You don't need batteries to store potential energy.

I recently read a great article about how one of our main problems is tackling energy, water, and food problems separately. Basically if you have unlimited water, food, or clean energy the other two issues are easily solved (hydro power, desalinated water, hydroponic farming, fuel from food, etc) so we can't continue to think of the problems separately.

So instead of converting mechanical wind-based energy to electricity, and then trying to store it in a battery, use it directly to pump water to a high elevation reservoir. It then becomes an on-demand water and hydro-electricity source during peak loads. Mechanical power can also be used to desalinate ocean water by pressurizing R.O. systems. Solar (not necessarily photovoltaic) can also be used similarly during low-demand periods.

What we really need is a nano-particle or algae that can directly produce a liquid fuel from sunlight, without the photovoltaic BS.