Heat pumps have the potential to save Australia at least 127 TWh of energy; this is a staggering amount as Australia only generated a total of 227 TWh of electrical power in 2018. This 127 TWh figures is divided into 100 TWh of savings from space heating and 27 TWh of savings from hot water heating.
Before we go any further let's get something out of the way. Though heat pumps use much less energy to do their job than traditional gas and electric heaters, they are actually producers of renewable energy, and here is why. Heat pumps work, as the name suggests, buy pumping heat from outside your home either into your home (via reverse cycle AC) or into your hot water tank. This is not really any different to a solar system that takes solar energy and 'pumps' it into your electrical system, the only difference being heat pumps require some electrical energy to operate whereas solar panels do not. So if solar panels are considered renewable energy, then heat pumps really can be considered producers of renewable energy also, as the thermal energy (heat) they gather from outside your home is ultimately provided by the sun.
But let's get back to the headline number of 127 TWh of savings. To save 127 TWh of energy via heat pumps involves replacing all the existing gas and electric hot water and space heating solutions in Australia; with the most efficient heat pump options on the market (admittedly a big task). The reason heat pumps can produce such enormous savings is that heating water or air (as in home heating) using a gas furnace or electric element is, making generous assumptions, only 70% efficient. Whereas heating water with heat pumps can be 500% efficient (using the Sanden EcoPlus) and home heating using heat pumps can be 600% efficient if you use Daikin US7s units to do the heating. Therefore heating water via heat pump cuts energy use by 86% and heating your home via heat pump cuts energy use by around 90%.
Incidentally, the space heating replacement in this example (replacing gas furnaces with reverse cycle AC units) is only considered for the states with cold winters i.e. SA, Vic, TAS and ACT, where the winter heating load vastly outweighs cooling loads in summer. Home heating in Victoria, for example, uses 80 times the energy compared with energy used for home cooling.
For transparency I'll list some of the other main assumptions that give you 127 TWh in savings:
- Homes have an average rating of 2 stars (in Vic it is actually 1.8 stars)
- Water heating is done via the Sanden EcoPlus (cop 5.0)
- Space heating is done via the Daikin US7 (cop 6.0)
- Heated area of the average home 200 m2 (the average Australian home is 240 m2)
- Only hot water consumption for showers is considered (1 shower per day, per person for an average of 7.5 mins)
- Space heating savings for houses in Vic, Tas, ACT and SA use capital city climate zone data.
Given the enormous amount of renewable energy accessible by using heat pumps why aren't they as well known and popular as solar power? It might be the fact that heat pumps don't quite have the PR of wind and solar and are slightly more difficult to understand. Or it might be that air-conditioners (aka space heating/cool heat pumps) have been demonised as power hungry villains (which they sort of are in the cooling mode; but are overall power saving champions). Or perhaps it is because people are unaware of the truly staggering potential heat pumps have in moving Australia to 100% renewable energy (to be fair these numbers also took the author by surprise).
Clearly moving to heat pumps as the dominant heating option makes moving to 100% renewable energy much easier by reducing the job renewables need to do. Heat pumps should be mentioned in the same breath as wind and solar as they are a natural partner to these other renewable energy sources. It is time the quiet achiever of the renewable energy industry got the recognition it deserves.