4 ms·

> The big difference is because of air conditioning and baseboard heating (...) Which makes you wonder why there is not as much high-profile attention on A/C (

by j1vms 10y ago

> The big difference is because of air conditioning and baseboard heating (...) Which makes you wonder why there is not as much high-profile attention on A/C (and to a lesser extent electrical heating) as being a problem worthy of rethinking by Silicon Valley (perhaps even ahead of solar, in North America).

jacquesm 10y ago
There is quite a bit of work being done on solar powered airconditioning. I experimented myself with this about 10 years ago using two back-to-back Stirling engines with the first powered by the sun and the second being run in reverse to cool a working fluid. It's an interesting field, you'll learn more about Carnot cycles and thermodynamics than you ever wanted to :)
- chmike 10y ago
  A climatization using DC current from capacitors charged with solar panels might be more interesting in mild hot regions. If I understood well AC is optimized for carrying current on long distance with minimal loss. But most electric devices use DC. They need an AC to DC convertor with some energy loss. Solar panels produce DC and is usualy converted to AC with some loss. Then, in most electronic devices, this AC is converted back into DC in the device power transformator. What waste of energy. Shouldn't we do something about this ?
  - kogepathic 10y ago
    > What waste of energy. Shouldn't we do something about this ? Most devices which operate on DC (e.g. computers, TV) have a switching power supply, which is around 90% efficient. So for a computer drawing 100W, only about 10W is lost in the conversion of AC to DC. Larger appliances such as microwaves, ovens, and air conditioners will use AC directly without conversion to DC (except maybe to power the control electronics). > But most electric devices use DC. Yes, but no national grids are DC. There is a lot of interest in using high voltage DC (HVDC) for long distance transmission (and wind farms), since you don't have to expend energy to generate and maintain the sine wave (and your collector field electronics are simpler), but the customer connection is always AC. With the insane amount of money invested in delivery to homes as 110/220VAC, no one is going to start selling DC devices. Even in regions where this is no electricity and people use off-grid systems, the economies of scale mean that DC appliances such as refrigerators are often 200-400% more expensive than their AC counterparts. A lot of research has been put into DC distribution, but the main issues are: - Devices still require a DC/DC converter to step up or down the distribution voltage to their operating voltage. This converter is again not 100% efficient - High voltage DC is deadly (your muscles will contract instead of releasing, so if you touch a cable you're dead) - Low voltage DC requires thicker wires, meaning higher cost for distribution Source: work for a utility company
    - jacquesm 10y ago
      Another factor is that high voltage DC step-down is significantly harder than AC step-down, especially once you get into the 100's of KV. With AC that's relatively easy, transformers are passive components, very well understood and can be made for extremely large power levels without getting into exotic engineering.
- deleted 10y ago
  [deleted]
Keyframe 10y ago
It might be (it is) anecdotal, but as someone from Europe it struck me odd how much Americans love their A/C. Too much, in fact. Almost everywhere I went it was too cold. Somewhat like in SE Asia. That might be the answer to high energy use.
- ghaff 10y ago
  For Americans, mostly read Texans or maybe Southerners more broadly. A lot of us joke that the hotter the climate in a US state, the colder they tend to crank the AC.
  - Keyframe 10y ago
    That can't be good for health! SE Asia like to do that too. I joked that tropics there were a sham since I had to wear a jacket all the time because of the polar-like A/C.
- kwhitefoot 10y ago
  I have the same experience in both US (mostly Raleigh, NC) and China; but China has got better over the last twenty years, possibly because air conditioning is no longer an unusual thing in the big cities so it being cold indoors is not such a status symbol, perhaps.
- actualdc1 10y ago
  It's worth noting that temperature control is only half the equation. In places like Houston, A/C plays a big part in controlling indoor humidity as well(for both comfort purposes and to prevent mildew from growing all over everything).
  - fbender 10y ago
    There's other (read: more efficient) ways to control humidity than using an A/C. Including making buildings more "airtight" so the dampness doesn't leak into the house (as long as you don't open doors/windows too much, of couse).
- 10y ago

by j1vms 10y ago

jacquesm 10y ago

There is quite a bit of work being done on solar powered airconditioning. I experimented myself with this about 10 years ago using two back-to-back Stirling engines with the first powered by the sun and the second being run in reverse to cool a working fluid. It's an interesting field, you'll learn more about Carnot cycles and thermodynamics than you ever wanted to :)

chmike 10y ago
A climatization using DC current from capacitors charged with solar panels might be more interesting in mild hot regions. If I understood well AC is optimized for carrying current on long distance with minimal loss. But most electric devices use DC. They need an AC to DC convertor with some energy loss. Solar panels produce DC and is usualy converted to AC with some loss. Then, in most electronic devices, this AC is converted back into DC in the device power transformator. What waste of energy. Shouldn't we do something about this ?
- kogepathic 10y ago
  > What waste of energy. Shouldn't we do something about this ? Most devices which operate on DC (e.g. computers, TV) have a switching power supply, which is around 90% efficient. So for a computer drawing 100W, only about 10W is lost in the conversion of AC to DC. Larger appliances such as microwaves, ovens, and air conditioners will use AC directly without conversion to DC (except maybe to power the control electronics). > But most electric devices use DC. Yes, but no national grids are DC. There is a lot of interest in using high voltage DC (HVDC) for long distance transmission (and wind farms), since you don't have to expend energy to generate and maintain the sine wave (and your collector field electronics are simpler), but the customer connection is always AC. With the insane amount of money invested in delivery to homes as 110/220VAC, no one is going to start selling DC devices. Even in regions where this is no electricity and people use off-grid systems, the economies of scale mean that DC appliances such as refrigerators are often 200-400% more expensive than their AC counterparts. A lot of research has been put into DC distribution, but the main issues are: - Devices still require a DC/DC converter to step up or down the distribution voltage to their operating voltage. This converter is again not 100% efficient - High voltage DC is deadly (your muscles will contract instead of releasing, so if you touch a cable you're dead) - Low voltage DC requires thicker wires, meaning higher cost for distribution Source: work for a utility company
  - jacquesm 10y ago
    Another factor is that high voltage DC step-down is significantly harder than AC step-down, especially once you get into the 100's of KV. With AC that's relatively easy, transformers are passive components, very well understood and can be made for extremely large power levels without getting into exotic engineering.
deleted 10y ago
[deleted]

Keyframe 10y ago

It might be (it is) anecdotal, but as someone from Europe it struck me odd how much Americans love their A/C. Too much, in fact. Almost everywhere I went it was too cold. Somewhat like in SE Asia. That might be the answer to high energy use.

ghaff 10y ago
For Americans, mostly read Texans or maybe Southerners more broadly. A lot of us joke that the hotter the climate in a US state, the colder they tend to crank the AC.
- Keyframe 10y ago
  That can't be good for health! SE Asia like to do that too. I joked that tropics there were a sham since I had to wear a jacket all the time because of the polar-like A/C.
kwhitefoot 10y ago
I have the same experience in both US (mostly Raleigh, NC) and China; but China has got better over the last twenty years, possibly because air conditioning is no longer an unusual thing in the big cities so it being cold indoors is not such a status symbol, perhaps.
actualdc1 10y ago
It's worth noting that temperature control is only half the equation. In places like Houston, A/C plays a big part in controlling indoor humidity as well(for both comfort purposes and to prevent mildew from growing all over everything).
- fbender 10y ago
  There's other (read: more efficient) ways to control humidity than using an A/C. Including making buildings more "airtight" so the dampness doesn't leak into the house (as long as you don't open doors/windows too much, of couse).
10y ago