When one thinks of hydroelectric systems, the most common vision involves one with massive dams and turbines. Naturally flowing rivers are temporarily stopped through the construction of these blockages. But when electric power is required, a portion of water is released from these dams allowing electricity generation. In many ways, this is an attractive system since hydroelectric energy is renewable. However, building such dams have their downside, which is why a new approach is becoming rapidly popular. Termed pumped storage hydropower, these new systems use a similar concept as a dam. Instead of having to build incredibly large retaining walls, the systems are much simpler.
Pumped storage hydropower also offers additional advantages, especially to countries pursuing other renewable energy sources. One of the major benefits of these hydroelectric systems is their capacity to store excess energy when made in surplus. As such, pumped storage can serve as a buffering system that helps avoid wasting energy production. At the same time, it can supplement systems in times of energy need. Given this, many countries are expanding pumped storage capabilities. The U.S. is pursuing these innovations aggressively, but so are others including China. Based on current investments into pumped storage hydropower, it looks like this technology will be an important future energy resource.
“Our data show that pumped storage is set to grow much faster than conventional dams. This trend is most pronounced in China, which accounts for over 80 percent of planned projects worldwide.” – Joe Bernardi, Head of Global Energy Monitor
A Pumped Storage Explainer
As far as hydroelectric systems go, pumped storage hydropower is a relatively newcomer to the green energy movement. The use of dams to generate electricity using gravity and water is highly effective. However, there are a few negatives to consider. The main ones relate to the construction costs, which are substantial. The second involves ecosystem disruptions as well as potential community effects. Lastly, dams create a vast amount of water surface area, which allows a significant amount of water to evaporate. All of these factors led to researchers and engineers seeking better alternatives to these existing hydroelectric systems. And pumped storage hydropower was the answer.
In essence, pumped storage hydropower utilizes two large reservoirs of water. One of these reservoirs sits atop a hill while the other resides at the bottom. When a grid creates excess electricity, this excess is used to move water from the lower to upper reservoir. As a result, this “energy” is stored in the upper reservoir. Then, when a deficit of electricity occurs, water is released from the upper reservoir back into the lower. In the process, the flowing water turns large turbines that generate the electricity. Notably, the construction costs are less than a dam, and environmental disruptions much less. And to a great extent, pumped storage hydropower operates more efficiently than dam hydroelectric systems.
China Leading the Way
In terms of countries and regions opting for pumped storage hydropower, most are invested in other renewables. Those pursuing solar and wind energy systems are particularly interested in pumped storage because of its capacity to store excess energy production. This naturally enhances the efficiency and benefits of wind and solar energy systems. Thus, even countries still using large amounts of coal are investing in pumped storage if using these other energy systems. And this certainly pertains to China, which now leads the world in pumped storage in its hydroelectric systems. Overall, it has a 45.8 gigawatt generation capacity compared to the U.S.’s 22 gigawatt capacity.
When it comes to China, they also lead the world in coal use for energy production. While coal is considered dirty from an environmental perspective, it remains highly efficient. However, China wishes to diversify its sources of energy, and therefore, it is rapidly expanding its wind, solar and pumped storage hydropower infrastructures. In this regard, China actually leads the world in each of these renewables in terms of capacity. Notably, China has a large population to support as well as vast amounts of terrain ideal for these renewables. This is why there has been a 50% rate of growth in pumped storage recently in China, enabling it to surpass other countries. Their 2030 plan intends to increase all forms of hydroelectric systems including wind and solar.
“For China, pumped storage is the winning horse to provide a flexible backup for wind and solar. It is cheaper than the other battery options and can store more energy.” – Liu Hongqiao, Independent Energy Consultant
Pros and Cons of Pumped Storage
Pumped storage hydropower offers many advantages when it comes to the renewable energy solution plan. Compared to dams, it costs less to construct and takes up less space. In addition, it is about 70-80% efficient in generating electricity from stored energy. This is better than dams due to the evaporation effects. Similarly, if the right terrain exists, it has been proven as a durable and lasting source of renewable energy. Research examining this has shown a typical lifespan of these hydroelectric systems exceeds 50 years. These account for the rising popularity of pumped storage hydropower.
Of course, there are a few downsides when it comes to pumped storage hydropower. Within the reservoirs, microbes can exist that generate methane, which is a detrimental greenhouse gas. Experts suggest the methane produced might be as high as 3-7% of human-related methane production. Though small, this undermines the positive environmental effects of these hydroelectric systems. Likewise, regions need the right topographical areas to create such systems well. Thus, this may not be feasible in many instances. Regardless, those that do can utilize pumped storage quite well as part of its electricity grid. In fact, Norway generates 99% of its electricity from hydroelectric systems. Based on these facts, the pros certainly outweigh the cons, and this suggests pumped storage hydropower is a keeper.