With all the talk about lithium ion batteries, and the unprecedented investment occurring in this area, it is easy to forget the most prevalent utility-scale energy storage technology, pumped hydro. Pumped hydro is the most mature and largest storage technology available. Worldwide, there are over 150 pumped hydro facilities with a total capacity of over 100 GW. In the United States, there are 38 pumped hydro facilities and a total capacity of approximately 19 GW. Battery deployments are just beginning and are typically measured in tens of megawatts rather than hundreds.
Pumped hydro is based on conventional hydroelectric technology. Facilities pump water from one reservoir into another at a higher elevation, typically using lower-priced off-peak electricity. When energy is required, the water in the higher elevation reservoir is released and runs through hydraulic turbines that generate electricity. One key advantage of this system is that the gravitational energy stored in the upper reservoir can be stored for long periods of time with virtually no energy loss. For pumped hydro to make economic sense, it must be constructed on a large scale, which involves a high initial facility construction cost and be able to leverage favorable geographic assets.
In 1985, a 2,100 MW pumped hydro facility in the United States cost $1.7 billion, or approximately $800 per kW. Today, a new pumped hydro facility costs approximately $1,500 per kW, give or take. Once built, the cost per kWh of storage is relatively economical, approximately $125 per kWh. While there are a myriad of citing and permitting issues, there are 40 pumped hydro facilities, totaling approximately 31 GW, planned in the United States alone. The question is: how much more growth will we see of this technology?
Pike Research believes it could reach upwards of 4.5 gigawatts per year, once the reality of large-scale renewables integration starts to happen in 2015 and beyond. This forecast may seem lofty, but really it comes down to building 20 – 40 facilities worldwide that average between 500 megawatts and 1 gigawatt. Is the forecast aggressive? Arguably yes. Is it feasible? Yes. Most close to the energy storage market acknowledge that a range of technologies are part of the solution. Only time will tell how much of the mix is comprised of pumped hydro, and perhaps more importantly when.
Article by David Link, appearing courtesy Matter Network.