We’ve all heard of CO2’s detrimental effects on the environment and the danger of an exacerbated greenhouse effect, but could it keep our planet cooler?

Heat pumps use a refrigerant to move heat around your home, warming it or cooling it as you desire. Because they’re just moving heat around, heat pumps are much more energy efficient than normal, fossil fuel-based devices. Conventionally, we used refrigerants such as CFCs (chlorofluorocarbons) or HCFCs (hydrochlorofluorocarbons), because of their ability to transfer heat on demand, but these turned out to be especially well suited to destroying the ozone layer, leading to them being phased out or banned since the 1990s. However, using CO2 has some surprising benefits.


The properties of CO2 mean that a heat pump can operate much more efficiently in both high temperature ranges and at low ambient temperatures. For instance, in the case of domestic water heaters where you want hot water around 90°C, CO2 can be more efficient as a heat transfer fluid. CO2 also has some other little bonus benefits. It’s cheap and easy to procure. It’s even non-toxic, odourless, and won’t explode!


CO2’s high specific heat, excellent ability at conducting heat, and how well it flows makes it almost ideal for moving heat around as part of a heat pump. Water, of course, is an excellent coolant. If it’s good enough for a nuclear reactor, then it’s good enough for CO2. So after dumping its heat in the water heater, CO2 is cooled off and ready to keep on moving heat around.


When everyone is using their climate control devices in the mornings and afternoons, that demand drives up electricity prices. It creates what’s known as the duck curve. The mornings and evenings have the highest costs, while the middle of the day tends to have the cheapest rates when there’s abundant, cheap solar electricity being created. But the California based company Harvest Thermal is breaking apart how and when a heat pump has to run. The system can run the heat pump in the middle of the day during the lowest part of the duck curve, store that heat in the water, then in the evening run the hot water through an air exchanger to warm the air in the home. Between the CO2 and this smart optimization, Harvest Thermal claims they can cut your bills by 45% versus a standard gas heater. But also like other heat pumps, there are programs and rebates in place to help make it more affordable. Harvest Thermal says that even without incentives, the system can offset the upfront costs in about 5-10 years. Soon we could see our own market adapting to these new technologies, and maybe the cost of living will go down for once!