Inclined to agree with the principle tony, but what the about gshp/ashp case history? Isn't 200-400% efficiency 'something for nothing' ?

I'll put my hand up and say I know nothing about this technology - but would be concerned about the toxic nature of the material and it's green credentials/disposability/recyclability. All things are possible, not all things desirable.

Posted By: crusoeIsn't 200-400% efficiency 'something for nothing' ?

Why it is called Coefficient of Performance rather than Efficiency, saves the confusion.
And we know where the extra 'free' energy is coming from (in both instances).

One advantage, or problem, depending on your point of view, is that we tend to think of the globe as infinite and all we do when using a heat storage or heat pump is delay or accelerate change that would happen anyway, and on such a tiny scale that it does not matter. Urban Heat Island studies show this not to be the case.

Posted By: tony In this world there is never something for nothing, I cant see it guys, sorry,

Super-insulation and airtightness reduces heat demand by 93%, solar heating can reduce it by a further 5% and Xsorb gives us the 2% we're missing carried over from the summer excess. Otherwise we would have to install a secondary heating system but solar plus xsorb I think can be installed for the price of a back-up heating system.

Here in Scandinavia where low indoor humidity can be a problem in the winter time they sell desk top units that emit puffs of steam to help raise the humidity.

I'd guess something similar could be plumbed up and incorporated into the duct before the Xsorb store?

Posted By: Chris P BaconI'd guess something similar could be plumbed up and incorporated into the duct before the Xsorb store?

Seems a bit like the cartoon of the chap in a boat blowing on the sails with a bellows. The energy to evaporate that water has got to come from somewhere.

The fact that adsorption in the zeolite or whatever can release more energy than the latent heat of vaporization of the water (i.e., the adsorbed water is in a lower energy state than it's in as a liquid) helps but not that much.

Posted By: Ed Davies Indeed it is.
If I've read it right then zeolite-based molecular sieves can store about 60% more energy for each kg of water adsorbed than I was assuming in my calculations which makes things a bit more plausible. Still, 1 GJ/m³ seems impressive but by no means out of the ball park. Say 600 kg of adsorber/m³ (that's a guess) adsorbing 25% by mass water vapour so 150 kg with 75 to 80 kJ/mol (let's say 4200 kJ/kg for easy memory as that's nicely 1000 times the specific heat capacity of water / K) gives 0.63 GJ/m³.

I'm more worried about where the moisture is going to come from and the fact that your MHRV heat-exchanger would have got at least some of the heat out of that moisture anyway.

Take a 200m2 Passive House, with a 20m2 (10% of floor area) Integrated Solar Roof , this reduces the heat demand from 3,000kWh to 650kWh/annum. So I'm only short in December and if all the moisture generated inside the house is extracted through the Xsorb in Dec then that's 300L (10L/day) of water, I suppose I would have 3m3 of Xsorb capable of storing 864kWh (if you believe the blurb). You seem to have a good handle on the figures so do you think 300L of water is sufficient to release 650kWh of energy?

Posted By: Viking HouseThis study from the 70's may be of interest!

It illustrates one of my concerns. People have been looking at this application of these materials for over thirty years. What is the specific factor that has xsorb have changed to make it commercial and why wasn't it done before? The paper mentions cost, but thought that might be overcome by 1982! It also mentions the low density of zeolites, so a big tank is needed, though that doesn't matter as much in a house. I'd still like to see some evidence about the useful lifetime.

I'm convinced that Xsorp can store energy for 3-9 months, I'm not convinced yet however about how much energy can be stored per m3!

Yes, I don't think there's any question that storage is for as long as you want.

Take a 200m2 Passive House, with a 20m2 (10% of floor area) Integrated Solar Roof , this reduces the heat demand from 3,000kWh to 650kWh/annum.

But that's just the space heating demand, isn't it? What are you using for DHW?

Posted By: davidfreeboroughSo does this mean that the only useful source of humidity is one that's outside the house?

Yes, or at least one whose energy source hasn't already been included in the calculations.

It does feel weird, thought, to be worrying about sources of humidity in, say, Ireland in the winter.

As I say, we had waaaaay too much humidity this last winter: turning some of into space heat with a capacity of ~300kWh/m^3 seems great: I could see us making a real impact on our winter heat demand and humidity with this if it does what the tin claims.

Rgds

Damon

Posted By: crusoeMy motorbike MOT man cannot sleep upstairs in his new extension in summer

He should not keep the engine running

he could try some large containers filled with water, they will absorb some of the heat, but bet it would not make enough difference

Posted By: djh...but is still less than the 70 K or so that is actually practical.

Interseasonally?

Posted By: beelbebubit would store it's energy well as long as it was kept air tight, but it would have to be properly air tight, as in hermetically sealed air tight, not building "air tight"

I keep coming back to this in my head, because the system will stand or fall on it.

It may well be good that the supplier normally deals with compressed gas, because the kind of fittings and valves you'd be needing to guarantee good air tightness would mean you'd be treating your ventilation air as a low pressure gas (as in a max pressure delta of 1 bar). I'm not gripped up on the state of ventilation tech, but I would imagine the normal gear isn't able to guarantee anywhere near the kind of air tightness required, so using gas fittings would seem a nice off-the-shelf solution to me.

What sort of container would the supplier be able to provide? I would imagine a simple steel cylinder threaded at both ends would satisfy the air tightness, longevity, reliability and price points. You could have several cylinders connected to a manifold to get the air volume through them. I'd be wary of installing anything that's experimental and that would require monitoring into the walls. You'd be best installing it into a loft of basement space IMO, at least until you had some data on what kind of reliability to expect.

Also, have you thought about how it would be instrumented? You'd be wanting to monitor the moisture content of the adsorbant at least, especially in trial units. That's another reason to think about replaceable modules rather than installed into walls in bulk. You'd want to be able to isolate, repair and replace parts of the system if they sprung a leak.

Posted By: dickstercould you fit it under a suspended floor?

Lots of things could, including soundproofing.

I hadn't spotted this thread until the UK agent posted his enthusiastic comments on another thread, with an advertising claim that is, unfortunately, a little off-the-mark in terms of accuracy ("worlds first heat battery", which it quite clearly isn't).

As others here have pointed out, the conversion efficiency of these compounds isn't good, they are a bit like an secondary electric battery that needs maybe double (or more) energy input for a given energy output. They are also subject to performance degradation from contamination, so those commercial processes that use the same stuff (and have been doing so for decades) take care to keep their systems clean. Using it in a domestic application would require filters and treatment to, for example, remove oils, fats, dust and other organic contaminants from the moist air extracted from the house, before allowing the moisture to react with the "charged" zeolite.

That's not to say that it isn't a viable way to recover waste heat from some processes - glass blowing would seem to be a good candidate, as even a 40% recovery rate into a store might well be seen as very useful. The same would apply to pretty much any high heat output commercial process, as long as the exhaust contamination can be kept within suitable limits.

I cannot still see how usefully large amounts of energy could be stored.