Article summary:
- Large, consistent power demands not currently met with electricity are overlooked in power system and utility planning: Domestic hot water and residential space heating are largely ignored by system operators and utilities. This is despite the potential for multiple 1,000+ MW new nuclear plants to serve these demands, which perhaps are just not sexy enough for investment.
- Space heating demand even in small to medium–size urban areas is significant: On minus-five days in Ottawa for example, residential space heating demand exceeds zonal electrical demand, suggesting that supplying this demand with grid electricity would require a large 1,000+ MW power plant.
- Unpredictability of heating demand may be what deters serious thinking about electrifying heat: Space heating demand is more variable and less predictable through the day than electrical demand, which may deter system operators from addressing it seriously. However, Quebec has for decades successfully met its heating needs with electrical resistance in the form of baseboard heaters.
- The nuclear industry, the largest potential beneficiary of heating electrification, neglects heating markets: Despite the natural gas industry’s dominance in Ontario’s heating markets, the nuclear industry appears uninterested in pursuing these opportunities, in spite of the fact they would generate substantial carbon-free revenue.
- Domestic hot water heaters can stabilize the grid: These appliances offer a simple but effective form of energy storage and grid stabilization, providing frequency control benefits that enhance grid reliability, making this approach a practical solution for energy management.
Let’s face it, there are large blocks of power demand that, en masse, amount to what a Darlington-size nuclear plant could and should supply. Remarkably, the prospect of capturing this lucrative market seems to be so unappealing that nobody is interested in building the nuclear plants to serve it. Domestic hot water, a singularly un-sexy block, is one of them. There is absolutely nothing appealing about serving this block of demand—the idea of serving demand that will only grow with Ontario’s population, a block of baseload demand that the electric utility that supplies it could prosper on for literally a century, is so uninteresting to utilities that they simply never talk about it.
Nor is there the slightest interest whatsoever in serving another even more substantial heating demand, i.e., residential space heating. As you can see in the figure below, January 2025 space heating in Ontario’s second-largest urban centre, Ottawa, outstripped the IESO-reported Ottawa zonal electrical demand by an average of about 100 MW through nearly all hours of all days in that month. Serving Ottawa residential space heating demand with grid electricity would have required a power plant of over 1,000 MW. Ottawa commercial and institutional heating demand is likely on a similar scale.
We must emphasize, these heating demands are in addition to, on top of, current electrical demand. This means that to meet not just current Ottawa Zone electrical demand but also the demand for Ottawa DHW and space heating, Ontario would need something in the order of three times the generating capacity it currently requires to meet Ottawa Zone electrical load.
Space heating demand, the left-hand plot, was both larger than zonal electrical demand, and more variable. The thin error bars are the standard deviation—as you can see they are much greater than those for zonal electrical demand. As you might guess, space heating demand is directly related to outdoor temperature, and tends to be greater in the 8 p.m. to 4 a.m. time slot.
The larger standard deviations for heat demand mean that heating demand is less predictable than electrical demand, which may provide a clue as to why electricity system operators outside Quebec are averse to even discussing it as a serious prospect let alone suggesting that policymakers actually consider it. But Quebec through most of its history has managed quite well with electric heat—and mostly with resistance and not heat pump.
The two plots in the figure above would be one plot in Quebec; it’s all supplied from the electrical grid. And Quebec does fine, except when there’s a Black Swan like last year and Quebec’s weather-dependent hydropower can’t meet provincial electrical demand, and its weather dependent wind can’t do anything about it. In that case, Ontario nuclear plants, not weather dependent, came to the rescue.
The natural gas industry owns not just Ottawa’s heating markets, but most of the entire province&squo;s as well. It is puzzling that the Canadian nuclear industry, based mostly in Ontario, seems not to want any of these heating markets. Puzzling, because these markets are thousands of megawatts in magnitude and would represents billions of dollars of carbon-free revenue for nuclear, the only industry capable of offering that. Is this market just not sexy enough?
Energy storage and stability
Electric DWH represents a rare viable prospect of bona fide energy storage, with exactly the grid-stabilization benefit that battery-storage proponents claim: frequency control. When grid frequency—a critical system parameter—drops below 59.8 or exceeds 60.2 cycles per second, the system operator becomes extremely nervous.
That’s because in those conditions the grid is literally, physically at risk. If a large block of baseload demand were able to rapidly increase or shed load, frequency could be brought quickly back inside the 59.8–60.2 Hz range. If that large block were DHW heaters, users wouldn’t even notice—that’s because the thermal “momentum,”—i.e., the heat capacity—of water is so high.
For this, reason, DHW heaters en masse offer a low-cost proven form of energy storage and frequency control. Again, we understand DHW is not sexy like data centres, thus not a shiny object to catch the attention of C-suite executives and politicians. But it is physically solid.
Electricity system planners in Ontario and other Canadian provinces should take a serious look at this. As we said last time, serving these currently fossil fuel–dominated markets with grid electricity would be economy-transforming.
The CNWC in November 2021 announced the results of a study of Ontario DHW baseload energy demand; you can find it here.
