With prices skyrocketing, and countries turning to the dirtiest coal power, is it the time for more pumped storage systems?
The scientific journal, Nature Communications, has produced the first estimate of the global potential for pumped hydropower storage (PHS), using an advanced analysis of the data. Simply put, a PHS reservoir is positioned above a water source: river, lake or reservoir, and when the electricity price is low, water is pumped to the higher reservoir. When the grid needs power, water is released to turn turbines. It is a fast response to increased demand, allows use of spare electricity at off-peak times, and is also a source of fresh water. The drawbacks are that pumped storage plants are expensive to build, and are only feasible in certain geographic conditions: where the terrain is “mountainous” enough to provide a suitable area for the upper reservoir.
unobtrusively blended into the mountainside,
showing the lower reservoir; image: Julian Jackson
Nevertheless, PHS should not be discounted as a viable, proven storage technology. The report calls this “Seasonal Pumped Hydropower Storage” (SPHS) but that seems a misnomer. Pumped storage can work all the year round, depending on the availability of water and the electricity needs of the consumers.
The Nature report says, “SPHS plants have lower land requirements than conventional hydropower dams, for a comparable energy and water storage potential, because the off-river reservoir design permits higher hydraulic heads variations. SPHS can also be attractive to deal with the load problems emerging from electricity consumption and supply seasonal variations and increasing use of intermittent sources of generation.”
The report estimates that the global technical and economic potential for water and energy storage with pumped storage is vast, but with an unequal spatial distribution across the world. Considering all the energy storage projects with the cascade, the total storage capacity is equivalent to 17,325 TWh, or ~79% of the world electricity consumption in 2017.
Obviously quite a few of these projects will be impractical: too expensive to build, too far from population centers, or the water is too valuable for other uses, such as irrigation. After removing what the authors considered non-viable projects, the results were: “1457 water storage projects with water storage costs lower than 0.2 US$ m−3 and 1092 energy storage projects with energy storage cost lower than 50 US$ MWh−1.”
The report says, “Conventional hydropower dams have been built in main river channels with the intention of managing water resources and generating low-cost, low-carbon electricity, but often they fragment flow and flood upstream areas. SPHS plants built adjacent to main rivers can provide similar water management and energy storage services while avoiding the large land footprint associated with conventional hydropower dams. This paper has identified where SPHS plants could be built and the associated unit costs for energy and water storage services. The estimated potential is restricted to mountainous regions with reasonable water availability and high hydraulic heads supporting cost-efficient SPHS system design. Significant potential exists in the lower part of the Himalayas, Andes, Alps, Rocky Mountains, Northern part of the Middle East, Ethiopian Highlands, Brazilian Highlands, Central America, East Asia, Papua New Guinea, the Sayan, Yablonoi and Stanovoy mountain ranges in Russia, with energy storage costs with cascade varying from 1.8 to 50 US$ MWh−1.”
There is considerable potential for these systems to be implemented as a low-emissions storage and load management technology. Construction can emit a significant of CO2, but the plants when running are low-carbon, and like hydropower dams, have a long lifespan.
Read the full analysis here:
Global resource potential of seasonal pumped hydropower storage for energy and water storage