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New NRDC video animation shows risks of burning trees for energy

Sasha Stashwick

Posted September 7, 2011

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Our forests work hard for us every day, absorbing and storing vast amounts of carbon. This makes forests one of our best defenses against global warming, one we Americans rely on to offset 13% of our annual greenhouse gas emissions each year.

Unfortunately, power companies are increasingly turning to our forests for fuel, and they try to get away with it by claiming that trees are a “sustainable” and “carbon neutral” source of biomass.  But trees are not the same as perennial grasses or harvest residues that can either regrow quickly, would otherwise be burned in the field, or are not needed for other purposes. We need trees.  And we need full grown trees because saplings require decades of care before they can absorb the same amount of carbon dioxide as full grown trees. 

As if that weren’t reason enough, the science is also clear that harvesting and burning whole trees for energy will result in as much if not more carbon emissions than burning coal for decades.  But our policies have all too often not kept pace with science, and EPA’s current policy fails to differentiate between the good, the bad, and the ugly when it comes to biomass and threatening our forests.

Let’s dig a little deeper: power companies and the forest industry sell the idea of burning trees as a renewable alternative to fossil fuels like coal with a simple argument: Trees grow back, right?  So how can burning trees not be better in terms of carbon pollution than burning coal?

I briefly explained the answer up above, but to fully understand it requires an explanation of the forest carbon cycle— not exactly most peoples’ idea of a good time. To help make what can be a wonky issue a bit more accessible, NRDC is releasing a new fact sheet today, along with a video animation showing what happens to the balance of carbon between and forest and the atmosphere when we burn forests to produce energy instead of allowing them to keep their day jobs—as massive carbon storage facilities. 



As the video shows, just like coal, when trees are burned in power plants, the carbon they have accumulated over long periods of time is released into the atmosphere. But unlike coal, trees will continue to absorb carbon if left alone. So burning forests for energy not only emits a lot of carbon, but also degrades our carbon sinks. Taken together, this creates a “carbon debt”—an increase in carbon pollution over the fossil fuel alternative—and forests can take decades to repay this debt, even if they are replanted immediately and managed carefully.

NRDC believes we must quickly transition from burning dirty fossil fuels like coal for energy to renewable resources like wind, solar, and low-carbon sources of biomass that can scale up sustainably and deliver real carbon savings. We cannot afford to wait multiple decades for biopower systems to start delivering carbon benefits.

But burning the worst forms of biomass, such as whole trees, will take us in the wrong direction, increasing carbon pollution at a time when we can least afford to. To avoid this, we need policies that differentiate between biomass that delivers carbon benefits soon—for example, sustainably produced energy crops like switchgrass grown on non-forested land—and unsustainable forms of biomass, like whole trees. Only biomass that is carefully chosen, grown responsibly, and efficiently converted into energy can reduce carbon pollution and other emissions compared to fossil fuels.

For more information and to tell Congress that our forests aren’t fuel, go to: .

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Concerned BreatherSep 7 2011 06:59 PM

Whole trees are far from the worst form of biomass- check out S. 1392 recently introduced in the Senate, which defines used tires as biomass.

Meg SheehanSep 7 2011 09:08 PM

Biomass combustion power facilities are incinerators and need to be exposed as such. Whether burning "energy crops" or other "sustainably grown" biomass, this is incineration.

Please watch the trailer for a new film on the toxic emissions from incinerators - biomass burners have essentially the same emissions profiles as other "waste" burners: dioxin, HAPs, nano-particulates, CO, etc.

It would be great if NRDC framed the issue as one of toxic incinerators vs. non-smokestack renewables like wind and solar.

Toby ThalerSep 8 2011 02:41 PM

I concur with Meg Sheehan's comment; we need to add a focus on the public health impacts of incinerating biomass. NRDC would get far more traction in local communities if you added this to your issue framing. GHG, carbon neutrality, and impacts on global warming is important, but it does not connect on a personal level like "you're kids will get asthma and your elders will die early from cardiopulmonary problems caused by particulates (PM 2.5 and smaller)."

Also, it is disturbing that the video encourages the use of biomass at the end, showing annual crops as the fuel. This is a horrible linkage; if we try to shift any significant portion of our energy source to this type of biomass, we'll drive up food costs and make it more difficult to feed the growing billions of people. Please do more research and get this issue right!

Jeff BorlingSep 8 2011 04:30 PM

I also have my concerns about using trees as a major source of fuel for baseload electric energy production at stand-alone power plants for grid energy, but I also think this article and video gloss over a few major nuances I'd like to see addressed on this blog, if possible:

1. Does/should the NRDC make distinctions between energy production for baseload electricity, heat production, or combined heat and power (CHP) in its messages about woody biomass? Baseload electricity may not be a sustainable use of woody biomass fuels, but the carbon equation looks a lot different when replacing fossil fuels with wood for heat and domestic hot water production, or for CHP for district heat and district energy projects in areas without natural gas access.

2. Does the NRDC understand the full implications of comments like, "Biomass combustion power facilities are incinerators," if those sentiments were to become law? Paper mills and wood products companies often burn the bark and waste wood that comes off their processes to help fuel their production plants. If this material is classified as solid waste, they will not gain permits to operate as garbage incinerators, so all this material will go to landfills and the plants will be forced to burn fossil fuels or buy power off the grid. Most states with paper mills depend on coal for the bulk of their power generation. I fail to see how driving fossil fuel demands and preventing the utilization of waste streams in an efficient manner of energy production is concurrent with your goals. Of course you may argue that we don't need paper and wood products, but we do need the jobs and the tax revenue to fund good environmental work in these states. The DNR also relies on timber sales to these entities to fund their work in resource management. Also, wind and solar projects are expensive. Where will the tax dollars come from to help drive down the costs of these investments (which I think is a good idea, mind you). We need industry, we need jobs and we need taxes to invest in the next generation energy technologies. The boiler MACT and other actions to classify wood-powered facilities as garbage incinerators is counterproductive. (As a side note: why is incinerating garbage so bad? Is burying it in landfills really a "greener" alternative? If incineration - or better yet, gasification - can be done efficiently, we can solve our garbage problem and our energy problem. It sure seems to work in countries like Sweden, which are clearly greener than the U.S...)

3. It is a fact that trees absorb less and less carbon as they age, as I think the video concedes. In parts of the upper midwest, there are documented tree stands where the trees are all well above the age of 40 years. Many are 70 years older or more. I don't contend that we should clear cut all old-growth forests, as I spend my weekends hiking and camping in these areas. However, we need to be honest about the facts here. Many of these tree stands demonstrate negative growth rates (they aren't growing any taller) and they are absorbing only minimal amounts of carbon. There is also evidence that rotting wood on the forest floor will release carbon and methane, the latter of which is actually far worse for the climate. It is a myth that the best thing we can do for forest health is to leave the forests alone.

4. From a purely fundamental standpoint, it seems odd to argue that "forests aren't fuel" at a time when thousands of firefighters are risking their lives in several different states to fight wildfires that are tearing through large amounts of fuel that has been left sitting on forest floors. I understand that fire is a natural occurrence that can be vital to forest health, but within the context of your argument, I think it is safe to say that when forests are not thinned and managed sustainability through industry demand, the wood will burn and the carbon will be released into the atmosphere, one way or another. Doesn't it make more sense to harness that energy in a sustainable fashion, rather than say that no wood should be used for energy production because of carbon emissions? Why not help improve the process/technology, rather than try to stop it altogether and, in turn, help the fossil fuels industries maintain their hold?

5. The article talks about planting dedicated energy crops on non-forested lands. Of course the prairie restoration groups and other habitat interests will say that non-agricultural land needs to be protected from the plows and combines as well. So that leaves existing farmland. We know that using corn and other food crops for energy is less than sustainable. If you stop planting food crops on agricultural lands and start planting energy crops, won't we displace food crops and cause the same issues in the end? Yes, we can use residuals from food crop production and forest lands, but there simply is not the volume needed in these materials to support our power needs. Given what we have learned from corn ethanol, it seems to be an incomplete thought to talk about energy crops without discussion food production and other unforeseen implications.

6. I absolutely love and support new renewable energy sources like wind and solar. However, for the next several decades that frame your argument, it is impossible to install enough wind and solar farms to meet the energy needs of our country, even if we put all efficiency practices into place. We have a growing population and we all like our electricity (how else are you blogging on your computer right now?). Short of mass genocide or some other form of population control, it will be hard to reverse the trend of increasing energy demands. Wood fuel may not be the best alternative to fossil fuels imaginable, but it may be the best tangible alternative we have in the short-term.

7. As a blanket question that ties into all those listed above, is NRDC at all concerned that your fight against wood-for-energy is having the unintended consequence of supporting the fossil fuels industries? We already see wind and solar projects fighting each other for funding, and now we have the NRDC fighting wood-based energy. Do you worry that we are creating a "divide and conquer" opportunity that will support the fossil fuels industries as they work to thwart renewables as a whole?

George WhitingSep 9 2011 01:31 PM

In this day and age, it's not an insurmountable challenge to manage forests sustainably. Trees do have a natural lifespan, and when they die, all that carbon stored in them gets released to the atmosphere, whether through decomposition or through forest fires. Harvesting older trees may speed up the process somewhat, but it also leaves more space and light for the remaining trees to grow faster (just look at the rings of trees for evidence of that).

Using trees for thermal energy to heat homes has been used for many thousands of years. Modern indoor wood and wood pellet central heating systems do this more cleanly and efficiently than ever before. From an environmental standpoint, it makes more sense to heat with wood from sustainably harvested trees that are going to die anyway, than it does to heat with oil, propane, coal, and even natural gas which releases carbon that is otherwise sequestered underground for eternity.

From an economic standpoint, it also makes sense to use trees and tree byproducts such as wood pellets because it supports regional jobs, and keeps heating dollars close to home. Shipping wood pellets 60 miles to someone's home is preferable to shipping oil 6000 miles to a refinery and then on to your home. Many or most of those dollars spent leave our economy, rather than supporting livelihoods closer to home.

Harvesting trees for thermal heat can be done sustainably, as can be seen by the example of other countries where this has been the case for many years.

I'll add that parts of the US have abundant forest, but not so much sun, wind, and available land for grassy biomass crops. The ideas in the video may make sense for some parts of the country, but not much sense for others.

Jeff WartluftSep 9 2011 09:30 PM

Thank you Jeff Borling and George Whiting for some balance to the comments. We need to appreciate that nature grows from 1 to 4 tons of new woody tissue per acre every year in our forests. How many forested acres are in your County? If we remove crowded, crooked and diseased trees in our timber stand improvement (TSI) activities, thereby concentrating the growth on the better stems, we improve the forest health and productivity. And where do we use this low grade wood? Energy, of course, in the form of firewood, chips or pellets.

Suz-Anne KinneySep 14 2011 03:34 PM

I disagree that the "science is also clear that harvesting and burning whole trees for energy will result in as much if not more carbon emissions than burning coal for decades."

I suggest that everyone take a look at Lippke et al. 2011. Life cycle impacts of forest management and wood utilization on carbon mitigation: knowns and unknowns. Carbon Management 2 (3), 303-333.

Two important findings of the study:

1) Peer reviewed primary life cycle data allowed the authors of the study to complete GHG emission comparisons for different power plants. They found that “each mega joule of electricity that a woody biomass plant produces generates only 4% of the emissions from a bituminous coal plant, using a fossil fuel base for comparison. This is in direct contrast to the proposed EPA method where the CO2 uptake in the wood from the atmosphere is treated the same as if it were mined like coal rather than sourced from sustainably managed forests.” Even using the EPA’s proposed method, the group found, a biomass plant’s emissions would equal just 86% of the emissions from a coal plant.

2) Fossil fuel emissions are by far the largest contributor of carbon emissions to the atmosphere. The study concludes that displacing fossil fuels with wood from sustainably managed forests will provide the maximum rate of carbon absorption possible.

“While maximizing forest growth contributes more wood to utilize, the dominant source of carbon mitigation comes from sustainably displacing fossil emissions through the use of wood since the carbon stored in the forest is a one-time creation and can only contribute to sustainably reducing carbon emissions by harvesting the wood to substitute for other materials.”

In essence, the amount of carbon that trees sequester drops as the trees age; they then die and decompose. At this time, the benefit of not harvesting the trees has been completely obliterated. From a life cycle impact perspective, harvesting trees when they can provide the most carbon benefits, including a) long-lived wood products (lumber, engineered wood products, trusses, etc.) that can be substituted for other building materials (steel, concrete) and b) energy products (biomass, in-woods chips, etc.) that can displace fossil fuels, is the best carbon mitigation strategy available.

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