OT-ish: "Powerwall" - will change the way the world uses energy

[The Natural Philosopher]

What? Closer than socialists?

[Simon Brown]

But there is no equivalent for keeping the place warm in winter with heat put into it over summer.

Without actually calculating it, I doubt even a very well insulated public swimming pool would even come close to being enough to do that for a house unless your idea of warm enough in winter is very low.

[The Natural Philosopher]

I did the calcs. It was actually OK if you have enough insulation. Both for the tank and for the house ;-)

Let's say you need 5kw average for 4 months: that's 4x30x24x5 kwh =

14400 units - or 52 gigajuoules

the specific heat of water is a 4 joules per gram per degree C.

So assuming we have the water at - say 90 degrees and we can extract useful heat down to 50C we have 40 C to play with.

So we need with perfect insulation about 52GJ/40C/4 grams = 325 mega grams or 325 metric tonnes

That's around a 7 meter cube of water. And a cube is probably optimal as a sphere is hard to make practically.

Now that's what every house needs to equalise power demand from summer to winter.

There are two points to make about why this works well.

Firstly heating required low grade (high entropy) heat - we dont have to try and convert that heat back to electricity or sunlight: we just use the low garde heat we stored.

Secondly there is no immediate rush to 'recharge' - it can take the whole summer. And you could use a heat pump to air-condition the house and heat the heat bank. Or in reverse in winter to do the opposite.

Its one of the very very few 'green' ways of dealing with energy that actually seems to make sense. Of course that's why the Greens have no idea that it even exists and no one is promoting it. Nothing to sell really part from a shit load of expanded polystyrene and some reinforced concrete

It is in effect the storage heater to end all storage heaters.

[Simon Brown]

Claimed them, actually.

You can with conventional cars too, far more places much more conveniently in fact.

they are by all accounts a

If you don?t mind twiddling your thumbs for an hour every 30 miles if you can even find a recharge point if you drive them like that.

And they are quiet

Yes, but that doesn?t make up for the much less convenient recharging.

And the fact about having to plan

I don?t believe that, essentially because I don?t believe it will ever sell enough of them to see that happen, for the same reason you don?t have one, the price.

I want to rent one

The trouble is the only real merit they actually have is being quiet and clean at point of use and that does not make up for the massive downsides with charging and the need to very carefully plan where to charge is and twiddling your thumbs while that happens.

Yes if you only use it for a relatively short commute to work and let it charge while you work and sleep it is quite viable, but insanely expensive. And that is why it will never fly and will see them go broke quite quickly.

[Simon Brown]

Me neither, essentially because they have to be much more expensive than conventional cars because of the cost of the battery.

That is much more likely to be done like parking meters.

It wouldn't be hard to ensure than only your car could use it and not much harder to charge anyone else who wants to use it.

[Simon Brown]

Not a patch on the Pajero which means wanker in one language.

Didn't sell too well in that area for some reason.

[damduck-egg]

The 1st model of the present day BMW owned MINI has a Supercharger.

G.Harman

[Tim Streater]

If you have 1g of water at 0C, to turn it to ice you have to remove enough heat from it to heat another 1g of ice to 80C. Nature provides us with ice in winter, but not water at 80C in summer (generally speaking). So I agree with you.

[Chris Hogg]

^^^ I know you mean water!

[Simon Brown]

That is never going to happen. It can be made from coal and gas much more cheaply than that.

[Tim Streater]

Tilt!

[Davey]

No argument, I was referring to the ability to have power provided to a parked car.

[Huge]

The limo company I use to get from the airport to my Mother's house in the States has a Tesla S, and I enquired about them using it to collect me on this trip, but it was an extra $120, so I decided I wasn't *that* interested.

[Dave Liquorice]

The makers are having to fit noise making devices to electric cars as people don't hear them coming...

Is the requirment to have front only stupidly bright day time running lights related? Get the masses used to looking for the lights and eventually be able stop the noise? Except noise travels round corners, light doesn't.

[Davey]

And the Chevrolet Nova, which means "Doesn't Go" in Spanish. Great if you want to sell in South America.

[Dave Plowman (News)]

Where did you get that from?

[Dave Plowman (News)]

Any electric car ever made might be viable for some. A milk float was viable for delivering milk. Harrods used electric vans for ages too.

The Tesla is sold as a sports car. Is it viable when driven as such? When Top Gear did, both the examples they had broke down.

[Tim Watts]

Unlucky and sod's law I guess. Youtube has plenty of videos of them not breaking down.

[Dave Liquorice]

Might not be technically illegal but having seen how some people treat cables and run them out the trip hazard is approaching infinity. By run out I mean like a stretched out slinky...

You and I know that where the public and cables are concerned is is best to keep them separate. Even matted with the edges of the matting tapped down with black and yellow hazard tape and warning signs each end of the matting some one will manage to trip over it.

[soup]

Just now, but in the future?