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The Sourdough Approach to Biomass

If you want to be greener than green when harvesting woody biomass for energy production make sure to leave a little bit behind.
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The folks at Dovetail Partners, a Minnesota-based nonprofit corporation whose stated vision is "to be the most trusted source of environmental information," released a report today detailing some best practices for harvesting "woody biomass" for energy. And the takeaway message is sourdough.

Burning twigs to power the world, as it were, isn't an environmental pipe dream — if you think about it, the whole planet pretty much used to be wood-powered back in the day — although the West still sees this as a "new" use of forests. Dovetail notes the International Energy Agency "believes the potential exists for biomass resources to meet 50 percent of world energy demands during the next century while still reducing carbon emissions from fossil fuels" — that up from the 14 percent it occupies today (think of those cook-fires across the Third World before you scoff).

Here at Miller-McCune, we've taken biomass to heart — if not as the answer to global energy and climate woes, then certainly as ananswer. Much of our enthusiasm has been driven by linking places with woody waste — or cow poop or municipal waste — to spare with power plants, even mobile ones. (And we'll have more later this year: John Perlin, who's covered solar energy for us but also wrote the book A Forest Journey: The Story of Wood and Civilization, is beavering away on stories about "peak wood" and what we can learn from that experience.)

But there are big issues about grabbing biomass willy-nilly, including deforestation and its collateral damage or the carbon-cost of producing biomass on demand.

What Dovetail — which has covered biomass for five years — has done is compile harvesting guidelines, specifically for forests, from the developed world. Apparently there's already a lively trade in woody biomass for energy production: The United Nations estimates that 11 million metric tons of the stuff changed hands in 2006, just about double the amount from four years earlier. Canada alone was responsible for more than a tenth of that.

We say "the developed world" for a reason. Says the Dovetail report's four authors, led by the group's executive director, Kathryn Fernholz :

"There is no evidence in the literature that guidelines have been developed for biomass harvesting in the developing regions of Asia, Africa or South America. Within these regions wood is already a primary source of energy and nations are generally seeking ways to increase the efficiency of biomass-to-energy conversion. In most cases, these nations are not looking to forests as sources of new raw materials for energy production. Rather, agricultural energy crops and crop residues, and tree and shrub plantations — especially plantations of oil-producing plants — are the focus of current attention in bioenergy development in these regions."

So what are the hallmarks of best practice in collecting woody biomass sustainably?

Oddly enough, leaving lots behind.

Finland's guidelines including leaving large dead wood in place (unless it's right after a storm or there's a question of insect or disease infestation), leaving stumps in place next to waterways and slopes or if they happen to be big, and leaving about a third of all the detritus behind period. And it's not just the Finns; Minnesota calls for intentionally leaving a fifth behind, with the understanding that another 10 to 15 percent gets left behind anyway.

Just like with sourdough bread, you leave a little, or a lot for forests, actually, to help get the next generation a branch up. Unlike any of the fossil fuels, the key to this particular renewable is leaving a little money on the table.

There are lots more, of course. Nobody wants you retrieving materials close to "riparian" areas, as areas next to waterways are called, or where erosion is a palpable concern. Be kind in areas with especially fragile soils or ecosystems. Grab your biomass in one fell swoop — at the same time as any logging, for example — so equipment isn't crushing the habitat repeatedly. And Dovetail, which has been very involved in forest certification efforts, believes that should have a role in biomass recovery, too.
But in the end, be kind. And leave some behind.

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