Pumped Hydro – A Technology Whose Time Has Come?

Pumped Hydro storage is a very useful technology in an era of renewable energy: it is clean, dependable, fast to bring online (less than a minute to spin up), and beneficial as it uses “spare” electricity to pump the water into the upper reservoir.

China has the greatest amount of pumped storage in the world, 36.39 MW, with the USA and Japan neck-and-neck in second place with nearly 22MW each. Wikipedia lists 78 operating global pumped storage plants with a capacity of over 1MW. There are also 77 under construction worldwide, most of them in China.

Unfortunately pumped storage has drawbacks: the initial capital cost is large, as lakes have to be modified or reservoirs constructed at altitude. The location may be far away from where the power is needed. Ecological considerations also apply, as prime locations may be in areas of natural beauty or conservation. For example, Dinorwig (1.7MW) in Wales is in Snowdonia National Park: it was constructed in the 1960s: most of it is underground, with a few above-ground buildings made of natural stone to blend in; it was the most expensive power plant built in the UK at that time.

Nevertheless, governments are taking a renewed interest in this form of power plant. In Nevada the $2.5 billion White Pine Project is moving forward. The final license application is with FERC at the moment: if granted the rPlus Hydro project would store 1000 MW, enough for eight hours energy delivery to users on a hot summer day. “White Pine is located at an important crossroads of existing, planned, and proposed electric transmission in Nevada,” rPlus Hydro CEO Matthew Shapiro, says. “From this location, the project would help the state meet peak power needs in its northern and southern load areas, and help stabilize the grid, while making the most effective use of renewable energy sources. With planned third-party transmission build-outs, the White Pine project will sit at the intersection of regional energy markets. It’s hard to imagine a more strategic location for this project.”

Pumped Storage in Australia

Australia is taking a different route: it is investigating “off-river” pumped storage: the idea is to utilize existing rivers and construct a pair of reservoirs nearby. Unlike traditional on-river hydro power, off-river (closed loop) requires two reservoirs that are generally 10–100 hectares in size, rather like oversized farm dams, located away from rivers and national parks in hilly country. These sites are separated by an altitude difference (head) of 200–900 meters and joined by a pipe or tunnel containing a pump and turbine. The water cycles between the upper and lower reservoirs in a closed loop, hence the name.

A joint study by the Australian National University (ANU) and Australian Renewable Energy Agency (ARENA), found no less than 1,770 potential sites in Australia. Of course, many of these sites will be unsuitable for various reasons, but there still are many possible locations which could support sufficient storage for a 100% renewable grid.

Currently a 325 MW pumped storage plant is under development at Yethome in New South Wales, Australia, 108 miles from Sydney. Global infrastructure and energy supplier ATCO is behind the project, which should have capacity to supply around 8 hours of power on demand when completed in late 2025.

Benefits of Pumped Hydro

Clearly the on-demand aspect of pumped-hydro complements the intermittency of renewables. It can use surplus power to pump water into the upper reservoir, to be available when needed. Despite the initial high cost, once built, these hydropower systems have a long life expectancy, which is clearly a major benefit to countries who commission these systems. China obviously thinks so, as it is putting a major effort into building dozens of new pumped storage plants.