New technique stores summer heat until it's needed in winter
newatlas.com
newatlas.com
One would only need to store solar thermal energy that is available on any sunny or partly sunny day for night time and cloudy days.
Where I live about half of all days produce abundant solar thermal energy even in the depth of winter. Calculating in night time, you end up with about 12.5% of total winter time having abundant free thermal energy.
So one would need to build a system of solar thermal collectors about 8 times the size one would need to heat a house on a sunny winter day, and that is not a very big system.
Space wise I think it would work for single family residential homes on .25 acre lots if the house was designed for it from the start.
You just need to go ~20 ft down for the thermal mass of the soil to significantly damp out even annual oscillations, so there the soil temperature equals the mean temperature where you live.
The main barrier to adaptation is that most people don't have a big enough lawn for the shallow method, and the cost of the deep method is big enough that it takes too long to break-even for most people.
What we really need for any such method to succeed is that governments must make it mandatory for new houses, then we can get economies of scale and probably make it viable also for retrofits.
What they describe is basically few twisted pipes and a tank.
I'd feel way more enthusiastic about the whole idea if it didn't involve large quantities of highly caustic 30%-50% NaOH solution.
Everyone always forgets about the part where you're cooling down the outside...
We abide by the rules of thermodynamics here boy.
You could have just googled it. The heat is moved around, it's not created. You can move energy, can't you?
Though the practically can be examined to determine how efficient an energy storage process can be versus no storage.
I read about this as a kid reading Freeman Dyson's "Imagined Worlds"[4]. Dyson's commentary is definitely worth reading. (Anything written by Freeman Dyson is worth reading.)
A cheese factory used ice ponds[5] for about 10 years, eventually abandoning them because the ice didn't last through the summer and it was difficult to maintain[6].
[1]: https://en.wikipedia.org/wiki/Ice_pond
[2]: https://www.washingtonpost.com/archive/opinions/1981/08/02/t...
[3]: https://en.wikipedia.org/wiki/Ted_Taylor_(physicist)
[4]: https://books.google.com/books?id=MOC8UJPuvO8C&pg=PA42
[5]: http://www.nytimes.com/1984/06/03/nyregion/dairy-hoards-500-...
Wouldn't you have to insulate your pond from below as well as above?
The storage facilities are called Ice House [0]. The large ones stored several thousand metric tons and could last through the whole summer, depending on the climate.
Of course there is eventually a limit in efficiency gains. When you reach that limit geothermal has advantages that will pay off eventually. 10 years ago at least you should not have installed geothermal. What the next 10 years will bring is beyond my knowledge.
[1] http://www.mass.gov/eea/energy-utilities-clean-tech/misc/hou...
edit: these numbers were for Massachusetts specifically
An in-floor heating system can easily cost $5K or more. Installation is the big cost on these things.
The real savings is that in new construction, you don't have to pay the extra cost to retrofit.
I mean, even regular heat pumps break down at certain population densities due to the same problem.
You can also go vertical into the ground with it.
It certainly takes some load off the HVAC system but I didn't get the sense from him that it was as much as 30%.
The original claim of a 30% saving seems like the jump from from air source to ground source heat pumps which are often quoted as giving back 3x or 5x the energy put in, respectively.
6' ≈ 1.8 m
55 °F ≈ 13 °C
90 °F ≈ 32 °C
80' ≈ 24 m
Any links?
One question though: why do they need a special high-tech material to do this? Why can't they just bubble warm air through cold water in the summer and vice-versa in the winter? Water has very large heat capacity, 400x that of air by volume.
PS.
Quote from Wikipedia for downvoters:
High tech is often viewed as high risk, but offering the opportunity for high profits.
Fact: Chemically produced lye dates back to at least 1791 with the Leblanc process: https://en.wikipedia.org/wiki/Leblanc_process
Fact: your processor is made from sand which was discovered by first human ever.
Processors are made from sand in the same way people are made from carbon. You're skipping a few important steps.
Is the Large Hadron Collider not high tech if it doesn't turn a profit?
I'd imagine there's not enough water to do this inland..
>I'd imagine there's not enough water to do this inland..
We quite often forget that there's no physical limitation on the amount of water available inland. Water is constantly flowing from the oceans onto land, being recycled (mainly by trees pushing it back up into the airstream), and flowing back out and mixing with the ocean.
So the amount of water per square meter of land is limited by only two variables:
* The rate at which fresh water falls on land (liters/hectare/year)
* The time it takes that water to flow to the ocean (years).
The amount of water available on land (liters/hectare) is simply these two quantities divided by each-other.
The flow is fundamentally limited by the energy balance of the sun, so there's not much we can do there. But the time is entirely determined by our ability to design infrastructure and land use patterns that store water on the land in useful catchments instead of draining it off rapidly. Farm-scale dams are one visible way of doing that, but it's much cheaper to store water in the ground via infiltration systems.
The amount of water is inversely proportional to the amount of time it takes water to flow back to the ocean after it falls. So if we want to "wet up" the landscape, we should make it follow a loooong path with a lot of passive friction and storage buffers.
Just to show my math here, in the USA on average there's 715 mm of rainfall per year, which works out to 19,000 gallons for the average 100 m^2 house footprint. And next year you get that much water again.
In extremely arid areas like California it would even be possible to use salt water for thermal storage.
How much water do we need? I wouldn't try to affect large regions, just specific urban areas. The water doesn't actually have to go anywhere, it just sits around storing heat. All we have to do is bubble a lot of air through it. As a nice side benefit, this should clean the air.
(This is my version of the Reber Plan).
High concentrations of NaOH in water are strongly basic. It will corrode many oxide-based ceramics (like toilet bowls) and aluminum, but it's no problem for most other common metals and plastics.
...and human flash quite rapidly. So if your NaOH radiator leaks you might get sprayed with meat dissolving viscous liquid.
The bigger problem that I found was that the efficiency was horrible. I wonder if having it in solution resolved this problem, if that's the case then there's going to be some applications for this with even a reasonable energy density.
https://en.wikipedia.org/wiki/Enthalpy_change_of_solution
With the heat released from 20 kg of NaOH dissolved in water you could heat 100 liters of water with 53,3 K, enough to take a hot bath.
That sounds like a huge amount of space.
As for the water, you're going to basically dump a bunch of water into this thing to generate heat. And when you're done, your NaOH will be more dilute and need a bigger storage vessel. So you need enough room to store all the water you'll ever add.
When you recharge, you'll produce a bunch of water, too. You either dump it or you store it for the next use. If you store it, then you double the amount of storage that you need for water because you have room premix and postmix.
So it might be relatively cheap to acquire the working material.
Wikipedia notes that it reacts with aluminum but not with iron. Iron is relatively plentiful as well and we know how to build holding tanks with that material.
It's probably not a good idea for earthquake-prone areas, but this method might work ok in places like Minnesota to replace burning LNG in a furnace or coal-plant-powered electric heating as the primary source of heat in the winter. I guess it depends on the reaction rate and efficiency of the system - how many tons of NaOH would be required to heat the house throughout the entire winter?
This is one of those cases where the fact that it wasn't mentioned leads me to believe "embarrassingly large amounts".
(That said, the technique may not be useless, and they may have a valuable machine. It's just that this particular application is setting off my energy-scale alarms. Press releases tend to get pretty breathless.)
I think you would need some of the tables typically found in chemical engineering manuals to work out the exact amount.
You would need the heat capacities for 50% and 30% (wt%) aqueous NaOH, mass fractions, enthalpy of dilution, and maybe activity coefficients. It sounds like a homework problem for a ChemE student.
On the optimistic side, we've mostly succeeded in doing that for other volatile things like gas tanks in cars and lithium batteries in electronics.
On the pessimistic side, the failure modes can be very catastrophic! I'd definitely want to know what failsafe mechanisms are in place to prevent my house from blowing up before I'd consider using it.
Still another heat exchanger will further lower the efficiency of the system. In my experience (maybe a tad bit dated) common heat exchangers (water/water) are difficult to maintain as - generally speaking - the most efficient ones have smaller passages for the liquid and they tend to become clogged and it is "normal" to clean them periodically.
I have no idea how large must be a heat exchanger (where one of the fluids is lye) to be efficient enough, considering also that the temperature is relatively low, but most probably it won't be exactly "compact".
This makes more sense than promoting the use of ammonia as a climate-friendly refrigerant, but barely (the ammonia will kill/burn/maim you faster):
https://ec.europa.eu/clima/policies/f-gas/alternatives_en
http://www.goodway.com/hvac-blog/2009/08/ammonia-as-a-refrig...
I think ammonia's next big application will be as an easier-to-use form of hydrogen for fueling ICEs with renewable energy.
The waste is Ammonium chloride which is used as fertilizer, or Calcium chloride which has a wide variety of uses.
They can both also be dumped in the ocean (it doesn't hurt the ocean).
But mainly I was answering the question about the waste chlorine, not about the process of making sodium hydroxide.
That is a neat approach. It works well for solar-heated water. Where winters are very cold and summers hot, one can also have cold-storage loops for summer cooling.
I'm not sure about the NaOH thing, however. I get that it enables heat transport. But as scotty79 notes, transporting concentrated NaOH is hazardous. It's already done, of course. But the scale for heat transport would be much greater than as chemical feedstock, I think.
But this actually looks like it would work!
that's 20 000 000 kg * 9.81 N/kg * 1 000 m = 196 200 000 000 Nm or 55.4 MWh stored energy (without efficiency factors, so not the usable energy at the end).
In comparison, a stored-hydro plant typically has between 200 MWh to 3 GWh capacity.
Maybe you could stack even more trains on it? But that again adds complexity and costs (more locomotives needed). I'm not convinced it will work out in all that many locations. And how fast can you transfer power in and out, with limited train speeds and overhead wiring?
Stored hydro is simpler and at least just needs space to scale the capacity, so you can make it a lot larger, even if it also only works in selected suitable locations.
(Sorry for editing this so much, should have written it out in a text file beforehand ;))
If you read the article you'll notice they refuse to compare to pumped hydro (because if they did people would laugh at them for how expensive they are). They are happy to compare to batteries though, because those are also not a usable way to store energy in bulk.
Sigh. With projects like this is it any wonder people are so skeptical of "green technology"?
There has to be some political reason this is getting built, because there sure isn't an economic or environmental one.
Pumped hydro works anywhere with a power source and a water source.
Dragging a train uphill for 5 miles to store energy sounds moronic. I bet the losses in this system are absurd. It also creates a 5 mile virtual chasm that's potentially unsafe to across.
Here are some links you can read: https://news.ycombinator.com/item?id=8646787 https://news.ycombinator.com/item?id=13094425
Hydro storage works because water is available in huge quantities without much special work, and you don't need any infrastructure except "big hole". Neither of those are true for a train or weights.
https://en.wikipedia.org/wiki/Thermal_energy_storage
It's just a different heat transfer fluid (and a very well known one).
The article is unwillingly misleading. It is not new technology per se, it is an improvement on a very old technology that is as simple as the Sterling engine.
Britain (France) has been a massive adopter of this, having a paradoxal effect on aggravating the power peak in the morning inducing the use of coal plants to be massively used in the morning to face this peak since pump were electricity driven.
But with mechanical wind mill, or solar power maybe they could finally become green.
As usual evil lies in the details, and most new new techs are deceptive because we lack knowledge. This is an old tech, and we know the trap.
Is the reaction extremely volatile? Does this require a high-tech ultra-low-tolerances system, or can it be DIY-ed?
I can see having a setup on a condo balcony (esp. if you're facing south / west), with heat exchangers on an otherwise-unused wall, and a few cylinders of NaOH. As long as the kit doesn't blow the wall off the building if it leaks or some such disaster..
A leak in some DIY setup would easily have horrific / disfiguring consequences.