Mountainous Japan has enormous pumped hydroelectricity storage potential. In fact, there are numerous pumped hydro stations already built in tandem with the now shut down nuclear plants. A recent development in Germany could remake the usefulness of these peak power generators.
Cheap solar power during afternoon peaks could double the number of pumped hydro cycles from one to two times per day. This sounds boring but the implications are quite large.
According to Photon, a German solar energy industry organization, pumped hydro operators have started operating two cycles per day, the standard one at night, and an additional one during the afternoon solar peak. Solar has driven down the afternoon wholesale price of electricity to approximately the same level as midnight when pumped hydro normally charge up their reservoirs.
Pumped solar relies on price differentials of daily electric markets. At night, when old fashioned coal and nuclear power is abundant and not in demand, power prices are cheap. Pumped hydro operators buy the cheap nighttime power to run pumps to move water to high ground. During daytime peaks, electricity prices are higher, so the pumped storage operator let’s the water run down through turbines to generate instant-on electricity to meet peak demand.
What’s new is that there is now a new low price trough in the afternoon in Germany since so much solar power has been installed. There is one peak price in the morning and another peak price in the late afternoon/early evening. In the mid afternoon on sunny days, wholesale prices are about the same as at midnight. This allows pumped hydro operators to recharge their reservoirs in the afternoon as well as the evening.
The ability to recharge reservoirs twice a day could make pumped hydro far more flexible, and increase the potential power generation capacity. The number of kilowatt or megawatt hours from pumped hydro could effectively double!
Anyone familiar with recent energy supply debates in post-nuclear shutdown Japan understands that doubling pumped hydro capacity makes an enormous impact on power supplies. Recently it was discovered that the projected shortages in Kansai area were predicated on using less pumped hydro since nuclear plants are shut down. The expected rapid increase in solar in Japan could make a huge impact on Japan’s pumped hydro capacity.
Heads up to the excellent Renewables International!