Hydro or Wind or.........
I'm both an electronic and a civil engineer, so hopefully the comments that follow will be more correct that the guesses of (for example) an IT professional.
Regarding converting 'base load' hydro to pumped storage, the heavy engineering required is actually pretty much an insurmountable problem. Aside from the mechanical and electrical components needing replaced or upgraded, all the hydraulic structures will need redesigned. Basically, you can't just run water backwards through existing structures. Bear in mind the 'plumbing' we're talking about might be a bifurcation, valve house, or surge chamber cut into a mountain core. It's a whole new hydro scheme you need, pretty much top to bottom. After this obstacle, many hydro stations discharge into rivers, which are not suitable sources to extract water from to pump up to retaining reservoirs. You need a hefty reservoir at the bottom too. There are also plenty of run-of -river schemes in the UK that cannot be converted to pumped storage either. It's a grand idea but not feasible for many schemes.
Having typed that, they're currently building the biggest hydro scheme in decades at Glen Doe in Scotland. Given it discharges into Loch Ness and it's general suitability for the pumped storage, someone needs shot that it hasn't been designed as pumped storage from the outset.
Regarding wind farms, I think we've had about enough now. How about the government stopping the subsidisation of this industry and diverting some money to other 'green' power generation? One of the issues with wind farms I think has been missed above is that they are often sited on peat bogs. The access roads, foundations, and borrow pits damage the hydrology of the area and dry the bogs out, leading to decomposition of thousands of years of stored vegetable matter. The gas produced is a much more efficient greenhouse gas than plain CO2.
I vote nuclear fission, here's hoping fusion is on the way.