Biomass Gasification Research at
Iowa State University
Iowa State University’s Biomass Gasification System
located in the Combustion and Gasification Laboratory in
Black Engineering.
(http://csetweb.me.iastate.edu/research/bioreburn.htm)
i
Biomass Gasification Research at Iowa State University
Submitted To:
Science and Engineering Committee (SEC)
in charge of the graduate program in
bio-renewable resources
c/o Dr. Robert C. Brown
Prepared By:
Alex Bumgardner
Neil Carroll
Bret Staehling
April 13, 2006
ii
2035 Sunset Dr.
Ames, IA 50014
April 13, 2006
Science and Engineering Committee
c/o chairman Dr. Robert C. Brown
286 Metals Development Building
Iowa State University
Ames, IA 50011-3020
Dear Dr. Brown,
As a professor and researcher at Iowa State University leading the way in bio-renewable
resources, you understand the importance of recruiting quality graduate students to the
bio-renewable resources program. Your personal research in the field of biomass
gasification has been instrumental in the development of Iowa State University’s
program, and promoting this field to future researchers and graduate students needs to be
a priority.
To recruit the highest quality graduate students, Iowa State University must provide
informative materials to help explain the diverse areas of research to potential graduate
school candidates. Currently, these materials either do not exist, or are not accessible to
the general student population. Your own published research documents contain a great
deal of information, but they are not easily accessible for potential graduate students to
obtain an overview of the program. This problem is easily remedied, and we have
prepared a demonstration of one such document. This document helps explain the
importance of biomass research and the major discoveries that Iowa State University
continues to make on a daily basis. If other instruments such as this were prepared to
show the advancements made in all areas of bio-renewable resources, it would increase
the already compelling appeal of the bio-renewable resources graduate program at Iowa
State University. An added benefit of this document is its availability as a response to
requests for proposals (RFP) in order to obtain funding for further research and
development for biomass gasification.
With the help of the Science and Engineering Committee’s, Iowa State University can
continue to lead the way in developing our bio-renewable resources. If you have any
questions about the following proposed document please feel free to contact Neil Carroll
at the above address.
Regards,
Neil Carroll
Alex Bumgardner
Bret Staehling
iii
Table of Contents
ABSTRACT
V
PROBLEM
1
BIOMASS GASIFICATION
1
THE SIGNIFICANCE OF BIOMASS GASIFICATION
1
THE BIOMASS GASIFICATION REACTOR
1
IOWA STATE UNIVERSITY RESEARCH
3
COMBUSTION AND GASIFICATION LABORATORY
BIOMASS FUEL SOURCES
BIOMASS ENERGY AND CONVERSION FACILITY (BECON)
“REBURN” FUEL
COMMODITY CHEMICALS
3
4
4
5
5
NATIONAL APPEAL OF BIOMASS GASIFICATION RESEARCH
6
CLEANER ENERGY
NATIONAL ENERGY SECURITY
ECONOMIC GROWTH
AGRICULTURAL ECONOMY
6
6
6
6
COSTS OF BIOMASS GASIFICATION
7
BIOMASS GASIFICATION RESEARCH AND GASIFIER OPERATION COSTS
TECHNOLOGY DEVELOPMENT AND COSTS
LARGE SCALE OPERATION OF BIOMASS GASIFICATION
7
7
7
CONCLUSION
8
APPENDIX MATERIAL
9
BIBLIOGRAPHY
11
iv
Abstract
In today’s society it is essential to focus efforts on bio-renewable resources, as they are
leading the way in promoting secure U.S. energy sources, clean air technology, and a
stimulated agricultural economy. Iowa State University is currently creating a pathway
to future technologies in biomass gasification, a clean method of obtaining energy from
natural resources such as switchgrass and corn stover. Iowa State University is a primary
institution for the research and development of the biomass gasification process.
Various studies are being conducted in the Combustion and Gasification Laboratory here
at Iowa State University, and also at the Biomass Energy and Conversions Facility
located near the Iowa State University campus. Several opportunities exist for
prospective graduate students to acquire positions in the research of biomass gasification.
The research and development of gasification processes will be beneficial to the entire
American society, as it will boost energy security and strengthen the U.S. economy.
v
Problem
The current consumption of nonrenewable resources such as natural gas,
petroleum, and coal in the United States
has become a major factor in
environmental devastation, international
relations, and the United States’
dependence on foreign countries. New,
renewable technologies need funding
and support if they are ever going to be
sufficiently developed to fuel U.S.
energy demands. One of these
renewable technologies, biomass
gasification, is currently under
development by researchers and private
companies here at Iowa State University.
Biomass Gasification
Biomass gasification is a process that
extracts energy from biomass through a
controlled, low oxygen combustion that
produces a flammable gas. Biomass is
any plant material or vegetation that can
be broken down and used for energy.
Some of the vegetation commonly used
for biomass gasification include
switchgrass and leftover crop material
such as corn stover.
The Significance of Biomass
Gasification
The potential use of biomass gasification
is growing in relative significance to the
average world citizen. Fossil fuels are
non-renewable and finite, and the United
States is quickly running out of
resources such as natural gas. If a
relatively inexpensive alternative could
be produced from a renewable resource
such as biomass, the damage to the
environment could be slowed, U.S.
dependence on foreign energy sources
could be decreased, and American
farmers could benefit. The Department
of Energy (DOE) and United States
Department of Agriculture (USDA) have
helped support research and
development of biomass gasification
technologies here at Iowa State
University through several grants.
Biomass gasification is one of the
countless opportunities for graduate
level work in the bio-renewable
resources sector here at Iowa State
University. Iowa State University is
spearheading the effort to secure U.S.
energy sources, promote cleaner
technology, and regenerate America’s
agricultural economy through biomass
gasification technologies. Current
research projects at Iowa State
University range from improving
efficiency of current gasification
processes to producing bio-based
plastics through the gasification process.
The U.S. Department of Agriculture has
performed resource assessments that
indicate the U.S. could sustainably
produce approximately 1.2 billion tons
of dry biomass per year. This amount is
enough biomass to cover about 21% of
the annual energy needs in the United
States. Since this figure represents a
significant portion of U.S. energy
requirements, the development of
technologies to tap into this resource
would be infinitely valuable.
The Biomass Gasification
Reactor
The biomass gasification reactor is a
combination of a fluid bed gasifier and a
combustor, which is used to test gas
1
produced by the low oxygen combustion
in the fluid bed. The fluid bed gasifier
makes a “fluid” out of the biomass when
the stream of hot gas mixes with the
biomass and sand causing it to “fluidize”
in the air.
As you can see in Figure 1, biomass is
ground up and fed into the fluidized bed
of sand. The fluidized bed is a
combustion technology that was
developed to reduce pollution emissions
from traditional power plants. In the
fluidized bed, the biomass mixes with
sand and is supported in the air by upward blowing hot air jets.
The partial combustion occurs in the
tumbling mix of solids and causes the
release of gases such as hydrogen,
carbon monoxide, carbon dioxide,
methane, ethane, and nitrogen. This mix
of gas is called producer gas or syngas.
Unfortunately, some tar and char are
also produced and need to be removed
from the syngas before it can be used as
an energy source. Figure 1 shows the
combustor combined with the biomass
reactor, which is used to test the fuel in a
reburning process.
The reburning process itself reduces
emissions by adding 10-20% of the fuel
after the primary combustion. This
decreases the amount of fuel wasted in
the ignition process. Early testing
indicates the syngas released from
biomass can be used for reburning and
due to its cost will most likely be a
competitive replacement for expensive
natural gas instead of coal. Future
research at Iowa State University will
help broaden the use of syngas produced
from biomass.
Figure 1: Biomass Gasifier Illustration – Biomass such as switchgrass is fed into
the feeder where it is shredded and inserted into a layer of sand. Inside this low
oxygen area, very hot air/steam is blown up through the biomass where it undergoes
partial combustion. The biomass releases H2, CO, CO2, CH4, C2H4, and N2 gasses,
which are then piped into the combustor where it is combusted to test its fuel
capabilities. (Figure from http://csetweb.me.iastate.edu/research/bioreburn.htm)
2
Iowa State University
Research
1
Combustion and Gasification
Laboratory
Some of the projects currently being
explored at Iowa State University are
performed in the Combustion and
Gasification laboratory located in the
Black Engineering building. Iowa State
University has created a lab solely
dedicated to research and development
of the biomass gasification process. The
lab is equipped with a biomass gasifier,
which can convert several different
varieties of plant and animal material
into energy, fuels, and commodity
chemicals.
Figure 2 shows the intake portion of
Iowa State University’s biomass gasifier.
The biomass gasifier apparatus located
in Black Engineering is a lab-scaled
version, which can easily be used for
research at the experimental level. A
major strength of the biomass gasifier is
its ability to accommodate new research
ideas and technologies. New
components can be added to the system
quite easily.
The Combustion and Gasification lab is
equipped with a 7 KW bubbling
fluidized bed gasifier, which operates at
atmospheric pressure. The lab also
includes a 37 KW downdraft combustor.
The gasifier works by inserting a solid,
biomass fuel such as ground corn into
the gasifier via an auger. When the fuel
is introduced to the gasifier it undergoes
a combustion process initiated by the
2
3
Figure 2: Biomass Gasifier –
Biomass fuels are introduced to
gasification system via the hopper
(1). The biomass is then fed into
the fluidized gasifier (2) through
the auger (3).
tumultuous movement of hot air through
a mixture of fuel and sand. Sand is
mixed with the fuel to act as a fluidized
bed, improving heat and mass transfer
which causes combustion of the solid
fuel. When the fuel is combusted it is
converted into a series of products
including: hydrogen, methane, carbon
monoxide, carbon dioxide, tar, and
particulate matter. The desired product
is syngas, a synthetic form of natural
gas, which can be used by public utilities
to heat homes. Traditional natural gas is
primarily methane, with smaller amounts
of ethane, nitrogen, and a handful of
other gases.
The byproducts of the gasification
process, such as tar and particulate
3
matter are currently creating a problem;
therefore, research is being conducted to
create a filtering system that can
effectively remove these waste products.
The gasifier system is housed with
several forms of instrumentation in order
to monitor the system and record
combusted products.
1
Biomass Fuel Sources
Iowa State University researchers are
currently focusing their efforts on the
effects of different biomass fuel
compositions including:
• Ground corn
• Alfalfa
• Switchgrass
• Sawdust
• Wood
• Animal manure
• Corn Stover
Each one of these materials reacts
differently in the gasifier, creating
distinctive quantities of products. For
instance, ground corn is considered to be
a good fuel because it is high in starch
content. The starch allows the fuel to
combust easily and creates minimal
amounts of tar and ash products.
Switchgrass and alfalfa are less desirable
fuels, as they tend to stick to the sand in
the reactor, producing high ash content.
The gasification lab is continuously
monitored while fuel products are being
analyzed. The average energy content
released from the various fuel sources is
recorded at approximately 50%
efficiency.
Biomass Energy and Conversion
Facility (BECON)
Iowa State University is actively
involved in several biomass gasification
projects located at the Biomass Energy
2
3
Figure 3: Filtration System –
The syngas produced must be
filtered to remove the tar and
char. The air filters for char are
located in the boxes (1) and (2),
while the cooling system (3)
removes the tar.
and Conversion Facility (BECON) in
Nevada, Iowa, approximately six miles
from the Iowa State University campus.
Graduate students are encouraged to
conduct studies in this larger, pilotscaled gasification laboratory. The
BECON facility is outfitted with a much
larger gasifier (900 KW compared to 7
KW in the Black Engineering lab) that
can convert five tons of fuel per day into
a synthetic natural gas product. Efforts
are focused on improving the removal of
char, tar, and particulate matter from the
syngas to produce cleaner burning fuel.
Figure 3 shows the filtration system that
is undergoing some of these tests at Iowa
State University.
4
One other major project in progress is
the development of a method for
creating hydrogen gas from a thermally
ballasted gasifier. A thermally ballasted
gasifier utilizes a single-phase reactor
for both combustion and pyrolysis.
Steam is used instead of air in the gasproducing phase, so nitrogen does not
dilute the produced gas. The high
hydrogen content can then be used to
power fuel cells.
“Reburn” Fuel
Efforts are presently underway at Iowa
State University to introduce biomass
gasifiers to coal-fired power plants.
Many power plants around the world
consume coal as their primary source of
energy to fire the boilers. Coal is an
extremely unclean fuel that creates large
amounts of emissions in the form of
nitrogen oxide. One way that Iowa State
University is looking to exploit biomass
gasification is by using the syngas as a
fuel for reburning in the coal firing
facilities. By introducing syngas to the
burning coal, it will act as a “reburn”
fuel to rid the coal products of
approximately 75% of emissions through
the release of nitrogen via gas phase
radicals. This implementation of
biomass technologies could have a huge
impact on American society, as
environmental cleanliness is an
important issue in safeguarding future
generations.
Commodity Chemicals
A material rapidly gaining attention
from biomass research analysts is
distiller’s dried grains (DDG), produced
as a waste product in ethanol production.
Ethanol plants are becoming a booming
enterprise across the nation because of
the high cost of oil. The use of ethanol
is one of the first steps in a process that
could eventually reduce or eliminate
U.S. dependence on foreign sources of
energy while improving the agricultural
economy. Ethanol plants are vital to the
future of America, and the waste
products created during ethanol
production may also become vitally
important. DDG from corn fueled
ethanol plants has a material
composition of dried grain consisting of
high lignocellulose (fiber), and a mixture
of cellulose, hemicellulose, and lignin.
Researchers are currently studying
methods for transferring the cellulose
and hemicellulose into sugars, which can
then be turned into industrial chemicals.
Iowa State University research is also
focusing on making use of proteins and
oils within the DDG from a biochemistry
perspective. When the proteins and oils
undergo gasification, syngas is
produced. The syngas then acts as
feedstock in an anaerobic fermentation
process for a bacteria which utilizes the
carbon monoxide and produces
hydrogen gas and a polyester. This
polyester can be used in the
manufacturing of bio-based plastics,
films, and fibers. A benefit of this biobased plastic is that unlike most plastics,
it is environmentally friendly and
completely decomposable.
Additional research projects are being
conducted in the field of biomass
gasification here at Iowa State
University. Both the Gasification and
Combustion Laboratory and BECON
facility are being utilized to enhance
knowledge of the biomass gasification
process. Continued efforts in the
research and development of biorenewable energy sources are vital for
the economic future of the United States.
5
National Appeal of Biomass
Gasification Research
On a national scale, support for research
in biomass gasification will yield three
main benefits: the production of cleaner
energy, potential national energy
security, and economic growth –
especially in agriculture.
Researching and developing biomass
gasification technologies could benefit
the nation by obtaining the capacity to
create self-sufficient fuel sources. By
increasing the number of options for
sources of energy and decreasing the
U.S. dependence on foreign energy
resources, the United States could attain
a higher level of international security.
Cleaner Energy
Economic Growth
The United States needs to be concerned
about the impact U.S. energy
consumption has on the environment.
One possible solution to the current
environmental issues is to replace the
use of fossil fuels with a fuel derived
from biomass. Fuels originating from
biomass, rather than petroleum, burn
much cleaner and release fewer
chemicals hazardous to the environment.
The use of biomass fuel decreases air
pollution and reduces the contribution to
ozone destruction and global warming.
Also, replacing fossil fuels with biomass
fuel shifts the energy usage from a
source that is virtually non-renewable to
a source that is renewable and as
abundant as daily waste material. Using
overly abundant, underutilized waste
material as fuel further cleans the
environment by disposing of waste in a
highly beneficial manner.
An important factor in making a decision
about the necessity of biomass
gasification research is the possible
impact and benefits such research could
have on the U.S. economy. The greatest
economic benefit of biomass gasification
comes from the extraction of valuable
energy from overly abundant and
underutilized waste produced in the
United States. To make biomass energy
a true competitor its efficiency must be
increased. Current data suggests the
overall efficiency of biomass
gasification to be significantly lower
than the efficiency of competing natural
gas and fossil fuels. With a gradual
increase in efficiency added to the
already low cost of biomass resources,
biomass gasification could be made
economically feasible. In fact, the
Michigan State Biomass Conversion
Research Lab website claims that
“Biomass costs much less than
petroleum on both a cost per ton and a
cost per BTU or kcal of energy content.”
Progress is clearly being made to make
biomass gasification the intelligent
choice from an economic standpoint.
National Energy Security
One of the nation’s top concerns is
dependence on foreign countries to
provide energy resources, especially
non-renewable fuels. In the near future,
the U.S. may not be able to depend on
other countries for a reliable source of
energy. A perfect solution to this
potential crisis is the development of
biomass fuels as a new energy source.
Agricultural Economy
The vast majority of the United States’
greatest resources and most fertile soils
are claimed by agriculture. Agricultural
6
communities form the heart of America,
and provide the vital supplies that are
needed to feed its citizens. Naturally,
agriculture is one of the largest scale
operations in the U.S., and produces an
enormous supply of waste material in the
form of biomass. The highest
concentrations of biomass in the nation
are made up of two agricultural products
known as switchgrass and corn stover.
Switchgrass and corn stover are both
perfect materials for biomass
gasification. Converting the biomass
into energy is the equivalent of
converting waste into money. For
example, corn based feed grain worth $3
per unit may be converted into fuel
worth $12 per unit simply by gasifying
it. With this rate of exchange, further
pursuit of biomass gasification research
is sure to create a new market for
agricultural products and promote a new,
healthy economic growth in the heart of
the nation.
Costs of Biomass
Gasification
Implementing biomass gasification into
the mainframe of U.S. fuel supplies
raises several important questions. What
does it cost to operate a biomass
gasifier? What does it cost to develop
the technology required to make biomass
gasification profitable? What will it take
to efficiently operate a large-scale
biomass gasification system?
Biomass Gasification Research
and Gasifier Operation Costs
In order for biomass gasification
research to be effective, society must be
willing to invest a great deal of time,
money, and innovative thinking. The
actual operation of a biomass gasifier is
also expensive. The costs of operating a
biomass gasifier include the cost of
heating the chambers in the gasifier,
maintaining the equipment, obtaining the
biomass, and the initial cost of setting up
a biomass gasification system.
Technology Development and
Costs
Today, one of the major goals of
biomass gasification research is to make
the conversion process of biomass to
fuel as efficient as possible. More
specifically, the aim is to make
gasification of biomass as efficient as the
processing of current fossil fuels.
Reaching or even coming close to
achieving this goal will make biomass
fuels undeniably the lowest cost and
ultimately the best energy source
available. Biomass fuels are already
proven to be cleaner and more
economical than conventional fuels. If
the conversion efficiency of biomass
fuels begins to rival conventional fuels
there will no longer be any advantage in
using conventional fuels. Any
breakthrough in conversion efficiency
should be considered well worth the
costs of research.
Large Scale Operation of Biomass
Gasification
One important factor in evaluating the
costs and benefits of biomass
gasification research is to consider the
implementation of research discoveries
into the real world. The efficiency of an
energy source is immensely impacted by
the location of the energy plant relative
to the raw materials and to the consumer.
As with any other energy conversion
facility, the biomass gasification
7
facilities will need to be located as close
to their fuel sources as possible. Placing
biomass gasification conversion
facilities in central agricultural locations
could cut down biomass shipping costs
immensely. Also, due to the widespread
location of agricultural communities, it
would be most beneficial to have a
larger number of medium-sized
conversion facilities, rather than having
a small number of large conversion
facilities. The most cost-efficient plants
have a capacity of about 1000-5000 kW.
frontrunner in new biomass
technologies. The initial costs may be
great, but eventually the United States
may be able to reap the benefits and cut
a path toward a cleaner, healthier
environment.
With widespread use of biomass
gasification conversion facilities there
would be less need for an enormous and
cumbersome pipeline system as
currently is used for natural gas. Since
the fuel and the consumers would be
much closer together, a considerably less
elaborate pipelining system would be
required to deliver the product to the
consumer.
Conclusion
Biomass gasification is a process that
can play a major role in the efforts to
secure U.S. energy sources, promote
cleaner technology, and regenerate
America’s agricultural economy. Iowa
State University is a leader in the
developments of biomass gasification
and will likely continue to be a
8
Appendix Material
Figure 1: Thermal Conversion Processes
Identifying Environmentally Preferable Uses for Biomass Resources. 31 Mar. 2004.
Natural Resources Canada, Commission for Environmental Co-operation, National
Research Council of Canada. 12 Apr. 2006
<http://www.cec.org/files/PDF/ECONOMY/Biomass-StageI_en.pdf>.
Figure 2: Chemicals From Syngas by Established Processes - Figure retrieved from
the BERA Biomass Energy Research Association website in an article titled “Biomass for
Renewable Energy and Fuels” by Donald L. Klass of Entech International, Inc. The full
article may be viewed at: http://www.bera1.org/cyclopediaofEnergy.pdf.
9
How Much Biomass Could Be
Fuel wood
Produced?
U.S. Biomass Potential
(million tons)
•
Total potential in
U.S. is in excess
of 1 billion tons
(about 21 EJ (21
x 109 GJ)
Milling residues
132
79
96
47
43
58
55
343
•
Logging residues
Forest thinning
Crop residues
• Could supply 21%
of U.S. energy
demand, or
33% of U.S.
transportation fuel
Urban wood residues
389
Dedicated crops
Grains for biofuels
Ag processing residues &
manure
Figure 3: Power point slide obtained from the OBP Annual Report 2003-2004 presented
by Robert C. Brown. The full presentation may be accessed at:
http://www.biorenew.iastate.edu/publications/BioeconomyComprehensive2006.ppt.
Figure 4: Potential Biomass Based Electricity Supply
The Economics of Biomass Production in the United States. 12 Apr. 2006
<http://bioenergy.ornl.gov/papers/bioam95/graham3.html>.
10
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12