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How ‘green’ is biomass energy? Science Cafe N.H. will discuss it.

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  • Wood chips may seem like an obvious, more eco-friendly fuel than coal, but it may not be so simple. That’s why Science Cafe N.H. will tackle the debate. Courtesy



Monitor staff
Tuesday, April 17, 2018

Here’s a no-brainer: Burning wood for electricity is better than burning fossil fuels from an environmental point of view.

Except that it’s actually a ... um, whatever the opposite of “no-brainer” might be. (Yes-brainer? More-brainer? No-kneejerkresponder?)

In this era of climate change, the argument for using wood as fuel is simple: The tree will die eventually and release its carbon, so it’s no big deal to release the carbon early via burning. You can’t say that of coal, oil or natural gas, which would never release their carbon if humans didn’t interfere.

The argument is doubly strong if you plant new trees after cutting other trees down, since the seedlings will take back the released carbon as they grow.

But that’s not the whole story, as it turns out. In the past decade, there has been a lot of research into this question, and the consensus seems to be forming that:

Cutting trees in a well-established wood releases more carbon than we had realized because of disruption to the carbon-containing soil and undergrowth.

The difference in energy density between wood and fossil fuels – it takes a lot more wood to generate a given amount of energy that it does coal, oil or natural gas – can tip the scales.

The carbon benefits of using wood-versus-coal occur over the time scale of tree generations, roughly 30 years, and that might be too long to be useful in the fight against climate change, which is accelerating faster than almost anybody predicted.

Other stuff I’m not going to mention because I don’t want to spoil the fun before Tuesday.

Yes, Tuesday, April 17. Science Cafe New Hampshire in Concord will ponder the question “How ‘green’ is burning wood for power and heat?” at our monthly discussion-in-a-bar series tonight. As always, it’s free and open to all, starting at 6 p.m. upstairs at The Draft Sports Bar.

The result of the above consensus is that there’s no clear answer as to when, or even whether, burning wood can be good for the environment.

Clear-cutting and old-growth forest to make wood chips for an electricity plant is certainly bad.

Making those same chips for a combined-heat-and-power plant using waste wood, such as the un-marketable tops of trees from a regular forest thinning, is certainly good.

Other cases, like the huge industry in the Southeast U.S. of planting and harvesting wood lots over and over to feed Europe’s appetite for wood pellets, are more open to debate.

Which is great, because Science Cafe N.H. loves debate. Especially when accompanied by beer.

If you’re curious about this topic, or just want to do something more interesting than play TV trivia while enjoying drinks and pub food, come ask questions of our three panelists – all of them forestry veterans but with different opinions about how to proceed.

We’ll concentrate on what is, and isn’t, known about the science and technology of burning things to make energy for human use. I imagine ancillary issues like North Country jobs will come up but as moderator I’m going to limit any discussion about ratepayer costs and subsidies in honor of The Science Cafe NH slogan: “No PowerPoint, no politics.” There are plenty of other places to debate policy on energy subsidies!

See you there.

If you go

What: Science Cafe NH, discussing the environmental impact of burning wood for electricity and power – how “green” is biomass energy? Free and open to all. Panelists are John Gunn, UNH assistant professor of forestry and resource management; Charles Levesque, founder of Innovative Natural Resource Solutions; Robert Perschel, executive director of the New England Forestry Foundation.

When: 6-8 p.m. Tuesday, April 17.

Where: The Draft Sports Bar, 67 S. Main St., Concord

For more information: ScienceCafeNH.org.

(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)