Warning: this article contains a lot of numbers. Numbers that tell a story. If you don’t like numbers, stop reading and spare yourself arithmetic anxiety.
It should not be news to you that people in Canada need to heat their homes. Some of us also need air conditioning if we want to be able to sleep in hot, humid July and August.
Home heating- emissions from residential combustion sources, resulted in 41 MT of CO2 equivalent emissions in 2017, or about 7% of Canada’s national GHG emissions. In contrast, road transport represented 141 MT- about 25% of total GHG emissions. Public electricity and heat production, lumped together, are larger at 79 MT. Oil and gas production and refining are larger still at 124 MT. Home heating is actually a surprisingly small fraction of our national and per capita emissions, given our cold climate. Figures are from Table ES-2 in this reference:
About 75% of Canadians- those of us living in Ontario, Quebec, Manitoba and British Columbia for instance- have access to an electrical grid which is extremely low in CO2 emissions. Ontario is highest in that group with 40 g CO2/kWh on average. All of those GHG emissions comes from the 6% of our grid power produced using natural gas. We burned our last coal for power in 2013. It’s an enviable situation that much of the world can only dream of achieving decades from now.
Most Canadians, who live in major or secondary urban centres, also have access to the natural gas distribution system. And those who do, almost exclusively use natural gas to heat their homes through long Canadian winters.
Why? One reason: price. Natural gas is, and has long been, the cheapest source of heat available to homeowners- as long as they are in a city or town on the natural gas grid.
Those who don’t- people who live in rural locations or a few provinces without natural gas distribution- have four choices: wood or wood pellets, propane, fuel oil or electricity. Wood is often used as either a primary or supplementary heat source in rural locations or for cottages and hunting camps, with back-up often provided by electric resistance baseboard heaters. Rural homeowners are otherwise left with expensive options: propane sells at a premium to natural gas, oil tends to be used only in very old houses which haven’t had their heating systems retrofitted yet, and although electrical resistance heaters are 100% efficient at converting work (electricity) to heat, they are very expensive to operate.
So natural gas heating is king in Canada. My own home is heated with a modulating condensing boiler with an annual fuel utilization efficiency (AFUE) of about 94%. . My domestic hot water is similarly produced by a flow-through modulating condensing water heater with an AFUE of 98%. AFUE is a measure of how much of the chemical potential energy of a fuel, measured by its HIGHER heating value (HHV), is converted into useful heat in the home. High AFUE appliances not only extract the heat from the combustion product gases, but also extract heat by condensing the water produced by combustion.
Natural gas is very cheap per unit of chemical potential energy. One cubic metre of natural gas has a typical HHV of 37 MJ – for comparison, that’s about 10.3 kWh. But it is important not to confuse heat energy (which the HHV of natural gas represents) with thermodynamic work- which electricity can be readily converted to.
My house used 2677 m3 of natural gas in 2018, which cost including taxes $1184 CDN, or $0.42 per m3. Of that, $271 were account fees and taxes on those fees, rather than the marginal cost of extra gas and its delivery.
Fed into my 94% AFUE boiler, that’s about 4.3 cents/kWh worth of useful heat, i.e. if we were to compare it to a 100% efficient electrical resistance heater. To look at it another way, for every m3 of gas I burn in my boiler, I get about 9.7 kWh worth of useful heat in my house. The average cost of electricity for us in 2018 in contrast was about 17 cents per kWh.
In GHG emissions terms, combustion and upstream/transmission energy use result in emissions of about 1.9 kg CO2/m3. That means for every kWh of heat my 94% boiler puts into my house, carbon emissions are about 0.2 kg or 195 g. In comparison, Ontario’s electricity CO2 generation is about 40 g total per kWh. In direct CO2 emissions from source, that’s about 4.9 times what I’d emit from my house if I used electric resistance heaters instead.
If we were to add estimates of methane leakage in production and distribution per my other paper:
-of 2.5 to 5% of the methane fed, using the 20 yr 86x factor for methane’s GHG equivalence to CO2, that would increase my heating plant’s GHG emissions from 195 g of actual fossil CO2 emitted to between 343 and 491 g of CO2 equivalent per kWh. That’s between 8.6 and 12.3 times as much total CO2(equiv) on the 20 yr time horizon as if I heated with electric resistance heaters. Environment Canada estimates fugitive emissions of GHGs from oil and natural gas production to be about 54 MT- more than the amount produced by all residential heating combined. They no doubt use the 100 yr 33x factor for methane vs CO2 in this estimate.
The house used 2677 m3 of natural gas last year. That’s all heating, domestic hot water and our cooktop and oven, but not the clothes dryer which is electric. My CO2 emissions were therefore 5.06 T of direct or 8.9 to 12.7 T of total CO2(equiv) including the 2.5 to 5% methane leakage factor. $1124 per year to meet all the heating needs of a roughly 2400 sq ft 2 storey house and a family of four. It’s a relatively efficient house, about half renovated 1920s and half modern, well-insulated addition with careful detailing. Better than average, not best in class.
For comparison, I commute 4 days per week, 122 km total per day. My commute in my 5L/100 km Prius C amounts to some 3.4 T of CO2 emissions from source, plus the associated toxic emissions breathed by the people I drive by on my way to and from work. That’s for one person to earn a living. A substantial fraction of the direct GHG emissions to keep a family of four warm through a Canadian winter, despite this being the most efficient IC engine car you can currently buy in Canada that doesn’t also have a plug. (Sure- I could move closer to work- but my options there are putting my wife out of HER career, and also quite likely a divorce. Not a practical option I’m afraid!)
Also in comparison, we have high speed internet, a VoIP home phone plan, and three cellphone plans, all modest and none with cellular data. Telecom services cost our family a total of $1650 per year. Yes, telecom services are expensive in Canada due to lack of competition and low population density. But we pay about 1.4 times as much for telecommunications as we pay to heat our house, in part because in 2018 we paid nothing to dump CO2 and methane to the atmosphere. Is that a correct statement of our relative values?
Recently, Canada’s federal government implemented a minimum carbon tax standard for the country. Ontario had a working cap and trade system with Quebec and California, but our provincial government elected about a year ago, spent hundreds of millions to destroy that working system- only to have it replaced by the federal government’s tax. The tax, per my most recent bill, was 3.91 cents per m3, or $20 per tonne of direct CO2 emissions ($8.50 per tonne of total 20 yr equivalent emissions at the 5% leakage figure). That would have increased my 2018 bills by $105, or nearly 10%.
My average electricity use costs me 17 cents per kWh- that’s the total of my 2018 bills divided by my home’s total kWh consumption. Electricity in Ontario has time of use rates, so electricity is cheaper at night than during peak hours during the day. But if I were to use my average cost per kWh to run resistance heaters, my heating bill would have been $4420 last year. My CO2 emissions would have dropped to about 1 tonne. That’s a $3300/yr increase in cost, to save 4 tonnes of real or up to 11.7 tonnes of CO2 equivalent emissions. A cost of between $820 and $280 per T of emissions averted.
Needless to say, we’d have noticed that extra cost- if we were to increase our heating costs by a factor of almost four.
Of course there are alternatives to resistance heaters! A heat pump can use work (electricity) to pump heat from a cold place (the air, or the subsurface). Air source heatpumps became briefly popular in Canada after the 1973 energy crisis, but fell rapidly out of favour again due to the poor durability and performance of the first generation units in extremely cold weather. Modern air-source heat pumps can generate a coefficient of performance (COP) of up to 2 at temperatures as low as -20 C. It rarely gets colder than -20 C in Toronto or Vancouver, but does in places like Calgary, Edmonton, Regina and even Montreal. Air source heat pumps are a modest cost increase over air conditioners, which happen to also be basically necessary in the warmer parts of Canada due to hot, humid summers.
Small Mitsubishi air source heat pump units deliver their full heating load at 21 C return air temperature and outdoor temperatures of -15 C. Coefficients of performance- the kW of heat pumped into the interior per kW of power used- range from about 1.5 at -25 C outdoor to about 3.4 at 5 C outdoor. An air-sourced heat pump unit returning a COP of 2.2 would have reduced my electric heating cost to $2010/yr. if I were to go all electric- again this is an approximation because the HP system wouldn’t heat my domestic hot water or fire my cooktop or oven. That is still almost twice what I paid for natural gas last year. There is therefore no payback to be had from installing an air-source heat pump, until carbon taxes become very substantial indeed.
Another alternative is ground sourced heat pumps. In urban areas, groundsource heat pumps require vertical wells to be drilled as there is insufficient land for heat collection trenches to be effective. Drilling costs vary, as do the cost of the equipment and installation, but it is clear that the costs of a groundsource heat pump system are many times the cost of a conventional furnace and air conditioner which they replace. Ground source systems can have coefficients of performance ranging from 2.5 to 5 for heating, with the bonus being that the COPs for cooling are very high indeed- air conditioning basically becomes “free”.
As a best case, assuming a system with a heating COP of 5, my electric heating costs would drop to $882 per year, a savings of $241 per year versus my current cost for natural gas heating. But $241 per year would never pay back the extra cost of that GSHP system. Real savings would be modestly larger because it would drop my cost for air conditioning. A rough estimate is that we spent a whopping $95 on air conditioning in 2018 as best I can estimate, by comparing our June, July, August and September electricity bills against our May and October bills- so not much to be saved there.
Significant carbon taxes would be required to make this investment make economic sense to someone whose primary interest was saving money rather than the planet. And frankly, if we’re honest, our actions and decision reveal that most of us don’t care much about either: we care far more about our own comfort and convenience.
Perhaps this analysis explains why my focus has been on the electrification of transport, rather than on heating. Savings in GHG emissions of 97% and a halving of daily operating costs can be achieved simply by switching from IC engine to battery electric cars and light trucks. The electrification of light personal transport is some of the lowest hanging fruit in the battle against global warming in my opinion. Heating, on the other hand, will definitely have to wait.