Editing Heat pump (section)

===Carbon footprint===
The [[carbon footprint]] of heat pumps depends on their individual efficiency and how electricity is produced. An increasing share of low-carbon energy sources such as wind and solar will lower the impact on the climate.

{| class="wikitable"
|-
! heating system !! emissions of energy source !! efficiency || resulting emissions for thermal energy
|-
| heat pump with onshore wind power || 11&nbsp;g{{CO2}}/kWh<ref>{{Cite web |title=How Wind Can Help Us Breathe Easier |url=https://www.energy.gov/eere/wind/articles/how-wind-can-help-us-breathe-easier |access-date=2023-09-13 |website=Energy.gov |language=en |archive-date=2023-08-28 |archive-url=https://web.archive.org/web/20230828230748/https://www.energy.gov/eere/wind/articles/how-wind-can-help-us-breathe-easier |url-status=live }}</ref>|| 400% (COP=4) || 3&nbsp;g{{CO2}}/kWh
|-
| heat pump with global electricity mix || 436&nbsp;g{{CO2}}/kWh<ref>{{Cite web |date=2023-04-11 |title=Global Electricity Review 2023 |url=https://ember-energy.org/latest-insights/global-electricity-review-2023/ |url-status=live |archive-url=https://web.archive.org/web/20230411233554/https://ember-climate.org/insights/research/global-electricity-review-2023/ |archive-date=2023-04-11 |access-date=2023-09-13 |website=Ember |language=en-US}}</ref> (2022) || 400% (COP=4) || 109&nbsp;g{{CO2}}/kWh
|-
| natural-gas thermal (high efficiency)|| 201&nbsp;g{{CO2}}/kWh<ref name="Quaschning 2022">{{harvnb|Quaschning|2022}}</ref> || 90%{{Cn|date=September 2023}}|| 223&nbsp;g{{CO2}}/kWh
|-
| heat pump<br />electricity by lignite (old power plant)<br />and low performance || 1221&nbsp;g{{CO2}}/kWh<ref name="Quaschning 2022"/> || 300% (COP=3) || 407&nbsp;g{{CO2}}/kWh
|}

In most settings, heat pumps will reduce {{CO2}} emissions compared to heating systems powered by [[fossil fuels]].<ref name="UK sabotaging decarbonize">{{Cite web|title=The UK is sabotaging its own plan to decarbonize heating|url=https://www.engadget.com/air-source-heat-pumps-uk-120044198.html|access-date=2021-06-06|website=Engadget |date=27 May 2021 |archive-date=2021-06-06|archive-url=https://web.archive.org/web/20210606155712/https://www.engadget.com/air-source-heat-pumps-uk-120044198.html|url-status=live}}</ref> In regions accounting for 70% of [[world energy consumption]], the emissions savings of heat pumps compared with a high-efficiency gas boiler are on average above 45% and reach 80% in countries with cleaner electricity mixes.<ref name=ieareport /> These values can be improved by 10 percentage points, respectively, with alternative refrigerants. In the United States, 70% of houses could reduce emissions by installing a heat pump.<ref>{{cite journal |last1=Deetjen |first1=Thomas A |last2=Walsh |first2=Liam |last3=Vaishnav |first3=Parth |journal=Environmental Research Letters |volume=16 |issue=8|title=US residential heat pumps: the private economic potential and its emissions, health, and grid impacts |date=2021-07-28 |page=084024 |doi=10.1088/1748-9326/ac10dc |bibcode=2021ERL....16h4024D |s2cid=236486619 |doi-access=free }}</ref><ref name=ieareport /> The rising share of renewable electricity generation in many countries is set to increase the emissions savings from heat pumps over time.<ref name=ieareport />

Heating systems powered by green hydrogen are also low-carbon and may become competitors, but are much less efficient due to the energy loss associated with hydrogen conversion, transport and use. In addition, not enough green hydrogen is expected to be available before the 2030s or 2040s.<ref>{{Cite web|date=2021-05-21|title=Can the UK rely on hydrogen to save its gas boilers?|url=https://inews.co.uk/news/can-the-uk-rely-on-hydrogen-to-save-its-gas-boilers-1014119|access-date=2021-06-06|website=inews.co.uk |archive-date=2021-06-06|archive-url=https://web.archive.org/web/20210606155711/https://inews.co.uk/news/can-the-uk-rely-on-hydrogen-to-save-its-gas-boilers-1014119|url-status=live}}</ref><ref>IEA (2022), Global Hydrogen Review 2022, IEA, Paris https://www.iea.org/reports/global-hydrogen-review-2022 {{Webarchive|url=https://web.archive.org/web/20230110225147/https://www.iea.org/reports/global-hydrogen-review-2022 |date=2023-01-10 }} , License: CC BY 4.0</ref>