Pump turbines in existing power plants
NVE has found that there are 86 power plants which currently has installed more than 20MW and has a lower reservoir that is either lake or regulated reservoir (NVE rapport: “Pumpekraft I Noreg”, 2011) .
Currently, 10800MW of conventional hydropower is installed at these locations. Many of these locations (and more) are candidates for installation of pumped storage power capabilities, which would drastically increase the total installed power at these locations and in the energy system.
Using existing infrastructure and expanding the powerhouse caverns horizontally whit several more units would be a cost effective way of doing this. However, pumping requires a bigger submergence than conventional hydropower and for this reason; the existing power plant cannot be used for such an expansion because they will be insufficiently submerged to avoid cavitation because the pressure becomes too low. '
Task 2.3 will develop a new booster pump technology for providing the necessary pressure increase, so that all existing power plant infrastructure can be reused for an expansion with pumping capabilities. This would give large cost savings, possibly shifting the installation of pumping capabilities from a bad to a good investment.
At the same time, the current state-of-the-art Reversible Pump Turbines (RPT) are equipped with variable speed capabilities due to increased efficiency and control of the pumping power. This technology is expensive and requires a lot of space. The new booster pump technology will make possible all the hydraulic benefits of using variable speed technology, without having to install variable speed technology.