The Only Genuine Advantage of Hydroelectric Power: Energy Efficiency
When harnessed on a small, localized scale, hydroelectric power can serve as an affordable and environmentally friendly source of renewable energy. Its high efficiency in converting potential energy into electricity makes it a noteworthy option. However, it is crucial to understand that this efficiency is relative; overall, the energy sector suffers from significant losses—approximately 60% of energy used during electricity generation is lost through various inefficiencies, according to the U.S. Energy Information Administration. This loss underscores the importance of evaluating hydroelectric power’s role within the broader energy landscape.
Understanding Energy Efficiency
Energy efficiency refers to using the least amount of energy possible to perform a given task, thus minimizing waste. For appliances, this is exemplified by EnergyStar-rated devices that consume less power for the same performance. Alternatively, efficiency can be viewed as the ratio of useful energy output to the total energy input, expressed as a percentage. When considering electricity generation, this involves comparing the energy produced (electricity output) with all the energy inputs—including capital, fuel, operational costs, environmental impact, and downtime.
Various energy sources differ significantly in efficiency. For instance, a comparison by The Wall Street Journal illustrates that hydroelectric energy surpasses fossil fuels and solar, with wind energy demonstrating extraordinary efficiency at over 1,100%. Geothermal energy also outperforms hydroelectric at around 514%, and with ongoing research, solar and wind efficiencies continue to improve, driven by technological advancements. Despite these promising figures, the environmental and social costs of hydroelectric power often overshadow its efficiency advantages, especially in a changing climate.
Major Drawbacks of Hydroelectric Power
While hydroelectric power is often lauded for its renewable nature, several critical disadvantages challenge its sustainability and environmental friendliness. These issues include the misconception that large-scale hydro projects are entirely renewable, environmental degradation, and the growing risks posed by climate change.
1. The Decline of Hydropower as a Truly Renewable Resource
Many states do not recognize large hydroelectric projects as renewable energy, primarily because their classification depends on the scale—typically, installations exceeding 25-30 MW are considered non-renewable. This distinction influences state renewable portfolio standards (RPS), which are policy tools that set targets for the percentage of electricity utilities must produce from renewable sources. These standards have historically driven growth in renewable energy, but the classification of hydroelectric power varies, affecting how much it contributes to these goals. For example, California aims for 100% renewable energy by 2045, while other states have more modest targets.
Effect of Climate Crisis on Hydropower
The climate emergency significantly undermines hydroelectric potential. Recent reports highlight that heatwaves and prolonged droughts—exacerbated by global warming—are diminishing water availability in regions like Europe and North America. Europe’s energy crisis exemplifies this, with hydro and nuclear power generation declining due to reduced water levels needed for cooling and power production. Similarly, in California, reservoir levels at critical hydroelectric dams are reaching historic lows, forcing shutdowns and power shortages. This pattern indicates that relying heavily on hydroelectricity in a warming world is increasingly risky, as water scarcity becomes more prevalent.
Projected Impacts of Climate Change on Hydroelectric Infrastructure
- By 2050, approximately 61% of existing hydropower dams worldwide could be situated in water basins facing extreme drought or flood risks.
- Fifteen percent of planned dams are expected to be in high flood-risk zones by 2050, up from 4% today.
- Over 80% of new dams could threaten biodiversity, with fish populations already declining sharply, partly due to dam-related habitat loss.
Seawater as a Potential Alternative
Given freshwater scarcity, marine hydrokinetic energy—tapping into tidal and wave power—represents a promising avenue. This method leverages the vast, inexhaustible energy of the oceans, which could complement solar, wind, and geothermal sources in a diversified renewable energy portfolio.
2. Environmental Damage Caused by Hydroelectric Projects
Hydroelectric dams profoundly alter river ecosystems and threaten local wildlife. Their construction and operation disrupt natural habitats, often with irreversible consequences.
Fish Migration Barriers
Many hydroelectric facilities incorporate fish ladders or bypass systems intended to facilitate the migration of salmon and other species. While these measures have improved survival rates somewhat, they are often ineffective, especially for juvenile fish. In some regions, survival rates through dams are as low as 3%, and the overall ability of fish to reach spawning grounds has been severely compromised. Warmer water temperatures and reduced flow levels, intensified by climate change, further threaten aquatic life, leading to mass die-offs and affecting endangered species like Chinook salmon.
Habitat Destruction from Reservoirs
The creation of reservoirs involves flooding vast areas, destroying forests, wetlands, and human settlements. This displacement results in significant biodiversity loss and cultural upheaval. For example, dams on the Coosa River caused the extinction of over thirty freshwater species. Similarly, damming on the West Coast has decimated salmon populations, with nearly a third now threatened or endangered.
Water Quality and Reservoir-Related Issues
- Algal Blooms: Nutrient buildup in stagnant reservoir waters promotes harmful algal blooms, which deplete oxygen and kill aquatic life. Some algae produce toxins hazardous to humans and animals.
- Methane Emissions: Decomposing organic matter in reservoirs releases methane, a potent greenhouse gas. Recent studies reveal these emissions are underestimated, meaning dams may inadvertently accelerate climate change.
- Evaporation Losses: Large reservoirs increase water loss through evaporation, especially during heatwaves, reducing water availability for downstream ecosystems and human use.
- Sedimentation: Sediment accumulation reduces reservoir capacity, damages infrastructure, and causes downstream erosion. It also leads to the phenomenon known as “hungry water,” which erodes riverbanks and habitats downstream.
Risks of Viral Spillover and Water Scarcity
Disruption of natural habitats fosters closer contact between humans and wildlife, increasing the risk of zoonotic viruses crossing into human populations, as seen with the COVID-19 pandemic. Additionally, the over-damming of rivers exacerbates water scarcity, threatening millions dependent on these water sources, especially amid the ongoing megadroughts.
Impacts of Dam Aging and Structural Failures
Many dams are aging and structurally vulnerable, with over 70% of U.S. dams exceeding 50 years of age. The risk of catastrophic failure during extreme weather events such as floods is increasing. Incidents like the Oroville Dam spillway failure and recent dam collapses in Michigan highlight the dangers of continued reliance on aging infrastructure, which could result in loss of life, property, and ecological damage.
Conclusion: Rethinking Hydropower for a Sustainable Future
Hydroelectric power’s primary advantage is its relative efficiency, but this benefit is overshadowed by its environmental, social, and economic drawbacks—especially amid a climate crisis. Its classification as a renewable resource is increasingly questionable, considering water scarcity, ecosystem disruption, and infrastructure vulnerabilities. The future of sustainable energy depends on prioritizing truly renewable and less harmful sources such as solar, wind, geothermal, and ocean-based tidal energy. These alternatives offer reliable, scalable, and environmentally conscious solutions that are essential for addressing the global climate emergency and ensuring energy security in the decades to come.