Yukonomist: Wood heat makes a comeback

Yukonomist Keith Halliday

The Yukon government gave the Grade 7 students of Elijah Smith Elementary School a wonderful social studies project next year: biomass heat.

This is because biomass — also known by its street name “wood” — is emblematic of the complex economic and environmental trade-offs we face during the climate transition.

The school received a new $2.3 million heating system powered by biomass, which will replace some of the fossil propane burned by the school’s furnace.

Government officials told the Yukon News that the new system is expected to replace at least 35 per cent of the propane currently used, reducing greenhouse gas emissions by 180 tonnes per year.

That’s the equivalent of 65,000 litres of home heating fuel.

Next year’s Grade 7 class will be able to dive into several meaty economic questions. The first is the cost of biomass heat compared to propane.

Let’s look at upfront costs first. That 65,000 litres is about the same as 30 homes burning a bit over 2,000 litres per year. To put this in context, consider dividing the $2.3 million investment by 30. It would be like paying about $77,000 to add a wood-pellet stove to your house so your main furnace burned less propane.

That’s steep.

But the US Department of Energy says that wood pellet heaters are generally cheaper to operate than oil or propane. The Yukon government did not release its estimates for cost savings, so Elijah Smith students can track the bills and estimate how long it will take to pay back that high upfront cost.

They can also calculate the cost per tonne of carbon dioxide eliminated. This is a standard policy wonk metric used to decide whether it makes more sense to invest in electric vehicles, more insulation or things like biomass heat. Less than $50 per tonne is considered cheap. The Canadian carbon tax is headed to $170 per tonne by 2030. Emerging technologies such as Direct Air Capture can cost more than $500 per tonne, and are considered expensive.

The Yukon government press release did not disclose this fact point. But we can help the class get started. If you take the $2.3 million capital cost, assume a 20-year life for the equipment, avoiding 180 tonnes per year works out to a cost of $639 per tonne just for the capital.

Again, the upfront costs look steep. Elijah Smith students can look at the monthly savings on pellets versus propane to see if this saves enough over time for the project to make financial sense.

The system also illustrates trade and the choices between tapping into efficient Outside supply chains versus trying to substitute Yukon products.

For example, the government says the wood pellets will be imported from British Columbia. It seems odd to burn large amounts of diesel trucking wood vast distances into a territory covered in spruce trees, but no one has yet invested in a large and efficient pellet factory here. In the longer run, some hope to start such a business. This would create local profits and jobs but would require the Yukon government to provide reliable access to firewood, something it has struggled with in recent years.

The environmental issues are also meaty. Some people do not even agree biomass should be described as “clean.”

The government’s press release represents one side of the argument. This view holds that when trees grow, they absorb carbon dioxide from the air. When you burn them for heat, this goes up the chimney into the air as with burning fossil fuel. However, a new tree grows where the old one did and absorbs the same amount of carbon. So biomass, over the tree’s life cycle, is carbon neutral.

The other side of the argument is represented by the BBC Panorama documentary on the giant Drax biomass power plant, which claimed to be extra green since it burned only waste wood and sawdust. The British broadcaster’s flagship investigative journalism show sent a team to Burns Lake, B.C., near the south end of the Stewart-Cassiar highway. They filmed virgin trees being logged and chipped before being shipped halfway around the world to power the Drax biomass electricity plant in England.

Biomass skeptics will observe that the Yukon government press release does not pledge that the pellets being used by Elijah Smith are made only from waste wood. They will also point to the greenhouse gas emissions from all the chainsaws, diesel logging equipment and 18 wheelers along the supply chain from B.C. to Elijah Smith.

Then there is the carbon cycle. The skeptics also point out that burning wood actually emits more greenhouse gas per unit of heat than burning oil or propane.

A 2018 paper by John Sterman from the Massachusetts Institute of Technology says wood emits even more than coal at the point of combustion: “Because combustion and processing efficiencies for wood are less than coal, the immediate impact of substituting wood for coal is an increase in atmospheric CO2 relative to coal.”

UK Forest Research, a government agency, put out a study comparing the carbon emissions of different ways to heat a typical British home. Natural gas emits 4,040 kilograms of carbon dioxide per year. Oil emits 5,200 kilograms. Wood ranges from 4,460 to 6,140 kilograms, depending on moisture content and whether you use chips or pellets.

So Elijah Smith may very well have higher carbon emissions in 2024 with its biomass plant than it did last year.

But what about the trees regrowing to absorb this extra carbon?

Skeptics go on to point out that it will take decades for a new tree to grow big enough to soak up that carbon, especially in a cold place like northern B.C.

The timing question is critical. Biomass heat in effect brings emissions forward in time. You get more emissions now, compensated in future decades by regrowing trees. But with the planet trying desperately to make its 2030 Paris Agreement targets, critics say bringing emissions forward is unhelpful.

Finally, environmentalists will point to the problem of air quality. A 2018 Whitehorse air quality study conducted by the Yukon Medical Officer of Health and others looked at dangerous micro particles in the air, known as PM2.5, in terms of micrograms per cubic metre. A value above 10 averaged over a year puts a location into the red zone.

The sensor at Elijah Smith capturing air quality in the neighbourhood regularly spiked above 100 during cold snaps. But the annual average, including summer months, remained below even the yellow zone.

The Yukon government press release does not contain any information about how air quality will be monitored after the addition of a major new smoke source at the school. This will be another fun citizen science project for the kids at Elijah Smith.

We will need to try many new things on our journey to Net Zero greenhouse gas emissions. Biomass may be an important part of this. Yukoners managing schools and other large buildings will be waiting with interest for the numbers on cost, net emissions and air quality from Elijah Smith.

Keith Halliday is a Yukon economist, author of the Aurore of the Yukon youth adventure novels and co-host of the Klondike Gold Rush History podcast. He won the 2022 Canadian Community Newspaper Award for Outstanding Columnist.