Boiler-Heat Pump Hybrids

[SteamyTea]

20 minutes ago, sharpener said:

Pumped storage. Air under pressure in underground caverns/salt mines/depleted oil fields.

Yes.

This is my favourite after thermal storage at point of delivery i.e. in my airing cupboard.

[sharpener]

On 29/11/2024 at 20:44, SteamyTea said:

Yes.

This is my favourite after thermal storage at point of delivery i.e. in my airing cupboard.

 

Just read a feature in the Economist predictions for 2025. To the foregoing list we can add:

 

• Chinese firm HiNa to start industrial production of grid-scale sodium battery technology in 2025. (I remember sodium-sulphur being the great hope for electric cars >30 years ago.)
• US co Form Energy are developing iron-air batteries and
• Italy's Energy Dome uses CO2 under pressure instead of air, both to start construction of US plants next year.

Over-capacity in Chinese EV battery manufacutre means capital cost of solar + batteries now less than new coal plant in China or new gas-fired in US.

 

 

[Beelbeebub]

2 hours ago, sharpener said:

Chinese firm HiNa to start industrial production of grid-scale sodium battery technology in 2025. (I remember sodium-sulphur being the great hope for electric cars >30 years ago.)

I think these are Sodium ion batteries rather than sodium sulphur. Basically the same tech as Lithium ion but with sodium (it's obviously more complex than that but that's the quick view). The big advantage being that sodium is very much cheaper and more availble than lithium. As a bonus the batteries are apparently longer lasting, less explosive and can withstand discharge to zero (making shipping much safer).

 

There is a company looking at the molten sodium sulphur tech which has some interesting advantages or at least ways of thinking of the disadvantages (primarily the high temps needed) as advantages.

2 hours ago, sharpener said:

US co Form Energy are developing iron-air batteries and

IIRC these are extremely low energy density on volume and weight but have the advantage of being very cheap per kwh. For long term grid use the space/mass is not a problem.

[SteamyTea]

A look at the periodic table will show why Lithium has become the go metal for storage.

 

If you want cheap, reliable and recyclable, then lead acid works a treat.

Edited December 1 by SteamyTea

[Beelbeebub]

49 minutes ago, SteamyTea said:

A look at the periodic table will show why Lithium has become the go metal for storage.

 

If you want cheap, reliable and recyclable, then lead acid works a treat.

I don't think the life cycle costs of LA batteries is very good. They tend not to have very many cycles before needing to be replaced.

[SteamyTea]

37 minutes ago, Beelbeebub said:

I don't think the life cycle costs of LA batteries is very good.

I am not sure now, lithium has reduced a lot in price, but a few years ago, they were by far the cheapest.

They are the most mature technology though, well understood, and easily recyclable.

 

Thermal storage is still the cheapest and most reliable.  At 7p/kWh (if you can get that rate) there is price parity with natural gas, with much simpler technology.

[Beelbeebub]

So. I had a gander and found this LA battery setup

 

https://www.photonicuniverse.com/en/catalog/full/359-24kWh-48V-500Ah-AGM-deep-cycle-battery-bank-with-metal-racking-24-x-2V-batteries.html

 

24kwh, £2k

 

Whilst a 9.5kwh Li pack is just over £3k.

 

https://www.green2go.co.uk/givenergy-9-5kwh-lifepo4-unlimited-battery-integrated-dc-breaker-giv-bat9-5.html

 

So game set and match for LA....right? 24kwh for 2k vs only 9.5kwh for £3k.

 

Except the LA has a cycle life of 1200 cycles *at 30% DOD*.  So it's really an 8kwh usable pack ie comparable to the Li pack and is only warranted for  1200 cycles/1 year, about 4 years daily use.

 

The Li pack has an unlimited /12y warranty.

 

So over the 12 years of the Li pack you will have had to buy 3 LA packs or £6k.

 

LA's have had over a century to get cheaper and better. They are currently pretty much at their peak cost/performance point - plus they are made in vast volumes so there isn't much scope for reducing manufacturing costs.

 

Li batteries and their cousins like Sodium ion are only at the start of thier development cycle. Volumes are still increasing, performance is still improving.

 

 

I looked into solar PV 15 years ago when building my old house. And ran up against the battery issue. I couldnt find a way to make it work. So I went with solar thermal.

 

Now it would be easy to sort out a battery PV system.

[sharpener]

9 hours ago, Beelbeebub said:

I think these are Sodium ion batteries rather than sodium sulphur.

 

 

9 hours ago, Beelbeebub said:

There is a company looking at the molten sodium sulphur tech which has some interesting advantages or at least ways of thinking of the disadvantages (primarily the high temps needed) as advantages.

 

Yes. The sodium-sulphur chemistry had the extreme disadvantage for EVs (as we now call them) that if you don't/can't maintain them hot enough to keep the sulphur molten they are completely bricked.

 

For completeness I should have mentioned the bromine-based flow batteries, which I like as a technology as the dimensions of power (size of flow cell) and energy (size of tanks) are determined quite separately.

[SteamyTea]

8 hours ago, Beelbeebub said:

So. I had a gander and found this LA battery setup

 

https://www.photonicuniverse.com/en/catalog/full/359-24kWh-48V-500Ah-AGM-deep-cycle-battery-bank-with-metal-racking-24-x-2V-batteries.html

Brilliant.  Well worth knowing.

There was a program on the World Service the other night about this, but I fell back to sleep during it.

[Beelbeebub]

8 hours ago, sharpener said:

Yes. The sodium-sulphur chemistry had the extreme disadvantage for EVs (as we now call them) that if you don't/can't maintain them hot enough to keep the sulphur molten they are completely bricked.

The newer versions are interesting. They imply that if they go cold they simply stop working until they are reheated. Essentially go into hibernation.

 

They also reframed the high (250-300c from memory) operating temp. Yes that's hot, but no hotter (cooler even) than temps encountered in an internal combustion engine. They use modern insulation materials to keep the heat in. 

 

But they also claim advantages to such high temps. Firstly, given all normal environmental temps are well below the operating temp the battery doesn't really notice the difference operating in 50C desert.  Secondly the high temps mean dissapating the waste heat from internal resistance (charging and discharging) can be done with an emitter at 250-300c.  Whereas a normal battery has to dissipate a few Kw at 40C.  So the molten battery can use simple air cooling with a variable speed fan and a much smaller airflow.

 

Whether or not anything comes of it, I thought it was an interesting alternative approach.

[Beelbeebub]

4 hours ago, SteamyTea said:

Brilliant.  Well worth knowing.

There was a program on the World Service the other night about this, but I fell back to sleep during it.

A occupational hazard listening to the world service 😁