Heat Battery

Reed_Richards · 20 October 2019 at 9:55PM

I heard a mention of this piece of technology this weekend; something I had not come across before. As far as I can tell a "heat battery" works like a thermal store but rather than using water as the storage medium it uses a material that undergoes a phase change at around 60 C. Cooling through a phase change often releases a lot of energy and this means that the same amount of energy can be stored in a much smaller volume then the equivalent water-based thermal store would require.
https://www.sunamp.com/

Martyn1981 · 21 October 2019 at 6:37AM

Hiya. Apologies for negativity but i followed Sunamp for a year or two, then they launched their product, which is a great idea, not knocking that, but when I did my research it was two or three thousand for a 5kWh heat battery, which is quite poor value, I think, others may disagree?

For about a grand you can get an ASHP installed, then convert that leccy unit into multiple kWh(t).

But to be clear, I think the idea is great, just the economics that need some movement.

Speaking of movement, a few years back there was talk of using Sunamp's technology to ship (or should that be 'barge') MWh's of heat along the canal network, from thermal powerstation waste heat, via containerisation. Sounded interesting, no idea if anything came of it.

Reed_Richards · 21 October 2019 at 6:53AM

Well the conventional alternative is an insulated tank of hot water. These can be quite expensive, £1000 or more for around 200 l of water storage. But water must be one of the cheapest heat storage media you can find so maybe these heat batteries are only useful when you haven't got room for a big tank of water?

mmmmikey · 21 October 2019 at 9:27PM

This is certainly intriguing and thanks for posting. On the one hand looks like a neat solution, on the other it just looks like a small but very expensive thermal store. Makes me wonder if I'm missing something, will do a bit of digging.

1961Nick · 21 October 2019 at 9:54PM

Martyn1981 wrote: »

Hiya. Apologies for negativity but i followed Sunamp for a year or two, then they launched their product, which is a great idea, not knocking that, but when I did my research it was two or three thousand for a 5kWh heat battery, which is quite poor value, I think, others may disagree?

A typical 200 litre tank @ 65°C is storing about 10kWh of energy. Many homes would need 2 or 3 units raising the cost considerably.

As other have said, it's a nice solution if space is tight.

Martyn1981 · 22 October 2019 at 7:45AM

mmmmikey wrote: »

This is certainly intriguing and thanks for posting. On the one hand looks like a neat solution, on the other it just looks like a small but very expensive thermal store. Makes me wonder if I'm missing something, will do a bit of digging.

It's been a few years since I read up on Sunamp, but I do recall another similar idea (not them though) using phase change materials within the main body of a dining table. The idea being that the phase change is around 20-22C helping to reduce/smooth out both rising temps, and falling temps. Cool idea, but I think it was a tad expensive.

JKenH · 22 October 2019 at 10:54AM

1961Nick wrote: »

A typical 200 litre tank @ 65°C is storing about 10kWh of energy. Many homes would need 2 or 3 units raising the cost considerably.

As other have said, it's a nice solution if space is tight.

I am not sure what purpose you are saving the heat for but you do need to make sure you can use what you store and have enough spare PV (if that is your energy source) at the time of year you are needing to store heat.

I have 210 litre and 140 litre hot water cylinders. On a good day when the hot water cylinders have cooled down the IBoost can save about 16 kWh of pv into my tanks. Most of the time through the summer though I only save 7-8 kWh as that’s all I will have used in the previous 24 hours. In winter very little goes in as I am now running ASHPs all day. I have to heat up my tanks using E7 which I try and do as late as possible during the E7 period to minimise heat losses during the day. When relying on PV I factor in losing at least 2 KWh per day of radiated heat from the tanks. (They are extremely well insulated, to the extent my wife has made me remove some insulation as the airing cupboard is not getting warm.)

Reed_Richards · 22 October 2019 at 11:46AM

1961Nick wrote: »

A typical 200 litre tank @ 65°C is storing about 10kWh of energy. .

For which Sunamp offer the UniQ 9 "10.5 kWh Replaces 210L cylinder"

I could only find one price quote for a UniQ 9 and that was £2362.10 . That looks expensive compared to a hot water thermal store but on the other hand it's cheap compared to a 10.5 kWh electrical battery. I found an interesting Sunamp presentation here: http://www.oref.co.uk/wp-content/uploads/2019/02/20190130-Sunamp.pdf .

Reed_Richards · 22 October 2019 at 1:05PM

JKenH wrote: »

When relying on PV I factor in losing at least 2 KWh per day of radiated heat from the tanks.

Just as a fun comparison, I have to run-off a bucket full of water before I get hot water out a hot tap from my combi boiler. The volume of the bucket is about 10 litres. Assuming I raise the temperature of the water by 40 C then the energy required to heat the water left standing in the pipe is about 0.47 kW h. So that's almost 0.5 kW h just to run a hot tap hot! Whats's more the water in the pipe cools quickly! Now the pipes mostly run under the floor so in winter the heat is not entirely wasted (there is no insulation beneath the pipes) but in summer it is.

markin · 27 October 2019 at 3:07AM

The sunamp can run the heating and hot water, The biggest plus is the size, How many millions of tanks have been ripped out to make the bathroom bigger and possibly fit a shower?

Sunamp Heat Battery | Fully Charged
https://www.youtube.com/watch?v=9upXeTMHUqE

Andy's amazing live energy monitor from this house.

http://wattson.energyhive.com/dashboard/AndyT

Reed_Richards · 27 October 2019 at 5:46PM

I have already looked into the option of pre-heating the water that goes to my combi boiler. The maximum specified input water temperature is 30 C and I reckon that is fairly typical. So Andy's configuration (featured in the videos) what not work for me nor, I think, the majority of people with a combi boiler.

Heat Battery

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Heat Battery

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