Why are wood pellets considered eco-friendly?

Stephen: Why are wood pellets considered eco-friendly? Fossil fuels used to be organic material (trees), and hundreds of thousands of years ago they also contained CO₂ the border. I would be interested to know why there is such a difference.

Joel Mesot: How we keep our rooms warm this winter is now a ubiquitous topic in many families. And how we can achieve this sustainable development in the future is one of the biggest challenges of our time.

Indeed, the various types of fuels that provide us with heat and energy in general have important common features. Coal, natural gas, oil, wood, and our food are ultimately available to us because plants carry out photosynthesis. They convert solar energy into chemical energy by converting CO₂ “build” high-energy organic compounds. During the combustion of these substances, part of the chemical energy is again released, and with it the temporarily stored CO.₂. It goes back into the atmosphere.

The main difference between the various energy carriers lies in the time scales we are talking about. For the compounds we use today as fossil fuels, the time for photosynthesis was not hundreds of thousands of years ago, but mostly hundreds of millions of years ago—before the dinosaurs died out. Part of the biomass created during this time turned into oil and gas over millions of years under high pressure and at high temperatures. On the contrary, the age of even the oldest trees is the blink of an eye.

These very different timescales also mean that we are practically on a one-way street when it comes to fossil fuels. We don’t have a reasonable way to start new oil fields. But we can restore forests, manage them properly and integrate timber into the circular economy. Because when it comes to the production of wood pellets and other types of firewood, we can influence a lot.

A natural question arises, where does the wood come from. Does it come from Swiss forests or is it imported? Was it obtained from logs or was it a by-product, or should it ideally be obtained from appropriately recycled wood that was previously used as a building material? And are forests managed sustainably, as required by Swiss law? Or is it from the clearing that destroyed the forest?

Thus, burning wood for heating is not always sustainable and climate neutral. But maybe under the conditions described above. First of all, wood is much more than just a source of energy – just think of the intangible value of our forests, their recreational value, or wood as a natural building material. Current research attempts to do justice to these different wood sizes through life cycle analysis and circular economy analysis. We can use this knowledge to make adjustments to make wood use as efficient and sustainable as possible.

Many thanks to Prof. Stefanie Hellweg and Prof. Harald Bugmann of ETH Zurich for their valuable input.