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Is Burning Biomass Green?

Wood is complicated. Sometimes it can be burned, and it is good for the environment because new trees breathe in the gases of the old. And sometimes, burning wood is bad. It is bad when burned in forest fires, and during no-burn days in polluted cities, and concerns have recently arisen over the importation of wood pellets from the U.S. to burn to fuel U.K power plants, some of those pellets may be OK—others not.

A recent feature in BBC News summarizes the dilemma and raises the issue that U.S. wood-pellet-imports may sometimes be fueling the fires of pollution.

burning biomassIn an apparently misguided attempt, the Eropean Union (EU) treats wood-pellet burning as part of its renewables policy under biomass. It is true that trees grow, that in the efforts to grow and harvest straight lumber for building that single-species of trees are planted close together. As the trees grow, they are then thinned; the thinned trees used to go for paper but now are just as likely to become wood pellets for pellet stoves and U.K. power plants.

And, according to the BBC, U.K. taxpayers subsidize energy firms to burn wood to meet EU renewables targets.

A report by the U.K.’s Department of Energy and Climate Change (DECC) says that leaving wood in the forests would result in much bigger carbon savings. Moreover, the subsidies may be “inadvertently making climate change even worse.”

BBC Environmental Analyst Roger Harrabin writes, “Burning biomass—such as wood—is not a zero-pollution option. It creates greenhouse gases to cut and transport the wood and when the wood is burned.

But supporters say that so long as the burned vegetation is replaced by new plants to absorb CO2 that should confer a significant advantage over using fossil fuels.

And it counts as renewable energy because new trees soak up the CO2 emitted by the burned trees.”

The DECC report says the government's previous calculations failed “to acknowledge the different types of impact that can be created in different types of forests when wood is removed to burn.” As we said, wood is complicated.

Burning whole logs from natural forests is not so good. Burning waste that would otherwise be burned anyway is not so bad. The argument stemmed from a U.S. academic paper that argued that burning whole trees produces more emissions than burning coal when time transport (cutting trees, loading them on trucks, delivering them, etc.) is factored in.

The Natural Resources Defense Council (NRDC) has a strong position as to why forests aren’t fuel.

Drax, U.K.’s biggest power plant, is switching half of its boilers from coal to wood pellets in a plan to reduce greenhouse gas emissions. Drax feels the pellets are OK because they come from waste.

The firm insists that it is using wood cutoffs that would be waste anyway. “But the issue is complex and disputed” because some firms are using whole trees harvested from endangered swamp forests. Thus, as with most wood, source, harvesting method and provenance are really important to determine which pellets are OK to burn. Perhaps a pellet certification process could help.

And other questions abound. Compost is brown gold. What happens to soil when even the waste wood is taken from the forest? What if pellets become more valuable than wood pulp? Would there be a sort of giant global shell game as the paper producers sought lower-priced pulp for papermaking from overseas?

If you have the time (it's roughly an hour long), watch this February 2014 Webinar from Dr. Zander Evans, the Research Director at the Forest Guild. The Forest Guild's mission is to promote ecologically, economically and socially responsible forestry as a means of sustaining the integrity of forest ecosystems as well as the human communities dependent upon them. In his Webinar, Dr. Evans reviews biomass harvesting guidelines from Maine to Missouri and how policy and public reaction to harvesting have changed over the last five years. He underscroes the importance of documenting the sustainability of forest biomass harvests by sustainability requirements under consideration by the EU, which would have a significant effect on the burgeoning wood pellet industry in the southeastern U.S. 

For more on this topic, see Matt Power's blog "Study: Biomass Plants May Pollute Worse Than Coal"