COMPARISON OF DARTMOUTH COLLEGE EXISTING COGEN PLANT AND NEW HEATING PLANT

The existing Dartmouth campus central cogeneration plant required about 3.5 million gallon of No. 6 fuel oil in 2018. The plant had a minimum heating load of 4 MW (13.65 million Btu/h) in summer and a maximum of 32 MW (109.2 million Btu/h) in winter. See page 11 of URL

 

The Dartmouth campus required about 50000 MWh of electricity in 2018, of which about 80% was purchased and the existing co-gen plant generated about 20%.

 

https://www.sustainability.dartmouth.edu/energy

https://dartmouth.app.box.com/s/6bs4ivyc67q9hg63g89j33jnfo0vl223/fi...

 

The existing plant would be replaced by:

1) A new 16 MW (54.6 million Btu/h) wood chip plant. It is likely the plant would use most of the available wood supply within a 50-mile radius, i.e., much wood exists within that circle, but only a small fraction is actually available/accessible for logging.

2) A new 32 MW biodiesel-fired plant, which would provide:

 

- Any heating from 0 MW to 16 MW, in case of the wood chip plant having a scheduled or unscheduled outage, or not being able to operate at low summer loads

- Any heating above 16 MW, up to a maximum of 32 MW, during the colder days of the year, about 1500 hours.

Heat Supply From New Wood Chip Plant

 

A tractor-trailer truck carries about 20 ton of woodchips.

Truckloads required would be about 16 per day for about 7.5 months of the year

About 2630 truckloads/y, or 52,600 ton of wood chips/y

Wood chip storage area would be about 20,000 cubic yards.

Truckloads of Wood Chips Required per Day: Truck loads required = 280,000 million Btu/y/ (20 ton x 7.6 million Btu/ton x 0.7, efficiency) = 2630 truckloads/y

 

Woodchips are not supplied during much of the winter (because of snow) and part of spring (forest floor too wet). Logging usually starts about late May and ends in December. Thus about 16 truckloads per day are required during 7.5 months, which would provide about 20,000 cubic yards in storage for winter/spring usage, when chips are not delivered. See table.

 

Ton/truckload

20

Million Btu/freshly cut ton

7.6

Plant annual average efficiency

0.7

Heat from plant, million Btu/truckload

106.4

Truckloads/y

2630

Days/year

365

Deliveries for 7.5 months of the year

0.625

Delivery days

228

Weekends + holidays

60

Delivery days

168

Truckloads/d

16

 

Heating Provided by Wood Chip Plant: A freshly cut ton of wood chips contains about 7.6 million Btu.

It contains about 50% water, i.e. 1000 lb.

Thus the wood heat content is about 7600 Btu/lb of dry wood. In reality, the wood chips would contain some moisture, which requires heat to evaporate it, and then heat the vapor to the flue gas exit temperature.

Also the combustion processes would be incomplete, and there are various other losses, i.e., less than 7000 Btu/lb would actually be available for making hot water for distribution to the buildings.

The woodchip heating plant has an assumed annual average efficiency of about 70%.

 

Heat from existing plant to campus = 3.5 million gal x 150,000 Btu/gal x 0.7, plant efficiency = 367,500 million Btu/y

Heat from wood chip plant to campus = 4 MW x 7000 h + 12 MW x 1500 h + 12/2 MW x (7000 - 1500) h = 82,000 MWh (280,000 million Btu/y).

The wood chip heating plant would provide about 280000/367500 = 76% of the heat to the campus.

NOTE: The biodiesel plant would provide about 24%, or 87500 million Btu/y, which would require 87500 million Btu/(127960 Btu/gal (HHV)/0.7, plant efficiency) = 977,000 gallon of diesel fuel/y (B100). See Appendix

 

Gallon of No. 6 fuel oil/y

3500000

Btu/gal, HHV

150000

Efficiency

0.7

To campus, million Btu/y

367500

MW

h

MWh

4

7000

28000

14

1500

21000

6

5500

33000

MWh

82000

Btu/MWh

3412000

To campus, million Btu/y

279784

Supplied by wood chip plant, %

76

Comparison of CO2 from New Wood Chip Heating Plant and Existing Cogeneration Plant

 

Wood Chip Fired Heating Plant: Combustion CO2 = 93.80 kg/million Btu, or 2.2046 x 93.80 = 207 lb CO2/million Btu of heat into the wood chip plant

Heat supplied by wood chip plant to campus is 280,000 million Btu/y

CO2 emissions = (207/million Btu x 280,000 million Btu/0.7, plant efficiency)/2204.62 lb/metric ton = 37,520 metric ton/y for 76% of heating.

 

On an A to Z basis, there would be about 15% of additional CO2 that has nothing to do with combustion, in case of wood chips, about 20%, in case of wood pellets. This includes CO2, such as fuel used for logging, chipping/pelletizing and transport, and energy to run the plant, and energy for decommissioning and reuse/landfill of the plant.

 

Biodiesel Fired Heating Plant: Combustion CO2 = 73.84 kg CO2/million Btu, or 2.2046 x 73.84 = 163 lb CO2/million Btu

Heat supplied by biodiesel plant to campus is 24%, or 367500 - 280000 = 87,500 million Btu/y.

CO2 emissions = (163 lb CO2/million Btu x 87500 million Btu/0.7, efficiency)/2204.62 lb/metric ton = 9,230 metric ton/y for 24% of heating.

 

Total CO2 = 37,520 + 9,230 = 46,750 metric ton/y    

https://www.epa.gov/sites/production/files/2015-07/documents/emissi...

 

On an A to Z basis, there would be about 45.24% of additional CO2 that has nothing to do with combustion. This includes CO2, such as fuel used for cropping, processing and transport, and energy to run the plant, and energy for decommissioning and reuse/landfill of the plant.

 

Existing Plant: Combustion CO2 = 75.1 kg/million Btu, or 2.2046 x 75.1 = 166 lb CO2/million Btu

Combustion CO2 from 3.5 million gallon of No. 6 fuel oil = (3.5 million gal x 150,000 Btu/gal x 166 lb CO2/million Btu)/2204.62 = 39,427 metric ton for 100% of heating.

https://www.epa.gov/sites/production/files/2015-07/documents/emissi...

 

On an A to Z basis, there would be about 28.19% of additional CO2 that has nothing to do with combustion. This includes CO2, such as fuel used for extraction, processing and transport, and energy to run the plant, and energy for decommissioning and reuse/landfill of the plant. See table

 

Plant

Woodchip

Biodiesel

No. 6 Fuel oil

CO2, kg/million Btu

93.80

73.84

75.10

Lb/kg

2.20462

2.20462

2.20462

Lb CO2/million Btu

207

163

166

To campus, million Btu/y

280000

87500

367500

No. 6 fuel oil, million gal

3.5

Efficiency

0.7

0.7

Btu/gal, HHV

150000

To plant, million Btu/y

400000

125000

525000

CO2, lb/y

82717342

20348643

86922655

Lb/metric ton

2204.62

2204.62

2204.62

37520

9230

CO2, metric ton/y; no upstream

(37520 + 9230 = 46750)

46750

39428

Upstream fraction

0.1500

0.4524

0.2819

Upstream CO2

5628

4176

11115

43148

13406

CO2, metric ton/y; with upstream

(43148 +13406 = 56554)

56554

50542

Sequestering CO2 From Wood Chip Burning Plants Takes Decades

 

Here is some information for those who have been led to believe, or persuaded themselves to believe, wood burning is environmentally friendly.

 

- Wood burning power plants emit about 4 times the CO2/kWh of high-efficiency gas power plants.

- The combustion CO2 of the first year of heating plant or power plant operation would be sequestered by re-growing trees according to an S-curve over a long period (See Note); slowly increasing during the first 1/3, rapidly increasing during the second 1/3, and slowly increasing during the last 1/3 of the period.

- That would be not much help to prevent the world’s climate from falling off the cliff during the next 20 to 30 years.

 

NOTE:

- 40 years is a US average. See Note.

- 80 to 100 years in northern climates with short growing seasons, such as northern Vermont and Maine. 

- 40 to 50 years in moderate climates with longer growing seasons, such as New Jersey and North Carolina,

- 25 years between harvests on planted, fertilized, and culled forests of fast-growing pines in Georgia. 

https://www.pfpi.net/wp-content/uploads/2011/04/PFPI-biomass-carbon...

 

NOTE: 

- The EPA assumes sequestering of CO2 by undisturbed, healthy forests at about 1.0 metric ton per acre per year, as a US average.

Disturbed, fragmented, less than healthy forests, as in most of New England and Maine, sequester much less than 1.0 metric ton of CO2 per acre per year, due to:

 

1) Acid rain and pollution from Midwest power plants, etc.,

2) Various encroachments, and

3) Cold climate and short growing season.

 

Yet the Vermont and Maine Environmental Departments claim 1.0 metric ton per acre per year!

 

Piling up the CO2 Year After Year: Re-growing trees would sequester the combustion CO2 of Year 1 of plant operation over about 80 to 100 years.

 

The CO2 of Years 2, 3, 4, ........and Year 40 would be added to the CO2 of Year 1, and be sequestered in a similar manner.

 

In Year 40, there would be 40 forest areas in various stages of regrowth, as a result of cutting trees for burning.

 

Year 40 is assumed to be the last year of plant operation. It is likely that plant would be replaced to repeat the cycle.

 

During Year 41 through 80, there would be 41 to 80 forest areas in various stages of regrowth, as a result of cutting trees for burning.

 

On an A to Z basis, there would be about 15% of additional CO2 that has nothing to do with combustion, in case of wood chips, about 20%, in case of wood pellets. This includes all non-wood-burning CO2, such as fuel used for logging, chipping/pelletizing and transport, and energy to run the plant, and energy for decommissioning and reuse/landfill of the plant.

Burning Wood Produces Extremely Small Particles Harmful to Public Health

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.

http://www.anapsid.org/cnd/mcs/fireban2.html

 

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.

https://www3.epa.gov/ttn/catc/dir1/fdespwpi.pdf

 

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

 

If 10 percent of building heating in Hanover would be by wood 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.

 

Each gas or fuel oil stove emits about 50 to 100 times less PM and PAH than an EPA-certified wood stove.

Most buildings have older wood stoves that emit much more PM and PAH than EPA-certified wood stoves. See table and URLs.

 

https://slate.com/technology/2008/11/it-s-better-to-heat-your-home-...

https://www.bnl.gov/isd/documents/71376.pdf

 

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

 

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

 

NOTE:

micron is a millionth of a meter.

mg/MJ is milligram/million joules.

 

Household Appliance

Water boiler

Warm air furnace

Wood worse than

Particle size

 PM2.5 and smaller

 PM2.5 and smaller

Units

mg/MJ

mg/MJ

Times

Natural gas

0.016

0.011

1851.9

Ultra low sulfur diesel/fuel oil

0.025

0.060

588.2

Low sulfur diesel/fuel oil

0.490

0.510

50.0

No.2 fuel oil

1.320

2.100

14.6

Wood chip or pellet

25.000

25.000

1.0

 

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, and 92% is PM 1.0 or less. Only about 4% is larger than PM10. See URL

https://www3.epa.gov/ttnchie1/efdocs/rwc_pm25.pdf

Particulate Loading in Flue Gases: 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., at an efficiency of (100 - 1)/100 = 99.00%, or (150 - 1)/150 = 99.33%. However, almost all of the sub-micron particles are not removed. They are invisible, so the stack looks reassuringly “clean”, but, in fact, it 1s not, because much of the small, sub-micron particles were not removed.

 

NOTE: During testing the boiler would operate at 10 to 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 o C (32F) and absolute pressure of 10^5 pascal (1 bar).

https://en.wikipedia.org/wiki/Standard_conditions_for_temperature_a...

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

http://www.verenum.ch/Publikationen/Particle_Size_PH_TN1998.pdf

 

Particle size

 Load, milligram/std m3

Less than 0.22 micron

 45

0.22

 21

0.35

 6

0.61

4

Greater than 7.22 micron

2

Total load

78

 

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

https://www.tandfonline.com/doi/pdf/10.1080/00022470.1974.10470025

 

-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

https://pdfs.semanticscholar.org/eb30/9818374e9236b689d6e66303e88a5...

 

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 submicron particles, which are most harmful to health.

 

Collection Efficiency of ESP versus 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

https://www.biomasscenter.org/images/stories/FSE_PM_Emissions.pdf

 

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

https://www.tandfonline.com/doi/pdf/10.1080/00022470.1974.10470025

 

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.

 

Removal efficiency

PM 10 and smaller

PM 2.5 and smaller

PM 1.0 and smaller

%

%

%

Single Cyclone

50

5

0

Multi-Cyclone

75

10

0

Core Separator

29 to 56

72 to 94

0

Multi-cyclone with fabric filter

99.84

99.90

99.95

Electrostatic Precipitator (ESP)

99

96

50 - 70

APPENDIX 1

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.

https://www.epa.gov/sites/production/files/2016-07/documents/fact-s...

- 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 submicron 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

https://www.epa.gov/pm-pollution/particulate-matter-pm-basics

 

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.

 

APPENDIX 2

Sequestering Combustion CO2 From Wood Chip Burning Plants Takes Decades

 

Here is some information for those who have been led to believe, or persuaded themselves to believe, wood burning is environmentally friendly.

 

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

 

Wood burning power plants (McNeil, Ryegate in Vermont) emit about 4 times the combustion CO2/kWh of high-efficiency gas turbine power plants.

 

Re-growing trees would sequester the combustion CO2 of year 1 of heating plant or power plant operation, as follows:

 

- Zero sequestration for 20 to 25 years to offset the CO2 emissions of clearcutting, etc.

- Rapidly increasing sequestration until about year 40 to 50

- Slowly increasing sequestration after year 40 to 50.

- That would be not much help to prevent the world’s climate from falling off the cliff during the next 20 to 30 years.

 

NOTE: The combustion CO2 of wood burning would be reabsorbed by new tree growth, if:

 

1) Logged forests would have the same acreage (they likely would not)

2) Forests would not further fragmented by roads or developed (they likely would be)

3) Forest CO2 sequestering capability, Mt/acre/y, remains the same (it could be less). See note

 

NOTE: Regarding the time period for sequestering the combustion CO2:

 

- 40 years is a US average, as promulgated by EPA. See Note.

- 80 to 100 years in northern climates with short growing seasons, such as northern Vermont and Maine. 

- 40 to 50 years in moderate climates with longer growing seasons, such as New Jersey and North Carolina

- 25 years between harvests of planted, fertilized, and culled forests of fast-growing pines in Georgia. 

https://www.pfpi.net/wp-content/uploads/2011/04/PFPI-biomass-carbon...

 

NOTE: On an A to Z basis, there would be about 10% of additional CO2 that has nothing to do with combustion, in case of wood chips, or about 15%, in case of wood pellets. This includes non-wood-burning CO2, such as from:

 

- Fuel used for managing wood lots, logging, chipping/pelletizing and transport,

- Energy to run the plant,

- Energy for decommissioning and reuse/landfill of the plant,

- Embodied energy in the A to Z infrastructures

 

NOTE: Conversion Factor for Carbon Sequestered in One Year by 1 Acre of Average U.S. Forest

0.23 metric ton C/acre/year* x (44 units CO2/12 units C) = 0.85 metric ton CO2 sequestered annually by one acre of average U.S. forest.

Please note that this is an estimate for “average” U.S. forests in 2016; i.e., for U.S. forests as a whole in 2016.

Significant geographical variations underlie the national estimates, and the values calculated here might not be representative of individual regions, states, or changes in the species composition of additional acres of forest.

https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculato...

 

NOTE: Disturbed, fragmented, less than healthy forests, as in most of New England, sequester about 1.0 metric ton of CO2 per acre per year, due to:

 

1) Acid rain and pollution from Midwest power plants, etc.,

2) Various encroachments, and

3) Colder climate and short growing season.

 

The Vermont and Maine Environmental Departments claim 0.976 and 1.10 metric ton/acre/year, respectively. See URLs.

 

https://fpr.vermont.gov/sites/fpr/files/Forest_and_Forestry/The_For...

https://www.fs.fed.us/nrs/pubs/ru/ru_fs119.pdf

 

https://fsht.files.wordpress.com/2019/04/maine-forest-carbon-estima...

http://www.forestecologynetwork.org/climate_change/sequestration_fa...

 

Piling up the CO2 Year After Year

 

Re-growing trees would sequester the combustion CO2 of Year 1 of plant operation over about 80 to 100 years, in New England.

 

The CO2 of Years 2, 3, 4 to Year 40 would be added to the CO2 of Year 1, and be sequestered in a similar manner, except shifted forward by a year.

 

In Year 40, there would be 40 layers of CO2 and 40 forest areas in various stages of regrowth, as a result of cutting trees for burning.

 

Year 40 is assumed to be the last year of plant operation. It is likely that plant would be replaced to repeat the cycle.

 

During Year 41 through 80, there would be 41 to 80 layers of CO2 and 41 to 80 forest areas in various stages of regrowth, as a result of cutting trees for burning.

 

Closing Down Wood Burning Power Plants

 

It would be far better for New Hampshire, Maine and Vermont to shut down wood burning power plants, as time is of the essence regarding “climate change”, according to some people. See table 5 and URL.

 

- In Vermont, utilities are forced to buy wood electricity at about 10 c/kWh, as part of the Vermont Standard Offer program, and as required by the Vermont Renewable Portfolio Standard program.

 

- In New Hampshire a law was passed in 2018 to subsidize money-loosing NH wood burning power plants. The plants need to be base-loaded to maximize production and need to sell at about 9 - 10 c/kWh to be viable. The subsidy would impose an extra cost on ratepayers of about $25 million/y. Implementing the law is held up in various court cases for environmental reasons.

 

- The wholesale prices of the NE grid averaged about 5 c/kWh since 2008, courtesy of abundant, domestic, near-zero-subsidized, clean-burning, low-CO2 gas at about 5 c/kWh, and near-zero-subsidized, near-zero-CO2 nuclear at 4.5 - 5 c/kWh.

http://www.windtaskforce.org/profiles/blogs/furnaces-for-heating-an...

 

Table 5/Fuel

 lb CO2/million Btu

 Plant efficiency, %

 lb CO2/MWh

CO2 Ratio

Wood chip; McNeal/Ryegate*

213

25

2907

4.0

Wood chip; Denmark

213

30

2423

3.3

Hard coal

206

41

1712

2.4

No. 2 fuel oil

161

35

1572

2.2

Natural gas, CCGT*

117

55

726

1.0

 

*

Plus upstream CO2 (logging, chipping, transport, etc.) of about 5 to 10%, if burning wood chips

Plus upstream CO2 (logging, chipping/pelletizing, transport, etc.) of about 10 to 15%, if burning wood pellets

CCGT = Combined-cycle, gas turbine plant

 

APPENDIX 3

Biodiesel CO2 Emissions: In case of biodiesel, B100:

 

- The combustion CO2eq emissions are 20.829 lb/gal (or 1000000/128490 x 20.829 = 162 lb/million Btu), and

- The upstream CO2eq emissions are 10.524 lb/gal (or 1000000/128490 x 10.524 = 82 lb/1000000 Btu).

- Some people do not count the combustion emissions, because biodiesel is “renewable”, but upstream emissions should be counted. See URL.

http://www.windtaskforce.org/profiles/blogs/replacing-gasoline-and-...

 

US Biodiesel Production is Very Small: US B100 consumption was 1985 million gallon, of which US production was 1596 million gallons in 2017.

 

US total “diesel” consumption (a blend of B100 and petro-diesel) was 45,833 million gallon, per EIA.

Replacing all petro-diesel with B100 would require 49,479 million gallon of B100, from 651 million acres planted with soybeans.

US total cropland, all uses, is about 334 million acres.

 

Source

Million gallon

Soy oil, from 10.857 million acres

826

All other sources

 770

Imports

 301

From inventory

 81

APPENDIX 4

An Alternative: Gas-Fired or LNG-Fired Plant

 

Trucking LNG from Massachusetts to Hanover would be very expensive.

Locally liquefying and then trucking would also be very expensive.

 

- The upstream CO2 of NG is about 17% of NG combustion CO2.

https://ceic.tepper.cmu.edu/-/media/files/tepper/centers/ceic/publi...

 

- The upstream CO2 of LNG is about 43% of NG combustion CO2.

http://www.igu.org/sites/default/files/node-page-field_file/LNGLife...

 

The EU may use different values.

 

- The upstream CO2 of E10 (90% gasoline/10% ethanol) is about 23.76% of combustion CO2; pure gasoline about 25%, per US EPA

http://www.windtaskforce.org/profiles/blogs/replacing-gasoline-cons...

 

APPENDIX 5

Low Temperature or High Temperature Hot Water Distribution to Buildings

 

Low temp hot water heating of buildings is feasible with adequately specified heating units in each room. It would be prudent to implement major upgrades of the buildings to reduce their Btu/sq ft/y for heating, cooling, and electricity.

Having high temperate hot water, HTHW, a la University of Vermont, for distribution provides flexibility, because it allows for: 

 

1) Lowering the HTHW temperature to LTHW within each building for building heating, and allows for having

2) HTHW for distributed, 2-stage absorption chillers for building cooling, and allows for having

3) The plant to be located further from buildings.

APPENDIX 6

Many people parrot the mantras “burning wood chips is renewable”, and "we are taking only about 50% of the new tree growth". They likely do not have a clue what that really means. So here is an explanation.

 

Each year, there would be hundreds of scars on the forest landscape where logging took place with big machinery to feed wood chips to the Dartmouth heating plant.

 

Some of those scars would be due to clear-cuts, the worst kind of logging, because it kills the belowground forest biomass, i.e., nature has no use for it, so it gets rid of it. That belowground biomass would have to rebuild itself as part of tree regrowth over decades.

 

Such killing of the belowground forest biomass, and consequential erosion of topsoil, took place on a NE-wide scale in the 1800s. NE soil and forests still have not recovered from that devastation. The big trees are gone and will not come back, likely because the damaged soil would not be able support them.

 

Taking wood from the forest for decades ultimately depletes the soil, which was already damaged due to clear cutting in the 1800s and due to acid rain since the 1950s.

 

We see mostly spindly trees that often become sickly and do not live long.

We see a gradual takeover of the forest by acid loving trees, such as white pines.

It would be better to chip the wood and spread it on the forest floor for more rapid nutrition, and to provide about 1 to 2 ton of dolomite lime per acre to reduce the acidy of the soil.

In sum, it appears the practice of wood burning has various consequential damages, which in addition to other human encroachments, have become a near permanent part of modern lifestyles, all to the detriment of forest health.

APPENDIX 7

Higher and Lower Heating Values of Fuels

 

The higher heating value, HHV, is the heat content in a fuel, such as Btu/lb

The lower heating value, LHV, is the heat content in a fuel available to an internal combustion engine.

 

The lower heating value should be used in any replacement of diesel fuel or gasoline with biofuels, if used in internal combustion engines

 

The higher heating value should be used in a heating or power plant, because significant heat is recovered from the flue gases.

 

- E10, usually called gasoline, also called gasohol, is a blend of 90% gasoline and 10% E100.

- B100 is 100% biodiesel

- B20 is a blend of 80% petro-diesel and 20% B100

See table 3 and URL.

 

https://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf

https://h2tools.org/hyarc/calculator-tools/lower-and-higher-heating...

 

Table

Ethanol

Gasoline

E10 (90/10)

Petro-diesel, LS

B100

B20 (80/20)

NG

LNG

 

 

 

 

 

 

 

Btu/lb

Btu/lb

HHV, Btu/gal

84530

124340

120359

138490

127960

136384

22453

23735

LHV, Btu/gal

76330

116090

112114

128488

119550

127500

20267

20908

APPENDIX 8

CO2 of Logging and Clearcutting and Burning

 

A nearby farm in Hartford, Vermont has 200 acres of open fields, plus 700 acres of woodland. During a recent logging operation, the trunks of the high quality healthy trees were set aside and cut to 8.5, 10.5 and 12.5 ft lengths, for transport to lumber mills, and the less valuable material, such as tops of trees and branches, misshapen trees, standing dead trees, sickly trees, etc., were gathered and piled up for chipping.

 

The less valuable material is 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 logging harvesting emits CO2 for harvesting, cutting, chipping and transport. CO2 emissions also occurred, due to setting up and maintaining in good working order the logging infrastructure. None of that CO2 is offset by any existing or new biomass growth.

 

The tree roots, a.k.a., belowground biomass, is no longer needed and rots away. The very fine, hair-like roots die off first. The stumps are the last the go. The aboveground part of a stump usually disappears within about 25 years, the larger branches of the belowground part in about 100 years. The rotting away process emits large quantities of CO2.

 

In fact, it would take new biomass growth about 20 to 25 years to become large enough to absorb a quantity of CO2 equal to the rotting CO2. At that point, the new biomass growth continues to sequester on-going rotting CO2 for about 80 more years, and sequester the combustion CO2 starting about year 20 and ending about year 100. The below table shows about 60% of carbon is belowground and about 25% of carbon is aboveground. See URL.

https://www.nrdc.org/sites/default/files/accounting-emissions-clear...

 

Forest carbon

C store

C store

C/ha

C/ha

C Incr.

Forest

Forest

Forest

Forest

1990

2015

1990

2015

1990

2015

1990

2015

MMt

MMt

MMt

MMt

%

ha

ha

acre

acre

Aboveground

110.1

131.8

62.22

72.53

19.7

1770

1817

4371

4488

Belowground

22.1

26.4

12.50

14.51

19.5

1768

1819

4367

4494

Dead wood

11.7

14.8

6.63

8.17

26.5

1765

1812

4359

4474

Litter

29.2

29.5

16.51

16.25

1.0

1769

1815

4369

4484

Soil organic carbon

275.7

277.9

155.85

152.95

0.8

1769

1817

4369

4488

Total

448.8

480.4

253.71

264.41

7.0

1769

1817

4369

4488

Figure 1, est.

Table 1

Year

1990

2016

Forest, acre

4550

4509

Forest, ha

1841

1825

59.8

72.2

20.8

1 ha

2.471

acre

2.47

 

Forest carbon

C/a

C/a

1990

2015

%

%

Aboveground

24.5

27.4

Belowground

4.9

5.5

Dead wood

2.6

3.1

Litter

6.5

6.1

Soil organic carbon

61.4

57.8

Total

100.0

100.0

 

Soon after clearcutting, new tree shoots start to appear. The CO2 absorption/acre of new growth starts from zero in year 1 and increases exponentially for about 40 to 50 years, as new underground and aboveground biomass grows. The biomass growth rate is at decreasing rates after about year 40 to 50.

 

The CO2 absorption, a.k.a., sequestering, for all of Vermont forestland, 4,488,000 acres in 2015, was calculated at about 4.38 million metric ton/y, or about 0.976 metric ton/acre, by using computer programs developed by the US Forest Service.

 

Vermont’s net CO2 emissions were 10.0 - 4.38 = 5.62 million metric ton in 2015, or 8.992 metric ton per person, near the lowest in the US. Vermont has many problems, but CO2 emission is certainly not one of them. It should be near the bottom of the list of priorities. However, fear mongering to induce GW hysteria, hyped by folks seeking overly generous federal and state subsidies, caused self-serving politicians to place CO2 reduction near the top. See URLs.

 

https://fpr.vermont.gov/sites/fpr/files/Forest_and_Forestry/The_For...

https://www.fs.fed.us/nrs/pubs/ru/ru_fs119.pdf

 

Generating electricity with various fuels releases CO2. A standard wood chip power plant in New England emits about four times the CO2 of an equivalent natural gas plant. The wood chip power plant wastes at least 3 out of 4 trees. The lb CO2/million Btu values are the EPA values for combustion only. See table.

Fuel

 lb/million Btu

 Plant efficiency, %

 lb CO2/MWh

CO2 Ratio

Wood chip; McNeal/Ryegate

213

25

2907

4.0

Wood chip; Denmark

213

30

2423

3.3

Bituminous coal

206

41

1712

2.4

No. 2 fuel oil

161

35

1572

2.2

Natural gas, gas turbine

117

55

726

1.0

 

Remember, the CO2 of year 1 plant operation has to wait for 20 to 25 years, before the combustion CO2 starts being absorbed by new biomass growth (the existing biomass growth is already busy doing other absorption). That new biomass growth will absorb that CO2 only as fast as it needs to, i.e., at a fast rate up to about year 40 to 50, and slower rates thereafter.

The CO2 of year 2, and each subsequent year, has to wait for 20 to 25 years, etc. In northern climates, with

4-month growing periods, the whole process takes about 80 to 100 years to completion. At the end of the period one can speak about wood burning as having been “renewable”. The non-combustion CO2 should be treated as any other CO2.

NOTE: The Vermont Biomass Energy Research Center, BERC, invented a method of calculated CO2 from wood burning plants that has no parallel anywhere else, and is likely not used anywhere else, but Vermont. It completely ignores the above 20 - 25 year delay and a slow absorption of combustion CO2 over about 80 to 100 years thereafter, and it ignores the year-after-year CO2 build-up in the atmosphere while it is slowly being absorbed by additional forest areas. The BERC-invented 82% CO2 reduction must give great comfort to wood burning proponents, because BERC purposely forgot to add "over about 100 years". Here is a quote:

 

“While the recommended carbon emission factor of 29.58 pounds per million Btu is far from the historic “carbon neutral” stance, when compared to the carbon emissions (165.5 pounds per million Btu) from burning heating oil, it represents an 82% reduction in CO2 emissions’.

https://www.biomasscenter.org/pdfs/veic-carbon-emission-and-modern-...

 

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Comment by Frank J. Heller, MPA on June 3, 2019 at 12:37pm

Is there a breakdown of heat produced, when, where and how much over time and the electricity produced? Detroit(?) has a W2E plant which distributes heat as well after steam is used to generate electricity. Apparently, waste to energy plants are closing for a variety of reasons. But what will replace them?

Comment by Willem Post on June 2, 2019 at 2:34pm

Frank 

Biodiesel, B100, has a lot of upstream/A to Z CO2; about 45.24% of combustion CO2.

Even if combustion CO2 were not counted "because it is renewable", there still would be a lot of CO2 associated with the biodiesel part of the central plant, which provides 24% of the heating.

Burning wood chips has about 15% of upstream/A to Z CO2.

Even if combustion CO2 were not counted "because it is renewable", there still would be a lot of CO2 associated with the wood chip part of the central plant, which provides 76% of the heating.

There will be hundreds of scars on the forest landscape where logging took place to feed wood chips to the new plant.

Some of those scars will be clearcuts, the worst kind of logging, as it kills the forest biomass below the ground, which would have to rebuild itself. That is what happened in the 1800s.

NE forests still have not recovered from that devastation. We mostly see spindly trees that become sickly and do not live long, and a takeover of the forest by acid loving trees, such as white pines.

Taking wood from the forest ultimately will deplete the soil, which was already damaged due to clear cutting in the 1800s and due to acid rain since the 1950s.

There is absolutely nothing about wood burning that is renewable, as various damages are near permanent.

Comment by Frank J. Heller, MPA on June 2, 2019 at 10:14am

Studied 'green waste' hauled to town dumps for disposal and found quite a bit of it...problem is aggregating it and chipping it--just another approach.

Surprised they didn't consider natural gas as an energy source combines with methane from anaerobic digesters. 

Dartmouth was one of the leaders in solar powered car and plane development,so I'm surprised they settled on wood chips and deforestation.

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."

https://pinetreewatch.org/wind-power-bandwagon-hits-bumps-in-the-road-3/

 

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

******** IF LINKS BELOW DON'T WORK, GOOGLE THEM*********

(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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