I have a had this idea in my head for many years. There are many ways of storing energy. For instance, you could pound heat into a large water tank stored under you home's foundation. You would take the power you're not using and divert it into what is called a Dump Load. In this case it's a simple heating element. This energy would preheat the water going into your hot water tank for instance and save you money. It would keep your home warm also.

But my original idea was to store energy mechanically. You could used the surplus energy you have to run a hydraulic pump. This pump would slowly lift a very heavy weight mounted on a tower. This potential energy could be used by reversing the process. You would let some fluid out under high pressure to run a motor connected to a generator. Bam! you have energy on demand. That weight can stay up there for months on end and never move, ready to be used anytime. This sort of structure would be very long lasting. Decades before any major repairs would be needed.

Batteries on the other hand have leakage currents that constantly rob you of energy. They tend to lose their efficiency as the years go by. And you're lucky to get a decade out of them before they fail. Not to mention all the environmental issues surrounding the technology involved in creating the battery in the first place.

Now I suspect that the numbers would show some pretty low efficiencies involved in the hydraulic process. I think it still is a real winning idea when you take the whole picture into account. A systems perspective if you will.

Just me rambling....:)

The Dawg

Jerry,

That is how they do it in Germany; to store excess power when wind and solar are making too much for the base load on the grid.  Another way is to compress air into spent underground gas fields.  You lose some energy, but when you have too much it is better to store some instead of none.

I think that one cubic meter of water dropping one meter can make 1kWh.  So either an elevated reservoir (on a hill or mountain) or a surface reservoir and an underground generator and tank.

Neil

I think any mechanical means of energy storage isn't going to be feasable unless you only want to store a kilowatt-hours...   Even then it's going to take quite the construction set up to get there.   I think batteries are the only feasible solution really at this point.  Heating a pool of water under you home or something of that nature would be fine during winter months, but summer wouldn't be so "hot" lol.. 

I don't like grid tied stuff simply because I don't want someone else telling me how to do it... you have to have certain grade equipment that produces a certain type of sine wave.  It has to be a pretty sophisticated piece of equipment and those are generally expensive as well... I'm seriously thinking about converting my homes lighting over to  LEDs and wiring the house with low voltage/amperage DC systems.  Just eliminating the AC lightbulbs would be a large energy reduction.  

Grid-tie is by far the best choice in the early phase, unless you have no grid (nearby). On a village scale and with accessible-tech (i.e. tech available through GVCS), pumped water storage is the simplest, cheapest, and best choice, if your geography supports it.

But anyway, wind power is a very good approach to independent power on the village scale. I argue the scale of the turbine should be at least 5-10kW per turbine for primarily power production (except in early phases). A village of 200 people with all the industry needed to sustain itself is going to need at least 1MW of wind power (probably 250kW of constant power, 1MW peak), plus a way to efficiently store that power. That's a lot of power, for sure! That's about one 5-10kW wind turbine (which is pretty large for a homebuilt turbine) per person, but that should be enough to provide for a comfortable amount of electricity for all the uses. (Stored biomass is required for mobile power and for long periods of low wind or drought, wintery conditions, etc.) Here's an example of something that could be relatively easily produced with the standard GVCS machines: http://www.prairieturbines.com/ The kit for the 10kW wind turbine (tower not included) is ~$8000. Maybe a little larger (logarithmically speaking) would be a sweet spot, like a 20-40kW machine so that you could do only ~30 of the wind turbines instead of 100 of them. Even so, this is likely to be a very difficult project, and some people will probably have to be devoted to producing and maintaining these wind turbines.