The other storage alternatives each have their major drawbacks. Lithium batteries work great for solar as there you only need a few hours of capacity, and the current economical setup seems to be about 80% of output for 4 hours. Each day they get charged and each night they discharge and provide a relative fast return of investment. This doesn't work for wind.
Massive amount of reverse hydro has also been suggested, but getting the capacity up to the same output as current wind installations are difficult. Having a country like Germany operating for months on only hydro power would require a lot of land and constructions, both which carries with them a lot of initial pollution in terms of both methane and co2. It is also very expensive.
There are a few other lesser know storage suggestions like rust batteries and heat storage, but I have yet to hear any of them being currently economical viable to run a whole country.
Green hydrogen can however be created through converting a wind farm into a hydrogen production farm. The cost is currently still prohibitively more expensive compared to nuclear, but it is still the place where those political parties I mentioned early is putting their bets. They are hoping that prices will go down enough that they can start building those kind of wind farms and then convert existing fossil fuel burning power plants and infrastructure to use hydrogen instead.
(I had switched green to blue. Whops. Fixed).