So, one of the things I've been pondering. Actually, it's more along the lines of something that I think would be really cool - One Day (tm).

A Zero Net Energy house. It's what's got me pondering about renewables, micro generation, and energy storage.
I mean, I think you can do a _lot_ to improve on the current design of houses, to improve their overall efficiency. But in addition, supplement it with your own sources of power. Not necessarily electrical either - I mean, lets face it, most of the power used in a house is thermal. Refrigerators, ovens, central heating.

Which has me pondering. I mean, in practice, solar and wind power are fine, but sporadic. The time of year of the highest energy demand is a calm, clear winter night.

You have the option of 'grid storage' of your energy - in which, you basically just 'feed back' the power you generate to the national grid, and 'buy it back' when you actually need it. All well and good, but that _also_ suffers the same problems - the best form of bulk power storage is to not use it in the first place, and leave the coal (oil, gas, uranium) un-burned.

So anyway. Any form of energy state transformation is inherently inefficient - every time you go from heat, to mechanical, to electrical to potential, you end up 'wasting' something in the transfer. You also waste in distribution. Would it surprise you to find that most power stations aren't even 50% efficient, at generating electricity?
It's why heating your house electrically is a horrible idea - they burn the coal, heat water, drive a turbine, make electricity (wasting 50% of the energy) and then you turn it back into heat, wasting even more of it.

That's why I've been thinking about energy storage - electricity in batteries is the obvious one, but ... actually, electricity probably isn't your most useful energy form. If you've ever been camping, you'll know that running a kettle or a heater of a generator or batteries is a bad idea.

I like the idea of microgeneration. I like the idea of using a combined approach of wind, water and solar power, in some degree. And I like the idea of being able to 'buffer' (If not long term store) energy generated, so those cold still winter's nights don't end up with you becoming an icecube. (Actually, I don't think 'going off grid' is a good idea anyway, so there'll always be a plan B).

So far I'm thinking in terms of 'heat storage and efficient circulation' to keep a house a stable temperature.
Energy storage via water pumping to a reservoir, to use any 'slack' capacity. And potentially (if I can find a suitable location) a water wheel, that runs off a river, and can also be driven via the 'stored' energy.

But it's still a bit of a pipe dream. New technologies pop up all the time - you can do 'ground source' heating. Flywheels might be a possibility - it's more or less what a water wheel is, after all.

It all also sort of involves starting with a low energy house in the first place.
(Oh and for bonus points - materials used that don't have an overhead in terms of non-renewable materials)