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Commentary: Burning wood for energy is not a climate-friendly policy

New projects to increase the use of wood and wood products as energy sources should not be promoted

Hilary Cooke & Don Reid

For hundreds of thousands of years before we burned fossil fuels and grew our population exponentially in the last four centuries, carbon dioxide concentrations in our atmosphere fluctuated between 200 and 300 parts per million (ppm).

They are now around 410 ppm and have been increasing rapidly. It is clear that absorption of carbon dioxide in the planet’s water and plants cannot keep up with what we send into the air from all the fuels we burn and our other activities. This imbalance is the heart of the climate crisis.

You can view this similar to draining a kitchen sink full of water, where carbon dioxide is the water and the drain is the ability of ecosystems to absorb the gas.

To avoid over-filling the sink and creating a flood, we have to balance the flow of water (carbon emissions) into the sink with the rate at which it can drain (carbon absorption by ecosystems or industrial processes).

Currently, we are increasing the flow of water into the sink, and we have a flood on our hands. That is a flood of carbon dioxide into our air which stays there and heats the planet because there are no new ways to drain it out. The climate crisis shows that we have to turn down the flow of water and make the drain work faster.

Given this stark reality, it is disturbing to see the Yukon government assert in its draft strategy for climate change, energy and a green economy – Our Clean Future – that biomass energy is “low carbon” and should be promoted (along with solar and wind).

Biomass energy is created by burning organic material that has quite recently been alive. In Yukon, this is wood (whole logs and slash) from trees, both dead and alive when harvested. When burned, the carbon that makes up much of the wood goes directly into the atmosphere as carbon dioxide.

The effect of this burning on the amount of carbon in the atmosphere depends on the time and spatial scales of accounting. When all of the carbon dioxide released from burning can be absorbed by new growth of plants at the same sites in the same annual cycle, there is no net contribution of carbon dioxide to the atmosphere.

Using the kitchen sink analogy, what flowed in drained back out in the same year. The process is then “carbon neutral”. We have to assess emissions on an annual basis because that’s what we do with all other sources of carbon dioxide such as fossil fuels.

The annual pulse of plant growth is what drives carbon absorption from the atmosphere. We have to assess carbon absorption at the same sites where the wood originally grew because at all other sites carbon absorption is already maximized as evidenced by the inability of ecosystems to keep pace with the ever-growing pool of carbon in the atmosphere.

When we burn wood for energy in Yukon we are almost always emitting many years and often decades of carbon stored in the wood into the air within one year. New plant growth, on sites where the fuel trees previously grew, cannot absorb all of this carbon in one annual cycle.

The effect is large net contributions of carbon dioxide to the atmosphere year by year. We can think of this as a “carbon debt” that has to be paid back through new plant growth which will take many years if not decades.

So biomass energy as practised in Yukon is not “low-carbon.” It is an energy source that is contributing large amounts of carbon to the atmosphere at a time when we should be reducing our carbon emissions. We are working hard to reduce our carbon emissions from fossil fuels that are “high-carbon” energy. Why aren’t we doing the same with respect to our carbon emissions from burning wood? Some science indicates that burning wood produces more carbon dioxide per unit energy received than burning fossil fuels. Biomass is “high-carbon” energy.

How did we get into this policy conundrum of promoting a source of energy that is environmentally unclean (high-carbon)? There seem to be three drivers. First, northerners have long relied on burning wood for space heating. Energy from wood is reliable, easily obtained, and does not require reliance on large institutions. Burning wood is a cultural attribute of life in the North.

Second, wood is a “renewable” resource that grows back, at least after many years. Its renewability led governments and industry to argue, decades ago, that it should be used as a replacement for fossil fuels. Jurisdictions as large as the European Union, and policy initiatives here in Yukon such as the Biomass Energy Strategy (2016), promoted biomass as carbon neutral, thinking that regrowth of wood over many years was sufficient to claim that the carbon was ultimately of no consequence to the atmosphere.

Scientific analysis has shown that it is rarely carbon neutral, and in fact, when the fuel source took decades to grow, it may provide marginal improvements compared to burning fossil fuels but is still “high-carbon” energy. The term “renewable” is warm and fuzzy in economic thinking (nature seems to provide something for nothing), but does not necessarily indicate “clean” or “green” in an environmental analysis.

Third, we have been searching for ways to build an economy out of the climate crisis. That has worked, and has been necessary, for solar and wind energy. The inaccurate allure of “carbon neutrality” and the substitution of “renewable” for “environmentally-friendly” have led to promotion of biomass as a “clean” or “green” energy source.

It really is not green, neither in terms of combating climate overheating nor in terms of human health given the documented negative effects of smoke and particulates on respiratory health in Whitehorse.

The Yukon government’s Our Clean Future strategy has a goal of reducing carbon emissions by 30 per cent below 2010 levels by 2030.

Carbon emissions from burning wood must be included in Yukon’s annual reporting of carbon emissions in this context. Also, new projects to increase the use of wood and wood products as energy sources (currently promoted in the draft strategy) should not be promoted because they will fix high-carbon emissions into our energy supply in the long term.

Burning wood for space heating is well established in Yukon, and will continue to contribute to our energy supply and annual carbon emissions for some years. However, biomass is best viewed as a “bridging” form of energy supply, to be phased out as we progress to truly cleaner sources of energy.

To reduce wood burning, the government’s strategy needs to include incentives to make other sources of energy for space heating economically more favourable.

Hilary Cooke and Don Reid are wildlife ecologists working for Wildlife Conservation Society Canada in Whitehorse.