Why can't we just upgrade existing hydroelectric plants?

In Norway, we have every possibility of succeeding with the ‘green shift’, but then it will be important not to set one thing up against another. Hydroelectric power has been a mainstay of the Norwegian power system for generations. This is set to continue in the future, but now we need all the renewable energy we can get – wind, water and solar. NVE estimates the potential of upgrades and expansion of hydroelectric at 5.1 TWh. This development will be one of many important contributions to more renewable energy. Non-regulable wind power, moreover, is a perfect complement to regulable hydroelectric power.