Biomass Gasification and Biodigestion

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Biomass Gasification and Biodigestion
Chris J. Zygarlicke
Deputy Associate Director for
Research Energy
Environmental Research Center Renewable Fuels
Action Summit Bismarck State College,
Bismarck, ND June 11 and 12, 2006
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Whats the Deal About Biogas?

• Fossil natural gas is a major supply of heat and
  electricity for the world.
• Environmental (greenhouse gas effects)
• Conversion of fossil gas produces CO2.
• Natural and anthropogenic methane emanations have
  a 22 times greater greenhouse gas impact.
• Cost
• Prices of gas have been increasing and
  fluctuating over the past few years.
• Huge impacts on fertilizer industry,
  manufacturing and heavy industry,
  schools/colleges, and average consumers

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Composition of Air

• 186 billion tons of CO2 enter earth's atmosphere
  each year.
• 6 billion tons are from human activity.
• Approximately 90 billion tons come from biologic
  activity.
• 90 billion tons from such sources as volcanoes
  and decaying land plants.
• At 368 parts per million CO2 is less than
  4/100ths of 1 of all gases present.

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CO2 and CH4 Levels
Niwot Ridge, U.S.A.
CO2
CH4
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U.S. Greenhouse Gases
Carbon Dioxide 66
Nitrous Oxide 5
CFCs 11
Methane 18
U.S. EPA, 1990
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U.S. Anthropogenic Methane
Landfills 36
Livestock Manure 10
Domestic Livestock 21
Other Sources 6
Natural Gas 10
Coal Mining 17
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Natural Gas Average Consumer Price
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What Can We Do About It?
New Technologies
Marketable Products

• To capture and convert biogas (extraneous
  emissions) from organic sources
• To convert biomass residues using gasification
  and combustion
• To convert extraneous fossil gas emissions

• Heat
• Electricity
• Hydrogen
• FT fuels
• Chemicals

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Two Main Methods to Extract Gas from Biomass
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Diversity of Biomass Types

• Wastes and residues
• Wood forest or tree trimmings, sawdust,
  demolition wood, crates, and railroad ties
• Lignin from ethanol processing of wood, ag
  residues, and MSW
• Ag Wheat straw, rice straw, alfalfa stems,
  potato and beet residue, and corn stover
• Animal poultry litter and manures (cows and
  hogs)
• MSW RDF and acidified biosolids
• Agricultural energy crops

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Biomass Feedstocks
Hybrid Poplar
Wheat Straw
Alfalfa
Wood Residue
Animal Manure
Sunflower Hulls
Beet Tailings
Switchgrass
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What Is Anaerobic Digestion?
Water heat (35C, 95F ) acid-forming bacteria
to convert organic wastes (proteins,
carbohydrates, fats-oils) to volatile fatty
acids acetogenic bacteria to convert volatile
fatty acids to acetic, propionic, and lactic
acids Methane-forming bacteria (methanogens) to
use acids to produce methane
Digestion-- AcidThermal Conversion
Product Gas
Gas Conditioning
Biomass (215 solids)
Utilization Boiler/Heat/Engine/ Generator
Residues Fiber Leachate
Typical Product Gas Combustibles CH4
(60) Diluents CO2 and N2 (40) Contaminants H2
S (0.20.4)
Fiber Product (bedding, compost, etc.)
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Anaerobic Plug-Flow Digester System Haubenschild
Farms Inc., East Central Minnesota
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EERC Developments

• Grand Forks, ND, Wastewater Biosolids-to-Biogas
  project
• EERC two-stage anaerobic digester application
• EERC assessment of landfill gas

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Reasons Why Anaerobic Digestion Is Not More Common

• Capital cost
• Return on investment
• Especially with low electricity costs
• Higher value as fertilizer
• Higher rates of return require more skilled
  monitoring (living systems).
• Not always well known that mechanical wastewater
  treatment plants often incorporate anaerobic
  processes into their treatment scheme, as do
  industries.

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What Is Gasification?
Air, Heat, Steam, Oxygen
Thermal Conversion
Product Gas
Gas Conditioning
Fuel
Utilization Boiler/Heat/Engine/ Generator
Residues Charcoal Condensate
Typical Product Gas CO and H2 (1530)
Each Combustibles CH4 (210) Diluents CO2
and N2 (over 50) Contaminants Particulate,
Organics
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Biomass Gasification Applications
Biomass

• Boiler add-on to save solid fuel maintenance or
  offset natural gas
• Other natural gas offsets such as grain drying
• Power generation
• Potential syngas products

Gas Burners
Gasifier
Boiler
Process Steam
Power Generation
CatalyticReactor
Grain Drying
Chemical Products/Fuels
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Keys to Success

• Low capital
• Simplified operation
• Automation
• Robustness
• Market-driven
• Cost-effective feedstock
• Distributed/industrial size
• Low tar and clean emissions
• CO2 sequestration
• Future syngas conversion to liquids potential

EERC 300-kW downdraft biomass gasifier power
plant being commercialized
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Biomass 06

• Trends and Opportunities in Utilizing Biomass
• Renewable Policies and Incentives
• Biodiesel and Ethanol Production
• Biorefinery Chemicals and Products
• Biopower Development for Heating
• Biopower Development for Electricity