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Is Burning Wood CO2 Neutral?

Willem Post's picture
President Willem Post Energy Consuling

Willem Post, BSME'63 New Jersey Institute of Technology, MSME'66 Rensselaer Polytechnic Institute, MBA'75, University of Connecticut. P.E. Connecticut. Consulting Engineer and Project Manager....

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  • Nov 30, 2016


The EU and US have declared, “Burning wood is CO2-neutral”. East Europe and the US Southeast still have significant areas with forests. Starting about 2005, major parts of these forests have been harvested by means of clear-cutting. In 2016, about 6.5 million metric ton of wood pellets will be shipped from the US Southeast to Europe for co-firing in coal-fired power plants. The EU authorities in Brussels have declared these coal plants in compliance with EU CO2/kWh standards, because biomass is renewable and the CO2 of wood burning is not counted.

Manufacturing pellets requires input energy of about 115 units, and shipping pellets to European coal plants requires about 10 units, for a total of 125 units to obtain 100 units of pellet energy; the CO2 emissions of pellet burning is declared CO2-neutral, and the other 25% of CO2 emissions is not mentioned.

Clear-cutting of Forests: Clear-cutting is extremely damaging to soils, because of leaching out of nutrients released by dead underground biomass. When most of the US northeast was clear-cut in the 1800s (Vermont lost 75% of its forests in a few decades), soils eroded, and nutrients leached out. That environmental destruction was followed by about 4 decades of acid rain, 50s – 80s, which had the same effect as clear-cutting regarding nutrients leaching out, such as calcium, a vital nutrient for biomass growth. The regrown forest is only, and can only be, a pale copy of what was before, and likely will never be as robust, unless forest soils are annually fertilized, as with most planted forest areas in the US southeast. 

In Vermont, about 45% to 50% of regrown forest is low-grade wood, i.e., suitable for burning. Vermont state government allows clear-cutting events of up to 40 acres “without a permit”; there is no statewide annual limit of such events. Considering the various known historical damages of clear-cutting, one would think the state would not allow it at all. 

NOTE: In the 1600s – 1700s, Vermont’s lakes and rivers were teeming with fish, according to settlers’ accounts. Eroded soils damaged/buried most of fish hatching grounds, due to the clear-cutting in the 1800s. A mere semblance of former fish populations is maintained by state fish hatcheries.

NOTE: Traditional biomass includes wood, agricultural by-products and dung. They usually are inefficiently burned for cooking and heating purposes. In developing countries, such as India, traditional biomass is harvested in an unsustainable manner and burned in a highly polluting way. It is mostly traded informally and non-commercially. It was about 8.9% of the world’s total energy consumption in 2014.

Most US states have significant areas covered with forests. As part of renewable energy programs, these forests are seen as useful for producing thermal and electrical energy. By using the mantra “Burning wood is CO2-neutral”, the CO2 from wood burning, and associated activities, is ignored, and thus not included in a state’s overall CO2 emissions. One of such states is Vermont, the subject of this article.

Burning Wood Declared CO2-Neutral in Vermont: Proponents of more wood burning, to achieve the Comprehensive Energy Plan, CEP, goal of “90% RE of All Energy by 2050”, are engaging in a fantasy by simply declaring, “Burning wood is CO2-neutral”. The difference of opinion regarding CO2 emissions from wood burning is not among scientists, but between scientists and wood burning proponents.

Burning wood is CO2-neutral” is used by wood burning proponents to bamboozle Vermonters. It conjures up the APPEARANCE of meeting CO2 targets. Proponents purposely forget to add: “Over a period of up to 60 years in New England, up to 40 years in the US southeast, if: 1) There is spare Vermont forest area for sequestering (there is not); 2) Logged forests have the same acreage (they do not); 3) Forests are not further fragmented or developed (they are); 4) Forest CO2 sequestering capability, Mt/acre, remains the same (it does not). See note.

Forests have aboveground and belowground new growth, which absorbs CO2 from the air and carbon, C, from the soil. Removing live biomass, low-grade and high-grade, reduces that absorption. In Vermont, about 50% of biomass removals are for high-grade purposes (the C stays sequestered, until some of it is burned); the other 50% is mostly for burning (the C becomes CO2 and is released to the atmosphere), and a small quantity is for pulp/paper mills (the C stays sequestered, unless some of it is burned).

Burning Wood Yields High CO2/Energy Unit Compared to Other Fuels: Forests, other biomass and oceans, acting as sinks, absorb atmospheric CO2 from any source. Those sinks are working at full capacity. The CO2 they cannot deal with has been building up in the atmosphere for at least the past 100 years.

It is irrational to make the claim “wood burning is CO2-neutral, because biomass growth is absorbing the wood-burning CO2”. Such a claim ignores the sinks are working at full capacity. There is no spare forest area reserved for absorbing the wood-burning CO2.

In addition, a wood chip power plant or heating plant adds CO2 to the atmosphere through:

– Logging, which adds CO2 due to soil disturbance; vehicle transport, equipment use, refurbishments and replacements; and diesel burning

– Building the plant, which adds CO2

– Plant O & M and refurbishments and replacements, which adds CO2

– Burning wood, which adds CO2 at much higher rates/energy unit than other fuels. See table.

– Decommissioning the plant, which adds CO2

The total CO2 of above 5 items would require about 15% more forest area than the harvested area to reabsorb that CO2 over at least 50 years. If wood pellets were used, about 30% more forest area is needed, as about 115 units of energy are required to produce pellets with 100 units of energy. Burning wood to produce electricity or heat yields more CO2/energy unit and more pollution/energy unit than any other fuel. The below table indicates only the combustion CO2.


lb/million Btu

Plant efficiency, %


CO2 Ratio

Wood chip*





Bituminous coal





No. 2 fuel oil





Natural gas





*Plus about 15%, if wood chips, plus about 30%, if wood pellets

VEIC and BERC: Vermont Energy Investment Corporation, VEIC, a non-profit, assumed control of Efficiency Vermont in 2008 (financed by a state-mandated surcharge on electric bills, about $60 million in 2016, which will be annually increasing), and of Biomass Energy Research Center, BERC, a non-profit, in 2012.

BERC performs biomass studies for VEIC, Vermont Energy Action Network, EAN, and others. EAN provides major inputs to updates of the Vermont Comprehensive Energy Plan, CEP, which has a goal (not legally required) of “90% RE of All Energy by 2050”, not just electrical energy, which is about 35% of all energy at present). BERC estimates, based on its criteria, about 46.8% of Vermont’s forests inventory of live trees is low-grade, i.e., suitable for wood burning.

Wood Burning Plants and CO2 Emissions: A wood chip power plant or heating plant adds CO2 through: 1) Logging soil disturbance, vehicle transport, equipment use, refurbishments and replacements, diesel fuel burning; 2) Plant construction; 3) Plant O & M, refurbishments and replacements; 4) Plant decommissioning. Those CO2 emissions would require a forest area up to 15% greater than the wood burning CO2 to reabsorb it over up to 60 years.

CO2 Emissions and Sequestering: Vermont CO2 emissions are about 8,370,000 Mt/y, of which Vermont forests sequester about 8,230,000 Mt/y, 1.82 Mt/acre/y*. The remaining 140,000 Mt/y becomes an annual addition to the atmosphere. Vermont forests cannot sequester all of Vermont CO2, i.e., there is NO spare forest area in Vermont, or elsewhere, to sequester ANY CO2 from wood burning.

*The 1,618,565 Mt of CO2 from wood burning in Vermont is improperly excluded, due to the historical myth, “Burning wood is CO2-neutral”. See Note.

NOTE: Conversion factor for carbon sequestered by 1 acre of average U.S. Forest = – 0.29 Mt C/acre/year x (44 CO2/12 C) = –1.06 Mt CO2/acre/y. Vermont claims 8.23 million Mt/y/4,511,000 forest acres = 1.82 Mt/acre/y; Maine claims 0.3 x 44/12 = 1.1 Mt/acre/y. It is not clear why Vermont has such a high value.

Vermont Excessive Harvesting: According to USFS standards regarding nutrition, habitat, etc., Vermont harvest removals should be limited to 980,410 dry ton/y. However, Vermont’s 2014 harvest was 1,330,674 dry ton, an excess removal of 350,265 dry ton, per USFS.

The CEP projects Vermont wood burning biomass, including pellets, to increase from 10.730 TBtu in 2010 to 14.533 TBtu by 2050, about a 35% increase; these end units, i.e., after burning. See pages 126 and 127 of CEP.

If the end units are green ton, and if burning is at the same average efficiency, the increase would be about 0.35 x 1,233,497, green ton (2014 Vermont wood burning harvest) = 431,724 green ton/y. This increase would feasible:

– If all of the increase were from NH, MA and NY. Vermont already imported about 371,691green ton for wood burning in 2015.

– If McNeil and Ryegate were shutdown to make available about 347,342 (in-state) + 371,691 (out-of-state) = 719,033 green ton/y for distributed wood burning.

NOTE: If NH, MA, and NY also increase wood burning, the wood available to Vermont likely would become less.

The below tables are based on data from: The 2016 USFS report (based on 2015 surveys); the 2010 BERC update report (mostly based on pre-2010 data); the 2015 VT-FPR report of the 2014 VT harvest; the 2015 wood burning by McNeil and Ryegate.

2016 USFS Report, based on 2015 survey data


dry ton/acre

Forest area, per USFS


Aboveground biomass, dry ton, per USFS



Timberland area, per USFS


Aboveground biomass, dry ton, per USFS



Harvested area, 41% of forest area, per BERC


Aboveground biomass, dry ton, per USFS




dry ton/y

dry ton/acre/y

Net growth of growing stock trees, per USFS



Mortality of growing stock trees, per USFS



Removals of growing stock trees, per USFS*



Net growth/Removals ratio


2014 Vermont Harvest, per VT-FPR

Harvest for all uses, cords


Harvest, dry, live and dead trees



Harvest, dry, live and dead trees, per USFS*



Harvest, dry, live and dead trees, difference*



*Removals” are estimated by measuring stumps in surveyed plots every 5 – 7 years; the stumps could be of live and dead trees.

* The “350, 265 dry ton difference” is due to USFS sampling being based on 1 plot per 6,000 acres, whereas VT-FPR harvest reports are based on mill surveys, and other, more detailed, information gathering.

Local loggers report taking a lot of dead, dying and other low-value trees, which appears to be true, based on my observations of watching chipping operations in my neighborhood. Nutrition and habitat benefits to a forest are reduced, if dead wood (mostly cull tops and limbs, and cull boles) is removed.

– Harvest for wood burning = mostly low-grade biomass + some dead biomass.

– Dead trees typically are left in the forest for habitat and nutrition. In case of clear-cutting (up to 40 acres is allowed without a permit), near zero is left for habitat and nutrition.

– Net growth = gross growth – mortality

BERC 2010 Report, based on pre-2010 data


green ton

green ton/acre

Forest area, per BERC


Accessible, Appropriate, Managed area, per BERC




Low-grade inventory of live trees, page 23



green ton/y

green ton/acre/y

Net Available Low-grade Growth, page 24



NALG rate (USFS used 1.871), %/y


VT 2014 wood burning harvest; see below table



Remaining NALG for burning and pulp


– NALG for burning and pulp is 894,893 green ton/y, per BERC report, mostly based on pre-2010 data.

– BERC uses a slightly lesser forest acreage than USFS.

– NALG wood is 1,466,982 green ton/y, per 2005 snapshot.

– NALG wood inventory is 51.03/109 = 46.8% of aboveground low-grade inventory, per BERC criteria.

– Low-grade wood consists of cull tops and limbs; cull boles; growing stock tops and limbs; growing stock boles.

– Vermont wood burning was 1,233,497 green ton (in-state harvest, 2014) + 371,691 green ton (out-of-state harvest, 2015).

– Pulp log uses are for firewood; pulp/paper mills; wood chip power plants; commercial & institutional heating plants.

– VT pulp tonnage to pulp/paper mills has been decreasing in recent years. FIA Annual Report.pdf Forests_of_VT_and_NH.pdf

Vermont’s wood burning harvest was 354,462 cords, or 886,155 green ton for firewood + 347,342 green ton for electrical generation = 1,233,497 green ton in 2014. See URL. HARVEST SUMMARY_final.pdf

About 347,342/719,033 = 48% of total electrical tonnage was harvested in Vermont. See below table and URLs.

NOTE: A standard ton of green wood is 45% H2O, and dry wood is 50% carbon. Burning one ton of green wood creates 2000 x (1- 0.45) x 0.5 x (44/12)/2000 = 1.00833 ton of CO2 emissions.

VT Harvest

Space heating



Total Electrical

Total burning




In Vermont





















NOTE: Below are listed the wood tonnage and combustion CO2 tonnage of Vermont’s wood chip power plants in 2015.

Vermont Wood Power Plants







Electrical, wood

2015, McNeil




Electrical, wood CO2

EPA, McNeil



725,025 Emissions 2015.pdf TECHNICAL.pdf Residential Fuel Assessment Report.pdf HARVEST SUMMARY_final.pdf


Photo Credit: InspireFate Photography via Flickr

Mark Heslep's picture
Mark Heslep on Nov 30, 2016

In 2016, about 6 million metric ton of wood pellets will be shipped from the US Southeast to Europe for co-firing in coal-fired power plants.

Increasing by a million tons per year.

Darius Bentvels's picture
Darius Bentvels on Dec 1, 2016

Nuclear is for sure not CO2 neutral.
Nowadays it’s emissions are even 2 – 8 times higher than those of wind & solar.

Engineer- Poet's picture
Engineer- Poet on Dec 1, 2016

The lying liar Bentvels/Bas Gresnigt repeats one of his favorite lies:

Nuclear is for sure not CO2 neutral.
Nowadays it’s emissions are even 2 – 8 times higher than those of wind & solar.

Only his estimate is lower than last time, when he claimed this:

Nowadays nuclear implies 2-10times more CO2eq emissions per KWh than renewable wind & solar.

Wind averages 26 gCO2/kWh, nuclear averages 29 g… but the fossil backup required by wind boosts its system-wide CO2 emissions to well over 350 gCO2/kWh in all existing grids.  Solar is 3x the emissions of wind or nuclear, with an energy-payback time measured in years to nuclear’s weeks.

(I have such a collection of refutations of Bas’ habitual lies that, given the ability to run scripts as a comment-filter here, links to the rebuttals could be automagically inserted as part of the posting process and save everyone the trouble.)

Nathan Wilson's picture
Nathan Wilson on Dec 1, 2016

The US NREL did a Life Cycle Analysis of CO2 emissions of energy sources. Of the 2,100 reference they evaluated, 85% did not meet their standards for quality and had to be discarded.
Here’s the NREL results (with the garbage studies removed), source. Basically all of the low carbon options (ignoring biomass) are so much better than coal, the difference is not worth mentioning (but PV is the worst). They did not consider the required fossil backup, but clearly any system that uses coal will be very bad.

Nathan Wilson's picture
Nathan Wilson on Dec 1, 2016

Here’s another LCA, which includes fossil gas and biomass. source

It shows that Lignite (e.g. German brown coal) is the worst of any fuel evaluated. Biomass beats solar PV, but both are significantly worse than nuclear, hydro, and wind.

Willem Post's picture
Willem Post on Dec 1, 2016


The graphic perpetuates the politically correct myth, “wood burning is CO2-neutral”.

Wood fired power plants have efficiencies of about 25%, ultra super-critical coal plants have efficiencies of about 43%, i.e., coal has much lower CO2/ kWh than wood.

See the important qualifier in my article.

Please, also read my other wood burning articles for additional information regarding that myth.

Darius Bentvels's picture
Darius Bentvels on Dec 1, 2016

Sorry! You are right. So it’s:
Nowadays nuclear implies 2-10times more CO2eq emissions per KWh than renewable wind & solar.
Thank you for remembering me.

Then we should also add the warming effect of inserting 3GW new heat into the atmosphere by a 1GW NPP. Considering e.g. that temperatures in cities are higher than in rural areas, it is substantial.

A pity that you promote outdated figures from a strong pro-nuclear institute. Even UNSCEAR is fraudulent with its figures, considering their 43 deaths estimate for Chernobyl.

Since the studies on which those figures are based:
Wind & solar becames 3-10 times cheaper due to efficiency improvements, which implies also 3-10times less emissions.
While nuclear became ~100% more expensive because the NPP’s had to become less unsafe, which implies ~100% more emissions.

When we talk about investments, we should consider next decades.
Then further price decreases (3%/a-8%/a) due to efficiency improvements hence emission decreases accordingly, are widely expected.

While little change regarding nuclear in the western world. Extrapolating the current trend, nuclear will become more safe hence more expensive, hence emit more CO2eq/KWh.

Darius Bentvels's picture
Darius Bentvels on Dec 1, 2016

Ultra super-critical coal plants (efficiency for the new types 46%) also can and sometimes do burn mixtures of coal and biomass.

Biomass burning doesn’t insert much new heat & CO2 into the atmosphere. If it’s not burned by humans, nature will do it in part via putrefaction & fire.

But agree: “Burning wood is CO2-neutral” is not correct,
though far less wrong than: “CO2-free nuclear”.

Darius Bentvels's picture
Darius Bentvels on Dec 1, 2016

While the NREL report is dated Jan.2013, it summarizes results of studies published in the 1989-2010 period. More specific for:
– PV . the period: 2000 – 2009 (av. ~2005)
– Wind a period: 1994 – 2010 (av ~2003)
– Nuclear period: 1989 – 2009 (av ~2004)

I couldn’t find corrections for the cost changes (hence the associated CO2eq emissions changes), since the original studies are published.
Realize also that usually studies are executed 1 -2 years before results are published!

So you should correct the NREL results for the cost =~ emission changes since the av. original studies were executed.
That implies that the emissions of:
– PV-solar are up to 10times less now*)
– Wind are >2 times less now;
– Nuclear are >2 times higher now.

When you apply those corrections you see that my original statement:
Nowadays nuclear implies 2-10times more CO2eq emissions per KWh than wind & solar” is supported.

And it will be supported more as efficiencies (cost/KWh) of wind & solar are widely expected to increase with 3%-8%/year, while the situation doesn’t improve for nuclear (may detoriate further).
*) With PV there is a big difference between:
– utility scale and small rooftop (also due to the high soft costs in USA)
– places where PV is installed. Abu Dhabi is now at $23/MWh.

Darius Bentvels's picture
Darius Bentvels on Dec 1, 2016

This is the same unreliabe source which EP linked above.
So please refer to my comment there.

Bob Meinetz's picture
Bob Meinetz on Dec 1, 2016

Willem, with all the current excitement about the dawn of a “post-truth” era, when verity becomes an unnecessary encumbrance to message, your contribution sounds refreshingly nostalgic. In retrospect it might one day mark the beginning of a “post-post-truth” era, but for convenience let’s agree two posts cancel. Let’s call it “truth”.

Truth can be messy. For, in truth, there’s no reason to disqualify burning old-growth timber from carbon-neutrality – we just need to extend our timeline out a century or two. And burning both oil and coal are 100% carbon-neutral if we extend it ten million years or so further into the past.

This dizzyingly-subjective objectivity only becomes more so. I move we ditch truth entirely, and relabel the current insanity humankind’s “post-thought” era. Even thought yields to message, if you give it a chance.

Rick Engebretson's picture
Rick Engebretson on Dec 1, 2016

An outstanding tabulation and interpretation, Willem. I’m overwhelmed, but offer other concepts to this many dimensional topic.

First (as you’ve discussed before) the type of tree, type of soil and moisture, and the type of environment are interdependent. Pure data of tons and dollars does not measure soil fertility, erosion, biodiversity, etc. I suspect original inhabitants (who taught us to plant corn) knew this well. The Naturalists of the 18th century wrote famously about it.

The question remains, how do we best help meet modern energy needs using bioproducts? The first obvious answer is what EP et. al. are advancing. High quality transportation fuels without oil don’t yet exist. All the energy inputs you describe for biomass pellets must be multiplied many times to yield liquid fuels. Only nuclear electric, excess wind electric, and concentrated solar seem useful energy to add for resultant fuel. Chemical energy storage made simple. The Feds seem to really want it.

Opportunity with great caution. Good post.

Engineer- Poet's picture
Engineer- Poet on Dec 1, 2016

High quality transportation fuels without oil don’t yet exist.

If Frank Shu’s paper on molten-salt “supertorrefaction” (actually, fast carbonization) is correct about the tar-free composition of the syngas product, we’re 90% of the way there.  There are turnkey methanol plants which convert any stream of CO+CO2+H2 into MeOH plus tail gas (and water in the case of CO2).  Methanol is a perfectly good motor fuel, superior to gasoline in many ways.  Shu’s figures suggest 7% MeOH yield from as-is wood chips (moisture content not specified) is achieveable.  There’s enough excess H2 in the tail gas that considerably more could be made if desired.

Rick Engebretson's picture
Rick Engebretson on Dec 1, 2016

I give you (“EP”) credit and hope it continues to advance.

The “molten salt” idea is very interesting. Heat buffering and optical catalytic properties can be highly engineered. Kind of like the synthetic mineral version of coals sustaining a fire.

Simon Friedrich's picture
Simon Friedrich on Dec 3, 2016

Biomass has a small role in meeting energy needs and sometimes provides an advantage over fossil fuels in reducing greenhouse per unit of useful energy. For example, combusting manmade biomass wastes for energy on a remote Pacific island. However, most of the useful energy obtained is attributable to the wastes carbon content. The resulting emissions are not carbon neutral.

The combustion of wood immediately adds additional greenhouses gases to the global warming momentum caused by these gases. The misuse of life cycle analysis (LCA) over the last couple of decades has hidden that fact. The products of wood combustion are almost all greenhouse gases carbon dioxide and water. There are no products of combustion left to recycle or remanufacture.

LCA assumptions (on any significant economic global scale) on how wood combustion today will be mitigated by additional photosynthesis sequestration over the next forty or more years are conjectures. The flawed view in the numerous LCA studies and comments giving bioenergy a carbon neutral ‘Good House Keeping Seal of Approval’ results from the IPCC guidance to not include biomass greenhouse gases in country totals. NREL (formerly SERI) as a government owned contractor operated research facility has a long time bias to showing biomass as a low carbon emissions energy source. It has been government policy under every administration since the 1973 oil crises to promote the use of biomass as an alternative to fossil fuels.

Rick Engebretson's picture
Rick Engebretson on Dec 4, 2016

Good luck EP If you search “diesel ban 4 world capitals” you can read how Mexico City, Paris, Madrid, Athens declared some intent by the year 2025. Just 8 years, better hurry.

The battle of the barnyard energy experts is about over for me.

Willem Post's picture
Willem Post on Dec 11, 2016

If an ultra-super-critical coal plant is fully loaded with SOX scrubbing systems and fabric filter particulate removal systems, then the overall plant efficiency is decreased to 43% or less, at rated output.

Darius Bentvels's picture
Darius Bentvels on Dec 11, 2016

That may be true.
Realize that developments to create more efficient plants are still ongoing, though I doubt whether these plants will surpass the 50% efficiency level. Also because developments are now moving towards burning mixtures of biomass & waste and coal.

I think that the new plant we have here, which claims 46% efficiency, also has SOX scrubbing systems and fabric filter particulate removal systems. Considering:
– that a plant without those won’t get a license here;
– it has a low chimney

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