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Not all Pellets are the Same in a Carbon-Neutral Society
by -- February 13th, 2015

While I was living in New England for the past 7 years, a new industry has popped up in North Carolina—the wood pellet industry. It has revitalized the sluggish demand for forest products in the Southeast. Biomass-powered utility plants in Europe are asking for the delivery of more than 5 million tons of wood pellets annually, which are burned to generate electricity. In the urge to fulfill its commitment to reducing CO2 emissions to the atmosphere, the European Union counts all biomass-energy as carbon-neutral.

If wood pellets are derived from construction debris, discarded shipping pallets, and the debris from forestry operations, that is probably a good assumption. All these materials are likely to decompose or get burned within a short period of time. Some live biomass also helps to reduce CO2 emissions, if it is derived from short-lived plants, such as weedy grasses and short-rotation forest trees, like loblolly pine. As long as any region retains about the same area of such vegetation, it can be regarded as carbon neutral. In this scenario an inventory of the carbon held in US forests would show little change that needs to be reported in our national emissions to the international bodies that monitor greenhouse-gas emissions of all nations.

But when pellets are derived from large and older trees, it’s a different story, which is difficult to unfold. And once they are in the bottom of a boat headed to the United Kingdom, who knows whether the pellets were derived from waste materials or whole trees. When whole trees are pelletized, the carbon in their biomass is released to the atmosphere when they are burned.   For decades, the carbon contained in the small trees that replace them is much less—so there is an overall release of CO2 to the atmosphere. Anticipating a climate “tipping-point,” all nations are trying to reduce carbon dioxide emissions during the next several decades. So, how much forest we have and the time it takes for forests to recover is the essence of any argument about whether pellets are good or bad for the environment.

If all woody biomass is considered carbon-neutral, we are likely to see increased logging of the remaining old-growth forests—important wildlife and biodiversity habitat in the Southeast. Pellet production is also increasing from the northern, boreal forests in Canada and the US. And, international demand for such biomass will undoubtedly lead to deforestation elsewhere. A worldwide reduction in standing forest biomass translates to greater CO2 in our atmosphere for decades.

All this casts a shadow on another well-meaning attempt to wean society from its diet of fossil fuels and reduce carbon dioxide emissions to the atmosphere. Coal is bad for CO2 emissions and a variety of other air pollutants that affect human health. Wind, tidal, and solar power emit almost nothing and should dominate our renewable portfolio. Compared to coal, wood has less energy per unit of its weight, so more of it must be burned to displace coal from the utility industry. When wood is derived from whole trees, it may actually increase CO2 emissions to the atmosphere.

Pellets provide a rich profit for the industry, but it is too simple to think that all pellets hit the target we are aiming for—a carbon-neutral economy.

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