Innovative Energy Technology 1
Biomass Energy Decision Making Framework
Biomass Energy Decision Making Framework
Cornell University Sustainable Design
Sustainability Research Facility
Innovative Energy Technology
Contributors: Jason Wright
Innovative Energy Technology 2
Biomass Energy Decision Making Framework
TABLE OF CONTENTS
Introduction to the Biomass Energy Decision Making Framework .............................................................. 3
Objective ................................................................................................................................................... 3
Introduction to Biomass Energy................................................................................................................ 3
Ithaca ........................................................................................................................................................ 3
Biomass Energy in the Facility................................................................................................................... 4
Biomass Energy Metrics Definitions and Discussion..................................................................................... 5
Specific Technologies .................................................................................................................................... 8
Wood boiler .............................................................................................................................................. 8
Anaerobic digestion ................................................................................................................................ 13
Pyrolysis .................................................................................................................................................. 15
Works Cited ................................................................................................................................................. 17
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Biomass Energy Decision Making Framework
Introduction to the Biomass Energy Decision Making Framework
Objective
The objective of this binder is to define biomass energy, describe the history of the evolution of
the technology and provide a framework for analyzing and grading the proposed technologies.
Ultimately this binder should be used to select technologies for use in the facility.
Introduction to Biomass Energy
Biomass energy, or energy derived from the combustion of organic matter, is one of the oldest
sources of renewable energy. For quite some time biomass supplied the majority of renewable energy in
the United States, more than solar, hydroelectric, geothermal and wind combined.[EIA 2010] Biomass is
often considered essential to a transition to a sustainable energy economy. According to the Union of
Concerned Scientists,
“If developed properly, biomass can and should supply increasing amounts of biopower. In fact,
in numerous analyses of how America can transition to a clean energy future, sustainable
biomass is a critical renewable resource.
Sustainable, low-carbon biomass can provide a significant fraction of the new renewable energy
we need to reduce our emissions of heat-trapping gases like carbon dioxide to levels that
scientists say will avoid the worst impacts of global warming. Without sustainable, low-carbon
biopower, it will likely be more expensive and take longer to transform to a clean energy
economy.” [UCS 2010]
Biomass energy can take many forms. The National Renewable Energy Laboratory describes
“Biomass energy supports U.S. agricultural and forest-product industries. The main biomass
feedstocks for power are paper mill residue, lumber mill scrap, and municipal waste. For biomass
fuels, the most common feedstocks used today are corn grain (for ethanol) and soybeans (for
biodiesel). In the near future—and with NREL-developed technology—agricultural residues such
as corn stover (the stalks, leaves, and husks of the plant) and wheat straw will also be used.
Long-term plans include growing and using dedicated energy crops, such as fast-growing trees
and grasses, and algae. These feedstocks can grow sustainably on land that will not support
intensive food crops.” [NREL 2010]
Ithaca
Sustainably managed biomass technology has precedent in the Ithaca area. One example we will
draw heavily on is the Cayuga Nature Center’s wood chip boiler:
“In the fall of 2009, the Cayuga Nature Center (CNC) installed a high-efficiency, gasification-type
wood chip boiler supplied by ACT Bioenergy, LLC. The boiler will heat the CNC’s 10,000 ft.²
building and is intended to serve as a publicly accessible demonstration of environmentally
responsible production and utilization of biomass energy. The CNC expects to reduce their
heating costs by more than 80% by replacing propane gas with wood chip fuel and part of the
estimated 75 tons per year of fuel for the boiler will come from the sustainably managed forest
that surrounds the Center.” [ACT 2010]
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Biomass Energy Decision Making Framework
New York State in general is also an excellent location for new biomass projects, specifically for
wood waste and anaerobic digestion
“The Biomass Resources Program emphasizes the use of low-cost waste biomass such as
agricultural and forestry waste streams to products including fuels and chemicals. Projects that
convert biomass to fuels and chemicals use methods that include anaerobic digestion, acid or
enzyme hydrolysis, and gasification. The largest source of biomass is wood and wood wastes, a
renewable and sustainable resource. As a general rule, New York State has an abundance of
biomass feedstocks compared to other states.” [NYSERDA 2004]
Biomass Energy in the Facility
In addition to increased energy generation and the promotion of sustainable agricultural and
waste management processes, incorporating biomass energy technology into the SRF would well serve
the goals of a broader University-wide project, the Cornell University Renewable Bioenergy Initiative
(CURBI), which seeks to “implement commercially available technologies along with Cornell-led
technologies and utilize campus biomass resources.” [CUAES 1 2010] Contact between CUSD and CURBI
has confirmed that there would be substantial university demand for a facility like the SRF to benefit the
goals of CURBI.
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Biomass Energy Decision Making Framework
Biomass Energy Metrics Definitions and Discussion
I.
EFFICIENCY, ENVIRONMENTAL IMPACT AND COST
1. Performance in Ithaca
a. Definition: the ability of a biomass energy module to operate at manufacturer
specified efficiencies in Ithaca, NY.
b. Units of Measure: ten point scale based on industry standard met below
c. Considerations:
i. Feed Availability (5 point scale): the proximity of the module to necessary
biomass inputs.
ii. Temperature (⁰C): the standard operating temperature of the module.
iii. Storage Area (m^3): the volume of space available to store excess biomass.
2. Module Performance
A. Manufacturer Module Efficiency
a. Definition: The ability of a biomass module to convert biomass to heat
and/or usable electrical energy as a function of the energy of the biomass
input.
b. Units of Measure: percent
B. Energy Generation/Module Area
a. Definition: the production of energy per unit area, calculated by dividing the
rated module energy output by the area the module.
b. Units of Measure: W/ m2
3. Module Price
a. Definition: the monetary cost per rated watt of capacity
b. Units of Measure: $/ W
c. Considerations:
i. Initial Cost ($): manufacturer listing of price per module
ii. Maintenance($/year): cost to maintain the module annually
iii. Government incentives($/W): government rebates or tax incentives per
Watt of energy capacity
 State
 Federal
iv. Sponsorship ($): willingness of a corporation to provide a module at a
reduced rate or free after the establishment of a mutual relationship with
CUSD.
v. Energy saved ($/kWh): the monetary value of energy produced by the
module at the local electricity rate per kWh
vi. Payback period (year): the time required for the monetary value of energy
produced by the module to breakeven with the cost of the module over its
useful life
4. Environmental Impact:
a. Definition: the life cycle analysis of the module’s total impact from cradle to grave
b. Units of Measure:
i. Manufacturing (produced): g CO2/ W
ii. Operation (mitigated): g CO2/ kWh
c. Considerations:
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Biomass Energy Decision Making Framework
i. Inputs:
- Inventory of energy and materials required for manufacturing and
distribution of a module throughout the supply chain
- Inventory of energy and materials required for the operation of a
module over its useful life.
ii. Availability of natural resources and material components
iii. Outputs: associated environmental emissions released from the
manufacturing and operation of a module
II. OPERATION AND INTEGRATION INTO THE FACILITY
5. Maintenance Required/ Ease of Operation
a. Definition: the cost and labor required to maintain and operate the module
b. Units of Measure: 5 point scale (1: high maintenance, 5: no maintenance)
c. Considerations:
i. Manual Operation: the labor required to operate machinery, store inputs,
etc.
ii. Input Provision: the labor required to acquire and transport necessary
biomass inputs.
iii. Upkeep & Repair: the labor required to repair, clean, and upgrade the
module.
6. Controllability
a. Definition: ability to control the generation and distribution of heat and/or
electricity produced by the module in an integrated facility control system.
b. Units of Measure: 5 point scale (1: not controllable , 5: effortless to control)
7. Modularity
a. Definition: (as defined by the modularity sub-team) the ability to assemble and
disassemble a technology with ease, and reuse or recycle all technology
components so there is no waste.
b. Units of Measure: 5 point scale (1: not modular, not reusable 5:
assembled/disassembled easily, zero waste)
8. Synergy
a. Definition:
i. Ability to operate efficiently and integrate seamlessly with other technology
utilized in the facility.
ii. Ability to integrate into the facility with minimal infrastructure modification
or addition
b. Units of Measure: 5 point scale (1: stand alone technology, 5: adds value to other
technologies in the facility)
c. Considerations:
i. Structural Integration: the space required to store the module, the
necessary rooms and exterior space required to operate the module
ii. Visual Effects: the potential impact on the image of the facility
iii. Noise: the potential sound emitted from the operation of the module
iv. Odor: the potential odor emitted from the operation of the module
9. On-Campus Researcher Support
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a. Definition: the quantity and usefulness of related research currently conducted by
Cornell faculty on campus
b. Units of Measure: 5 point scale (1: no campus research, 5: large research initiative)
c. Considerations:
i. Laboratory: ability to test on campus research within the limits of the facility
and surrounding property
ii. Monitoring: ability to monitor energy output for the benefit of the facility
and the enhancement of the technology
iii. Student Involvement: ability for both undergraduate and graduate students
to access and maintain the technology for advancement of their research
goals as they pertain to the mission of CUSD.
III. FEASIBILITY AND LONGEVITY
10. Current Technological Feasibility and Availability
a. Definition: is the technology available commercially and is it feasible to produce
adequate energy at reasonable monetary costs.
b. Units of Measure: 5 point scale (1: not market ready, 5: commercially common)
11. Useful Life
a. Definition: the predicted life time of the module at the rated efficiency
b. Units of Measure: years
c. Considerations
i. Degradation: at what rate does the efficiency degrade per year
ii. Warranty: the manufacturer defined time period in which a product is
insured. The manufacturer will perform a specified level of service in this
time period.
IV. SUBJECTIVE ANALYSIS
12. Subjective Analysis
a. Definition: the Innovative Energy Technology Sub-team’s preference for a given
technology based on its “coolness”, novelty, and aesthetic appeal.
b. Units of Measure: 5 point scale (1: No Interest, 5: Full Team Interest)
c. Considerations:
i. Innovation: the innovative nature of the technology given other commercial
solutions in the industry
ii. Novelty: the uniqueness of the technology given other commercial solutions
in the industry
iii. Aesthetic Appeal: the visual appearance of the technology as a perception
of a viewer
Note: All specified units of measure will be weighted as a function of the specified industry standard
(see grading system)
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Specific Technologies
Wood boiler
“Wood pellet boilers have proven to be a reliable and effective way to heat homes and businesses, with
one million units now in service throughout Europe. Functioning much like oil and propane boilers, the
operation of these boilers is automatic. Typically, an electric ignition coil lights the pellets as needed,
while wood pellets are fed to the burner in measured doses via an auger connected to an attached
hopper or adjacent storage bin. These systems are convenient enough to be a great alternative to fossil
fuel fired boilers.” [EcoHeat 2009]
One add-on technology we should strongly consider is emission gasification, which can significantly
improve efficiency and reduce adverse environmental effects. This is the process used by the Cayuga
Nature Center’s boiler.
Greenwood (renewable energy company) explains:
“In gasification wood boilers the wood gases don't just go up and out the chimney, as is the case
with standard wood boilers. Instead, the reaction is continued and the emitted woodgas is
superheated and mixed with air resulting in complete combustion. The heat is then transferred
to a boiler for efficient distribution. An additional benefit of the gasification process is that the
complete combustion leaves little or no ash.
There are several common schools of thought for applying wood gasification and secondary
combustion principles in the design of a residential or small-scale wood boiler, here are two of
the most common approaches:
Continuous burn: Dual combustion chambers. Many of the wood gasification models imported
from Europe employ this technique. These units are designed to operate properly when they burn
a load of wood in one continuous burn and transfer the resulting heat to a water storage
container (usually 400 gallons or greater) where it is stored until the heat is needed.
In these systems, the gases flow down through the fire into a secondary chamber where firebrick
(or a ceramic material) creates the superheated environment necessary to complete the efficient
combustion process. Keeping this secondary chamber at high temperatures is key to the
performance of the overall system, hence the need for one continuous burn so that this chamber
does not cool and lower the boiler efficiency.
On-demand burn: Single combustion chamber. The Greenwood wood boiler uses a single burn
chamber to foster wood gasification. During normal operation, a patented thermal mass
maintains the firebox at the extreme temperatures required for complete combustion. This
enables the system to operate as an on-demand system, thereby removing the need for the
water storage tank outlined above. This design not only simplifies the operation and
maintenance of the unit, but also enables a greater variability of fuel composition (e.g. whole log
wood and wood moisture content).
Conclusion
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So, if you are researching a purchase of a wood boiler, the bottom line is that wood gasification
boilers that provide complete combustion are better than traditional water-jacketed wood
boilers. Some key points to take away from this article include:
In general, gasification is very efficient in extracting energy from different types of organic
materials, including wood.
Extremely high combustion efficiency is obtained by gasification, thereby creating minimal
emissions.
With respect to wood boilers, wood gasification means:
-Less wood is required,
-Significantly lower emissions/smoke, and
-Less ash.” [Greenwood 1 2011]
Building code requirements will likely apply mostly to outdoor wood boilers as opposed to indoor
models, in general regulations concerning fire safety, air pollution, and zoning will apply. One important
issue that will apply is whether any outdoor wood boiler is classified as residential or commercial--- a
commercial-size boiler would likely trigger stricter regulations that would prevent development because
of proximity to many other public spaces.
NY State recently published new regulations concerning outdoor wood boilers:
The particulate emission limits, stack height and setback requirements for residential-size new
OWBs are set forth in Section 247.5. Residential-size new OWBs will be subject to a weighted
average particulate emission limit of 0.32 pounds per million British thermal units (mmBtu) heat
output. In addition, the particulate emission rate for any test run conducted pursuant to Test
Method 28-OWHH may not exceed 15.0 g/h when the burn rate is 1.5 kilograms per hour (kg/h)
or less and 18.0 g/h when the burn rate is greater than 1.5 kg/h. Further, residential-size new
OWBs must be located 100 feet or more from the nearest property boundary line (or 100 feet
or more from the nearest residence not served by the OWB if the OWB is sited on contiguous
agricultural lands of 5 or more acres) and must be equipped with a permanent stack extending
a minimum of 18 feet above ground level. Notwithstanding the foregoing, the Department may
require that the permanent stack extend up to two feet above the peak of any roof structure
within 150 feet of the OWB when necessary to adequately disperse smoke emitted from an
outdoor wood boiler.
Commercial-size new OWBs (Section 247.6) will be subject to a weighted average
particulate emission limit of 0.32 pounds per million mmBtu heat output. In addition, the
particulate emission rate for any test run conducted pursuant to Test Method 28-OWHH may not
exceed 20.0 g/h. A commercial-size new OWB must be equipped with a permanent stack
extending a minimum of 18 feet above ground level. Notwithstanding the foregoing, the
Department may require that the permanent stack extend up to two feet above the peak of any
roof structure within 150 feet of the OWB when necessary to adequately disperse smoke emitted
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from an outdoor wood boiler. Finally, a commercial-size new OWB must be located 200 feet or
more from the nearest property boundary line, 300 feet or more from the nearest residential
property boundary line, and 1000 feet or more from a school. Notwithstanding the above, a
commercial-size new outdoor wood boiler installed on contiguous agricultural lands larger than
five acres must be sited 300 feet or more from the nearest residence not served by the outdoor
wood boiler and 1000 feet or more from a school.
A memo from Ronald E. Piester, R.A., Director, Division of Code Enforcement and Administration, New
York Department of State, clarifies the applicability of new regulations:
“The outdoor wood boiler is an appliance and is accessory to the building being heated
on the same piece of property. As an outdoor appliance both the Residential Code of New York
State (RCNYS) section M1401.4 and the Mechanical Code of New York State (MCNYS) section
303.6 require the boiler to be listed and labeled for outdoor installation, and installed in
accordance with the manufacturer’s installation instructions. The penetration of the building
wall by the pipes suppling the heated water to the building needs to be inspected. The
requirements for a building permit for the pipe penetrations in the building wall are the
jurisdiction of the individual local government. The outdoor boiler is an appliance and is not an
accessory structure. The codes regulate the location of an accessory structure relative to the
adjacent building and relative to the property line. The codes are silent relative to the location of
an outdoor appliance. Therefore, the location of an outdoor wood boiler is a zoning issue.”
[Piester 2003]
Two units—a boiler and a firebox/storage unit—are required, with the boiler ranging from 9 to 20 ft^2
and the firebox from 2 to 4 ft^2. Depending on the size of the boiler, an outdoor boiler would require a
stack at least 18 feet off the ground—perhaps more, depending on the applicability of regulations on
smoke dispersal.
Specific Technology Charts
Econoburn Wood Boiler comparison chart (2011)[10]
Boiler Model
EBW-100
EBW-150
EBW-200
EBW-300
EBW-500
EBW-150-O
EBW-200-O
Design Application
Indoor
Indoor
Indoor
Indoor
Indoor
Outdoor
Outdoor
Btu Output
100,000
150,000
200,000
300,000
500,000
150,000
200,000
Boiler Dimensions
EBW-100
EBW-150
EBW-200
EBW-300
EBW-500
EBW-150-O
EBW-200-O
Depth
47" / 119.4cm 47" / 119.4cm 47" / 119.4cm
50" / 127cm
63" / 160cm
54.25" /
137.8cm
54.25" /
137.8cm
Width
25" / 63.5cm
36" / 91.4cm
41" / 104.1cm
48.4" /
122.9cm
48.4" /
122.9cm
26" / 66cm
30" / 76.2cm
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Height
60.25" /
153cm
63.75”/
161.9cm
64.25" /
163.2cm
70" / 177.8cm
76" / 193cm
80" / 203.2cm
80.5" /
204.5cm
Weight Empty
1,560 Lbs /
708 kg
1,670 Lbs /
757 kg
1,980 Lbs /
898 kg
2,515 Lbs /
1,141 kg
3,405 Lbs /
1,544 kg
~1,800 Lbs/
816 kg
~2,100 Lbs /
953 kg
Firebox Dimensions
EBW-100
EBW-150
EBW-200
EBW-300
EBW-500
EBW-150-O
EBW-200-O
Depth
23" / 58.4cm
23" / 58.4cm
23" / 58.4cm
26" / 66cm
32" / 81.3cm
23" / 58.4cm
23" / 58.4cm
Width
15" / 38.1cm
16" / 40.6cm
21" / 53.3cm
24" / 61cm
27" / 68.6cm
16" / 40.6cm
21" / 53.3cm
Height
25" / 63.5cm
28" / 71.1cm
29" / 73.7cm
33" / 83.8cm
39" / 99.1cm
28" / 71.1cm
29" / 73.7cm
Maximum Log length
21" / 53.3cm
21" / 53.3cm
21" / 53.3cm
33" / 83.8cm
33" / 83.8cm
21" / 53.3cm
21" / 53.3cm
Firebox Door Height
12" / 30.5cm
12" / 30.5cm
12" / 30.5cm
12" / 30.5cm
12" / 30.5cm
12" / 30.5cm
12" / 30.5cm
Firebox Door Length
15" / 38.1cm
15.75" / 40cm
20.5" /
52.1cm
23.5" / 59.7cm
27.5" / 69.9cm
Piping Data
EBW-100
EBW-150
EBW-200
EBW-300
EBW-500
EBW-150-O
EBW-200-O
42 Gal / 159 L
79 Gal / 299 L
95 Gal / 360 L
37 Gal / 140 L
42 Gal / 159 L
Water Volume
30 Gal / 114 L 37 Gal / 140 L
15.75" / 40cm 20.5" / 52.1cm
Supply Pipe (female
connection)
2"
2"
2"
2.5"
4"
2"
2"
Return Pipe (female
connection)
2"
2"
2"
2.5"
4"
2"
2"
Min Boiler Loop Size
1-1/4"
1-1/4"
1-1/2"
2"
3"
1-1/4"
1-1/2"
Fill/Drain Valve Size
3/8"
1-1/4"
1-1/2"
1-1/2"
1-1/2"
1-1/4"
1-1/2"
Flue Dimensions
EBW-100
EBW-150
EBW-200
EBW-300
EBW-500
EBW-150-O
EBW-200-O
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Flue Outlet Diameter
8"
8"
8"
8"
12"
8"
8"
Height to Center of Flue
47.25"
50.75"
51.25"
57"
61.5"
50.75"
51.25"
Operating Data
EBW-100
EBW-150
EBW-200
EBW-300
EBW-500
EBW-150-O
EBW-200-O
EBW-500
EBW-150-O
EBW-200-O
200
175
175
Max Operating
Temperature
210° F / 99° C
Max Operating Pressure
30 PSI / 207 kPa
Output Temperature
(range)
170° F - 200° F / 77° C - 93° C
Specified Fuel
Wood (recommended moisture content: 15-22%)
Minimum Draft Required
-0.02 to -0.06 inch WC / -0.005 kPa to -0.015 kPa
Flue Gas Temperature
280° F - 400° F / 138° C - 204° C
Electrical Data
EBW-100
EBW-150
EBW-200
Boiler Power
Requirement
Electrical Consumption
(watts)
EBW-300
110 volt, 15 amp
100
175
175
175
Aquastat Overheat
Setting
220° F / 104° C
Electrical Consumption
5 amps
Frontier Series Wood Gasification Boiler (indoor) specifications (2011)[Greenwood 2 2011]
Model
Furnace dimensions
Boiler Capacity
Frontier CX
32”w x 54.5”h x 48”d
6 US gallons
Frontier LX
Avail 2011
-
Frontier MX
Avail 2011
-
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Approximate Shipping
Weight
Limited Warranty
Operating Range
Output per Firebox
Min./Max. Supply Water
Temp.
Fuel type
Maximum log length
Maximum log diameter
1250 lbs
-
-
1yr / 7 yr upon
registration
30 – 75 MBtuh
550 MBtu
140F / 195F
1yr / 7 yr upon
registration
85 – 120 MBtuh
1000 MBtu
140F / 195F
1yr / 7 yr upon
registration
150 – 225 MBtuh
1600 MBtu
140F / 195F
Log wood
21 inches
14 inches
Log wood
Log wood
Denali Series Pellet Boiler (indoor) specifications (2011)[Greenwood 3 2011]
Model
Maximum Output
Turndown Ratio
Approx. Heating Capacity
Boiler Dimensions
Firebox Volume
Height
Approximate Weight
Flue Size
Denali 100
110,000 Btu/hr
1:5
Up to 4,500 ft2
22”w x 45”h x 62”d
3 cu ft
45 in
748 pounds
6 inches
Denali 150
155,000 Btu/hr
1:5
Up to 7,500 ft2
23”w x 47”h x 65”d
4 cu ft
47 in
836 pounds
6 inches
Denali 300
315,000 Btu/hr
1:5
Up to 15,000 ft2
27”w x 49”h x 74”d
6 cu ft
49 in
1144 pounts
8 inches
Residential wood pellet boiler.
(Windhager BioWin Wood Pellet Boiler, http://www.woodpelletstovesboilers.com/News/Windhager_BioWIN_Wood_Pellet_Boiler.html)
A useful photo gallery of the boiler at the Cayuga Nature Center is available from ACT Bioenergy at
http://www.actbioenergy.com/brochure/Cayuga%20wood%20boiler%20photos.pdf
Anaerobic digestion
Anaerobic digestion technologies could convert food and/or animal waste produced within the facility or
elsewhere on campus to biogas that could heat the facility or provide electrical energy. The Oregon
Department of Energy explains:
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“Biomass that is high in moisture content, such as animal manure and food-processing wastes, is
suitable for producing biogas using anaerobic digester technology.
Anaerobic digestion is a biochemical process in which particular kinds of bacteria digest biomass
in an oxygen-free environment. Several different types of bacteria work together to break down
complex organic wastes in stages, resulting in the production of "biogas."
Symbiotic groups of bacteria perform different functions at different stages of the digestion
process. There are four basic types of microorganisms involved. Hydrolytic bacteria break down
complex organic wastes into sugars and amino acids. Fermentative bacteria then convert those
products into organic acids. Acidogenic microorganisms convert the acids into hydrogen, carbon
dioxide and acetate. Finally, the methanogenic bacteria produce biogas from acetic acid,
hydrogen and carbon dioxide.
Controlled anaerobic digestion requires an airtight chamber, called a digester. To promote
bacterial activity, the digester must maintain a temperature of at least 68° F. Using higher
temperatures, up to 150° F, shortens processing time and reduces the required volume of the
tank by 25 percent to 40 percent. However, there are more species of anaerobic bacteria that
thrive in the temperature range of a standard design (mesophillic bacteria) than there are
species that thrive at higher temperatures (thermophillic bacteria). High-temperature digesters
also are more prone to upset because of temperature fluctuations and their successful operation
requires close monitoring and diligent maintenance.
The biogas produced in a digester (also known as "digester gas") is actually a mixture of gases,
with methane and carbon dioxide making up more than 90 percent of the total. Biogas typically
contains smaller amounts of hydrogen sulfide, nitrogen, hydrogen, methylmercaptans and
oxygen.
Methane is a combustible gas. The energy content of digester gas depends on the amount of
methane it contains. Methane content varies from about 55 percent to 80 percent. Typical
digester gas, with a methane concentration of 65 percent, contains about 600 Btu of energy per
cubic foot.” [Oregon DOE 2009]
Many facilities at Cornell, such as dining halls, the plantations, and the vet school, produce appropriate
biomass for this purpose. Several faculty members at Cornell have expressed interest in creating such a
facility on campus. The Sustainability Research Facility could be an appropriate test case for a small-scale
implementation of anaerobic digestion technology. According to CURBI, “CUAES currently composts
approximately 8,000 tons of organic waste per year and could generate up to an additional 15,000 tons
of biomass from energy crops as appropriate.” [CUAES 2 2010]
The preferred implementation of anaerobic digestion technology would be using a plug-flow digester.
Plug flow digesters are typically large canals dug into farm landscape that contain organic material
within a covered sheath. Biomass is put into one end of the canal, and the act of putting more biomass
into the canal on a regular basis pushes the material through the canal, which is treated with special
organic material to undergo digestion. Biogas is produced and can then be used for energy purposes.
Plug flow digestion has also been used in developing countries to promote sustainable agriculture.
Small, localized digesters can be an effective way to easily handle agriculture waste. The technology is
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already available, and ongoing research into plug flow digestion is being done at Cornell’s Agriculture
Waste Management Laboratory.
Experimental plug flow setups at Cornell’s Agriculture Waste Management Laboratory.
Imagery depicting small-scale plug flow digestion in Indonesia.
Pyrolysis
CURBI explains the operation and utility of pyrolysis systems:
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“Slow pyrolysis systems produce gas by heating organic matter in the absence of oxygen. The
resultant biogas or synthetic gas (syngas) is high in carbon monoxide, hydrogen, and other
combustible gases. Pyrolysis also produces a charcoal byproduct (biochar) that is a valuable soil
amendment with a multitude of beneficial properties and is a carbon “sink”, making it the only
currently known “carbon negative” energy technology. Pyrolysis can use a range of biomass
wastes, including most urban, agricultural, or forestry residues, such as wood chips, straw or
mulch hay, tree bark, animal manure, and recycled organics. The demand for biochar by the
research community is very high, with numerous collaborations being formed to study its effect
in soils;” [CUAES 2 2010]
The Center for Public Environmental Oversight explains some of the drawbacks:
“The technology requires drying of soil prior to treatment.
Limited performance data are available for systems treating hazardous wastes containing
polychlorinated biphenyls (PCBs), dioxins, and other organics. There is concern that systems that
destroy chlorinated organic molecules by heat have the potential to create products of
incomplete combustion, including dioxins and furans. These compounds are extremely toxic in
the parts per trillion range. The MSO process reportedly does not produce dioxins and furans.
The molten salt is usually recycled in the reactor chamber. However, depending on the waste
treated (especially inorganics) and the amount of ash, spent molten salt may be hazardous and
require special care in disposal.
Pyrolysis is not effective in either destroying or physically separating inorganics from the
contaminated medium. Volatile metals may be removed as a result of the higher temperatures
associated with the process, but they are not destroyed. Byproducts containing heavy metals
may require stabilization before final disposal.
When the off-gases are cooled, liquids condense, producing an oil/tar residue and contaminated
water. These oils and tars may be hazardous wastes, requiring proper treatment, storage, and
disposal.” [CPEO]
According to CURBI, “pyrolysis has attracted attention from media and public policy makers, including in
the Obama Administration, but there is no existing facility in the U.S. that generates biochar at a scale to
evaluate the overall energy efficiency. CURBI would be the first. Various types of high-efficiency direct
combustion and anaerobic digestion are also being considered.”[CUAES 3 2010]
Biochar is a highly porous organic charcoal made from organic waste. Biochar has received significant
praise for its pollution reducing potential:
“Biochar is considered by many scientists to be the "black gold" for agriculture.
Its high carbon content and porous nature can help soil retain water, nutrients, protect soil
microbes and ultimately increase crop yields while acting as natural carbon sink - sequestering
CO2 and locking it into the ground.
Innovative Energy Technology 17
Biomass Energy Decision Making Framework
Biochar helps clean the air two ways: by preventing rotting biomass from releasing harmful CO2
into the atmosphere, and by allowing plants to safely store CO2 they pull out of the air during
photosynthesis.
"Soil acts as an enormous carbon pool, increasing this carbon pool could significantly contribute
to the reduction of CO2 in the atmosphere," said Christoph Steiner, one of the leading research
scientist studying biochar. "It gives us a chance to produce carbon negative energy."
Worldwide use of biochar could cut CO2 levels by 8 parts per million within 50 years, according
to NASA scientist James Hansen.”[CNN 2009]
Given the delays and finance trouble in implementing some of the proposals of CURBI, the SRF could
supplant this goal by providing the background equipment and laboratory space to develop Cornell into
a leader in biochar production.
Works Cited
Energy Information Administration, “Renewable Energy Trends in Consumption and Electricity 2008
Edition” released August 2010,
http://www.eia.doe.gov/cneaf/solar.renewables/page/trends/rentrends.html
Union of Concerned Scientists, “How Biomass Energy Works” last revised 10/29/2010,
http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-biomassenergy-works.html#1
National Renewable Energy Laboratory “Biomass Energy Basics” last updated 2/9/2010
http://www.nrel.gov/learning/re_biomass.html
ACT Bioenergy LLC “High-Efficiency Wood Chip Boiler at Cayuga Nature Center, Ithaca, NY” 2009
http://www.actbioenergy.com/brochure/Cayuga%20wood%20boiler%20photos.pdf
New York State Energy Research and Development Authority “Biomass Resources” 2004
http://www.powernaturally.org/programs/BiomassResources/default.asp?i=2
[1] Cornell University Agricultural Experiment Station, “Cornell University Renewable Bioenergy Initiative
– CURBI” 2010 http://www.cuaes.cornell.edu/cals/cuaes/ag-operations/curbi/index.cfm
EcoHeat Solutions “Solid Biofuel: Wood Pellet Boilers” 2009
http://www.ecoheatsolutions.com/heatingsolutions/woodpelletboiler.html
[1] Greenwood “All You Need to Know About Wood Gasification” 2011
http://www.greenwoodusa.com/Article_All_You_Need_To_Know_About_Wood_Gasification.php
Ronald E. Piester, “Outdoor wood boilers” memo, January 1, 2003,
http://www.dos.state.ny.us/CODE/pdf/outdoorwoodboilertb.pdf
Econoburn, 2011, http://www.alternativefuelboilers.com/products.htm
Innovative Energy Technology 18
Biomass Energy Decision Making Framework
[2] Greenwood, “Frontier Series Wood Gasification Boiler” 2011,
http://www.greenwoodusa.com/frontier-series-indoor-gasification-boiler.php
[3] Greenwood, “Denali Series Pellet Boiler” 2011, http://www.greenwoodusa.com/denali-seriesindoor-pellet-boiler.php
Oregon Department of Energy, “Biogas Technology,” March 27, 2009,
http://www.oregon.gov/ENERGY/RENEW/Biomass/biogas.shtml
[2] Cornell University Agricultural Experiment Station, “Cornell University Renewable Bioenergy
Initiative” concept proposal, January 20, 2010, http://www.cuaes.cornell.edu/cals/cuaes/agoperations/upload/CURBI_concept_Jan10.pdf
Center for Public Environmental Oversight, “Pyrolysis,” no date,
http://www.cpeo.org/techtree/ttdescript/pyrols.htm
[3] Cornell University Agricultural Experiment Station, “Cornell University Renewable Bioenergy
Initiative” FAQ, January 20, 2010, http://www.cuaes.cornell.edu/cals/cuaes/agoperations/upload/CURBI_concept_Jan10.pdf
CNN, “Can 'biochar' save the planet?,” March 30, 2009, http://articles.cnn.com/2009-0330/tech/biochar.warming.energy_1_carbon-co2-organic?_s=PM:TECH