Coppicing and Pollarding
September 23, 2020 9:15 AM   Subscribe

How to make biomass energy sustainable again (solar-powered website) (backup link if the solar is off)
posted by aniola (21 comments total) 31 users marked this as a favorite
No comment on the content, but I love the look and feel.
posted by Going To Maine at 9:31 AM on September 23, 2020 [4 favorites]

If nothing else, this gives me a proper justification for taking an aggressive pruning stance towards a badly situated crape myrtle. Coppice technique comes up quite a bit on Mother Earth news, too.
posted by jquinby at 9:44 AM on September 23, 2020 [1 favorite]

Its worth noting that just under 10% of total global energy supply currently comes from biomass, much of it converted into energy with pretty nasty impacts in terms of local ecology, comfort and health, often by people with few or no alternative options. Finding ways to make that sustainable as well as safer to use has been a major undertaking of international development activity but I think there is still a long way to go.
posted by biffa at 10:14 AM on September 23, 2020

We don't need trees to get renewable biomass. You can burn perennial grass Miscanthus × giganteus annually and have a negative carbon budget. The lifecycle analysis was a huge research topic for cellulosic liquid biofuels. That's probably not going to happen any time soon, but we can still in principle pelletize it and burn it to heat buildings and generate electricity, all while sinking carbon in to the soil.
posted by SaltySalticid at 10:40 AM on September 23, 2020 [6 favorites]

Also planting out Miscanthus would probably be a net improvement to the agroecology because you'd be replacing mostly corn and soy fields. This means not using massive doses of fertilizer and glyphosate, not tilling or using insecticides, etc.
posted by SaltySalticid at 10:49 AM on September 23, 2020 [1 favorite]

Interesting! I have kind of been doing this with Leucaena leucocephala, which is invasive where I live. I cut them down, which gives native trees a chance to grow (and eventually succeed them). I make wood chips with them for paths and use for campfire wood. Then they regrow from the stumps. It would be too much work to dig them out and I have never been motivated to import the right herbicide to kill them.

I have also essentially pollarded a few Ziziphus mauritiana which were just overgrown for their location.
posted by snofoam at 10:57 AM on September 23, 2020

This is important stuff, but I fear too subtle for "the market" to handle.

In the lifts at Heathrow Airport, they proudly proclaim that they are using renewable energy to heat the place: they burn locally-sourced trees! Hooray! Trees from Hounslow and Hillingdon are being burnt right beneath your feet!

Now this is renewable but tells me nothing about whether or not any of this is actually being renewed!
posted by rum-soaked space hobo at 11:45 AM on September 23, 2020 [3 favorites]

Renewable isn't a good enough goal. Renewable just means maintaining the status quo. We know that's not good enough.

Most of the leading discussion now is about restorative or regenerative, which means doing better than renewable. And then the whole debate runs straight into what "better" means.

For example, we've just taken ten big sycamores down on public land next to our property. The sycamores ended up as firewood for ourselves and our neighbours. If we just wanted carbon-neutral heating from biomass, then we'd coppice exotic eucalypts on a five-year rotation. Those grow very well around here.

Instead, we're replacing them with native trees to match those growing on that land, because that gives a diversity and range of net benefits.

Benefits are: removing an invasive species (the sycamores are not native and will take over), providing more biodiversity, more food for birds, less fire risk (coz no eucalypts) , and carbon-neutral heating from the sycamore wood.

Negatives are: natives here grow slowly and won't get bigger than the sycamores so that'll be a net carbon loss for maybe five decades before the natives catch up.

Is that better, meaning a net win? I think so. Is that fast enough regeneration? Umm...

And every change to land use has , or should, be asking these kinds of questions.
posted by happyinmotion at 12:55 PM on September 23, 2020 [4 favorites]

I loved this article for its historical perspective, but their answer to sustainability is not coppicing and pollarding. In fact--and its one thing I like--they talk about the challenges of applying this on an industrial scale. It's not remotely clear it can happen; it's labor intensive and the transport networks would be insane (and, at the moment, fossil-fuel driven.)

Their actual answer to sustainability is for everyone to use far, far less energy and resources.
posted by mark k at 1:22 PM on September 23, 2020 [4 favorites]

@Going To Maine: Yes, I love how much mileage they get out of small, dithered, monochromatic images. They make super-lightweight web design really aesthetically pleasing.
posted by Artifice_Eternity at 1:29 PM on September 23, 2020 [1 favorite]

I had a moment where an ecology expert was asked just that question: "if the non-native trees grow more quickly than the native, aren't they taking more carbon out of the air?"

And the answer was "there's a lot of complicated stuff going on here, but..." and the "but..." was mostly about the local ecosystem's ability to take the carbon from the dead trees and return it to the soil. If the cycle of decay just results in all that going back out into the atmosphere again, you've lost.
posted by rum-soaked space hobo at 1:38 PM on September 23, 2020 [1 favorite]

When I was travelling in India I kept noticing some very hacked-upon trees. My host explained that they were neem trees and the wood was harvested for, IIRC, kitchen fires and that there were understandings about how much wood could be hacked so that the trees would remain healthy and productive. I’ve no reason to doubt it works but those were some really hacked up trees. So these techniques have long been used traditionally and are still in use.

Relatedly, there are cut-your-own Christmas tree farms around here. They tell you to cut at least a foot (again IIRC) above the ground so that the tree will grow back. Many of the trees were clearly second or third growths. I now know this is called coppicing, so thanks!
posted by sjswitzer at 4:34 PM on September 23, 2020

my last name is Pollard and people often ask me what it means. i usually tell them "to take the top off, usually of trees" but that is rather vague. it is useful to now have all this detail. thanks for posting.
posted by lapolla at 4:54 PM on September 23, 2020 [2 favorites]

Ha! Pollard is also a de-horned animal and a term for a haircut iirc.
posted by SaltySalticid at 5:54 PM on September 23, 2020

Favorited this post sight unseen based on the title.
posted by whuppy at 7:45 PM on September 23, 2020 [1 favorite]

The previous article, which covers thermoelectric generators (think solar but for infrared, I guess), is post-worthy in and of itself.
posted by whuppy at 7:52 PM on September 23, 2020 [1 favorite]

We have really terrible trees called hackberries that I generally just pull up and throw in the trash to prevent their spread, but making making a wall of them and coppicing them (really faux-coppocing, because I have no use for very much wood) might be kind of a fun project and make me less pissed off to see them growing.
posted by The_Vegetables at 7:34 AM on September 24, 2020

Yay windbreaks! Hey, whattya know about hackberry?
posted by aniola at 8:46 AM on September 24, 2020 [1 favorite]

You can bury unwanted wood and it puts nutrients in the soil and releases them over time. It's called hugelkultur.
posted by aniola at 8:49 AM on September 24, 2020

aniola, there has been quite a bit done on converting waste wood to charcoal, then burying the charcoal or 'biochar' to lay down carbon and also improve soil quality.
posted by biffa at 10:59 AM on September 24, 2020

I asked a question here about biochar once!
posted by aniola at 7:37 PM on September 24, 2020 [1 favorite]

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