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Heat pumps are great, but it’s the dc inverter and advances in compressor efficiency that is really the biggy on energy usage here. Every one of these “heat pu

Heat pumps are great, but it’s the dc inverter and advances in compressor efficiency that is really the biggy on energy usage here. Every one of these “heat pumps are the future” articles is so soft on data, and they often fail to explain the basics or a simple “why.” Once we get past the clickbait heat pump articles, we can actually make an impact.

glogla 3y ago
I think the consensus on why heat pumps _should_ be the future is that you can power them with low carbon electricity, as opposed to literally world destroying natural gas.
- gizmo686 3y ago
  A quick Google search says that natural gas -> electricity has an efficiency of about 44%, with an additional 5% loss during transmission. Lets call this about 40% efficiency for getting energy from natural gas to your electric heat pump. A heat pump operating at 250% efficiency will use just as much natural gas as a furnace operating at 100% efficiency. Modern heat pumps can often exceed 250% efficiency, making them use less natural gas, even if they are ultimately powered by a natural gas burning power plant.
  - gooseyman 3y ago
    I made a note for myself to go do this math. You beat me to it and answered the question. Thank you :) I vaguely recall I did some back of envelope math a couple years back and determined that a natural gas powered heat pump was actually more efficient (in terms of emissions) based on my grid power source mix. Solar breaks that equation obviously.
brnt 3y ago
I think many people suddenly realized that moving heat translates to efficiencies far north of 100%, also for heating. Moving in opposition to creating heat, which tops out at 100% in the best case. Plus, they can run on any power source, including green and/or decarbonized.
- t0mas88 3y ago
  Above 100% being 350-400% in home heating cases. They're quite popular in the Netherlands due to high natural gas prices (since the Ukraine war) and two types of government subsidies. One is a direct subsidy on buying a heat pump device, the other is based on our energy pricing. Basically you can offset all energy-taxes across the year with solar production. Everything you over-produce in summer carries over to the winter. So if I assume for example that my solar system is written off in 10 years to zero (reality is probably better than that) my total energy cost per kWh is only 7 cents all year round. A pretty low capacity heat pump is able to provide 90% of the heating and cooling of a normal house. They're combined here with gas based systems to cover for the few days a year that it's exceptionally cold or when you need more hot water than the heat pump could deliver. That means you can buy a much smaller capacity (cheaper) heat pump. If you compare the running cost of heating at only 7 cents per kWh with a heat pump to natural gas prices "pre Ukraine" it'a already roughly about 4 to 5x cheaper. Now with gas prices nearly doubled you're looking at a 8x cost saving with a heath pump vs using natural gas. The only hurdle is that you need to buy and install a heat pump device, so it takes some time to make that back. The government is planning to slowly reduce the energy-tax offset from 2025 to 2031. But even without that it's expected that the move from gas to heat pumps will continue.

glogla 3y ago

I think the consensus on why heat pumps _should_ be the future is that you can power them with low carbon electricity, as opposed to literally world destroying natural gas.

gizmo686 3y ago
A quick Google search says that natural gas -> electricity has an efficiency of about 44%, with an additional 5% loss during transmission. Lets call this about 40% efficiency for getting energy from natural gas to your electric heat pump. A heat pump operating at 250% efficiency will use just as much natural gas as a furnace operating at 100% efficiency. Modern heat pumps can often exceed 250% efficiency, making them use less natural gas, even if they are ultimately powered by a natural gas burning power plant.
- gooseyman 3y ago
  I made a note for myself to go do this math. You beat me to it and answered the question. Thank you :) I vaguely recall I did some back of envelope math a couple years back and determined that a natural gas powered heat pump was actually more efficient (in terms of emissions) based on my grid power source mix. Solar breaks that equation obviously.

brnt 3y ago

I think many people suddenly realized that moving heat translates to efficiencies far north of 100%, also for heating. Moving in opposition to creating heat, which tops out at 100% in the best case. Plus, they can run on any power source, including green and/or decarbonized.

t0mas88 3y ago
Above 100% being 350-400% in home heating cases. They're quite popular in the Netherlands due to high natural gas prices (since the Ukraine war) and two types of government subsidies. One is a direct subsidy on buying a heat pump device, the other is based on our energy pricing. Basically you can offset all energy-taxes across the year with solar production. Everything you over-produce in summer carries over to the winter. So if I assume for example that my solar system is written off in 10 years to zero (reality is probably better than that) my total energy cost per kWh is only 7 cents all year round. A pretty low capacity heat pump is able to provide 90% of the heating and cooling of a normal house. They're combined here with gas based systems to cover for the few days a year that it's exceptionally cold or when you need more hot water than the heat pump could deliver. That means you can buy a much smaller capacity (cheaper) heat pump. If you compare the running cost of heating at only 7 cents per kWh with a heat pump to natural gas prices "pre Ukraine" it'a already roughly about 4 to 5x cheaper. Now with gas prices nearly doubled you're looking at a 8x cost saving with a heath pump vs using natural gas. The only hurdle is that you need to buy and install a heat pump device, so it takes some time to make that back. The government is planning to slowly reduce the energy-tax offset from 2025 to 2031. But even without that it's expected that the move from gas to heat pumps will continue.