Wood pellets offer NC’s best carbon-neutral energy source

By Fred Cubbage and Robert Abt, professors at NC State University’s Department of Forestry and Environmental Resources

Source: The News & Observer

The N&O just ran a three-part series with front-page coverage on wood pellets and whether they are carbon neutral. The series was fascinating, full of information, but not well balanced. None of the cited experts commenting on the negative carbon consequences of pellets seem to do research related to forest markets, which are the basis that translates a demand for wood into a forest carbon outcome.

As noted by the N&O “special correspondent” Justin Catanoso, some advocate that cutting down small tracts of forests are not carbon neutral, because it takes decades — 80 to 100 years or more — to regrow the trees. This is misleading for several reasons, as different life cycle analyses show:

First, trees grow slowly in the northern U.S., at maybe 1-2 tons per acre per year. In North Carolina, even hardwoods grow about twice as fast, and pine forests grow several times faster. Thus it only takes about 50 years (hardwoods) to 25 years (pines) to regrow a single stand of equivalent wood and carbon volume in North Carolina.

Second, one stand is not the right metric for carbon neutrality and sustainability. The overall forest volume in the region or the state is correct. Forest stands always mature, die, regenerate — naturally by old age and mortality (like people) or by planned timber harvests and planting or natural regrowth. That is why the Interstates and highways are lined with trees, even after massive forest destruction to build them. So, since the state has increasing overall timber volumes per acre and in total, we are sustainable, and we are carbon neutral or better.

Third, timber sales for wood biomass and pellets make owning forest land more valuable, and encourage many landowners to keep and regenerate their forests.

Fourth, while timber harvest, transport to a pellet mill, processing there, and shipping to European Union nations increase costs and loses some carbon, they are still way more efficient and emit less net carbon than fossil fuels. Trees do regrow and add carbon by taking CO2 out of the air, adding water and nutrients and making wood, and recycling it when burned. Former dinosaurs/ pits and petroleum only emit carbon. The EU scientists did not make spurious conclusions about carbon neutrality; wood must meet a standard of being about 80% or better than coal. They did the math very closely and painstakingly over a couple of decades, and came out with a justified net gain with forests, wood, and pellets.

So, the carbon bottom line is that forests at a regional scale in North Carolina are sustainable. Forest volume and carbon are increasing. Life cycle analysis and dynamic timber markets and investments at the state level support the merits of this renewable resource. We have published articles that offer these scientific findings. Science panels with the Society of American Foresters all come to the same conclusion. The N&O series missed the boat with selective research from afar, and should go back and write headlines with a fair review that includes all sides, not just a polemic that supports their predetermined conclusion.

Furthermore, North Carolina should add biomass to their renewable energy portfolio. It remains the most pervasive and renewable energy source we have; provides income for landowners; jobs for local residents; and rural development in areas of the state that need it the most. Wood remains our best carbon-neutral energy source in the short run, we have gigatons of it available now, and more use of it will prompt far more carbon neutral, sustainable quantities in the future.

Fred Cubbage and Robert Abt are professors at NC State University’s Department of Forestry and Environmental Resources.