Tesla home battery energy

[ExRes]

An interesting article on the BBC website news this morning, as far as I'm aware Tesla are one of the better battery powered car manufacturers although their product is more than a little expensive

http://www.bbc.co.uk/news/technology-32545081

US electric carmaker Tesla Motors has unveiled batteries that can power homes and businesses as it attempts to expand beyond its vehicle business.

Chief executive Elon Musk announced the firm would build batteries that store solar energy and serve as a back-up system for consumers during blackouts.

The device would allow consumers to get off a power grid or bring energy to remote areas that are not on a grid.

The rechargeable lithium-ion battery unit would be built using the same batteries Tesla produces for its electric vehicles, analysts said....

It will be enlightening to see how this turns out and whether it is a major step towards reducing fossil fuelled power generation or just another false dawn

 

[DownSouth]

It will be enlightening to see how this turns out and whether it is a major step towards reducing fossil fuelled power generation or just another false dawn

The energy to charge those batteries will still have to come from somewhere, as will the energy to extract the rare minerals and manufacturing the batteries.

A more plausible option would be to get over the Fukushima problem and get back to nuclear power which, when operated properly instead of ignoring safety directives as was done at Fukushima, is clean, safe and ridiculously plentiful.

 

[Bletchleyite]

A more plausible option would be to get over the Fukushima problem and get back to nuclear power which, when operated properly instead of ignoring safety directives as was done at Fukushima, is clean, safe and ridiculously plentiful.

Agreed. At least our Government has had the sense not to abolish it in a knee jerk reaction, unlike Germany.

OTOH I do see a role for microgeneration (wind, photovoltaic) charging a battery for LED lighting. But you're still going to need a proper high voltage feed (if no gas) for the cooker and the heating. So nuclear (and other methods) retain their role.

 

[dgl]

I suppose the idea is for the batteries to be charged by home solar panels/wind in periods of low/no demand and then the stored power to be used when the electricity being generated is lower than demand. Quite sensible really, expensive though.

 

[LexyBoy]

Hmm. I can see the appeal for off-grid people (probably a bigger demand in the US than here) but not for normal homes. The power companies might like it though, as if they can spin it well enough they'll get homeowners to pay for infrastructure they should be building.

Stored energy is vital for renewables to continue to grow, but small-scale stuff like this won't be economically or energy efficient. Much cheaper and safer to build pumped storage or flow battery technology (don't know how much that has taken off though).

 

[SS4]

The energy to charge those batteries will still have to come from somewhere, as will the energy to extract the rare minerals and manufacturing the batteries.

A more plausible option would be to get over the Fukushima problem and get back to nuclear power which, when operated properly instead of ignoring safety directives as was done at Fukushima, is clean, safe and ridiculously plentiful.

I think the idea is that it's generated either by renewables or when there is surplus energy in the grid (ie when the baseline generation exceeds usage)

 

[Jonny]

I suppose the idea is for the batteries to be charged by home solar panels/wind in periods of low/no demand and then the stored power to be used when the electricity being generated is lower than demand. Quite sensible really, expensive though.

It does seem rather expensive - it would be worth a comparison with an equivalent rig-up of car batteries and a mains output inverter.

 

[LexyBoy]

It does seem rather expensive - it would be worth a comparison with an equivalent rig-up of car batteries and a mains output inverter.

Yes, why use expensive an Li-ion battery when weight is of no concern?

I'd also be concerned the safety aspect of having so much stored energy in my house - fire risk should there be a short or battery failure.

 

[DownSouth]

I'd also be concerned the safety aspect of having so much stored energy in my house - fire risk should there be a short or battery failure.

Oh dear, you didn't study physics did you?

The electrical potential energy stored in a large Li-ion battery is far less than the chemical potential energy (i.e. energy released if it burns) stored in a cigarette lighter. The energy released by burning a battery does not change regardless of whether it is flat or fully charged.

 

[AM9]

Oh dear, you didn't study physics did you?

The electrical potential energy stored in a large Li-ion battery is far less than the chemical potential energy (i.e. energy released if it burns) stored in a cigarette lighter. The energy released by burning a battery does not change regardless of whether it is flat or fully charged.

However, according to some recent incidents, it's the presence of electrical stored energy coupled with a failure (internal short-circuit), that provides the spark - sorry about the pun, that ignites the chemical breakdown.
Although the failure mechanism has been largely eradicated by design and better manufacturing process control in small batteries, in any competitive market with buyers saving money at all costs, similar risks may return with slightly bigger consequences.

 

[Jonny]

However, according to some recent incidents, it's the presence of electrical stored energy coupled with a failure (internal short-circuit), that provides the spark - sorry about the pun, that ignites the chemical breakdown.
Although the failure mechanism has been largely eradicated by design and better manufacturing process control in small batteries, in any competitive market with buyers saving money at all costs, similar risks may return with slightly bigger consequences.

Lithium ion batteries are notorious for their failure mode - it can be explosive. At least with lead-acid cells, there isn't the risk of explosion.

The issue with lithium ions is that in extreme circumstances such as short circuit, they can end up being re-united with their electrons and turned into lithium metal. Bear in mind that lithium sits just above sodium in the periodic table, the inevitable results are rather spectacular, but not something that one would want indoors.

 

[NSEFAN]

Excess energy needn't necessarily be stored as electricity. For those who have immersion heating, adding a secondary heating element to the tank and using that to dump excess solar energy may be good solution. Storage heating may also be a good system here.

 

[LexyBoy]

Oh dear, you didn't study physics did you?

The electrical potential energy stored in a large Li-ion battery is far less than the chemical potential energy (i.e. energy released if it burns) stored in a cigarette lighter. The energy released by burning a battery does not change regardless of whether it is flat or fully charged.

I did as a matter of fact; perhaps I put my point poorly.

Though the amount of "electrical" energy stored is low, it can be released very quickly, which if it occurs in a way which was not designed for can lead to a fire starting and/or further breakdown of the battery's structure.

Remember that batteries do not store electrical potential energy, but rather chemical potential: to get higher energy densities the energy gap between "anode" and "cathode" materials is typically higher, so the potential for a violent reaction should they come into unfettered contact is also higher. A charged battery would release more heat if burned than if uncharged (not massively so though, roughly 5% as a guesstimate).

 

[Harpers Tate]

If the risks were that great, I doubt they would ever have been sanctioned for use in aircraft electrical systems. And I don't recall seeing anything about a Tesla car catching fire - yet!

 

[Marton]

Lithium ion batteries are notorious for their failure mode - it can be explosive. At least with lead-acid cells, there isn't the risk of explosion.

That can explode. It's a result of the electrolysis producing hydrogen and Oxygen.

Hence the H&S requirement for goggles or face shield.

 

[AM9]

That can explode. It's a result of the electrolysis producing hydrogen and Oxygen.

Hence the H&S requirement for goggles or face shield.

It's amazing what a few media stories of batteries of flawed manufacture catching fire can do.
As far as the Tesla is concerned, with over 30,000 in use, the number that have caught fire is less than one in 10,000. As a comparison, about one in 1,300 petrol cars catches fire, but don't let the facts spoil a panic story to keep a green technology down.

 

[LexyBoy]

Actually any risk of fire is probably not much worse than that from any other battery – and we’re happy to have a few of those lying around the house. Once a fire's started it makes little difference whether it's a massive battery under the stairs or a laptop battery on a sofa.

As a comparison, about one in 1,300 petrol cars catches fire, but don't let the facts spoil a panic story to keep a green technology down.

Is it particularly green though?

Where it enables people to switch to solar+storage, replacing a diesel generator, then undoubtedly yes.

If it's being put into a grid-connected house, then I doubt it. The battery technology used is pretty energy intensive compared to older batteries. More pressingly, electricity storage could be achieved much more efficiently with more centralised systems – not only could cheaper systems be used, but the power requirement of 10,000 houses is much more predictable than that of one, so storage can be used much more fully with less need for redundancy in case of unusually high loads. Plus, the shift to greener technology should be policy-led, not left to a small minority of individuals.

BTW, amazing that the numbers are so low for petrol cars really – we all know from Hollywood that cars explode in a ball of flame whenever they crash / break down / mount the kerb / go over a sleeping policeman...

That can explode. It's a result of the electrolysis producing hydrogen and Oxygen.

Hence the H&S requirement for goggles or face shield.

More likely because they're filled with 40% sulfuric I'd think? Not disputing that they can explode.

 

[AM9]

BTW, amazing that the numbers are so low for petrol cars really – we all know from Hollywood that cars explode in a ball of flame whenever they crash / break down / mount the kerb / go over a sleeping policeman...

That was sort of true in the days of the Ford Pinto, (see Kentucky Fried Movie).

 

[Jonny]

That can explode. It's a result of the electrolysis producing hydrogen and Oxygen.

Hence the H&S requirement for goggles or face shield.

I forgot - if the pressure escape valve fails, but Lithium ion batteries don't have that feature.

 

[OneOffDave]

Speaking to a friend in the US, their electricity distribution grid isn't as stable as the one in the UK and back up generators for houses are far more common than they are over here. He thinks one of the uses of these batteries will be to provide back up power where a generator isn't practical. Because of the frequent outages that there are in the US, there's a much bigger market for them over there.