A Cloud of Wood Smoke Forms Every Winter


Most people do not know the pollution emitted by wood-burning appliances, or know the emission limits of new appliances, as required by the EPA. 


Open-hearth fireplaces and wood-burning appliances produce particulate pollution far in excess of most other sources commonly considered to be very polluting.



Here are the hourly and daily PM10 emissions of different sources: 

Table 1/Pollution source






Open-hearth fireplace

 30 - 59

720 - 1416

Pre-1988 cordwood stove/furnace






Non-EPA-certified fireplace insert



EPA-certified, Phase 2, fireplace insert, effective July 1, 2013






EPA certified, Phase 1, stove/furnace, effective July 1, 1988



EPA-certified, Phase 2, stove/furnace, effective July 1, 1990



EPA-certified, Phase 3, stove/furnace, effective Feb. 3, 2015



EPA-certified, Phase 4, stove/furnace, effective May 1, 2020



Wood Smoke Mostly Affects People Closest to the Source


As deleterious as wood smoke is on regional air quality, the effects are much more serious when wood smoke accumulates under stagnant conditions in the neighborhood or general vicinity of the wood smoke source, such as a school, senior center, etc. When stagnant air conditions occur with near zero wind, a blanket of air traps smoke and other pollutants near the ground. People most affected by PM and toxic fumes are the elderly, the young and those with heart and/or lung disease.


These conditions result in the rapid build-up of outdoor smoke that can affect all neighbors within the source's immediate vicinity. Depending on the type of fireplace or insert used and the burning duration, smoke can concentrate under such conditions to many times the allowable Federal 24-hour Particulate Standards within a matter of hours. 

For instance, with completely still air, a single open hearth fireplace emitting 59 grams/hour of PM particulate pollution into the air surrounding a normal city block (16 houses) will cause the concentration of PM in a 100-ft. high environmental envelope above that block to increase to over 4,500 micrograms per cubic meter, over 30 times the 24-hour Federal Standard for PM10 pollution of 150 micrograms per cubic meter and over 131 times the 24-hour Federal Standard for PM2.5 pollution of 35 micrograms per cubic meter. 




Particulate Emissions of Wood-Burning Appliances



- In the 70s airtight air-heating cordwood stoves and water heating furnaces emitted about 40 to 60 grams/hour of PM10


- Per EPA, all wood stoves manufactured after July 1, 1988 must emit less than 8.5 g/h (5.5 g/h, if catalytic type). Existing inventories of non-approved wood stoves may continue to be sold until 1990.


- Per EPA, all wood stoves manufactured after July 1, 1990 must emit less than 7.5 grams/h (4.1 g/h, if catalytic type). Existing inventories of non-approved wood stoves may continue to be sold until 1992.


- Per EPA, all wood stoves manufactured after May 15, 2015 must emit less than 4.5 g/h. Existing inventories of non-approved wood stoves may continue to be sold until December 31, 2015


The 2015 revision also includes several types of biomass heaters which were previously exempt: pellet stoves; indoor and outdoor wood-fired hot water heaters; wood-burning forced-air furnaces; and a type of previously unregulated wood stove known as single burn-rate stoves. 


- Per EPA, all wood stoves manufactured after May 15, 2020 must emit less than 2.0 g/h. Existing inventories of non-approved wood stoves may continue to be sold until December 31, 2020


This final phase would lower the emissions limit to 2.0 g/h as measured by existing test protocols using dimensional lumber "cribs", or 2.5 g/h as measured by a still-in-development procedure using cordwood.




Pellet Furnaces versus Fuel oil, Natural Gas and Propane Furnaces


Pellet furnaces, EPA-certified, are a major improvement over fireplace inserts.

However, their pollution is far worse than of furnaces burning low sulfur fuel oil, natural gas, and propane. See below sections.

Having near-zero net energy buildings, instead of energy-hog buildings, would greatly reduce any burning.


Justifying wood burning and pollution because "burning wood is renewable" is far beyond rational. See note.

Justifying wood burning and pollution because "burning wood is renewable" (yes, over 80 to 100 years in northern climates with 3 to 4 month growing seasons) is far beyond rational. See note.

NOTE: In case of clearcutting, any of our combustion CO2 of year 1 would have to wait around in the atmosphere until about year 35 - 40 to start its absorption period, which takes about 90 to 100 years. After it is fully reabsorbed by new tree growth on our harvested area, it has fulfilled the assertion: “Burning wood is renewable”.

In case of light and medium cuts, that waiting period would be shorter. See URL.

Other CO2, upstream, downstream, embedded, plant operation and distribution system operation, etc., which is not combustion CO2 of wood chips, would be added to the atmosphere just like any other CO2.



Vermont, and likely other NE states, has been losing forest area since 2000 due to logging and encroachments. See URL


Comparison of Non-Certified and EPA-Certified Furnaces


Here is an example of an EPA-certified pellet furnace that emits 25 milligram of PM10 per million joules of heat input, which complies with the 2.0 g/h required by EPA. See last column in table 2


On a cold day, at a fuel input of 75000 Btu/h, and an efficiency of 75%, it would deliver 56250 Btu/h to a standard 2000 sq ft house in upstate NY, or VT, or NH, etc., and emit PM10 at about 48 g/day. See bold values in table 2.


A pre-1988, uncertified cordwood furnace would emit about 10 times more than the example pellet furnace.


Table 2

Not certified







Phase I

Phase II

Phase II


May 15, 2015

May 15, 2020


Furnace type

Pre-1988 cordwood






47 25 25







Fuel heat input






Fuel heat input





























Heat output





Cord Wood and Pellet Stoves are Big Polluters Compared With Gas and Fuel Oil Stoves


If 10 percent of building heating in Hanover would be by cord wood and pellet stoves, the PM and cancer-causing, polycyclic aromatic hydrocarbons, PAHs, would account for about 30 to 40 percent of all such compounds in Hanover’s ambient air.


The other ambient air PM and PAH would be from 1) other heating units that provide 90% of building heating in Hanover, and 2) other sources, such as traffic. See table.


As shown below, each gas (and propane) stove emits about:


- 1852 times less PM and PAH than a pellet stove,

- 588 times less than an ultra low sulfur fuel oil stove,

- 50 times less than a low sulfur fuel oil stove,

- 14.6 times less than a typical sulfur No. 2 fuel oil stove.


See  below table, URL and Appendix



If in the future 20 percent of building heating in Hanover would be by cordwood and pellet stoves, the ambient air PM and PAH would increase by about 35%, if other sources remained the same.


The dirty outdoor ambient air leaks into buildings, which results in the indoor air having about 70% of the dirtiness of the ambient air.



micron is a millionth of a meter.

mg/MJ is milligram/million joules.

1 MJ = 947.8 Btu


Test Results of Residential Water Heating Boilers and Air Heating Furnaces


Here are some results of PM and efficiency testing of various heating units, using various fuels, performed by engineers of the Brookhaven National Laboratory and the EPA.


PM Tests: The PM emissions were based on MJ of fuel input. The results of the tests were:


1) Gas-fired units have the lowest PM emissions averaging 0.011 to 0.016 mg/MJ


2) Regarding fuel oil units:

- Ultra low sulfur fuel-oil-units have PM emissions of 0.025 to 0.060 mg/MJ,

- Low sulfur fuel-oil units have PM emissions of 0.49 to 0.510 mg/MJ

- Typical sulfur No-2 fuel-oil units have PM emissions of 1.320 to 2.100 mg/MJ

- Pellet units have PM emissions of 25 mg/MJ; even the cleanest ones in 2020 would be off the charts dirtier than all fuel oil and gas units.


3) Wood pellet stoves have emissions averaging 25 mg/MJ, about 1852 times worse than gas.


NOTE: Cordwood stoves were not tested.


Older cord wood stoves have about 5 times the PM and PAH of EPA-certified pellet stoves.

New cord wood stoves, EPA-certified, have about 2 times the PM and PAH of EPA-certified pellet stoves.


Table 3/Household Appliance

Warm water boiler

Warm air furnace

Times worse than gas

Particle size

 PM2.5 and smaller

 PM2.5 and smaller






Natural gas




ULS fuel oil, 15 ppm




LS fuel oil, 500 ppm




No. 2 fuel oil, 2000 ppm




Wood pellet; 3-stove average





Efficiency Tests of Various Type Boilers: The results of the efficiency tests are shown in below table. Some stoves are more efficient than others, i.e., for a given fuel input they deliver a greater useful heat output.


Almost all buildings require circulating hot water at about 180F and baseboard units are designed accordingly.


Condensing heating units have efficiencies up to 95%, higher than any other heating unit, i.e., they produce more useful heat for a given heat input.


Condensing heating units, operating at high efficiency in condensing mode, can circulate hot water as low as 120F, but baseboard units need to be designed to heat a building with such low-temperature water. If that is not the case, the heating unit will operate in normal mode (non-condensing) at about 80% to 85% efficiency, for most of the hours of the heating season.


It would make absolutely no sense to replace gas and propane condensing heating units with a pellet unit, nor would it make sense to prevent the use of such units by not allowing gas pipeline and gas storage infrastructures and propane infrastructures to be built.


The data in below table are from the URL. See figure 20 on page 54 of URL


Table 4/#


Efficiency, %


 Oil-fired cast iron boiler

 87.4 - 91.6


 Oil-fired warm air furnace

  85.7 - 89.5


 Gas-fired sectional cast iron boiler



 Gas-fired warm air furnace



 Gas-fired condensing aluminum boiler



 Oil-fired condensing steel boiler



 Oil-fired condensing warm air furnace

93.5 - 93.7


 Oil-fired cast iron boiler



 Wood pellet stove



 Wood pellet stove



 Wood pellet stove


Real-World Efficiencies of Pellet Stoves Less Than ClaimedDuring 30-day testing (5 Sep 2015 - 3 Oct 2015; no involvement by manufacturers) of 6 popular pellets stoves they had average efficiencies of about 60 to 75 percent, well below the 75 to 88 percent claimed by manufacturers. See page 6 and 7 of URL.



Particle Size Distribution From Wood Chip Boiler


About 96% of PM in the raw (untreated) smoke from a wood chip boiler is PM10 or less,

About 93% is PM2.5 or less,

About 92% is PM1.0 or less.

About 4% is larger than PM10.


The volatile organic compounds, VOCs, are 50% methane and 50% other organic compounds. See URL


Particulate Loading in Flue Gasesof Wood Chip Plants


Wood chip plants have particle loading in the flue gas of about 100 milligram/standard cubic meter. See note.


With ESPs, particle emissions less than 1 mg/std m3 can easily be obtained, i.e., the ESP efficiency would be (100 - 1)/100 = 99.00%. If 0.5 mg/std m3 is desired, the efficiency would be (100 - 0.5)/100 = 99.5%.  


The 0.5% of the weight of the particle emissions not removed would entirely consist of sub-micron particles.

There are about 12 - 19 million PM10 particles per cubic centimeter and about 140 million PM0.6 particles/cm3 in the flue gases leaving wood chip boilers. See page 156


Each cubic meter of flue gases would contain trillions of such particles.

About 45% of the particulate load is 0.22 micron or less.

They are invisible, so the stack looks reassuringly “clean” to the lay neighborhood person (good PR).

It is not “clean”, because the ESP did not remove much of those sub-micron particles.


NOTE: During testing the boiler would operate at about 15% more air supply than is needed for complete combustion, and the flue gases would be hot. Corrections for 1) excess air and for 2) temperature and pressure are required to enable proper comparison of different operating conditions, fuels and boilers. Standard conditions (std) are defined as 0 C (32F) and absolute pressure of 10^5 pascal (1 bar).



NOTE: The plant is kept at negative pressure, from combustion chamber to stack outlet, to prevent flue gas out leakage. Some air in leakage likely does occur, which would dilute the flue gases and make any EPA test readings appear less than in reality.


Particle Size Distribution in Flue Gases: It is important to know the particle size distribution in the flue gases to ensure proper selection of air pollution control systems. This article determined the particle size distribution in the flue gases of wood chip boilers.


It was found more than 80% (by weight) of the particles have diameters less than 1 micron and the mean particle diameter was less than 0.25 micron, i.e., half were larger and half were smaller than 0.25 micron. See figure 3 in URL


Table 5/Particle size

 Load, milligram/std m3

Less than 0.22 micron








Greater than 7.22 micron


Total load


Fabric Filter Systems Much Preferred for Sub-Micron Particle Removal:

- Fabric filter systems remove PM9.5 and smaller at 99.84% efficiency, and PM0.36 and smaller at 99.98% efficiency. Table 1 on page 1145


- ESPs remove PM9.5 and smaller at 99.85% efficiency, and PM0.36 and smaller at about 50 - 70% efficiency. Figure 5 on page 1146



-There are about 12 - 19 million PM10 particles per cubic centimeter and about 140 million PM0.6 particles/cm3 in the flue gases leaving wood chip boilers. See page 156



Because, as stated above, more than 80% (by weight) of the particles are 1 micron and smaller, and the mean particle diameter is 0.25 micron, ESPs remove hardly any of the sub-micron particles, which are most harmful to health.


Collection Efficiency of a Multi-Cyclone/Fabric Filter Combo: The PM2.5 collection efficiency of a cyclone followed by a fabric filter system is at least 99.90%, including sub-micron particles. See table.


A cyclone system removes the larger particles, including the particles that are still hot, which protects the fabric filter system. If the cyclone system is followed by a fabric filter system, the combo is far superior to only an ESP. See URL



The below table includes collection efficiencies for PM 1.0 and smaller. That data was obtained from this URL.



NOTE: The data in the column “PM 1.0 and smaller” in below table was not provided by the BERC likely to avoid drawing attention to the harmful sub-micron particles.


NOTE: The Biomass Energy Resource Center (BERC) is a division of Vermont Energy Investment Corporation (VEIC), a quasi-state entity that also includes Efficiency Vermont, which is financed by electric ratepayers at about $65 million per year.


BERC works to advance the use of community-scale biomass energy throughout North America and beyond by providing technical consulting services, biomass energy program design and delivery, and education and outreach on benefits and best practices.


The table below compares the collection efficiencies of common emissions control systems of wood chip fired plants.


- PM10 and smaller particles are inhalable and toxic.

- The sub-micron particles have a large total surface area. They penetrate more deeply into tissues and do more damage.

- An ESP is inadequate to remove the harmful sub-micron particles.


Table 6/Removal efficiency

PM 10 and smaller

PM 2.5 and smaller

PM 1.0 and smaller




Single Cyclone








Core Separator

29 to 56

72 to 94


Multi-cyclone with fabric filter




Electrostatic Precipitator (ESP)



50 - 70


EPA Particulate Matter Standard


The EPA periodically issues and revises its standards regarding particulate matter in flue gases. The EPA PM standards were initially issued in 1997.


- In December 2012, the EPA revised the primary annual PM2.5 standard from 15 micrograms per cubic meter (μg/m3) to 12 μg/m3 for the protection of public health.

- During the 2012 review of the standards, the EPA retained the 1997 secondary annual PM2.5 standard of 15 μg/m3 for the protection of public welfare.  

- The 2006 24-hour primary PM2.5 standard was set at 35 μg/m3, and was not revised in 2012.


- The EPA may have to issue a PM1.0 standard in the near future, because as biomass burning is increasing, more people would be exposed, plus there is increasing evidence sub-micron particles have a significantly greater adverse impact on health than was thought. BTW, the particulates of tobacco smoke consist almost entirely of sub-micron particles.

EPA PM2.5 and Peace of Mind: The PM2.5 standard is supposed to give “peace of mind” to people, because there appears to be nothing coming out of the stack, a so-called “clear stack”.


In fact, the PM2.5 standard, issued in 1997, is grossly inadequate, because whatever is measured by means of standard EPA stack testing methods tells nothing about the number, size, weight and chemical composition of the invisible sub-micron particles, which are the most harmful to health.


PM10 and PM2.5: Two types of PM are shown: PM10 (particles 10 microns and smaller) and PM2.5 (particles 2.5 microns and smaller), the latter of which are of greatest concern relative to impacts on public health. See URL



PM10: Inhalable particles, with diameters generally 10 micrometers and smaller

PM2.5: Fine inhalable particles, with diameters generally 2.5 micrometers and smaller


- How small is 2.5 micrometers?

The average human hair is about 70 micrometers in diameter, making it about 30 times larger than a PM2.5 particle.

- How small is 0.5 micrometers?

A hair diameter is about 70/0.50 = 140 times larger than a PM 0.5 particle


Sub-micron particles stay in the air a long time, become widely dispersed before settling down, i.e., plenty of time to be ingested by humans 24/7/365.



Particle and gaseous emissions of four different wood chip-fired district heating units, in the size range 5−15 MW, were studied.



Three of the units were fire-tube boilers based on rotating grate combustion technology, and one was a gasification combustion boiler.


All of the units were equipped with cyclones to remove coarse particles from the flue gas.


In addition, two of the rotating grate boilers were equipped with single field electrostatic precipitators (ESP), and one with a condensing flue gas scrubber.


The particle filtration efficiencies of these particle removal appliances were measured.


The grate boilers produced on average 211−483 mg/million joules of total suspended particles (TSP) and 55−92 mg/MJ of fine particles (PM1) upstream of the secondary particle filters.


The gasification combustion boiler produced on average 50 mg/MJ TSP and 13 mg/MJ PM1.


The ESPs removed about 95% of the PM1s and 93% of TSP, leading to relatively low particle emissions.


The lowest collection efficiency for particles PM10 or less was achieved in the size range 0.2−1.0 micron.


The condensing flue gas scrubber removed on average 44% of PM1 and 84% of TSP.


Air Pollution in Residential Areas from Wood-Fired Heating in Germany


Wood burning for building heating has increased in Germany during the past 20 years. This has caused significant increases in PM10 or less and PAH in the residential areas of towns. In Germany, as in Vermont, a very small percentage of wood burning units are EPA-certified. Older wood burning units have 7 to 15 times the PM10 or less and PAH of the latest EPA-certified units.


An important source of inhalable particles in residential areas, particularly in the winter season, is the biomass combustion when wood is used for domestic heating, i.e. PM10 or less. This report is a continuation of our previous investigation about wood smoke pollution in residential areas of southern Germany (Bari et al., 2009).

The target of this study was to characterize ambient levels of criteria pollutants, their risk assessment and determine the influence of hardwood combustion on local air quality.


Particle-phase PM10 samples were collected at a residential site Dettenhausen southwest of Stuttgart during 2005/06 and winter 2009. Dettenhausen area 11 km2, altitude 500 m above sea level ,and 5389 inhabitants


Samples were analyzed by gas chromatography–mass spectrometry for polycyclic aromatic hydrocarbons (PAHs) and other wood smoke tracer compounds (e.g., laevoglucose, methoxyphenols).


High concentrations of PM10 and total PAHs were found during the winter of 2009, similar to the winter of 2005/06.


Carcinogenic PAHs were detected in high concentrations and contributed 44% of the total PAHs in the ambient air.


The significant concentrations of hardwood markers (i.e., syringaldehyde, acetosyringone) found in the ambient air suggest that the influence of hardwood combustion on ambient air quality is significant.


Based on the emission ratio of hardwood markers and PM10, it can be concluded that in the investigated residential site about 57% of ambient PM10 pollution can be attributed to hardwood combustion for winter heating.


WOOD HEATING IN VERMONT, A Baseline Assessment for 2016


Building heating requires about 28% of Vermont’s total energy consumption.

Wood burning for building heating has increased in Vermont from 4.5% in 2000 to 19% in 2009, slowly increasing to 21% in 2014.

About 79% is from other sources, such as LPG, NG, heating oil, and electricity.

Only 2% of building heating is by “Advanced Wood Heating”.


AWH is distinguished from other wood heating systems as AWH systems can be relied on as a primary source of central heating, and have the ability to continuously operate, without manual loading of pellets or other servicing, for at least a week. An additional heating system would be required in case of going on a 2-week vacation, etc.





Future Wood Heating: Increasing the use of wood heating in Vermont from 21% in 2014 to 35% by 2030 would not only displace oil, but also propane and to some extent natural gas.


If wood heating is to increase significantly more AWH systems and pellet stoves would need to be installed across the residential, commercial, and institutional building market sectors. We would need to:

- Install 38,905 additional wood pellet stoves (or about 30% of all single family homes)

- Install 10,519 additional bulk pellet boilers (or about 16% of all single family homes with centralized hydronic heat distribution networks)

- Install 2,574 additional pellet boilers in small commercial buildings (or about 6% of that market segment)

- Install 221 additional woodchip boilers in larger commercial/institutional buildings and district heating plants (or about 4% of that market segment).



Health Hazards of Wood Burning: The increase in wood burning has caused significant increases in PM10 and PAH in the residential areas of towns and near schools and other building complexes during winter.


An important source of inhalable particles in residential areas, particularly in the winter season, is biomass combustion when wood is used for domestic heating, i.e. PM10 or less.



Older wood burning units have 7 to 15 times the PM10 and PAH of the latest EPA-certified units. Almost all PM and PAH is from the older wood burning units. See table



Heating value of freshly harvested wood chips is about 7.6 million Btu/ton; 45 - 50 percent water

Heating value of wood pellets is about 7817 Btu/lb; 6.93% water


Table 7/Vermont wood heating in 2014




Wood chips








Houses heated in part with wood






Firewood burned






Average per house






Households with pellet heating units






Bagged pellets burned






Total energy (138530/9000 x 100,000)

million Btu

















Residential pellet boilers, bulk pellets






Installed 2015






Installed 2016






Total residential end 2016












Commercial/institutional, bulk pellets






Commercial/institutional, wood chips






Installed 2015






Installed 2016






Total commercial end 2016






Total advanced = 505 + 118 + 62












Residential, bulk, 2016






Commercial, bulk, 2016






Total end 2016






Wood chips









Bulk pellets

Wood chips


Total energy

million Btu






Carbon Content of Wood: The carbon contents in heartwood of softwood and hardwood species were determined. C in kiln-dried hardwood species ranged from 46.27% to 49.97%, and in conifers from 47.21% to 55.2%. Heartwood is the older harder non-living central wood of trees that is usually darker, denser, less permeable, and more durable than the surrounding sapwood.



The average higher heating value, HHV, of the more resinous softwoods is about 9,000 Btu/lb of dry trunk wood, and for the less resinous hardwoods about 8,300 Btu/lb of dry trunk wood. The EPA selected an average value of 8600 Btu/lb of dry trunk wood.


Wood Chips for Burning: Wood chips are made from whole trees that are fed into very large chippers. It is a noisy sight to behold. A large crane grabs an 18-inch diameter tree, feeds it horizontally into the big hopper, and within about a minute the entire tree has become wood chips that are blown into a 40 ft trailer!!! The trees are low quality trees, and often are misshapen, sickly and dead trees. The wood chips have low carbon content and low heating values, Btu/lb, compared to tree trunk wood.


Dry tree trunk wood consists of about 50% carbon and about 6% hydrogen.

Dry wood chips consist of about 45% carbon and 5.5% hydrogen.




In the US northeast wood chips are assumed to have a heat content of 7.6 million Btu/green ton at 45% moisture, i.e., as harvested, and a heating value of 7.6 million/{2000 x (1 - 0.45)} = 6,909 Btu/lb of dry wood chips.


The EPA-calculated CO2 emissions of dry trunk wood are (1000000/8600) x 0.50, C fraction x 44/12, mol. wt. ratio = 213.18 lb/million Btu.


The CO2 emissions of dry wood chips are (1000000/6909 x 0.45, C fraction x 44/12, mol. wt. ratio) = 238.82 lb/million Btu



NOTE: The 44/12-molecular weight ratio is calculated as follows:


The combustion equation is C + O2 --> CO2. 

Molecular weight of CO2 = 12 lb C + 32 lb O2 = 44 lb, or 1 ton C + 32/12 ton O2 = 44/12 ton CO2



NOTE: The higher heating value, HHV, is determined by bringing all the products of combustion back to the original pre-combustion temperature and condensing any water vapor produced by burning hydrogen (H2 + O2 --> H2O).


The laboratory tests are performed with pure oxygen to achieve near 100% completion of reactions. Such measurements often use a standard temperature of 15C or 59F. Needless to say HHV is a fantasy number, as far as the real world is concerned.


NOTE: The lower heating value, LHV, is determined during laboratory tests by subtracting the heat of vaporization of the water from the HHV.


Wood Chip Plants Have 2 Times and 4.9 Times the CO2 of Coal and Gas Plants


A 500 MW ultra-super-critical, base-loaded coal plant, at a CF of 0.9, would produce 3,944,700 MWh/y, and require 8,865,227 MWh/y (thermal) of coal, at 44% efficiency, which would emit 210 lb CO2/million Btu.


A 500 MW combined-cycle gas turbine, base-loaded gas plant, at a CF of 0.9, would produce the same electricity, and require 6,574,500 MWh/y (thermal) of gas, at 60% efficiency, which would emit 117 lb/million Btu.


TWENTY 25 MW, base-loaded wood chip plants, each requiring a FOREST circle of 60-mile in diameter (total area: 20 x 3.14 x 30^2 = 56,520 sq miles!!!), at a CF of 0.9, would produce the same electricity, and require 15,778,800 MWh/y (thermal) of wood chips at 25% efficiency, which would emit 238.82 lb CO2/million Btu.


In the real world, the plant would get its wood from an area with a 30-mile radius, or 3.14 x 30^2 = 2,826 sq. mi. In some cases a 50-mile radius. As a result, Vermont or New Hampshire could have only a few additional 25 MW wood chip plants.



The wood chip plant would have 2 times the CO2 of the coal plant and 4.9 times the CO2 of the CCGT plant. See table.



The EPA-calculated CO2 emissions of dry trunk wood are (1000000/8600) x 0.50, C fraction x 44/12, mol. wt. ratio = 213.18 lb/million Btu.


The CO2 emissions of dry wood chips are (1000000/6909 x 0.45, C fraction x 44/12, mol. wt. ratio) = 238.82 lb/million Btu.



NOTE: The 44/12-molecular weight ratio is calculated as follows:


The combustion equation is C + O2 --> CO2. 

Molecular weight of CO2 = 12 lb C + 32 lb O2 = 44 lb, or 1 ton C + 32/12 ton O2 = 44/12 ton CO2



Table 8/CO2 comparison

Wood chips



Plant capacity, MW




















MWh fuel/y




lb CO2/million Btu















Dartmouth Wood Chip Heating Plant: Dartmouth issued a Request for Proposal for the wood chip heating plant that specifies an electrostatic precipitator, ESP, for removing the toxic particulate matter, PM, from the plant exhaust gases.


That likely is a serious mistake, because ESPs are very poor at removing sub-micron particles, PM1.0 and smaller, which are most harmful to students, faculty and nearby residents. 


PM10 or smaller is inhalable and dangerous because such particles can penetrate deep into the lungs and are inhaled 24/7/365.



The removal of PM1.0 and smaller, is an extremely important consideration when attempting to control hazardous particles in the respirable range.


In general, the most difficult particles to remove are between 0.1 and 1.0 micron. Particles between 0.2 and 0.4 micron usually are hardest to remove and likely would be least removed. See URLs.





Beyond Particulates: Toxins in Wood Smoke





In many areas, wood burning is the largest single source of particle pollution in winter months.

But what about toxic compounds?


recent study by the Australian EPA sheds some light on this topic, and it’s an eye opener. For example, look at formaldehyde, which is a potent irritant and carcinogen. The study found that in the Sydney region, 38% of the formaldehyde in the air is generated by residential wood heaters.


Another example is polycyclic aromatic hydrocarbons (PAHs), which also cause cancer: 35% comes from wood burning.

Perhaps most frightening is the data for dioxins and furans, which are some of the most toxic compounds known to man–39% is generated by wood burning.


These numbers are even more troubling when you consider that they are annual figures and that wood burning in the Sydney area takes place for only about a third of the year. During the winter months, residential wood heaters likely account for more than 50% of these toxic compounds in the air.


Before you breathe a sigh of relief that you are not living Down Under, bear in mind that wood burning activity in the Sydney area is not any worse than in many areas in the United States and around the globe.


To date, attention has focused mainly on wood burning as a source of particle pollution. This study makes it clear that wood burning’s role as a source of toxic and carcinogenic compounds may pose an even greater threat to human health and to the environment.



Wood Burning vs. Natural Gas: No Contest



Families for Clean Air recently received a letter that asked for references backing up our assertion that the emissions from EPA-certified wood stoves are greater than those from devices that burn natural gas. This information is available from many sources, including the US EPA, but we think the chart below from the Puget Sound Clear Air Agency illustrates the point in a clear and simple manner (See URL and click on the image to enlarge).


As bad as this chart may make things look for wood burning devices, we’d like to note that it actually makes the relative performance of wood burning stoves seem more favorable than it actually is.


First, the emissions of wood burning stoves are tested under laboratory conditionsthat bear only a passing relationship to how they are likely to actually be used in the real world.


Second, studies have shown that the performance of EPA-certified wood stoves can deteriorate over time.

Thus, the wood stove data probably reflect ‘best case scenario’ stove performance in laboratory conditions.

Any way you slice it, it’s clear that gas burns much more cleanly than wood, leading to less particulate pollution.



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Hannah Pingree on the Maine expedited wind law

Hannah Pingree - Director of Maine's Office of Innovation and the Future

"Once the committee passed the wind energy bill on to the full House and Senate, lawmakers there didn’t even debate it. They passed it unanimously and with no discussion. House Majority Leader Hannah Pingree, a Democrat from North Haven, says legislators probably didn’t know how many turbines would be constructed in Maine."



Maine as Third World Country:

CMP Transmission Rate Skyrockets 19.6% Due to Wind Power


Click here to read how the Maine ratepayer has been sold down the river by the Angus King cabal.

Maine Center For Public Interest Reporting – Three Part Series: A CRITICAL LOOK AT MAINE’S WIND ACT


(excerpts) From Part 1 – On Maine’s Wind Law “Once the committee passed the wind energy bill on to the full House and Senate, lawmakers there didn’t even debate it. They passed it unanimously and with no discussion. House Majority Leader Hannah Pingree, a Democrat from North Haven, says legislators probably didn’t know how many turbines would be constructed in Maine if the law’s goals were met." . – Maine Center for Public Interest Reporting, August 2010 https://www.pinetreewatchdog.org/wind-power-bandwagon-hits-bumps-in-the-road-3/From Part 2 – On Wind and Oil Yet using wind energy doesn’t lower dependence on imported foreign oil. That’s because the majority of imported oil in Maine is used for heating and transportation. And switching our dependence from foreign oil to Maine-produced electricity isn’t likely to happen very soon, says Bartlett. “Right now, people can’t switch to electric cars and heating – if they did, we’d be in trouble.” So was one of the fundamental premises of the task force false, or at least misleading?" https://www.pinetreewatchdog.org/wind-swept-task-force-set-the-rules/From Part 3 – On Wind-Required New Transmission Lines Finally, the building of enormous, high-voltage transmission lines that the regional electricity system operator says are required to move substantial amounts of wind power to markets south of Maine was never even discussed by the task force – an omission that Mills said will come to haunt the state.“If you try to put 2,500 or 3,000 megawatts in northern or eastern Maine – oh, my god, try to build the transmission!” said Mills. “It’s not just the towers, it’s the lines – that’s when I begin to think that the goal is a little farfetched.” https://www.pinetreewatchdog.org/flaws-in-bill-like-skating-with-dull-skates/

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