The curious case of burning wood

The following is an excerpt from a data-related longread from Tideal's showering challenge, one of the early challenges we are launching our service with. To put it in context, the excerpt is preceded by a table where burning wood is revealed to result in more carbon dioxide equivalents being released into the atmosphere (per one unit of energy produced) than oil, for instance.

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A curious point which might need some elaboration and reassurance is that of emissions from burning wood to heat water, the highest emissions number of all the energy sources in the table above. Trees and other biomass are renewable, so why such a high emissions number for burning them? Especially as some other sources cite them as being zero emissions?

Indeed, there is a relatively common perception that burning wood or other biomass to generate heat should be seen as zero emissions. Or, to rephrase that sentence for clarity: no one is claiming that there isn't any carbon dioxide coming out of the chimney as the burning happens, but many sources claim that we should nevertheless treat burning wood as zero emissions.

This perception relies on something called "carbon accounting:" that the wood has already sequestered the carbon it is releasing now as it burns, or that that carbon will be sequestered back into solid matter as future trees grow in its place, and hence the emissions coming out of the chimney should be treated as, well... zero emissions. We are sure a lot of lobbying has gone into getting these accounting principles into country, EU, and UN level definitions and regulation.

We at Tideal see these specific carbon accounting manoeuvres as dangerously delusive:

• First, burning wood to generate one unit of energy (or heat) results in more greenhouse gas emissions than heating one unit of energy by burning oil, for instance. Unfortunate, but true.
• Second, if the claim is that the burning wood has already sequestered the carbon it's releasing now as it burns, we could easily say the same thing of oil. After all, all oil is is biomass that once lived on this Earth. (The timeline, of course, is massively different, but does that make a difference in our current predicament? More on this in the next bullet.)
• Third, if the claim is that the carbon will be sequestered back into solid matter as a future trees grow in the place of this wood burning now, there are serious timeline issues we need to talk about: it will take decades, if not a century, for a new tree to sequester the carbon back from the tree which we logged and are now burning. Climate change is happening now, and the costs of delaying emission cutbacks are high. (More on carbon payback timelines in Laganière et al.)
• Lastly, if we are to say that solar, wind, geothermal, and wood are all equally zero emissions, we are not doing justice to solar, wind, and geothermal. At this point in time, we are far better off using energy that originates from outside of Earth and does not result in any carbon being released into our atmosphere.

So, in this specific case we decide to go against conventions and call burning wood as we see it: a non-zero emissions energy source. If this is something that you see as a misjudgement from us, we are happier to err on the side of caution than on the side of destruction.

This decision also reflects a more profound stance that we are aiming to take with the emissions data on Tideal: in our data, we include only the net emissions that result from some human activity. We won't, for instance, take into account any carbon offsetting measures that companies and individuals may take to compensate for some emissions. "Smokestack emissions" is a term that sometimes gets used to describe our approach.

However, we understand that these are tricky decisions to make, and make sure to cover the curious case of burning wood in even more detail in a later blog post. End of rant.