around $90 per MWh. This is because nuclear plants require much more complicated technology and highly trained staff to operate safely (source).

Existing hydroelectric facilities are extremely cost effective, often able to generate power for as little as $10 per MWh simply by diverting water through existing dams and turbines. Overall, hydroelectric consistently ranks as one of the cheapest sources of electricity generation.

Environmental Impact

chart comparing costs of hydroelectric and nuclear power

When it comes to environmental impact, both hydroelectric and nuclear power have significant drawbacks to consider. Hydroelectric power relies on damming rivers, which can disrupt natural ecosystems and wildlife habitats. The flooding caused by hydroelectric reservoirs covers vegetation and forces animals to relocate. Dams also prevent nutrients from flowing downstream and can impact the migration patterns of fish like salmon.

Nuclear power produces radioactive waste as a byproduct, which must be carefully stored for thousands of years while its radioactivity declines to safe levels. There is no permanent storage site for high-level nuclear waste in the United States, so it currently remains on nuclear plant sites, creating a long-term environmental risk. The disposal of nuclear waste is extremely challenging and costs are often underestimated.

In summary, hydroelectric power disrupts river ecosystems, while nuclear power creates hazardous radioactive waste. There are environmental tradeoffs with both technologies that must be carefully weighed.


Both nuclear and hydroelectric power have high capacity factors, meaning they can generate electricity consistently (1). Nuclear power plants in the U.S. have averaged capacity factors of over 90% in recent years, making nuclear the most reliable energy source. Hydroelectric also performs well but with some seasonal variability, averaging around 50% capacity factors for run-of-river plants that depend on constant water flow and over 90% for facilities with reservoirs that provide water storage (2).

According to the U.S. Department of Energy, nuclear power plants rarely face disruptions, operating over 90% of the time. This gives nuclear an advantage in reliability over renewables like hydroelectric that rely on weather and seasonal precipitation patterns. The consistent performance of nuclear contributes to the stability and resilience of the electric grid (3).






When it comes to safety, hydroelectric power has some advantages over nuclear power. There have been very few large-scale accidents related to hydroelectric dams over history, with the most serious being dam failures that can unleash floods downstream. However, the number of deaths from dam failures has been relatively small compared to other energy industries. According to one analysis by HR Ritchie, nuclear energy results in 99.9% fewer deaths than brown coal, 99.8% fewer than coal, 99.7% fewer than oil, and 97.6% fewer than gas (1).

In contrast, nuclear power carries some inherent risks that simply aren’t present with hydroelectric power. Nuclear accidents like Chernobyl and Fukushima, while rare, can have catastrophic impacts on human health and the environment when they do occur. The complex nuclear fission process also results in radioactive waste that must be carefully stored for thousands of years. As such, nuclear requires extensive safety systems and protocols to operate safely, although human errors and natural disasters can still lead to accidents. Overall, hydroelectric power’s simplicity gives it safety advantages over nuclear.

Public Opinion

Public opinion on nuclear power tends to be more controversial compared to hydroelectric power. According to Pew Research, while a majority 57% of Americans favor building more nuclear power plants, there is still significant opposition. In contrast, public support for hydroelectric power is very high. reports that nearly 80% of Americans believe hydroelectric power is a clean energy source. Nuclear energy faces more political contention given concerns around safety and radioactive waste disposal. Hydroelectric enjoys broad, bipartisan support and minimal organized opposition.

Growth Potential

While hydroelectric power has provided consistent and reliable renewable energy for decades, the potential for major growth and expansion is limited. According to the MIT article, the best hydroelectric sites with dams and reservoirs have already been utilized, especially in developed countries. While smaller or low-impact hydro projects may still be built, the big sites have been tapped. Nuclear power, on the other hand, has significant room for growth globally. The IEA report notes that nuclear power currently provides 10% of global electricity, but has potential to expand and provide up to 25% in a net zero emissions scenario. With new reactor designs and advanced technologies, nuclear can be scaled up to provide far more clean electricity worldwide compared to hydroelectric in the coming decades.


In summary, the research shows that on most factors, hydroelectric power is generally better and more efficient than nuclear power. Hydroelectric has lower costs than nuclear since the plants are less complex and don’t have the same safety issues. Additionally, hydroelectric power is renewable and produces zero emissions, while nuclear creates radioactive waste. However, nuclear does have some advantages like reliability since it doesn’t depend on precipitation or weather conditions. Overall though, hydroelectric power tends to be more cost effective, better for the environment, and renewable compared to nuclear power. Therefore, the evidence suggests that hydroelectric is generally the superior energy source over nuclear.

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