At last: a practical Energy Harvesting proposal?

In summary, there are several options for utilizing waste warm water from plumbing systems, such as shower heat recovery and whole house systems. These systems require regular maintenance and may involve separate drainage for foul water. However, they can provide more usable heat per electrical kWh than air source heat pumps in the winter and could be a cheaper alternative. There are also existing systems for this purpose, such as greywater heat recovery systems and balanced ventilation systems with heat recovery.
  • #36
cmb said:
Just put the plug in your shower and let it fill up, as you shower.
The problem with hot water is that it warms and saturates the air with water. That moisture then condences on surfaces in the slightly cooler house. To prevent humidity problems there must be a heat exchange barrier somewhere in the system.
 
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  • #37
Baluncore said:
The problem with hot water is that it warms and saturates the air with water. That moisture then condences on surfaces in the slightly cooler house. To prevent humidity problems there must be a heat exchange barrier somewhere in the system.
Such water is pretty cool by the time it ends in the pan, and not very likely to add much in proportion to the level of moisture from the shower itself.

I actually do do this myself. Long hot showers cause elevations in humidity, but if energy efficiency is your thing, take shorter cooler showers.

More the former than the latter I find. Personally, I find a short hot shower feels more cleansing than a longer luke-warm shower, and it uses less gas. (I have a smart meter and can see exactly how much it uses.)
 
  • #38
Stormer said:
And balanced ventilation systems with heat recovery via a Enthalpy Wheel or other forms of heat exchangers has been a rule that every new building has to have in Norway for many years now, and that is probably the same in other countries as well.
Not Down Under, @Stormer, but our federal gov doesn't believe in climate change so there's no top-down pressure for such ideas, it's mostly our state governments stepping into the chasm to establish efficiency standards for new builds. Not this idea, though, it hasn't worked its way through the system as far as I've seen.
 
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  • #39
sophiecentaur said:
People have all sorts of versions but few are cheap.
Actually, the only one I've found to have consistent return point is this kind of non-pressurized direct system.
Needs extra devices like a pump to provide pressure and a temperature-limiting mixer: also needs some care at autumn, but at least it's cheap, lasts long and has good 'harvesting' potential.
 
  • #40
Rive said:
Actually, the only one I've found to have consistent return point is this kind of non-pressurized direct system.
Needs extra devices like a pump to provide pressure and a temperature-limiting mixer: also needs some care at autumn, but at least it's cheap, lasts long and has good 'harvesting' potential.
Your link takes me to a google results page. Is the what you meant or was it finger trouble? :smile:
 
  • #41
sophiecentaur said:
Is the what you meant or was it finger trouble?
I've tried to link the thing some AD-free way. Clearly, an unsuccessful and and not well thought through attempt😫

https://www.researchgate.net/profile/Ahmed-Hussein-61/publication/283771351/figure/fig46/AS:660835772923904@1534566934573/Components-of-evacuated-tube-solar-water-heater-collectors-Hossain-et-al-27.png
 
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  • #42
Stormer said:
The funny thing is we are not a member of the EU. We voted no two times. But still we are following more EU rules and regulations than most EU member countries because the politicians made us members of the EEA with no peoples vote. So now we are draining our hydropower magazines to supply Germany's power shortage because they closed all of their stable powerplants to go for solar and wind and end up with massive power shortages. Plus China buyed up all of the gas from EU so their gas prices went up and the energy prices is tied to the gas prices. And we are setting our energy prices according to the EU countries prices even if our production cost for the hydro power is really low.

I figure in an average hot shower (10 gallons @38C) about 2 million Joules are lost.

The geopolitics above sounds a little like the plot of the Netflix show 'Occupied' which is about Norway losing its independence to bigger powers related to energy policy.
 
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  • #43
bob012345 said:
I figure in an average hot shower (10 gallons @38C)
Egads. :woot: I use less than 1.5 gallons to shower. Surely, shorter showers should be practiced before getting into dodgy energy harvesting schemes.
 
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  • #44
anorlunda said:
Egads. :woot: I use less than 1.5 gallons to shower. Surely, shorter showers should be practiced before getting into dodgy energy harvesting schemes.
Absolutely. There speaks a true Engineer. Now tell your message to teenage kids who don't understand about economy. If everyone turned the flow off when soaping yourself and didn't just stand there 'enjoying it', we'd be a long way down the road to saving the planet.

Same could be said about always wearing a jumper indoors in winter, cooking as many items as you can in one oven cavity, giving and taking lifts in the car, wearing last year's clothes etc. etc. None of that involves any sort of gizmo nor doe it involve actual suffering.
 
  • #45
sophiecentaur said:
None of that involves any sort of gizmo nor doe it involve actual suffering.
We are in agreement. Until we get to the point where people start changing their behavior and life style rather than write a check to buy something, being green will fail.
 
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  • #46
anorlunda said:
Egads. :woot: I use less than 1.5 gallons to shower. Surely, shorter showers should be practiced before getting into dodgy energy harvesting schemes.
What? Do you still live on a boat? I probably use 40!
 
  • #47
anorlunda said:
Egads. :woot: I use less than 1.5 gallons to shower. Surely, shorter showers should be practiced before getting into dodgy energy harvesting schemes.
That seems more like a sponge bath than a shower! Actually, the average shower is more like 17 gallons and lasts about 8 minutes. As for the future of showers, one could envision voice controlled cycles with an initial short wash, a nice warm steam cycle that uses very little water followed by a short final rinse.
 
  • #48
bob012345 said:
As for the future of showers, one could envision voice controlled cycles with an initial short wash, a nice warm steam cycle that uses very little water followed by a short final rinse.
You are a tad bit late with that.
 
  • #49
Rive said:
Did not see my steam function. I'm thinking of a shower heads than can provide hot mist as well as hot water streams.
 
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  • #50
anorlunda said:
We are in agreement. Until we get to the point where people start changing their behavior and life style rather than write a check to buy something, being green will fail.
If we demand people change behaviors and do a little suffering to be green it will fail. Better to design things to handle the being green part and make them cheaper and better so people actually want them. Writing a check to buy something is the key to transforming society in the long run.
 
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  • #51
russ_watters said:
What? Do you still live on a boat? I probably use 40!
Not far off the mark. Conserving water was a habit we acquired on the boat, and never lost. Even today when we go to a restaurant, my wife won't leave until she finishes the water in her glass. And I waste energy on hot water in the bathroom sink because I'm unwilling to let the water run long enough for the hot water to make it to the sink.

From the urban dictionary: navy shower
When taking a shower get in, turn water on, get wet, turn water off, lather, turn water on, rinse, get out.

bob012345 said:
Writing a check to buy something is the key to transforming society in the long run.
I disagree. The planet is finite and the growth in demand for resources is unbounded.
 
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  • #52
anorlunda said:
I disagree. The planet is finite and the growth in demand for resources is unbounded.
How am I going to get a more efficient car, water heater, or anything except by buying it? Just using less and less of inefficient technology and being miserable is not much of an answer to me.
 
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