The Charlie is the world’s first energy storage equipped induction electric stove (Source: Copper)
People, and businesses, don’t just want energy or technologies for their own sake. They want services they value, such as health, comfort and entertainment.
If we don’t provide those services, we will not succeed in transforming energy costs and cutting carbon emissions.
As we develop strategies to drive rapid electrification, we need to confront some practical obstacles.
Creative options for lovers of gas cooking
A key aim is to facilitate more cost-effective street/neighbourhood gas grid shutdowns faster. However, the “right” to keep gas cooking has emerged as an important issue that needs to be addressed as we electrify communities.
It can provoke unnecessary conflicts but these can be managed by encouraging creative solutions and analysing the relative costs and benefits of options outlined below.
It is likely that street or neighbourhood gas grid shutdowns will be far more cost-effective and faster than individual gas disconnections, so it is important that we consider options that will:
- Capture financial savings,
- Reduce the time needed for scarce trades people to implement transition,
- reduce damage to roads,
- reduce logistical impediments to households changing from gas and,
- accelerate emission reduction.
Some options may potentially avoid the need for and costs and hassles of electrical wiring upgrades, which will reduce a barrier to the transition.
However, if one or two households block a neighbourhood transition from gas, the financial and emission savings from rapid bulk electrification and potential for economies of scale of appliance conversion will be reduced.
So it will also be important to offer practical options to the few households who may prefer to keep gas cooking, hot water and space heating options, that address their concerns and reservations about electrification, (eg induction won’t work if the power fails) or who just have a preference for gas cooking.
Some of the potential options include:
- Shift to LPG cooking. As Elgas point out on their website, for low gas consumption LPG is cheaper than grid gas, as its much lower fixed charges more than offset its higher unit price. For small households with instantaneous gas hot water, LPG can be cheaper if cooking and hot water remain on gas using LPG.
- Run education programs and offer trials with quality plug-in induction cooktops to familiarise households with the performance of induction cooking for the kinds of food they prefer, and educate them regarding heat pump hot water systems.
- Accelerate access to emerging flexible induction cooking options that incorporate energy storage and other features to limit peak demand, such as battery boosted induction stoves.
We need to invent indoor heat pump hot water systems
Existing heat pump hot water system (HWS ) units involve installing equipment outside, which requires owner and Owners Corporation approvals – often a challenge for renters or apartment owners.
It will be important to develop practical options for apartment dwellers, and those with limited outdoor space, to shift from gas for water heating.
My analysis suggests that an indoor heat pump hot water system (HPHWS) is a practical option, especially for smaller households. They could offer significant energy benefits, especially in mild climates when the cool air they produce is beneficial in warm or hot weather, and even in cold climates if a reverse cycle air-conditioner is being used for heating.
But, to my knowledge, such products do not yet exist.
The energy analysis of an indoor HPHWS is complicated. It produces cold air as it heats water, but there are complex interactive effects.
In warm or hot weather, the cold air produced is a benefit, as it reduces space cooling costs. But heat loss from the storage tank adds some heat to the local environment, offsetting the cooling benefit to some extent.
However, many people squeeze their large fridges into tight cavities, which lessens fridge efficiency because of the limited ventilation.
If the cold air from the HPHWS flows into the refrigerator cavity, it will improve the efficiency of the refrigerator, and reduce its electricity consumption.
So some cold air can be useful.
If indoor temperatures are lower than outdoors, the efficiency of the hot water heat pump will be slightly lower than if it was outside. And the cool air it produces provides free space cooling.
In cold weather, the cold air produced by the HPHWS increases space heating cost and energy use, though heat loss from the tank reduces space heating requirements to some extent.
If space heating is being supplied by a reverse cycle air-conditioner (RCAC) with a COP of 4 (that’s an efficiency of 400%), the amount of extra space heating required to offset this cooling effect is reduced by a factor of 4.
Furthermore, the COP of the HW heat pump is improved if the indoor temperature is higher than outdoor temperature, and there is no risk of ‘icing up’ adversely impacting on heating output and efficiency in extreme weather.
So the impact of the cold air from the HPHWS is offset to some extent by its higher efficiency than if it was outdoors and its impact on electricity consumed for space heating is dramatically reduced by the high heating efficiency of the RCAC.
Overall, the installation of an indoor HPHWS looks as though it would deliver high efficiency in an efficient all-electric home in most Australian climates.
This highlights the importance of someone developing a practical indoor heat pump HWS. I suspect that the compressor and heat exchangers could be installed in the fairly inaccessible space above the refrigerator, and it could be connected to a storage tank located nearby via insulated water pipes.
The energy impact of an indoor HPHWS should also be kept in perspective though. For example, running an exhaust fan or rangehood draws large amounts of outdoor air into a building, with significant impact on heating and cooling energy use.
Quality of service for space heating
We need to ensure quality service delivery from electric options if consumers are to enthusiastically adopt an all-electric future.
Unfortunately, most reverse cycle air conditioners (RCACs) installed in Australian homes have been selected for cooling purposes, not space heating.
While, in principle, an RCAC can provide effective and very efficient space heating, significant numbers of consumers complain that they don’t feel comfortable. A study I and RMIT colleagues published in 2023 showed that the lived experience of people in poorly insulated, thermally leaky rooms, feeling cold drafts, was consistent with the laws of physics, as shown below.
Case 1: temperature distribution in uninsulated room with single glazing.
Case 2: temperature distribution in insulated room with double glazing.
Some ‘experts’ recommend turning air-con thermostats down to 19-20°C. But this actually makes the experience even worse by making the cold drafts feel even colder.
There are alternatives. For example, floor mounted RCACs are available but not widely promoted. Upgrading building thermal performance with insulation, draft-proofing and improved glazing or window coverings ,can transform comfort and save energy.
Careful selection and placement of furniture can also help. In the Middle Ages, when people relied on open fireplaces and didn’t have today’s insulation products, they employed some smart options.
Putting feet up on an ottoman meant that the cold air flowing towards the fireplace went under your legs. Wingback chairs concentrated radiant heat from a fire on people’s bodies. Large tapestries reduced heat loss and raised radiant temperatures of walls, improving comfort.
We can learn a lot from the past.
