Pumped storage hydro (PSH) reservoirs need to allow for significant water level variations to store substantial amounts of water and energy. The development of PSH projects face challenges related to environmental and social impacts, technical constraints in the design and operation of turbines and pumps, and the need for substantial upfront investments. To be viable, PSH plants necessitate specific site conditions, including a high head, advantageous topography, suitable geotechnical conditions, access to electricity transmission networks, and water availability. 

 

The implementation of PSH systems, regardless of their power capacity size, leads to substantial alterations in land use, particularly when constructing new reservoirs, dams, and other infrastructure. These changes lead to habitat loss, fragmentation, and degradation, affecting local ecosystems and biodiversity. Additionally, the construction and operation of pumped storage hydro systems alter natural water flow patterns, impacting both aquatic and terrestrial habitats.

 

PSH systems have been associated with deforestation, soil erosion, and landslides, particularly during the construction phase. The operation of pumped hydro storage systems can have significant effects on water quality, particularly in terms of temperature, oxygen levels, and nutrient concentrations. When water is stored in reservoirs, its temperature and oxygen content can change, affecting downstream ecosystems. Moreover, the release of water from reservoirs can cause erosion and increased sedimentation, which negatively impacts aquatic habitats and species.

 

Sedimentation can lead to the loss of spawning grounds for fish and the smothering of benthic organisms, while altered water temperatures and oxygen levels can affect the survival, growth, and reproduction of aquatic species. Pumped hydro storage systems are generally considered low-carbon energy storage options. However, they still produce greenhouse gas (GHG) emissions, particularly in the form of methane (CH4) and carbon dioxide (CO2) from reservoirs. The decomposition of organic matter in reservoirs can result in the release of these gases, contributing to climate change.

 

The extent of GHG emissions from pumped hydro storage systems varies depending on factors such as reservoir size, water depth, temperature, and the amount of organic matter present. Some studies suggest that emissions can be higher in tropical regions due to warmer temperatures and higher levels of organic matter. 

 

History of Pumped Storage Hydro

 

The first use of pumped storage was in 1907 in Switzerland, at the Engeweiher pumped storage facility near Schaffhausen, Switzerland. In the 1930s reversible hydroelectric turbines became available. This apparatus could operate both as turbine generators and in reverse as electric motor-driven pumps. The first use of pumped storage in the United States was in 1930 by the Connecticut Electric and Power Company, using a large reservoir located near New Milford, Connecticut, pumping water from the Housatonic River to the storage reservoir 230 ft above.

 

Between the 1960s and the late 1980s, the chronological development of pumped storage hydro (PSH) in many countries was primarily driven by energy security concerns and nuclear energy growth following the oil crisis in the early 1970s. PSH development had remained slow until the 1960s, but the search for secure energy alternatives in the wake of the oil crisis led to a significant increase in the construction of PSH plants. This was particularly evident in countries striving to ensure energy security and support the growth of nuclear power as PSH was closely correlated with nuclear development.

 

The 1990s witnessed a decline in the development of new PSH plants, primarily due to growing environmental concerns and the scarcity of suitable sites. As the most cost-effective locations became saturated and nuclear development growth waned, fewer facilities were constructed during this period. However, the landscape changed after 2000 as a renewed interest in PSH emerged, driven by the increasing demand for renewable energy sources and the liberalization of electricity markets. This shift led to the development of several large PSH plants in Europe, such as Goldisthal in Germany with a capacity of 1060 MW and Kopswerk II in Austria with a capacity of 450 MW.

 

Socioeconomic Impacts of Pumped Storage Hydro

 

Pumped storage hydro (PSH) projects can lead to the displacement of local communities, the loss of land and property, and changes in traditional livelihoods. In some cases, the construction of reservoirs and other infrastructure can require the relocation of entire communities, resulting in social and cultural disruptions. To mitigate these impacts, it is essential to involve affected communities in decision-making processes.

 

In the United States, federal and state-level policies have played an essential role in promoting renewable energy and energy storage. The USA’s Department of Energy (DOE) has identified energy storage as a solution for grid stability via the Energy Storage Systems Program (DOE OE/ESSP). At the federal level, the Federal Energy Regulatory Commission (FERC) has issued several orders to facilitate the integration of energy storage into wholesale electricity markets, such as Order No. 841 (2018), which requires grid operators to establish market rules for energy storage resources. The Department of Energy’s Hydropower Vision report underpins its commitment to pumped storage systems, emphasizing clean energy innovation, grid reliability, and sustainable hydropower expansion as vital components for tackling climate change and bolstering national energy security. (Papadakis C. Nikolaos, 2023)

 

However, the Department of Energy is wrong. The reason why so many pumped hydropower storage projects are being proposed today is that private electricity corporations are hoping to make a profit from the schemes. In many parts of the U.S., electricity utilities charge consumers higher rates during peak daytime hours, and lower rates at night. Thus, pumped hydropower schemes propose to pump the water uphill during the night when rates are low, and then sell the electricity back to the grid during the daytime when rates are higher. “Clean energy innovation” is not PSH. Pumped hydropower projects do not “generate” energy; rather, they are electricity storage devices, not electricity generating devices. Further, like all electricity storage devices, they are never 100% efficient and actually lose about 25% of the electricity throughout the pumping and storage process. As a general rule, pumped hydropower storage is about 70% – 80% efficient, depending on the project, such that they take more electricity off of the grid, requiring that more total electricity be generated, than they put back onto the grid. These projects are being greenwashed for the public to believe PSH is good for U.S energy policies. Don’t be fooled! 

 

Read about Cuff’s Run Pumped Storage Hydro project.