At last: a practical Energy Harvesting proposal?

[sophiecentaur]

You're being inconsistent.

I was not actually rejecting the home DIY solar heating project, just not discussing it. The two are not mutually exclusive.
One thing about thermal solar energy is the actual details. Pipes up on the roof need to be protected from the frost unless you have an indirect system (with anti freeze fluid) or you drain down the system in frosty weather. You have to choose an operating pressure. Would it be at mains pressure? If so, a coil of rubber tube would not be suitable and the next step it has other refinements and turns into a complicated system with fancy reflectors and double glazed panels etc etc.
People have all sorts of versions but few are cheap. We could have another thread just about thermal solar, which is very attractive because there are few difficulties interfacing with other services.

I think you're being human like the rest of us

I'll take that as a compliment. But we all have heat pumps in our homes and they do their job exceptionally well. So using them for other purposes is really not that exotic, is it?

 

[sophiecentaur]

Solar water heat is very common. In fact, it was very common 100+ years ago - until the ice company which was to become the dominant power utility started paying people to remove solar systems and install electric water heaters.

An interesting bit of history there. Our lives are always subjected to other interests and it's even worse when the public are not in a position to vote those perps out of office. (But many voting systems don't in fact give us that power in practice.)

 

[anorlunda]

And it is only the Norwegian people that have to suffer.

I thought of the idiom now. "Snatching defeat from the jaws of victory." (An ironic reversal of the more common "snatch victory from the jaws of defeat.")

I would feel sorry for Norwegians, but actually many countries today are having the similar difficulties with very bad government. [I hope that wasn't too political. I didn't mention names.]If you like irony, the electric power disaster in the Canadian Province of Ontario, sounds very similar to your story about Norway. Ontario also had abundant hydro resources plus nuclear. They too snatched defeat from the jaws of victory thanks to government decisions.

https://www.fraserinstitute.org/art...ice-crisis-how-did-it-happen-and-who-got-hurt
https://www.spiked-online.com/2020/09/17/ontarios-green-energy-catastrophe/
https://ep.probeinternational.org/2...tricity-liberalization-promise-crisis-part-1/@sophiecentaur , here's a UK source's advice on solar hot water.

https://energysavingtrust.org.uk/advice/solar-water-heating/

 

[gmax137]

I lived in the Florida Keys at one time and solar hot water was not uncommon. These seemed to be mostly home-built systems cobbled together in the 1970s. I remember the water got so hot in the summer, the relief valve on the roof tank would lift, sending a plume of steam into the air.

 

[cmb]

Summary:: Use the waste warm water from your plumbing system.

I was enjoying my (very short) hot shower this morning and realized that the lovely warm water was flowing over my body (sorry - too much information) only once and then disappearing down the drain.

This water - and what comes out of the washing machine, dishwasher etc. could be at a seriously 'useful' temperature for a heat pump. There must be many kWh lost over a day. You can find systems for shower heat recovery, advertised but they seem to be passive and are low hanging fruit, afaics. A whole house system would be better and would involve a hot water storage tank (which I have).

Obviously the heat exchanger plumbing would need to be maintained (cleaned out) on a regular basis and I would imagine that separate drainage would be needed for foul water. Also, the discharge water temperature would need to be well above freezing but the usable heat would be a lot more, per electrical kWh, than what can be obtained from an air source heat pump in winter. An installation could be a lot cheaper than heat pumps that are being considered today.

Many years ago I heard of a scheme to recycle heat from a house via a ventilation system where outgoing air is passed through a heat exchanger to warm up incoming air. That's a similar principle.

I ask myself why there aren't dozens of these alternative systems to be found working in houses all ov er the country.

If it is that time of year when you heat your house, there is a very simple way to recover that heat.

Just put the plug in your shower and let it fill up, as you shower.

You'll have to paddle around in a couple of inches of slightly soapy water, but assuming it is at a higher temperature than the rest of your house, then simply leaving it there to find temperature equilibrium with your house, that heat will find its way to displacing heat you have to otherwise generate with input power by heating equipment.

 

[Baluncore]

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.

 

[cmb]

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.)

 

[Melbourne Guy]

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.

 

[Rive]

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.

 

[sophiecentaur]

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?

 

[Rive]

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

 

[bob012345]

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.

 

[anorlunda]

I figure in an average hot shower (10 gallons @38C)

Egads. I use less than 1.5 gallons to shower. Surely, shorter showers should be practiced before getting into dodgy energy harvesting schemes.

 

[sophiecentaur]

Egads. 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.

 

[anorlunda]

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.

 

[russ_watters]

Egads. 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!

 

[bob012345]

Egads. 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.

 

[Rive]

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.

 

[bob012345]

You are a tad bit late with that.

Did not see my steam function. I'm thinking of a shower heads than can provide hot mist as well as hot water streams.

 

[bob012345]

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.

 

[anorlunda]

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.

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.

 

[bob012345]

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.