Seacoast NRG

Further to the question, is burning wood carbon neutral, several readers have posted very good comments, often trying to make the case that the burning of wood, or other biomass, as fuel, is a positive step toward mitigating climate change.  In an earlier post (part one), I noted that the topic of wood as a fuel can evoke a strong response, one that I correlate with the wish to have a natural, abundant material like wood be our saving grace.

Let me revisit the issue with a restatement of my answer to the burning question above:  no, in general, burning wood as a fuel is not a carbon neutral activity.  Only if the wood fuel is being harvested in a sustainable fashion can burning wood be considered even close to carbon neutral.  Does that mean that burning wood for fuel is a bad choice?  Not necessarily.  But in general, the practice is not carbon neutral. 

Here are some perfectly good questions that probe the reasoning of my conclusion, and my responses to them:

The carbon released by the burning of the wood will be absorbed by other trees…
This is the central idea of being carbon neutral:  the carbon produced by burning gets re-sequestered in living biomass.  And yes, it’s true, provided the fuel is being harvested sustainably.  If not, then the net effect is a reduction of the living biomass, and a net increase of carbon in the atmosphere.

But it’s simply going to rot anyway…
True, the wood will rot, but will do so over the course of years, slowly releasing carbon to the soil and atmosphere.  Burning greatly accelerates the cycle, and leaves little carbon to be absorbed into the soil; almost all of it is spent to the atmosphere.

If I don’t burn it, someone else will…
That may be true, but I again revert to my original argument:  if not harvested sustainably, it doesn’t make a difference who does the burning–the end result is not carbon neutral.

I’m only burning low grade wood or fallen trees from my property…
If it is coming from your own property, then you need to assess whether your havesting practices are sustainable.  If so, then I think you can be comfortable that you are approaching a carbon neutral practice.  On the other hand, if you are taking from a public resource, such as a park or public forest, I think you should ask what would happen if everyone made the same assumptions you did.

These are just chips or byproducts of our lumber industry…
This is exactly what is happening with the wood-fired boiler at Schiller Station.  Some 50 truckloads of wood chips per day are delivered to Schiller for burning.  Though only the byproducts may be burned, the key question is whether the primary lumber and forests are being sustainably harvested and managed.  I can only hope they are.

What about other biomass?
Good question.  If we think about fuels that can mature and be harvested in a short time frame, then it’s much easier to approach sustainability.  Even better is to find an annual agricultural product that has byproducts suitable for burning as fuel.  For example, bagasse, the leftover biomass from sugar cane processing, can be burned in one season; the next season’s planting of sugar cane then absorbs the prior season’s carbon back out of the atmosphere. 

But isn’t burning wood better than burning fossil fuels?
Yes and no.  It’s certainly better than burning coal, since burning wood avoids many of the other poisons, such as mercury and sulfur, that are emitted when coal is burned.  However, the ratio of carbon-to-energy in wood fuels is only roughly as good as coal, generally worse than oil, and much worse than natural gas.  That is, to get the same amount of energy output, you’d actually produce more more carbon by burning wood than by burning almost any fossil fuel.