5 ms·

Good luck trying to get rid of such an amount of heat anyway near your batteries.

by looofooo0 1y ago

doener 1y ago
Well in times of negative energy prices wouldn't it even be good if the air conditioning ran at full capacity?
- Energiekomin 1y ago
  In summer? If its not getting to cold for you. In winter yes also if its not getting to warm for you, but also heating water is easy enough. But you don't need that much hot water Potentially also cooling down your fridge more and your freezer. But that is not that much energy. While that works, it would still be quite a waste. It would be a lot better to save it and discarge it later
- WJW 1y ago
  Depending on how powerful your air conditioner is, it would rapidly start cooling down the building to a temperature which is too low to still be comfortable. You could maybe buffer this with more thermal mass, but then you are back in the game of storing energy and might as well just get extra batteries.
  - sib 1y ago
    Why not place the air conditioner next to a large electric space heater?
  - amluto 1y ago
    Many heat pumps already have a mechanism for deliberately wasting energy for defrosting the coils. I bet that the same hardware with a different control algorithm could be convinced to heat out the outdoors without much net change in indoor temperature. (The solution involving the smallest amount of extra hardware is to run the system in reverse periodically. There are other solutions.) Whether the negative energy price is enough to balance wear on the system and potential noise is a different question.
- KeplerBoy 1y ago
  Yes, it's not much of an issue if you have free energy.
  - lazide 1y ago
    It only makes sense if you have ‘more than free’ energy you need to get rid of, because not getting rid of it causes problems. Similar to flaring natural gas, but for actual electricity. This is not a common occurrence or situation, or shouldn’t be anyway, or someone is screwing up pretty badly somewhere.
    - AndrewDucker 1y ago
      With variable sources of electricity it can be cheaper to have capacity at a level that you sometimes overproduce than to have a capacity that produces at a lower level, and so mostly needs a backup source of power.
    - infecto 1y ago
      It’s actually quite common. You have base load generation stations and your highly variable solar and wind. There are often times when the power at a wholesale rate dips below zero. It’s too costly to turn off your base load plants and maybe both solar and wind are generating above normal.
      - lazide 1y ago
        Solar inverters can just not draw the solar current, and wind can generally just change the pitch on their rotors at the individual level. The only ones that generally can not help ‘over produce’ are baseload power stations as they have actual physical inertia in very large turbines and can’t respond as quickly to demand.
        infecto 1y ago
        Right but keep in mind these events are generally short lived and depending on the market there may be reliability guarantees that keep these open or specific federal funding rates. But like I said before when rates go negative you will typically see it in occurrences where you have abnormal conditions (wind and solar generating at the same time) or aggressive night winds. And it does not happen long enough to need to curtail generation.
_trampeltier 1y ago
Some years ago, I helped with battery load tests in a nuclear power station. The constant test load was just a big (~500kW) heater. We burned the battery energy for 5 hours. So it's easy possible to do such things.
- horsawlarway 1y ago
  Exactly this. And the same thing for residential scale is literally just a ceramic space heater running at ~1500w. They're dirt cheap, usually have temp safety checks built in, work on a residentially sized circuit, and are available everywhere. I needed a cheap and consistent load to do LFP battery testing, and I could spend $5,000 for a real test unit, or $21 for a ceramic heater that will do basically the same thing. If you've already got the monitoring for the batteries/inverters, a heater is a GREAT load choice.
  - petertodd 1y ago
    HAAS CNC mills are famous for using electric stove elements for the spindle brake resistor: https://www.reddit.com/r/CNC/comments/1es1d01/someone_didnt_believe_me_when_i_said_that_our/ https://www.reddit.com/r/CNC/comments/1es1d01/someone_didnt_... I'm not sure that this really is a completely off-the-shelf stove element. But obviously, the technology is basically identical to what you'd have on your stove.
    - _trampeltier 1y ago
      It is cery common for Frequency Inverter for AC Motors to have a break resistor. It's expensive to push energy back to the grid with from an inverter. So in most case just a break resistor is used. Just if you break a lot and a long time it is worth to buy an inverter who can do it. If you have multiple axis in a machine, often they are coupled with DC, so the break energy is used by another drive.
      - petertodd 1y ago
        Yup. On a much bigger scale it's common for the power supplies going to electric trains to do this too. They like to use regenerative braking because it's efficient. But the electricity grid can't always handle the extra power, so in some designs they have a backup mechanism to dissipate the power if needed; diesel-electrics usually just have a big bank of air-cooled load resistors on the roof. A neat example of regenerative braking being important is the London Underground: they've had a persistent problem with high temperatures in the subway, of which a decent % is actually heat from trains braking. By using regenerative braking rather than putting that energy into the tunnels as heat, they can transport that energy outside the tunnels, keeping them cooler.

Good luck trying to get rid of such an amount of heat anyway near your batteries.

doener 1y ago

Well in times of negative energy prices wouldn't it even be good if the air conditioning ran at full capacity?

Energiekomin 1y ago
In summer? If its not getting to cold for you. In winter yes also if its not getting to warm for you, but also heating water is easy enough. But you don't need that much hot water Potentially also cooling down your fridge more and your freezer. But that is not that much energy. While that works, it would still be quite a waste. It would be a lot better to save it and discarge it later
WJW 1y ago
Depending on how powerful your air conditioner is, it would rapidly start cooling down the building to a temperature which is too low to still be comfortable. You could maybe buffer this with more thermal mass, but then you are back in the game of storing energy and might as well just get extra batteries.
- sib 1y ago
  Why not place the air conditioner next to a large electric space heater?
- amluto 1y ago
  Many heat pumps already have a mechanism for deliberately wasting energy for defrosting the coils. I bet that the same hardware with a different control algorithm could be convinced to heat out the outdoors without much net change in indoor temperature. (The solution involving the smallest amount of extra hardware is to run the system in reverse periodically. There are other solutions.) Whether the negative energy price is enough to balance wear on the system and potential noise is a different question.
KeplerBoy 1y ago
Yes, it's not much of an issue if you have free energy.
- lazide 1y ago
  It only makes sense if you have ‘more than free’ energy you need to get rid of, because not getting rid of it causes problems. Similar to flaring natural gas, but for actual electricity. This is not a common occurrence or situation, or shouldn’t be anyway, or someone is screwing up pretty badly somewhere.
  - AndrewDucker 1y ago
    With variable sources of electricity it can be cheaper to have capacity at a level that you sometimes overproduce than to have a capacity that produces at a lower level, and so mostly needs a backup source of power.
  - infecto 1y ago
    It’s actually quite common. You have base load generation stations and your highly variable solar and wind. There are often times when the power at a wholesale rate dips below zero. It’s too costly to turn off your base load plants and maybe both solar and wind are generating above normal.
    - lazide 1y ago
      Solar inverters can just not draw the solar current, and wind can generally just change the pitch on their rotors at the individual level. The only ones that generally can not help ‘over produce’ are baseload power stations as they have actual physical inertia in very large turbines and can’t respond as quickly to demand.
      - infecto 1y ago
        Right but keep in mind these events are generally short lived and depending on the market there may be reliability guarantees that keep these open or specific federal funding rates. But like I said before when rates go negative you will typically see it in occurrences where you have abnormal conditions (wind and solar generating at the same time) or aggressive night winds. And it does not happen long enough to need to curtail generation.

_trampeltier 1y ago

Some years ago, I helped with battery load tests in a nuclear power station. The constant test load was just a big (~500kW) heater. We burned the battery energy for 5 hours. So it's easy possible to do such things.

horsawlarway 1y ago
Exactly this. And the same thing for residential scale is literally just a ceramic space heater running at ~1500w. They're dirt cheap, usually have temp safety checks built in, work on a residentially sized circuit, and are available everywhere. I needed a cheap and consistent load to do LFP battery testing, and I could spend $5,000 for a real test unit, or $21 for a ceramic heater that will do basically the same thing. If you've already got the monitoring for the batteries/inverters, a heater is a GREAT load choice.
- petertodd 1y ago
  HAAS CNC mills are famous for using electric stove elements for the spindle brake resistor: https://www.reddit.com/r/CNC/comments/1es1d01/someone_didnt_believe_me_when_i_said_that_our/ https://www.reddit.com/r/CNC/comments/1es1d01/someone_didnt_... I'm not sure that this really is a completely off-the-shelf stove element. But obviously, the technology is basically identical to what you'd have on your stove.
  - _trampeltier 1y ago
    It is cery common for Frequency Inverter for AC Motors to have a break resistor. It's expensive to push energy back to the grid with from an inverter. So in most case just a break resistor is used. Just if you break a lot and a long time it is worth to buy an inverter who can do it. If you have multiple axis in a machine, often they are coupled with DC, so the break energy is used by another drive.
    - petertodd 1y ago
      Yup. On a much bigger scale it's common for the power supplies going to electric trains to do this too. They like to use regenerative braking because it's efficient. But the electricity grid can't always handle the extra power, so in some designs they have a backup mechanism to dissipate the power if needed; diesel-electrics usually just have a big bank of air-cooled load resistors on the roof. A neat example of regenerative braking being important is the London Underground: they've had a persistent problem with high temperatures in the subway, of which a decent % is actually heat from trains braking. By using regenerative braking rather than putting that energy into the tunnels as heat, they can transport that energy outside the tunnels, keeping them cooler.