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Energy Storage, micro generation, and the grid - Ed's journal
sobrique
sobrique
Energy Storage, micro generation, and the grid
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)
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Comments
necessitysslave From: necessitysslave Date: May 25th, 2011 06:57 am (UTC) (Link)
Biggest problem is micro generation is only really small amounts of energy.
The only way solar power currently makes money for houses in the uk is that the government has dictated that the grid will buy energy from households at a vastly increased rate.

According to the energy savings trust (an organisation that will have an overly optimistic view of micro generation) the average install will generate a maximum of 250kWh in the hottest months.

I don't think this would power my computer.

sobrique From: sobrique Date: May 25th, 2011 01:38 pm (UTC) (Link)
Well, 250kWh is enough to run 300W all month.
So if you're running a low energy 'puter, you might manage.

But yes, you're right - micro generation isn't big numbers. Which is why I think it's important to be as efficient as possible - lower energy usage overall, and less waste. And by 'waste' I mean both 'not re-using it effectively' and 'waste' in the generation. There's no point converting thermal energy to electric and back again. Or for that matter mechanical/rotational - why have a 'rotation' device generating electricity, when you could be using it to drive the compressor in your heat pumps (fridge).
serpentstar From: serpentstar Date: May 25th, 2011 11:28 pm (UTC) (Link)
With good design, like large, south-facing roofs covered in solar panels, plus really top-notch insulation, you can have power to spare.
sobrique From: sobrique Date: May 26th, 2011 02:50 pm (UTC) (Link)
I've seen some design program, where they did actually build a house that was - pretty much - self sustaining. The heat supplied by a human body is actually quite significant, if your house is well insulated.
The problem isn't so much one of accumulating heat, as distributing it and maintaining a stable temperature.
Traditionally - in this country at least - we have houses that naturally get cold, and we use energy to warm them up.

But a greenhouse, or anywhere in a really hot country, does more or less the opposite. The trick isn't in 'making it hot' or 'making it cold' it's in stablising the temperature at a comfortable level day and night.
serpentstar From: serpentstar Date: May 26th, 2011 02:56 pm (UTC) (Link)
Ours is pretty good for that, thanks to good quality insulation (well above regulation levels) and good design (again, big, sloping south-facing roof with five Velux windows, plus sizable high-spec insulating windows on the E and W walls). We don't generally use any heating for 7+ months of the year, it's very rare we need heating beyond the small wood-burning stove even in winter, and it never gets so warm in summer that opening a window or two won't sort it.

But yeah, a person will give off around 150w of heat, so with good insulation, lots of people, and/or smallish rooms, you don't need much more than that.
jorune From: jorune Date: May 26th, 2011 12:40 pm (UTC) (Link)
I saw this link on power storage and thought it notable enough to mention.
sobrique From: sobrique Date: May 26th, 2011 02:45 pm (UTC) (Link)
Interesting article that. Sort of the thing I was thinking about.
At a previous employer, the datacentre was actually run off a flywheel. This flywheel was driven by the mains, normally.
It has a massive advantage that it could smooth out the mains supply, which is a big problem in a factory environment.

I wonder if they ever mooted 'idling' it on peak demand, or accepting brief outages.
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