Scottish nightclub to generate power from dancers' body heat
October 10, 2021 10:28 AM Subscribe
This sounds like nonsense, or really, geothermal described by someone who doesn't understand geothermal?
posted by muddgirl at 10:58 AM on October 10, 2021 [8 favorites]
posted by muddgirl at 10:58 AM on October 10, 2021 [8 favorites]
Doesn't look to me like it's generating power. Supposedly it stores heat underground by fluid exchange until it's needed, which would be when? How long can that heat be stored? My vacuum bottle is only good for a few hours.
posted by The Half Language Plant at 11:15 AM on October 10, 2021
posted by The Half Language Plant at 11:15 AM on October 10, 2021
In the winter and/or during the week, when it's used as an arts space, as I understand it.
HVAC&R News has some more detail, and they call it a geothermal heat pump system.
posted by box at 11:17 AM on October 10, 2021 [5 favorites]
HVAC&R News has some more detail, and they call it a geothermal heat pump system.
posted by box at 11:17 AM on October 10, 2021 [5 favorites]
How long can that heat be stored? My vacuum bottle is only good for a few hours.
To be fair, their system is probably going to consist of more than one vacuum bottle.
posted by Greg_Ace at 11:34 AM on October 10, 2021 [6 favorites]
To be fair, their system is probably going to consist of more than one vacuum bottle.
posted by Greg_Ace at 11:34 AM on October 10, 2021 [6 favorites]
Like the disclaimer at the bottom of the article says, "Planet Ark does not take responsibility for the accuracy of the original information". Instead you need a physicist... :)
Ground-source heat pumps are extremely efficient methods for heating or cooling indoor spaces. They work in the same way as an air conditioner or a refrigerator -- those are both heat pumps, which use mechanical work and thermodynamics to move heat from one place (the inside of your fridge or the inside of your house) to another (the outside of your fridge or the outside of your house). The work done also gets dumped as heat on the "output" side. A heat pump used for heating moves heat from outside your house to inside your house -- it's just the same thing in reverse.
Using the ground, via bore-holes, as the "outside" heat reservoir is useful because the ground stays at a relatively constant temperature rather than swinging wildly between winter and summer. For example, cooling a house (at 20 degrees C) to the outside during a hot summer (at, say, 40 degrees C) requires pumping heat across at 20 degree temperature difference, while the ground around your boreholes is probably closer to 10 degrees C year-round. Similarly, when you want to heat your house with a heat pump, you have to pump the heat from the cold outside air (-20 degrees C in the winter in Canada is totally common) to the warm inside of the house; a huge temperature difference! Pumping heat from the relatively warm ground into the warmer house takes far less work (and hence electricity) per unit heat moved.
In practical terms, the amount of work (done by your electrical grid) required to move a given amount of heat "uphill" from a cold reservoir to a warm one is roughly proportional to the temperature difference between the two reservoirs. (Look up the efficiency of the Carnot cycle if you want more details.) This is why ground-source, with its relatively stable thermal reservoir, is so promising.
posted by heatherlogan at 11:36 AM on October 10, 2021 [25 favorites]
Ground-source heat pumps are extremely efficient methods for heating or cooling indoor spaces. They work in the same way as an air conditioner or a refrigerator -- those are both heat pumps, which use mechanical work and thermodynamics to move heat from one place (the inside of your fridge or the inside of your house) to another (the outside of your fridge or the outside of your house). The work done also gets dumped as heat on the "output" side. A heat pump used for heating moves heat from outside your house to inside your house -- it's just the same thing in reverse.
Using the ground, via bore-holes, as the "outside" heat reservoir is useful because the ground stays at a relatively constant temperature rather than swinging wildly between winter and summer. For example, cooling a house (at 20 degrees C) to the outside during a hot summer (at, say, 40 degrees C) requires pumping heat across at 20 degree temperature difference, while the ground around your boreholes is probably closer to 10 degrees C year-round. Similarly, when you want to heat your house with a heat pump, you have to pump the heat from the cold outside air (-20 degrees C in the winter in Canada is totally common) to the warm inside of the house; a huge temperature difference! Pumping heat from the relatively warm ground into the warmer house takes far less work (and hence electricity) per unit heat moved.
In practical terms, the amount of work (done by your electrical grid) required to move a given amount of heat "uphill" from a cold reservoir to a warm one is roughly proportional to the temperature difference between the two reservoirs. (Look up the efficiency of the Carnot cycle if you want more details.) This is why ground-source, with its relatively stable thermal reservoir, is so promising.
posted by heatherlogan at 11:36 AM on October 10, 2021 [25 favorites]
"store it at depth via a dozen 150m bore holes"
That sounds like a heat sink to me, as opposed to a heat storage situation, such as a tank with molten salt in it. Is this in fact a regular geothermal heat pump? Which would be an OK thing.
posted by The Half Language Plant at 12:17 PM on October 10, 2021 [2 favorites]
That sounds like a heat sink to me, as opposed to a heat storage situation, such as a tank with molten salt in it. Is this in fact a regular geothermal heat pump? Which would be an OK thing.
posted by The Half Language Plant at 12:17 PM on October 10, 2021 [2 favorites]
I have another question. The article says there's no air conditioning. My question is: humidity? It's going to get funky in there, isn't it?
posted by The Half Language Plant at 12:21 PM on October 10, 2021
posted by The Half Language Plant at 12:21 PM on October 10, 2021
I have been in dance rooms hot and packed enough that the sweat was pouring from the ceiling down the doorframes...the gross bit has already happened. so I can buy if you just had some heat exchange pipes coiled along the drainage pipes,, or in the ceiling before the sweat condensed, you could likely capture some heat, and send the funk to the water treatment plant
posted by eustatic at 12:29 PM on October 10, 2021 [2 favorites]
posted by eustatic at 12:29 PM on October 10, 2021 [2 favorites]
Storing this kind of low grade heat is challenging, and incredibly inefficient/expensive. This is more like a reversible ground source heat pump, except someone is under the illusion that they're meaningfully storing the heat they're dumping to ground?
posted by Dysk at 12:34 PM on October 10, 2021 [4 favorites]
posted by Dysk at 12:34 PM on October 10, 2021 [4 favorites]
I have been in dance rooms hot and packed enough that the sweat was pouring from the ceiling down the doorframes...the gross bit has already happened.
I have seen a dance club rain sweat so many times. I used to love it and the idea of it but now... *waves at the pandemic* not so much, eww.
Back in the 90s I went to a rave that somehow managed to book one of those indoor playgrounds and adventure centers for kids. I think it was going out of business or something, and it might have been a last hurrah for the owners to make some under the table money and run away from their bills.
That place got so sweaty that the plastic playground tunnels and ball pits and stuff were just soaked with sweat and god knows what else. The tiled floors were practically flooded and sopping wet.
That place got so sweaty that the suspended acoustic ceiling tiles were soaking through, getting soggy and then failing and falling right out of the frames holding them up. That was wild, and super gross. But fun.
posted by loquacious at 12:37 PM on October 10, 2021 [16 favorites]
I have seen a dance club rain sweat so many times. I used to love it and the idea of it but now... *waves at the pandemic* not so much, eww.
Back in the 90s I went to a rave that somehow managed to book one of those indoor playgrounds and adventure centers for kids. I think it was going out of business or something, and it might have been a last hurrah for the owners to make some under the table money and run away from their bills.
That place got so sweaty that the plastic playground tunnels and ball pits and stuff were just soaked with sweat and god knows what else. The tiled floors were practically flooded and sopping wet.
That place got so sweaty that the suspended acoustic ceiling tiles were soaking through, getting soggy and then failing and falling right out of the frames holding them up. That was wild, and super gross. But fun.
posted by loquacious at 12:37 PM on October 10, 2021 [16 favorites]
Also this sentence from the article:
This heat can then either be used immediately to cool the audience
Umm, yeah no. That's not how heat works.
posted by Dysk at 12:40 PM on October 10, 2021 [3 favorites]
This heat can then either be used immediately to cool the audience
Umm, yeah no. That's not how heat works.
posted by Dysk at 12:40 PM on October 10, 2021 [3 favorites]
I wish there was a white paper or application notes on the contractor's website because I'm struggling to see how this is different from regular geothermal. The big difference seems to be they are using the hot air to warm their circulating liquid before it goes back underground? Vs just dumping the hot air outside. That may make a difference for their environmental efficiency certification but i don't think they're actually "capturing" that energy in any meaningful sense.
posted by muddgirl at 12:53 PM on October 10, 2021 [1 favorite]
posted by muddgirl at 12:53 PM on October 10, 2021 [1 favorite]
Right, most of the energy of a commercial operation is probably going to heat water.
Most of what the dance floor does is import hot water in the form of sweat. Which you usually spend energy to expel from the premises with forced air, fans or otherwise.
I would assume this is not so much generating power so much as storing the heat in water to save on their kitchen energy costs.
I would also assume that the heat exchange wouldn't be worth the cost if you aren't as far from the equator as Scotland
posted by eustatic at 12:54 PM on October 10, 2021 [1 favorite]
Most of what the dance floor does is import hot water in the form of sweat. Which you usually spend energy to expel from the premises with forced air, fans or otherwise.
I would assume this is not so much generating power so much as storing the heat in water to save on their kitchen energy costs.
I would also assume that the heat exchange wouldn't be worth the cost if you aren't as far from the equator as Scotland
posted by eustatic at 12:54 PM on October 10, 2021 [1 favorite]
Wait what I described is literally just geothermal 🤦
posted by muddgirl at 12:56 PM on October 10, 2021 [1 favorite]
posted by muddgirl at 12:56 PM on October 10, 2021 [1 favorite]
I also used to know a club that had some kind of floating metal dance floor that was supposedly generating or harvesting power from the dance floor, but in hindsight I think this might have been some made up greenwashing bullshit from long before the term "greenwashing" was coined.
If I'm remembering the history of the place correctly they stopped using whatever power harvesting function that it might have had because it just wasn't really worth the cost of upkeep.
The floating part of the dance floor was super cool, though. If I'm recalling it correctly the floor was comprised of machined metal billet plates about 1/2 to 2/3rds of a square meter each that floated on a reservoir of oil or even water or something so that the floor had a noticeable shock absorbing quality. It wasn't like dancing on foam or springs in that there was a noticeable rebound or sensation that the floor was moving, but you sure could stomp yourself silly on it without getting as sore as you might get from dancing on solid concrete or metal decking or something.
Like you could stand on the tiles and they just barely moved and displaced some of the liquid underneath and it was a really unique and subtle experience as far as dance floors are concerned. It was like the "sprung" wood dance floors they used to use back in the big band era but without the creaky noises and rebound. I've never seen anything like it before or since.
On a similar tangent and note about how difficult it is to harvest useful power from human input, I've seen people attempt to do bicycle powered sound systems.
They had something that was built up like a cross between an indoor bike trainer and a bike rack with room for something like 8-12 bikes and one long friction-driven drive shaft plus a set of stabilizing rollers to support the rear of each bike. The drive shaft fed the mechanical energy into a converter motor or alternator which powered an inverter and a battery controller/charger.
The sound system they used was tiny. Just two small full range self powered speakers, no subwoofer. Maybe 500-1000 watts of total power for the sound system.
It took a lot of work to keep running. Even when there were 6 or more people on bikes pedaling away as hard as they can it was still barely able to run the system without drawing the rest of the power from the pre-charged battery system.
And you could feel the resistance increase drastically with every bass kick, volume increase or long, sustained bass note.
I still remember how it would kick back at you and you could feel it through the pedaling difficult and how the people riding and pedaling would groan a little every time there was a heavy bass note or bassline happening from the DJ.
It's a really cool idea but the reality of it is that most people have difficulty sustaining more than 150-200 watts or so for any length of time. Even world class or Olympic class pro cyclists struggle to sustain more than about 300-500 watts with peaks and sprints in the 750 to maaaaybe 1000 watt range. Your average casual cyclist will get their ass kicked by trying to sustain more than 200-250 watts for more than 15-60 minutes.
1000 watts is roughly equal to about 1.25 mechanical horsepower before any mechanical, friction, heat waste or other losses.
People seriously underestimate how much power they use in everyday modern life. You could spend all day just trying to charge up your cell phone with a bicycle powered generator, much less keep the lights on, heat water or run a fridge.
posted by loquacious at 1:23 PM on October 10, 2021 [22 favorites]
If I'm remembering the history of the place correctly they stopped using whatever power harvesting function that it might have had because it just wasn't really worth the cost of upkeep.
The floating part of the dance floor was super cool, though. If I'm recalling it correctly the floor was comprised of machined metal billet plates about 1/2 to 2/3rds of a square meter each that floated on a reservoir of oil or even water or something so that the floor had a noticeable shock absorbing quality. It wasn't like dancing on foam or springs in that there was a noticeable rebound or sensation that the floor was moving, but you sure could stomp yourself silly on it without getting as sore as you might get from dancing on solid concrete or metal decking or something.
Like you could stand on the tiles and they just barely moved and displaced some of the liquid underneath and it was a really unique and subtle experience as far as dance floors are concerned. It was like the "sprung" wood dance floors they used to use back in the big band era but without the creaky noises and rebound. I've never seen anything like it before or since.
On a similar tangent and note about how difficult it is to harvest useful power from human input, I've seen people attempt to do bicycle powered sound systems.
They had something that was built up like a cross between an indoor bike trainer and a bike rack with room for something like 8-12 bikes and one long friction-driven drive shaft plus a set of stabilizing rollers to support the rear of each bike. The drive shaft fed the mechanical energy into a converter motor or alternator which powered an inverter and a battery controller/charger.
The sound system they used was tiny. Just two small full range self powered speakers, no subwoofer. Maybe 500-1000 watts of total power for the sound system.
It took a lot of work to keep running. Even when there were 6 or more people on bikes pedaling away as hard as they can it was still barely able to run the system without drawing the rest of the power from the pre-charged battery system.
And you could feel the resistance increase drastically with every bass kick, volume increase or long, sustained bass note.
I still remember how it would kick back at you and you could feel it through the pedaling difficult and how the people riding and pedaling would groan a little every time there was a heavy bass note or bassline happening from the DJ.
It's a really cool idea but the reality of it is that most people have difficulty sustaining more than 150-200 watts or so for any length of time. Even world class or Olympic class pro cyclists struggle to sustain more than about 300-500 watts with peaks and sprints in the 750 to maaaaybe 1000 watt range. Your average casual cyclist will get their ass kicked by trying to sustain more than 200-250 watts for more than 15-60 minutes.
1000 watts is roughly equal to about 1.25 mechanical horsepower before any mechanical, friction, heat waste or other losses.
People seriously underestimate how much power they use in everyday modern life. You could spend all day just trying to charge up your cell phone with a bicycle powered generator, much less keep the lights on, heat water or run a fridge.
posted by loquacious at 1:23 PM on October 10, 2021 [22 favorites]
We need more power! More E!
posted by No Robots at 1:38 PM on October 10, 2021 [3 favorites]
posted by No Robots at 1:38 PM on October 10, 2021 [3 favorites]
It's going to get funky in there, isn't it?
George Clinton In Da House!
posted by hippybear at 1:39 PM on October 10, 2021 [4 favorites]
George Clinton In Da House!
posted by hippybear at 1:39 PM on October 10, 2021 [4 favorites]
"I thought the emissions from peat were terrible from a climate change perspective."
"Sorry, we meant Pete. P-E-T-E. The bouncers only admit people named Pete."
posted by mandolin conspiracy at 1:39 PM on October 10, 2021
"Sorry, we meant Pete. P-E-T-E. The bouncers only admit people named Pete."
posted by mandolin conspiracy at 1:39 PM on October 10, 2021
On a similar tangent and note about how difficult it is to harvest useful power from human input, I've seen people attempt to do bicycle powered sound systems.
Isn't there an entire Black Mirror episode about this?
posted by hippybear at 1:40 PM on October 10, 2021
Isn't there an entire Black Mirror episode about this?
posted by hippybear at 1:40 PM on October 10, 2021
I feel like I've heard similar ideas about this termed'seasonal battery'. Yes, it's a heat pump.
But what you're trying to do in the summer, when you have more heat than you can use; instead of pumping it into the air above, to be carried away by convection, you pump it into the ground far below.
It takes all summer to raise the temperature of a huge cube of dirt from its natural 10c to say, 15c. But then you spend all winter pumping it back out again. It's not sealed in a pressure vessel or anything, but you _are_ increasing that ground-source-heat-pump differential.
You turn summer heat into warm clay (instead of blowing it as hot air out of an AC), a tiny bit at a time. In autumn, it starts leaking out of course, but there's a lot of mass with a lot of intertia inolved. Enough so that you can still recover some in midwinter. Depleted back to (or below) its natural temp by spring, you set up some solar hot water panels and a pump feeding underground radiators, and spend the summer months charging it up again.
A seasonal heat battery.
I don't know how much of an input 'all the heat we can capture via the ventilation system during an all night rave' is. But I appreciate the principle. If you had a cold underground unheated cave, you get the kids to throw dance parties on Saturday night, enough to heat up the walls; then the cave is still warm for the elders who use it for a church on Sunday mornings.
posted by bartleby at 1:46 PM on October 10, 2021 [9 favorites]
But what you're trying to do in the summer, when you have more heat than you can use; instead of pumping it into the air above, to be carried away by convection, you pump it into the ground far below.
It takes all summer to raise the temperature of a huge cube of dirt from its natural 10c to say, 15c. But then you spend all winter pumping it back out again. It's not sealed in a pressure vessel or anything, but you _are_ increasing that ground-source-heat-pump differential.
You turn summer heat into warm clay (instead of blowing it as hot air out of an AC), a tiny bit at a time. In autumn, it starts leaking out of course, but there's a lot of mass with a lot of intertia inolved. Enough so that you can still recover some in midwinter. Depleted back to (or below) its natural temp by spring, you set up some solar hot water panels and a pump feeding underground radiators, and spend the summer months charging it up again.
A seasonal heat battery.
I don't know how much of an input 'all the heat we can capture via the ventilation system during an all night rave' is. But I appreciate the principle. If you had a cold underground unheated cave, you get the kids to throw dance parties on Saturday night, enough to heat up the walls; then the cave is still warm for the elders who use it for a church on Sunday mornings.
posted by bartleby at 1:46 PM on October 10, 2021 [9 favorites]
muddgirl: The big difference seems to be they are using the hot air to warm their circulating liquid before it goes back underground? Vs just dumping the hot air outside. That may make a difference for their environmental efficiency certification but i don't think they're actually "capturing" that energy in any meaningful sense.
What they are talking about is actually storing some of the energy in the warmer months to then use in the colder months, by pumping it underground and then pumping it back out (through a heat pump). The efficiency of this is, of course, generally not great from an energy storage perspective, but it doesn't really matter because you are just trying to get rid of the summer heat anyways, so any you can store is basically just free energy for later use.
I believe it depends quite a bit on geological conditions, but this is certainly something people have done before. Most of the heat storage schemes I've seen have been significantly shallower, usually right underneath the foundation of a building or in the tens of meters, so it would be interesting to see how this deep storage actually works.
posted by ssg at 1:56 PM on October 10, 2021 [4 favorites]
What they are talking about is actually storing some of the energy in the warmer months to then use in the colder months, by pumping it underground and then pumping it back out (through a heat pump). The efficiency of this is, of course, generally not great from an energy storage perspective, but it doesn't really matter because you are just trying to get rid of the summer heat anyways, so any you can store is basically just free energy for later use.
I believe it depends quite a bit on geological conditions, but this is certainly something people have done before. Most of the heat storage schemes I've seen have been significantly shallower, usually right underneath the foundation of a building or in the tens of meters, so it would be interesting to see how this deep storage actually works.
posted by ssg at 1:56 PM on October 10, 2021 [4 favorites]
The Half Language Plant: I have another question. The article says there's no air conditioning. My question is: humidity? It's going to get funky in there, isn't it?
I think they mean there is no air conditioning in the sense we normally mean (air source heat pump on the roof), but there certainly is air conditioning from the geothermal heat pump, which is functionally the same from the perspective of the inside of the building. Air conditioners just dry the air by condensing moisture out of it onto cold surfaces. It doesn't matter what the source of the cold is.
posted by ssg at 2:01 PM on October 10, 2021 [2 favorites]
I think they mean there is no air conditioning in the sense we normally mean (air source heat pump on the roof), but there certainly is air conditioning from the geothermal heat pump, which is functionally the same from the perspective of the inside of the building. Air conditioners just dry the air by condensing moisture out of it onto cold surfaces. It doesn't matter what the source of the cold is.
posted by ssg at 2:01 PM on October 10, 2021 [2 favorites]
the utter lack of documentation coupled with the press-release language and battle bolding, i will conclude for now that this is utter bullshit. i am open for deeper explanations but i suspect it will not be forthcoming.
posted by glonous keming at 2:17 PM on October 10, 2021 [2 favorites]
posted by glonous keming at 2:17 PM on October 10, 2021 [2 favorites]
FYI, in many climates ventilation is actually the primary source of dehumidification. Even in a fairly humid climate you’d get better performance just by exchanging the air with this kind of humidity load then by attempting to reduce it through condensation. It may be just a DOAS (direct outside air exchange) with some conditioning though the heat pump. That combined with fans is an extremely efficient way to cool (and get a little bit of heat).
posted by q*ben at 2:28 PM on October 10, 2021
posted by q*ben at 2:28 PM on October 10, 2021
Also, seems like a good use for an enthalpy wheel, but maybe I just like typing “enthalpy wheel”.
enthalpy wheel
posted by q*ben at 2:33 PM on October 10, 2021 [3 favorites]
enthalpy wheel
posted by q*ben at 2:33 PM on October 10, 2021 [3 favorites]
The wikipedia page on Seasonal thermal energy storage is interesting.
The club is doing a variation of BTES (borehole thermal energy storage), but probably not to the higher temperatures that other installations have used. See that BTES section halfway down the wiki page.
Instead of dumping excess heat outdoors, at least part of it will be recovered in the cooler seasons. But I wonder what their heating and cooling loads are? Maybe cooling is needed even in winter when the venue is full of people. Warmer ground is helpful for heating with the heat pump, but not for cooling.
posted by jjj606 at 3:01 PM on October 10, 2021
The club is doing a variation of BTES (borehole thermal energy storage), but probably not to the higher temperatures that other installations have used. See that BTES section halfway down the wiki page.
Instead of dumping excess heat outdoors, at least part of it will be recovered in the cooler seasons. But I wonder what their heating and cooling loads are? Maybe cooling is needed even in winter when the venue is full of people. Warmer ground is helpful for heating with the heat pump, but not for cooling.
posted by jjj606 at 3:01 PM on October 10, 2021
"A resting human male gives off around 100-120 Watts of energy". Hmmpf, must be a straight guy. Sparkling fabulous queers are just positively glowing, certainly at least 200W.
Yeah this sure sounds like "we're cooling our building with a heat pump" followed by someone being clever and saying "wait a minute, but we heat with a heat pump too!".
For context, 70 tons of carbon is somewhat meaningful. America's per-capita carbon is 16 tons. (And whadda ya get? Another 1C warmer and carbon debt.) The UK is 5.5T/person. I assume a lot of that number is national industry and not, you know, personal activities like glowing on the dance floor.
posted by Nelson at 3:04 PM on October 10, 2021 [4 favorites]
Yeah this sure sounds like "we're cooling our building with a heat pump" followed by someone being clever and saying "wait a minute, but we heat with a heat pump too!".
For context, 70 tons of carbon is somewhat meaningful. America's per-capita carbon is 16 tons. (And whadda ya get? Another 1C warmer and carbon debt.) The UK is 5.5T/person. I assume a lot of that number is national industry and not, you know, personal activities like glowing on the dance floor.
posted by Nelson at 3:04 PM on October 10, 2021 [4 favorites]
Even if the end result isn't net zero, this is a plus for energy use.
Imagine if every building which COULD use this for cooling in summer and heating in winter did. Over the entire globe. How much of an effect would that have?
Bully on them for doing this, and I hope a lot of other places take similar steps.
posted by hippybear at 3:05 PM on October 10, 2021
Imagine if every building which COULD use this for cooling in summer and heating in winter did. Over the entire globe. How much of an effect would that have?
Bully on them for doing this, and I hope a lot of other places take similar steps.
posted by hippybear at 3:05 PM on October 10, 2021
Imagine if every building which COULD use this for cooling in summer and heating in winter did. Over the entire globe. How much of an effect would that have?
Maybe enough that the ground wouldn't be as good a source of heat relative to winter or cold relative to summer.
posted by Dysk at 3:31 PM on October 10, 2021 [1 favorite]
Maybe enough that the ground wouldn't be as good a source of heat relative to winter or cold relative to summer.
posted by Dysk at 3:31 PM on October 10, 2021 [1 favorite]
Maybe enough that the ground wouldn't be as good a source of heat relative to winter or cold relative to summer.
This is a reasonable concern; in very densely populated areas this may be possible, but for the most part it's unlikely. The calculations involved are reasonably well-known and nailed down, because every ground-source system has to do the math to figure out how large their ground system is (in terms of horizontal area and total system depth). Unlike the London Tube system (which is heating the surrounding earth, making the Tube hotter and hotter and hotter), a competently designed ground field won't slowly become hotter and hotter, it'll effectively "zero out" over the course of a year.
...I mean, if they fuck up the math then yes, but competent installers won't make that mistake.
posted by aramaic at 3:38 PM on October 10, 2021 [5 favorites]
This is a reasonable concern; in very densely populated areas this may be possible, but for the most part it's unlikely. The calculations involved are reasonably well-known and nailed down, because every ground-source system has to do the math to figure out how large their ground system is (in terms of horizontal area and total system depth). Unlike the London Tube system (which is heating the surrounding earth, making the Tube hotter and hotter and hotter), a competently designed ground field won't slowly become hotter and hotter, it'll effectively "zero out" over the course of a year.
...I mean, if they fuck up the math then yes, but competent installers won't make that mistake.
posted by aramaic at 3:38 PM on October 10, 2021 [5 favorites]
Most uses of heatpumps in the UK are heating only. With ground-source, which has better performance but is more capital intensive, one of the concerns is that over time you deplete the available heat. So every winter, your borehole is slightly colder and performance degrades. If you need cooling anyway, then dumping your excess heat into your boreholes both makes your cooling more efficient (since the borehole is probably colder than the outside air that you would otherwise use for air conditioning heat sinking) and recharges your borehole for the winter.
Getting the balance right is pretty challenging for smaller systems and I've worked on a number of systems in The Netherlands that ended up thermally imbalanced. My preference now is to specify them slightly imbalanced deliberately in one direction and have an auxiliary system in the opposite direction. For instance, bias the system to put more heat in than out over the year and then have an aux air-source air-conditioner as a backup for when your reservoir is nearing saturation. That lets you tune performance to get net thermal balance to the reservoir. The reason I prefer deliberate unbalancing of the heating and cooling loads is that then you only need to put in one aux system (since you know the direction of imbalance) and the alternative is either putting in two or taking the risk that your modelling is correct.
We have done models as well of whole new neighbourhoods of houses on shared ground loop arrays. If there's gas on any part of the site, we like to put an aux boiler in that warm the loop up by a few degrees if it ever comes close to freezing up. Domestic estates tend to be all-heat so there is more of a seasonal imbalance risk and I'd rather burn some occasional gas rather than have thousands of people decide that heat pumps don't work.
posted by atrazine at 3:48 PM on October 10, 2021 [34 favorites]
Getting the balance right is pretty challenging for smaller systems and I've worked on a number of systems in The Netherlands that ended up thermally imbalanced. My preference now is to specify them slightly imbalanced deliberately in one direction and have an auxiliary system in the opposite direction. For instance, bias the system to put more heat in than out over the year and then have an aux air-source air-conditioner as a backup for when your reservoir is nearing saturation. That lets you tune performance to get net thermal balance to the reservoir. The reason I prefer deliberate unbalancing of the heating and cooling loads is that then you only need to put in one aux system (since you know the direction of imbalance) and the alternative is either putting in two or taking the risk that your modelling is correct.
We have done models as well of whole new neighbourhoods of houses on shared ground loop arrays. If there's gas on any part of the site, we like to put an aux boiler in that warm the loop up by a few degrees if it ever comes close to freezing up. Domestic estates tend to be all-heat so there is more of a seasonal imbalance risk and I'd rather burn some occasional gas rather than have thousands of people decide that heat pumps don't work.
posted by atrazine at 3:48 PM on October 10, 2021 [34 favorites]
America's per-capita carbon is 16 tons. (And whadda ya get? Another 1C warmer and carbon debt.)
*slow clap*
posted by Greg_Ace at 4:56 PM on October 10, 2021 [7 favorites]
*slow clap*
posted by Greg_Ace at 4:56 PM on October 10, 2021 [7 favorites]
Nightclubbing, we're nightclubbing
We're generating
Nightclubbing, we're nightclubbing
We're a heat machine
We do dances, hot new dances
Like a nuclear bomb
posted by RobotVoodooPower at 5:04 PM on October 10, 2021 [5 favorites]
We're generating
Nightclubbing, we're nightclubbing
We're a heat machine
We do dances, hot new dances
Like a nuclear bomb
posted by RobotVoodooPower at 5:04 PM on October 10, 2021 [5 favorites]
I have seen a dance club rain sweat so many times. I used to love it and the idea of it but now... *waves at the pandemic* not so much, eww.
As I haven't been hanging out in dance clubs, this phenomenon is new to me. However, that must just be distilled water, no? So on the one hand, that sounds good. But then I imagine that mold and bacteria are probably growing prolifically where the water condenses. That sounds less good.
posted by polecat at 5:48 PM on October 10, 2021 [1 favorite]
As I haven't been hanging out in dance clubs, this phenomenon is new to me. However, that must just be distilled water, no? So on the one hand, that sounds good. But then I imagine that mold and bacteria are probably growing prolifically where the water condenses. That sounds less good.
posted by polecat at 5:48 PM on October 10, 2021 [1 favorite]
So, assuming it's true, 70 tons. That's. ... a lot? A little?
The social cost of carbon is (perhaps) around $50 a ton. So this is worth around USD$3500. Not a huge deal, especially if it's costly to implement. On the other hand, per capita UK emissions is about 5 tons, so if it worked and could be scaled up at low cost, maybe something to think about?
posted by Mr.Know-it-some at 6:12 PM on October 10, 2021
The social cost of carbon is (perhaps) around $50 a ton. So this is worth around USD$3500. Not a huge deal, especially if it's costly to implement. On the other hand, per capita UK emissions is about 5 tons, so if it worked and could be scaled up at low cost, maybe something to think about?
posted by Mr.Know-it-some at 6:12 PM on October 10, 2021
Single-building, closed-loop, ground-source heat pumps are really cool as an idea, but are VERY expensive for what they provide. It used to be that air-source heat pumps were terrible in cold weather so couldn't really be used as a heating system in places where it matters, but this has changed. They are slightly less efficient (because you are trying to pull heat from air that could be 0C or colder instead of the ground which is more or less 15C year round) but on the other hand, there's no drilling. Which is a HUGE benefit!
It's possible that for a large building that needs twelve boreholes, the expense and difficulty of getting the drilling rig going is worth it compared to the ongoing energy costs of air source, but the really exciting heat pumps are at the district level.
posted by goingonit at 6:33 PM on October 10, 2021 [2 favorites]
It's possible that for a large building that needs twelve boreholes, the expense and difficulty of getting the drilling rig going is worth it compared to the ongoing energy costs of air source, but the really exciting heat pumps are at the district level.
posted by goingonit at 6:33 PM on October 10, 2021 [2 favorites]
the expense and difficulty of getting the drilling rig going is worth it compared to the ongoing energy costs of air source
Wasn't there a startup trying to address the drilling problem? I don't recall who they were, but I swear there was someone promising to cut the drilling cost.
posted by aramaic at 6:52 PM on October 10, 2021
Wasn't there a startup trying to address the drilling problem? I don't recall who they were, but I swear there was someone promising to cut the drilling cost.
posted by aramaic at 6:52 PM on October 10, 2021
I send heat down
I bring it up again
And it’s never gonna keep me down
I send heat down
I bring it up again
And it’s never gonna cool me down
posted by armoir from antproof case at 7:05 PM on October 10, 2021 [3 favorites]
I bring it up again
And it’s never gonna keep me down
I send heat down
I bring it up again
And it’s never gonna cool me down
posted by armoir from antproof case at 7:05 PM on October 10, 2021 [3 favorites]
aramaic: These guys maybe?
idk, I might also be biased against ground-source because these seem like such a...suburban solution, like the septic systems of HVAC or something, while the district level alternatives or even roof-mounted air-source seem far more city-friendly.
posted by goingonit at 7:06 PM on October 10, 2021 [1 favorite]
idk, I might also be biased against ground-source because these seem like such a...suburban solution, like the septic systems of HVAC or something, while the district level alternatives or even roof-mounted air-source seem far more city-friendly.
posted by goingonit at 7:06 PM on October 10, 2021 [1 favorite]
Air source definitely makes more sense for a single family home, but for a commercial building that is using as much gas as a few dozen of homes, ground source can make a lot of sense.
posted by ssg at 7:07 PM on October 10, 2021
posted by ssg at 7:07 PM on October 10, 2021
Air-source doesn’t seem city friendly to me because you’re making your neighbors worse off.
posted by clew at 8:19 PM on October 10, 2021 [1 favorite]
posted by clew at 8:19 PM on October 10, 2021 [1 favorite]
It's possible (though somewhat less efficient) to do ground source without drilling If you have some space and are willing to do some digging. Instead of going deep and narrow, you can go shallow and wide, e.g. under a garden. Can be much cheaper and quicker to do, though obviously you don't get the sink temperature stability of a deeper bore hole. Still significantly more efficient than air source, and effective in a wider range of climates.
posted by Dysk at 8:42 PM on October 10, 2021
posted by Dysk at 8:42 PM on October 10, 2021
This is a reasonable concern; in very densely populated areas this may be possible, but for the most part it's unlikely....
...
...I mean, if they fuck up the math then yes, but competent installers won't make that mistake.
I was responding to the hypothetical where literally every single building in the world was doing this. Single building installers' maths might work out in isolation, but still be a problem in this sort of systemic scale.
I mean, it's an irrelevant hypothetical in our current world, but it's the one that was posed.
posted by Dysk at 8:46 PM on October 10, 2021
...
...I mean, if they fuck up the math then yes, but competent installers won't make that mistake.
I was responding to the hypothetical where literally every single building in the world was doing this. Single building installers' maths might work out in isolation, but still be a problem in this sort of systemic scale.
I mean, it's an irrelevant hypothetical in our current world, but it's the one that was posed.
posted by Dysk at 8:46 PM on October 10, 2021
Single building installers' maths might work out in isolation, but still be a problem in this sort of systemic scale.
But, again, not really. The equations hold in depth and width; I've only been involved in three installations before bailing the fuck out for more, um, highly-constrained problem domains (yay structural!), but in one of those it was required that the soil temperature at the property line be controlled such that the installation could not interfere with a potential installation next door (the wonders of someone filing a lawyers letter, they may have never installed anything but we still had to proceed as if they might). Tetra Tech proceeded to do some wizardry to demonstrate that at full operation the installation being proposed could not affect the soil temperature in the adjacent plot; target a bit below maximum efficiency and you've got room (as suggested above) to make up the difference with heating/cooling (as necessary, plus global warming can fuck things up, who knows how that's gonna go).
It wasn't even that hard; Tetra had the solution in like three days (plus the adjacent weekend, because why the hell not, right? I mean, how many times do you get the consultants solution on a Monday?), which realistically means they solved it on day one and then waited just in case. I mean, sure, it took up pages and pages of math, but it was pretty much plug-and-play for them, and it didn't even occupy much of the intended plot. They buried a big chunk of it under the car park, iirc.
(left as an exercise for the reader is whether TetraTech can be trusted, but hey they convinced the code officials and that's what matters right? The answer may be different if you hire an MEP to run the numbers since their incentives are different, and hell if I know how things ultimately turned out [a different, but related, problem in engineering])
posted by aramaic at 9:45 PM on October 10, 2021 [5 favorites]
But, again, not really. The equations hold in depth and width; I've only been involved in three installations before bailing the fuck out for more, um, highly-constrained problem domains (yay structural!), but in one of those it was required that the soil temperature at the property line be controlled such that the installation could not interfere with a potential installation next door (the wonders of someone filing a lawyers letter, they may have never installed anything but we still had to proceed as if they might). Tetra Tech proceeded to do some wizardry to demonstrate that at full operation the installation being proposed could not affect the soil temperature in the adjacent plot; target a bit below maximum efficiency and you've got room (as suggested above) to make up the difference with heating/cooling (as necessary, plus global warming can fuck things up, who knows how that's gonna go).
It wasn't even that hard; Tetra had the solution in like three days (plus the adjacent weekend, because why the hell not, right? I mean, how many times do you get the consultants solution on a Monday?), which realistically means they solved it on day one and then waited just in case. I mean, sure, it took up pages and pages of math, but it was pretty much plug-and-play for them, and it didn't even occupy much of the intended plot. They buried a big chunk of it under the car park, iirc.
(left as an exercise for the reader is whether TetraTech can be trusted, but hey they convinced the code officials and that's what matters right? The answer may be different if you hire an MEP to run the numbers since their incentives are different, and hell if I know how things ultimately turned out [a different, but related, problem in engineering])
posted by aramaic at 9:45 PM on October 10, 2021 [5 favorites]
Isn't there an entire Black Mirror episode about this?
Yep, but that episode isn't really about human powered electricity. It's about classism, consumerism and how it isolates and abuses people.
posted by loquacious at 1:29 AM on October 11, 2021
Yep, but that episode isn't really about human powered electricity. It's about classism, consumerism and how it isolates and abuses people.
posted by loquacious at 1:29 AM on October 11, 2021
aramaic, how big was the building? How big (and how balanced) was the heating/cooling demand? How much bigger than the footprint of the building was the plot?
posted by Dysk at 4:46 AM on October 11, 2021
posted by Dysk at 4:46 AM on October 11, 2021
Are we sure this headline and the fetid effluvia headline didn't get switched around?
posted by lewiseason at 5:45 AM on October 11, 2021 [2 favorites]
posted by lewiseason at 5:45 AM on October 11, 2021 [2 favorites]
Air-source doesn’t seem city friendly to me because you’re making your neighbors worse off.
Fundamentally, heat pumps are just moving heat from one place to another. The heat you move into a building doesn't disappear — it actually just leaks back out into the surrounding air. So because the heat pump adds more heat in the process (the electricity used ends up as heat), a building with an air-source heat pump is actually slightly warming the surrounding air (all the electricity you use in a building for other purposes also ends up heating the surrounding air). But because air moves and there's a lot of it, the overall impact is negligible.
Air conditioning also heats the surrounding air because of the waste heat from the heat pump itself and from electricity used inside the building, but it's not particularly significant, even in dense areas where every building uses air conditioning.
posted by ssg at 9:45 AM on October 11, 2021 [2 favorites]
Fundamentally, heat pumps are just moving heat from one place to another. The heat you move into a building doesn't disappear — it actually just leaks back out into the surrounding air. So because the heat pump adds more heat in the process (the electricity used ends up as heat), a building with an air-source heat pump is actually slightly warming the surrounding air (all the electricity you use in a building for other purposes also ends up heating the surrounding air). But because air moves and there's a lot of it, the overall impact is negligible.
Air conditioning also heats the surrounding air because of the waste heat from the heat pump itself and from electricity used inside the building, but it's not particularly significant, even in dense areas where every building uses air conditioning.
posted by ssg at 9:45 AM on October 11, 2021 [2 favorites]
It's going to get funky in there, isn't it?
It's called Northern Soul.
posted by srboisvert at 12:17 PM on October 11, 2021
It's called Northern Soul.
posted by srboisvert at 12:17 PM on October 11, 2021
Only tangentially related but Leafcloud is a Dutch server hosting company that puts their servers in apartment buildings and hotels so that the heat the computers generate can warm the buildings.
posted by Nelson at 12:55 PM on October 11, 2021 [1 favorite]
posted by Nelson at 12:55 PM on October 11, 2021 [1 favorite]
how big was the building?
It's been a number of years, but iirc on the order of 15000sf (so, not NYC ha), U-shaped, roughly 60-75 parking spaces in the usual absurdly wasteful use of space, ground source being borehole-style (not horizontal loop). Wasn't too terribly many holes, like 20-30 or something thereabouts, like 15ft apart, pretty easy to fit -- the building being a U-shape was a huuuge help since it made it trivial to drop the field into the near-center of the lot with the fancy landscaping and "executive" parking, no foundations or utilities to dodge. Biggest pain in the ass was the drilling time, and that wasn't too terrible since they were drilling out there by themselves, not too much in the way of other things, although it meant they had to move the center crane sooner than otherwise planned. If the drill rig was smaller (they may have gotten smaller, I haven't had to care about fitting drills in a while) they could probably drop boreholes down most basements even after construction, slide it between the foundation piles. Whole thing seemed pretty easy, at the time. Amusingly, the architect was a little irked the owner didn't want to spring for an ice storage loop for the cooling.
I don't know what current practices are, but as long as you kept the boreholes like 10-20ft apart depending on soil etc., things worked just fine. Tetra just wrote up a doc saying "look, the heat curve in the soil won't even exit from underneath the structure, never mind reach your lot".
posted by aramaic at 12:55 PM on October 11, 2021 [1 favorite]
It's been a number of years, but iirc on the order of 15000sf (so, not NYC ha), U-shaped, roughly 60-75 parking spaces in the usual absurdly wasteful use of space, ground source being borehole-style (not horizontal loop). Wasn't too terribly many holes, like 20-30 or something thereabouts, like 15ft apart, pretty easy to fit -- the building being a U-shape was a huuuge help since it made it trivial to drop the field into the near-center of the lot with the fancy landscaping and "executive" parking, no foundations or utilities to dodge. Biggest pain in the ass was the drilling time, and that wasn't too terrible since they were drilling out there by themselves, not too much in the way of other things, although it meant they had to move the center crane sooner than otherwise planned. If the drill rig was smaller (they may have gotten smaller, I haven't had to care about fitting drills in a while) they could probably drop boreholes down most basements even after construction, slide it between the foundation piles. Whole thing seemed pretty easy, at the time. Amusingly, the architect was a little irked the owner didn't want to spring for an ice storage loop for the cooling.
I don't know what current practices are, but as long as you kept the boreholes like 10-20ft apart depending on soil etc., things worked just fine. Tetra just wrote up a doc saying "look, the heat curve in the soil won't even exit from underneath the structure, never mind reach your lot".
posted by aramaic at 12:55 PM on October 11, 2021 [1 favorite]
Pfft...the explanation of the technology is right there in the FPP title:
"It was fuelled by combinations of "fetid effluvia""
Oh wait, that's the next FPP...
posted by darkstar at 5:45 PM on October 11, 2021
"It was fuelled by combinations of "fetid effluvia""
Oh wait, that's the next FPP...
posted by darkstar at 5:45 PM on October 11, 2021
> You could spend all day just trying to charge up your cell phone with a bicycle powered generator, much less keep the lights on, heat water or run a fridge.
You're right about the lights, hot water, and fridge, but cell phones use very little energy. An average, non-athletic person on an exercise bike can put out around 75 watts. An iPhone 13 battery holds ~15 watt hours. So that's about 12 minutes of cycling for a full charge (assuming that energy can be stored somewhere - the phone can't actually ingest power at that rate). Not "all day".
posted by dmd at 11:12 AM on October 12, 2021 [2 favorites]
You're right about the lights, hot water, and fridge, but cell phones use very little energy. An average, non-athletic person on an exercise bike can put out around 75 watts. An iPhone 13 battery holds ~15 watt hours. So that's about 12 minutes of cycling for a full charge (assuming that energy can be stored somewhere - the phone can't actually ingest power at that rate). Not "all day".
posted by dmd at 11:12 AM on October 12, 2021 [2 favorites]
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posted by mbrubeck at 10:50 AM on October 10, 2021 [19 favorites]