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 Global Warming Research
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As a Global Warming/Greenhouse Gas mitigation strategy, co-
firing energy crop biomass at existing coal-fired power plants
achieves the greatest reduction of any renewable energy
resource option, where:
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Electricity produced from biomass
fuel is carbon cycle neutral -- just like wind or solar energy.
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However, unlike other renewable energy options, tree energy
crop biomass
also sequesters carbon (a sustainable long-term storing)
through the trees' root system. |
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Co-firing energy crop biomass fuel in base load power plants
directly displaces/reduces coal use, which achieves almost two
times the Green-house gas reduction benefit of placing wind or
solar power facilities on an intergrated electricity power
grid. |
Below ground Carbon Sequestration of Tree Energy Crops:
In December 2001, Common Purpose/University of Florida excavated
14 month old whole eucalyptus trees at our Energy Crop
Plantation. The trees averaged ~20
feet in height, and had ~ 3 inch trunk diameters at their base.
The proceedure used a Caterpillar back-hoe to
excavate whole trees including their root system.
Above & Below Ground Tree Weight
| Tree
Component:
|
Kilograms |
Pounds
|
Percent |
|---|
| Stem Mass | 16.85
| 37.07 |
|
| Leaf Mass | 6.65
| 14.63 |
|
| Branch Mass | 4.85
| 10.67 |
|
| Above Ground Mass | 28.35
| 62.37 |
61.55% |
| Main Root Mass | 16.55
| 36.41 |
|
| Feather Root Mass (1) | 1.16
| 2.55 |
|
| Total Root Mass | 17.71
| 38.96 |
38.45% |
| Total Whole Tree Mass | 46.06
| 100.33 |
100.00% |
Significance of Findings: While the overwhelming "main-
stream" scientific research concludes that that the combustion
of biomass fuels (e.g., in our case, the harvested above ground
mass of energy crop trees) is carbon cycle neutral, our research
clearly shows that this does not tell the complete story. In
using harvested energy crop trees as fuel at electricity
generation power plants, an
additional benefit occurs at the agriculture source of the
trees -- through long-term carbon sequestration below ground.
The overall "net impact on carbon emissions" of using tree
energy crops can be illustrated in the following
formula:
| Energy Crop
Carbon Component:
|
CO2 Emissions Impact |
|---|
| Carbon Released in Fuel
Combustion | Increase |
| Minus, Carbon Stored in Tree Fuel | Decrease
|
| Equals, Fuel Carbon Cycle Neutrality | Zero
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| Minus, Carbon Stored Below Ground | Overall Net Reduction
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To estimate the amount of below ground sequestration that will
occur through energy crop use, we can take the above University
of Florida measurements -- dividing the percent of below ground
weight of whole trees (i.e., 38.45%) by the percent of above
ground weight (i.e., 61.55%). By doing this simple math, we can
estimate that for every 10 green tons of energy crop fuel
harvested (i.e., the above ground mass of the trees), that
approximately 6.3 green tons of biomass will be sequestered
below ground.
Percent of Below Ground
Carbon Storing to Energy Crop Fuel Use
Conversion of Tree Weights to Carbon and CO2
Sequestration: Based on a fuels
analysis performed by the Southern Research Institute on our
energy crop trees, the
percent carbon content in green (as received) tree fuel is ~25%.
A final step is to use the molecular weights of Carbon and O2
to calculate the Carbon to CO2 conversion factor of 3.6667
2.
Example Calculation of Carbon Sequestration & CO2
Reductions Through Tree Energy Crop Fuel Use
| Component
|
Tons |
Notes:
|
|---|
| Harvested Energy Crops | 10.00
| Green Tons |
| Trees' Root System Weight | 6.30
| Green Tons |
| Ground Carbon Sequestration | 1.58
| 25% |
| CO2 Reductions | 5.78
| 3.67x Conversion |
Comparing Biomass Co-firing To Other Renewable Energy
Options:
As discussed in out Outreach
Section and also the Union of Concerned Scientists' White
Paper:
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Biomass co-firing will directly reduce/displace coal use in
base load, high capacity factor (~70 to 80% range) power plants.
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Renewable Energy options such as wind and solar have much
lower capacity factors (~30 to 35% range) as a result of natural
resource limitations (i.e., sunlight). |
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Implementing technologies such as solar energy will not
generally displace generation from lagre MW coal-fired units,
but rather displace generation from smaller natural gas fired
peaking and intermediate load units. |
As the below information supplied by the Electric Power Resarch
Institute (EPRI) reflects, displacing coal use through biomass
co-firing has approximately twice the CO2 benefit of wind or
solar power's displacement of natural gas generation.
| Energy
Source:
|
Fossil Carbon Intensity (lb-C/MBtu)
|
|---|
| Coal | 56.9 |
| Oil | 47.2
|
| Natural Gas | 31.9
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| Wood, Solar, Wind | Zero
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1
In
excavating trees, small feather roots were left in the ground.
According to University of Florida Scientists, approximately 7
to 10% of a tree's total root system is comprised of small
feather roots.
2
The
molecular weight of Carbon to CO2 (C + O2 = CO2) equals 12 lbs.
of carbon + 32 lbs. of O2 = 44 lbs. of CO2.
Dividing 44 lbs. of CO2 by 12 lbs. of Carbon, results in a
Carbon to CO2 conversion factor of
3.6667.
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