A professor at the Massachusetts Institute of Technology warns that Nova Scotia’s plan to switch from oil to wood for heating some public buildings will only speed up climate change, but the province is confident in the approach it is taking.
John Sterman, director of MIT’s Sloan Sustainability Initiative, analyzed carbon emissions from burning wood for heat and energy, and found it’s as bad as burning coal, 30 per cent higher than burning fuel oil and 80 per cent higher than natural gas.
“Turns out that wood and coal have about the same amount of carbon per unit of useful energy in them, but burning wood is less efficient,” Sterman told CBC’s Information Morning.
Sterman said burning biomass releases carbon dioxide into the atmosphere right away, while it takes decades for enough trees to grow to offset those emissions.
“When we started our research on this because the climate situation is so dire, I sincerely hoped that wood would prove to be part of the solution for the climate crisis, but unfortunately we have to be true to the science, and it just doesn’t work out,” he said.
Last week, the province announced it was converting six public buildings from using furnace oil to wood heat in an effort to use renewables from private woodlots and reduce Nova Scotia’s carbon footprint.
It has identified 100 buildings that would be good candidates for converting to this type of heating.
But while Sterman cautions governments against assuming biomass is a carbon-neutral solution, Nova Scotia’s minister of Lands and Forestry said the professor’s calculations don’t take everything into account.
‘A decisive decade’
Sterman’s research, published in Environmental Research Letters, looked at forests in the eastern U.S. that supply wood pellets to the U.K. He calculated the “payback” time for these forests compared to the emissions from burning coal.
“If you replant the forest or allow the forest you’ve harvested to regrow — and that’s a big if — it will take 50 to well over 100 years to pay back that carbon, even if the wood that you’ve burned is displacing coal or fuel oil,” he said.
Sterman argues that every time someone switches from coal or oil to wood, “they’re making climate change worse” during “a decisive decade.”
Countries have committed to keeping global temperature rise below 2 C above pre-industrial levels.
“We’ve simply waited so long that we have to make large emissions cuts as fast as possible,” Sterman said.
He said simply planting more trees isn’t the answer because “plantations don’t have the carbon density of a natural forest.”
Plantations with a single species of tree also typically use herbicides and pesticides, he said.
“Planting trees is always a good thing to do, but it’s illusory to believe that planting trees can substitute for reducing our fossil fuel emissions,” he said.
Waste wood already cut, says minister
Biomass is seen by many as a green alternative to burning coal and oil. Europe, where biofuels have been deemed carbon neutral, is now accepting huge quantities of woodchips from the U.S. and Canada.
Exploring the use of heating fuelled by low-grade wood was one of the recommendations in University of King’s College president Bill Lahey’s review on forestry practices in Nova Scotia.
Iain Rankin, minister of Lands and Forestry, said burning low-grade wood that’s already been cut is better than using oil that’s shipped to Nova Scotia from overseas.
“I believe that this is a better alternative, and I think Nova Scotians will see that,” he told CBC’s Information Morning.
Rankin said biomass furnaces in the six buildings that are part of the province’s pilot project are over 90 per cent efficient.
“If you’re using material that is largely waste from material that’s being thinned off of woodlots, and you have a highly efficient system, the conclusions that we have seen so far is there are net carbon benefits,” he said.
But Sterman said using “so-called waste wood” is not sustainable, and that his research takes into account wood from thinning, not clearcuts.
He said lower grade wood is an important source of nutrients for forests and provides carbon for the soil as it decays.
Finding markets for woodchips
Woodchips for the six biomass projects will come from private woodlots, Rankin said.
“It reduces the risk of some of these landowners, say, converting their forest to another type of land use, whether it be agricultural or development, because that would be more harmful for the environment and deplete the carbon stocks that we have in the province,” he said.
He added that the province is also looking for new markets for woodchips from sawmills following Northern Pulp’s closure.
Sterman said his research doesn’t mean governments should continue to rely on coal and oil, but what’s really needed is a commitment to build energy-efficient buildings.
“We have technologies ready to go today that can cut our greenhouse gas emissions and still provide us with what we need to generate that warmth, make sure the lights stay on,” he said.
Rankin said he’s open to reading Sterman’s research and having Nova Scotia’s science peer reviewed.
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