3 ms·

This is a generational buildup of heat, being tackled seasonally. TfL must run its cooling operations in the winter as well as the summer. It’s about net ener

This is a generational buildup of heat, being tackled seasonally. TfL must run its cooling operations in the winter as well as the summer. It’s about net energy difference over the whole year. Finding cold air in the winter will also be substantially cheaper

MichaelZuo 1y ago
I dont quite understand what’s stopping them from just buying hundreds of chillers, putting them on the surface close to each station, and running chilled water loops down. Other than cost of course.
- mnw21cam 1y ago
  They're running trains. Trains use a lot of electricity, and they turn almost all of it into heat. You'd have to have as much chilling capacity as the current electricity demand of the entire tube line, which is quite a lot. However, if the buildings above were to sink ground source heat pump loops into the warmed ground to heat the buildings in winter, this would basically be what you just suggested, and would be a win-win situation.
  - MichaelZuo 1y ago
    Huh? Modern modular air cooled chillers go up to 800 tons each and can remove multiple MW of heat load continuously pretty much 24/7. 500 of them could remove 1.4 GW of heat. Of course there are many ways to improve efficiency, but even assuming the worst case it’s still technically feasible to remove many times more heat than the line generates.
    - avianlyric 1y ago
      And where is the energy to power all of them coming from? GP is saying that you can approximate the energy going into the system by looking at the electricity consumption of the trains, as all then energy is eventually going to end up as heat. A heat pump can have a CoP topping out at 5. So 1 unit of energy needed to move 5 units heat out. That means a “net zero” cooling system would consume a minimum of 20% as much energy as the trains themselves. Realistically it’s probably closer to a CoP of 3.5, so 28% more energy. For something like the underground that gonna be a 5-10% increase in there operational costs at a minimum. Where does the funding for all that come from? And that before we even look at the capital costs of heat pumps and various ancillary equipment needed to run them. As a point of reference TfL underground trains have an average power consumption of 140MW continuous. Now only about 45% of the underground is actually underground, but that’s still 63MW in just the underground parts. At an optimistic CoP of 5, that means 12.6MW of additional energy needed to cool the tunnels using your approach. Wholesale electricity prices in the UK are something like 7p per kWh. So over a year that’s an additional £17m of electricity, just for cooling.
      - ShroudedNight 1y ago
        £17 million doesn't sound that unreasonable for climate control for a system as large as London's
        mike_hearn 1y ago
        That's £17M of electricity, not including all the equipment, staff, installation costs etc. To put this in perspective, Sadiq Khan already runs the system at a massive loss. They just about cover their operating costs at the momemt, and rely entirely on grants from the rest of the country to do upgrades of any kind. So cooling efforts have to be very cost efficient. Also the UK grid is very supply constrained. New nukes are being built but there have been the expected massive cost overruns and problems, so any large new energy demands in the UK just aren't happening anytime soon. It's actually been deindustrializing due to very high electricity costs.
        Starlevel004 1y ago
        TfL spends close to 100% of its income on operating costs. It does not get any other money.
      - MichaelZuo 1y ago
        Doing things on a large scale cost money… often more than what taxpayers are willing to bear, are you genuinely confused about that?
        avianlyric 1y ago
        Yes doing things at scale does cost lots of money. That often why doing the “obvious” is the wrong approach. When you’re operating at that kind of scale, small savings are still substantial, and scale often makes more innovative, less obvious solutions a better pick. Especially given the cost of exploring those options is so cheap compared to total cost of the project. Also the underground is funded pretty much entirely by fares paid. Past UK governments have cut any tax payer subsidies for TfL to zero for day-to-day operational costs, and there’s zero indication that’s going to change any time soon.

MichaelZuo 1y ago

I dont quite understand what’s stopping them from just buying hundreds of chillers, putting them on the surface close to each station, and running chilled water loops down. Other than cost of course.

mnw21cam 1y ago
They're running trains. Trains use a lot of electricity, and they turn almost all of it into heat. You'd have to have as much chilling capacity as the current electricity demand of the entire tube line, which is quite a lot. However, if the buildings above were to sink ground source heat pump loops into the warmed ground to heat the buildings in winter, this would basically be what you just suggested, and would be a win-win situation.
- MichaelZuo 1y ago
  Huh? Modern modular air cooled chillers go up to 800 tons each and can remove multiple MW of heat load continuously pretty much 24/7. 500 of them could remove 1.4 GW of heat. Of course there are many ways to improve efficiency, but even assuming the worst case it’s still technically feasible to remove many times more heat than the line generates.
  - avianlyric 1y ago
    And where is the energy to power all of them coming from? GP is saying that you can approximate the energy going into the system by looking at the electricity consumption of the trains, as all then energy is eventually going to end up as heat. A heat pump can have a CoP topping out at 5. So 1 unit of energy needed to move 5 units heat out. That means a “net zero” cooling system would consume a minimum of 20% as much energy as the trains themselves. Realistically it’s probably closer to a CoP of 3.5, so 28% more energy. For something like the underground that gonna be a 5-10% increase in there operational costs at a minimum. Where does the funding for all that come from? And that before we even look at the capital costs of heat pumps and various ancillary equipment needed to run them. As a point of reference TfL underground trains have an average power consumption of 140MW continuous. Now only about 45% of the underground is actually underground, but that’s still 63MW in just the underground parts. At an optimistic CoP of 5, that means 12.6MW of additional energy needed to cool the tunnels using your approach. Wholesale electricity prices in the UK are something like 7p per kWh. So over a year that’s an additional £17m of electricity, just for cooling.
    - ShroudedNight 1y ago
      £17 million doesn't sound that unreasonable for climate control for a system as large as London's
      - mike_hearn 1y ago
        That's £17M of electricity, not including all the equipment, staff, installation costs etc. To put this in perspective, Sadiq Khan already runs the system at a massive loss. They just about cover their operating costs at the momemt, and rely entirely on grants from the rest of the country to do upgrades of any kind. So cooling efforts have to be very cost efficient. Also the UK grid is very supply constrained. New nukes are being built but there have been the expected massive cost overruns and problems, so any large new energy demands in the UK just aren't happening anytime soon. It's actually been deindustrializing due to very high electricity costs.
      - Starlevel004 1y ago
        TfL spends close to 100% of its income on operating costs. It does not get any other money.
    - MichaelZuo 1y ago
      Doing things on a large scale cost money… often more than what taxpayers are willing to bear, are you genuinely confused about that?
      - avianlyric 1y ago
        Yes doing things at scale does cost lots of money. That often why doing the “obvious” is the wrong approach. When you’re operating at that kind of scale, small savings are still substantial, and scale often makes more innovative, less obvious solutions a better pick. Especially given the cost of exploring those options is so cheap compared to total cost of the project. Also the underground is funded pretty much entirely by fares paid. Past UK governments have cut any tax payer subsidies for TfL to zero for day-to-day operational costs, and there’s zero indication that’s going to change any time soon.