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Is Burning Wood CO2 Neutral?
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.
http://www.eia.gov/todayinenergy/detail.php?id=20912
https://www.nrdc.org/sites/default/files/wood-pellet-biomass-pollution-FS.pdf
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.
http://www.ren21.net/resources/publications/
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.
| Fuel | lb/million Btu | Plant efficiency, % | CO2/MWh | CO2 Ratio |
| Wood chip* | 213.0 | 30 | 2423 | 3.6 |
| Bituminous coal | 205.7 | 41 | 1712 | 2.6 |
| No. 2 fuel oil | 161.3 | 35 | 1572 | 2.4 |
| Natural gas | 117.0 | 60 | 665 | 1.0 |
*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.
https://www.veic.org/company/our-story
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.
http://www.theenergycollective.com/willem-post/2394110/is-burning-wood-co2-neutral
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.
https://www.epa.gov/energy/ghg-equivalencies-calculator-calculations-and-references
http://www.forestecologynetwork.org/climate_change/sequestration_facts.html
http://www.biomasscenter.org/images/stories/VTWFSSUpdate2010_.pdf
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 | acre | dry ton/acre |
| Forest area, per USFS | 4,511,000 |
|
| Aboveground biomass, dry ton, per USFS | 282,016,000 | 62.5 |
| Timberland area, per USFS | 4,288,000 |
|
| Aboveground biomass, dry ton, per USFS | 266,610,000 | 62.2 |
| Harvested area, 41% of forest area, per BERC | 1,851,548 |
|
| Aboveground biomass, dry ton, per USFS | 115,121,551 | 62.2 |
| dry ton/y | dry ton/acre/y | |
| Net growth of growing stock trees, per USFS | 2,153,563 | 1.163 |
| Mortality of growing stock trees, per USFS | 1,021,390 | 0.552 |
| Removals of growing stock trees, per USFS* | 980,410 | 0.530 |
| Net growth/Removals ratio | 2.197 |
|
| 2014 Vermont Harvest, per VT-FPR |
|
|
| Harvest for all uses, cords | 2,419,408 |
|
| Harvest, dry, live and dead trees | 1,330,674 | 0.719 |
| Harvest, dry, live and dead trees, per USFS* | 980,410 | 0.530 |
| Harvest, dry, live and dead trees, difference* | 350,265 | 0.189 |
*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.
http://www.maforests.org/Timberspeak-Timber_Industry_Propaganda.pdf
– 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 | acre | green ton | green ton/acre |
| Forest area, per BERC | 4,414,884 | ||
| Accessible, Appropriate, Managed area, per BERC | 1,812,097 | 197,518,573 | 109.00 |
| Low-grade inventory of live trees, page 23 | 92,476,639 | 51.03 | |
| green ton/y | green ton/acre/y | ||
| Net Available Low-grade Growth, page 24 | 1,757,056 | 0.970 | |
| NALG rate (USFS used 1.871), %/y | 1.900 | ||
| VT 2014 wood burning harvest; see below table | 1,233,497 | 0.671 | |
| Remaining NALG for burning and pulp | 523,559 |
– 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.
https://blogs.cornell.edu/nesungrant/files/2014/06/sungrant_2007conf2_Recchia-pdf-1nmdn0a.pdf
– 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.
http://www.biomasscenter.org/images/stories/VTWFSSUpdate2010_.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.
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 | Electrical | Electrical | Total Electrical | Total burning | |
| Fuel | In-state | Out-of-state | In Vermont | |||
| ton | ton | ton | ton | ton | ton | |
| Wood | 1,233,497 | 886,155 | 347,342 | 371,691 | 719,033 | 1,605,188 |
| CO2 | 1,243,776 | 893,540 | 350,237 | 374,789 | 725,025 | 1,618,565 |
NOTE: Below are listed the wood tonnage and combustion CO2 tonnage of Vermont’s wood chip power plants in 2015.
| Vermont Wood Power Plants | McNeil | Ryegate | Total | |
| ton | ton | ton | ||
| Electrical, wood | 2015, McNeil | 469,190.0 | 249,843 | 719,033 |
| Electrical, wood CO2 | EPA, McNeil | 473,100.4 | 251,925 | 725,025 |
http://www.maforests.org/McNeil Emissions 2015.pdf
http://www.maforests.org/RYEGATE TECHNICAL.pdf
http://www.maforests.org/VermontBiomassBiomess.pdf
Photo Credit: InspireFate Photography via Flickr
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