A big enough wind farm could generate that. The main flaw is you cannot guarantee the amount of power they will produce.
Energy can be stored and moved around, and different energy generation technologies can be combined to even out the variation in the production of each one. A common way of storing energy is to pump water into an elevated reservoir when excess power is available and then to drain the water into a lower reservoir through a turbine to generate power when it's needed. Another common method is in large flywheels which operate in vacuum cases on magnetic bearings and store energy in their angular momentum. The flywheels are spun up when excess energy is available and the process is reversed to extract the energy when it's needed. With moving energy around, an area with an energy surplus can power an area with an energy deficit, so even if there's no wind in one region for a while, another region that does have wind can export their surplus through those wonderful cables that are strung between those pylon thingies we see all over the place.
That is a possibility I guess, though the most logical way of solving it would be a hydrogen economy, so when you need the extra power, you have a power plant that you can turn on with a switch. Though of course such a system is going to take longer to set up than building a few nuclear power plants, and will be an awful lot more costly. Bear in mind the deadline in practise to sort out this mess is around 20:20, we should have been building stuff years earlier.
The other thing with all these storage systems is that they tend to waste energy by the bucketload, so you would need a lot more wind turbines to do it. That costs.
In what way would hydrogen be an improvement? You need energy to produce the hydrogen in the first place, whether it's hydrocarbons that you crack or electrolysis of water using electricity from coal, nuclear, wind, solar or other sources. Hydrogen in the sense of the 'hydrogen economy' isn't a source of energy; it's just a way of storing energy that you've already produced, and it's not a particularly efficient way of storing energy. Hydrogen is difficult and expensive to store, whereas it's extremely cheap by comparison to have a big-ass water reservoir in some unpopulated upland region, and those reservoirs are needed even with traditional coal and nuclear plants, since the boilers in power stations take hours or days to heat up and can't respond to rapid changes in demand, whereas the flow rate through a water turbine can be quickly adjusted to match demand.
Hydrogen you need the energy to produce and store, but once stored you are not losing anymore energy until you need it. There are two easy ways we can store it, either shove it back underground where gas initially was and mined years back, or this:
http://www.physorg.com/news98556080.html Also there are simple cycle plants you can turn on in seconds, in a similar manner to a car. Whilst a little inefficient, they are brilliant for emergency supply with peaking demand.
In contrast, all your other suggestions have energy leakage, and are in many cases difficult to build. For example, hydroelectric power there is a limit as to where you can build dams, and they lose quite a lot of potential energy due to evaporation. Flywheels always lose some energy due to damping forces constantly, you have to keep putting energy in to maintain the angular momentum.
