Some Problems with Converting Home Heating from Natural Gas to Heat Pumps, in Cold Climates

The Principle behind the Heat Pump

Recently, the case for replacing furnaces powered by fossil fuels (mostly methane, also known as natural gas) with heat pumps has been strongly advanced. The idea is that heat pumps are generally powered by electricity, which can be produced by renewable sources, thus allowing buildings to be heated without producing any greenhouse gases. This is to be accomplished via the avoidance of CO2 caused by combustion, as well as by the elimination of methane leakages in the natural gas distribution systems.

Heat pumps can be thought of as reverse refrigerator. If you ever felt around the back of a refrigerator, you would have noticed heat escaping. That’s the heat from within the refrigerator that is being moved outside of it, via motors, compressors and the concept of latent heat of change of state.

Heat pumps work on the same principle of moving heat from one area to another, though in this case rather than moving heated air from within a structure to the outside world (as a refrigerator or air conditioner does), they move heat from the outside world (air or ground) to the inside of a structure. Because they are moving heat, rather than creating it from combustion or electrical resistance, they can heat a building with efficiencies higher than straight combustion of electrical resistance heating.

Often, efficiencies as high as 4 or 5 are quoted. This means that for each unit of energy consumed by the heat pump, 4 or 5 units of energy are moved from the outside world to the inside of a building. This measure is often referred to as COP (Coefficient of Performance).

The Effect of Cold Weather

This all sounds wonderful, there is a catch, as there usually is with wonderful-sounding things. The catch is, that efficiencies of a heat pump (COP) fall off quickly with outside temperatures. In fact, they work best when it is not actually very cold at all outside. That is shown in the accompanying graph adapted from the website https://learnmetrics.com/best-heat-pumps-for-cold-climates/), for a typical cold-weather heat pump. You can see that the COP goes from about 4.5 at moderately warm temperatures (15C or 60F) to about 2 at relatively cold temperatures (-15C or 5F). 

The graph is for a heat pump designed to work at colder temperatures. Standard heat pumps, that are not rated for very cold weather, will just stop working at all, once the temperature falls to about -12 C (10 F). It is also worth noting that the cold-weather type is more expensive than the type not rated for very cold weather.

These facts mean that in truly cold-weather climates, a backup source is needed. In other words, you have to keep that natural gas furnace, That means paying the gas company fixed charges during months when you don’t actually use any natural gas. Alternatively, you can switch to backup resistance-based electrical heating (e.g. baseboard heating elements) during cold weather. Both of these expedients can add up to a lot of money, on top of the money to install and operate the heat-pump system.

A Real World Cold Climate Simulation of the Costs of a Heat Pump

So, given these factors, I thought it would be interesting to simulate how well such a heat pump would work in a cold-weather environment, namely my house in Edmonton Canada. It can get rather cool here in the winter; for example, temperatures of -30 to -40 Celsius are not unknown in the depths of winter.

To begin with, I used the 12 month period between Nov 2022 and Oct 2023, but I discovered that this was probably a bad period to use for comparison, as the Alberta government had some natural gas and electricity rebate plans going on (an election period), so comparisons might of prices for different forms of energy might not generalize well, outside of this election period.

So, instead I used the period from Nov 2010 to Oct 2011, which seems to represent market prices better, without these artificial government manipulations. The cost ratio for Electricity to Natural Gas, once converted to the same metric was 5.0, which was quite typical of the 1997-2012 data that I have, which averaged 5.06. The same figure for 2022-23 was 11.2, which is definitely atypical. 

 

The table above shows natural gas charges (gas only, not including fixed charges, taxes, etc.) for the 12 month period from Nov 2022 to Oct 2023, in the first three columns after the month name column.

The next three columns show what that energy use would be, after converting GigaJoules to Kilowatt-hours (1 GJ=277.8 Kwhr) and the costs that would be expected, based on electricity prices in the area during the same period. The final column shows the ratio of the cost of energy purchased as electricity compared to natural gas.

The take-away from this is that a straight conversion to electrical energy from natural gas is considerably more expensive, making the energy-component costs of heating go from about $550 to about $2750, an increase by a factor of five.

The Heat Pump Efficiency Effect

But, what about the heat pump efficiency effect? The table below shows that this does bring costs down quite substantially, from about $2750 to about $1100. But remember that the natural gas cost was only about $550, so costs have still doubled from the conversion.

This doesn’t take into account the fact that some of the lows experienced during the cold months will be far below the average, in the range where the heat pumps have a very low COP, approaching 1.0 (assuming that they work at all). So, during those periods, backup heating is needed, either via electrical elements (which are 5 times as expensive as natural gas) or via a backup natural gas furnace, which rather negates the whole point of the conversion. I estimate that the additional costs during those cold months would be about $300 if using natural gas, and about probably double that if electrical resistance heading was used.

Keeping a natural gas furnace in operation as a backup will most likely include a lot of fixed costs, which the gas company charges regardless of how much gas a household actually uses. These costs are quite substantial – during the 2022-23 12 month period, the fixed costs came to about $900. So, those costs wouldn’t go away, as long as backup heating was needed.

Then, there is the cost of the heat pump and related installation costs themselves. The federal government has a heat pump cost calculator, which gives some idea of what the costs would be. For my home, the calculator estimates $12,000 to $15,000, though there might be government support available, if you qualify. That could bring the costs down to $7000 to $10,000. That’s about 1000 per year, amortized over 15 years.

Summary

By these estimates, annual costs for heating a modest-sized house via a heat pump in Alberta would probably increase by:

• about $500 because electricity is more expensive than natural gas, joule for joule.

• About $1000 for the purchase and installation of the heat pump, amortizing the costs over 15 years.

• About $500 for backup heating during cold winter temperatures, where the heat pump would be extremely inefficient, and might not work at all.

So, a minimum estimate of an extra $2000 per year.

And the final kicker of all this, is that in many areas of the country the electricity would be generated by natural gas anyway, so the carbon emission reductions wouldn’t really exist. Certainly, without ample hydro power, the amount of renewable power required for this plan would be far more that what could reasonably be expected for many more years. This may be doable in Quebec, but not in Alberta.

Solar panels are great (I have 16 of them on my garage) but they just aren’t yet up to the job. I estimate that I would have to up my solar panel count by a factor of a least 4, to even theoretically power the house’s electrical and heating needs, probably much more in practice. And that assumes that one could store the extra energy generated in the summer, for those long, cold, dark winter nights.

This also doesn’t include the costs of building out the additional electrical infrastructure and decommissioning the natural gas infrastructure. Not to mention that much of the world is blithely ignoring the carbon emissions targets anyway (e.g. China is said to be opening two new coal-fired electrical-generating plants per week).

In summary, the plan seems ill-considered and unrealistic, at least for much of the country.

Here’s an American source that says much the same thing:

Electricity Versus Natural Gas

Meanwhile, a recent report from the U.S. Energy Information Administration (EIA) found that the cost of heating a home this coming winter using natural gas is going to be roughly 40 percent lower than using electricity.

Households using electricity to heat homes are projected to pay $1,063 on average between November and March, according to a Nov. 7 winter fuels outlook report by EIA. By contrast, households using natural gas are only expected to fork over $601.

The stark findings come as the Biden administration ramps up its war on gas appliances, including furnaces, while touting electrically-powered alternatives (such as heat pumps), all in the name of fighting climate change.

Recently, the Department of Energy (DOE) announced that President Joe Biden will use emergency wartime powers to boost U.S. production of electric heat pumps as his administration continues its push to replace furnaces that run on fossil fuels.

Earlier, the DOE proposed new energy efficiency standards for residential water heaters that would require electric water heaters of the most common size to use heat pump technology and gas-fired instantaneous water heaters to use condensing technology to achieve energy efficiency.

At the time, Republicans on the House Subcommittee on Economic Growth, Energy Policy, and Regulatory Affairs argued that the DOE’s proposed appliance efficiency standards would be burdensome and costly for Americans, hitting lower-income families the hardest.

https://www.zerohedge.com/energy/residents-blue-states-pay-much-more-electricity-red-states-study

Here’s the document that the article above used as source material:

https://www.eia.gov/outlooks/steo/report/perspectives/2023/10-winterfuels/article.php#vinttab1

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And, here’s a pleasant little travel story about a place where a solar-heated reading nook could be quite useful. You would definitely have to be careful about your unit being knocked over by the wind, though.

A Drive Across Newfoundland

U.S.: https://www.amazon.com/dp/B07NMR9WM8

U.K.: https://www.amazon.co.uk/dp/B07NMR9WM8

Germany: https://www.amazon.de/dp/B07NMR9WM8

Japan: https://www.amazon.co.jp/dp/B07NMR9WM8

Canada: https://www.amazon.ca/dp/B07NMR9WM8

Australia: https://www.amazon.com.au/dp/B07NMR9WM8

India: https://www.amazon.in/dp/B07NMR9WM8

Newfoundland, Canada’s most easterly province, is a region that is both fascinating in its unique culture and amazing in its vistas of stark beauty. The weather is often wild, with coastal regions known for steep cliffs and crashing waves (though tranquil beaches exist too). The inland areas are primarily Precambrian shield, dominated by forests, rivers, rock formations, and abundant wildlife. The province also features some of the Earth’s most remarkable geology, notably The Tablelands, where the mantle rocks of the Earth’s interior have been exposed at the surface, permitting one to explore an almost alien landscape, an opportunity available on only a few scattered regions of the planet.

The city of St. John’s is one of Canada’s most unique urban areas, with a population that maintains many old traditions and cultural aspects of the British Isles. That’s true of the rest of the province, as well, where the people are friendly and inclined to chat amiably with visitors. Plus, they talk with amusing accents and party hard, so what’s not to like?

This account focusses on a two-week road trip in October 2007, from St. John’s in the southeast, to L’Anse aux Meadows in the far northwest, the only known Viking settlement in North America. It also features a day hike visit to The Tablelands, a remarkable and majestic geological feature. Even those who don’t normally consider themselves very interested in geology will find themselves awe-struck by these other-worldly landscapes.