# Presentation: 481413

## Biomass Gasification and Biodigestion

***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

## What’s the Deal About Biogas?

**What’s 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

## Composition of Air

| Component | Symbol | Volume |  |
| --- | --- | --- | --- |
| Nitrogen | N2 | 78.084% | 99.998% |
| Oxygen | O2 | 20.947% |  |
| Argon | Ar | 0.934% |  |
| Carbon Dioxide | CO2 | 0.033% |  |
| Neon | Ne | 18.2 parts per million |  |
| Helium | He | 5.2 parts per million |  |
| Krypton | Kr | 1.1 parts per million |  |
| Sulfur Dioxide | SO2 | 1.0 parts per million |  |
| Methane | CH4 | 2.0 parts per million |  |
| Hydrogen | H2 | 0.5 parts per million |  |
| Nitrous Oxide | N2O | 0.5 parts per million |  |
| Others | Xe, O3, NO2, I2, CO, NH3
That are less than 0.09 ppm |  |  |

- 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.

## CO2 and CH4 Levels

- CO2

- CH4

- Niwot Ridge, U.S.A.

## U.S. Greenhouse Gases

- Carbon Dioxide 66%

- Nitrous Oxide 5%

- CFCs 11%

- Methane 18%

- U.S. EPA, 1990

## U.S. Anthropogenic Methane

- Landfills 36%

- Domestic Livestock 21%

- Livestock Manure 10%

- Other Sources 6%

- Coal Mining 17%

- Natural Gas 10%

## Natural Gas – Average Consumer Price

## What Can We Do About It?

- 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

**New Technologies**

**Marketable Products**

## Two Main Methods to Extract Gas from Biomass 

## 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**

**Notes:**
Lignin from wheat straw, rice straw, various wood residues, barley straw, corn stover

## Biomass Feedstocks

- Hybrid Poplar

- Wheat Straw

- Alfalfa

- Wood Residue

- Sunflower Hulls

- Animal Manure

- Switchgrass

- Beet Tailings

## What Is Anaerobic Digestion?

- Biomass (2%–15% solids)

- Digestion-- AcidThermal Conversion

- Product Gas

- Gas Conditioning

- Utilization
- Boiler/Heat/Engine/ Generator

- Residues
- Fiber Leachate

**Typical Product Gas:**
- Combustibles		CH4 (60%)
- Diluents			CO2 and N2 (40%)
- Contaminants		H2S (0.2%–0.4%)

**Water**; **heat (**35°C, 95°F ); **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

**Fiber Product:** (bedding, compost, etc.)

**Notes:**
Benefits are greenhouse gas reduction, compost, energy, odor control, bedding, bio-hazard control, etc.
Process---1. Acidification Acid-forming bacteria break complex organic wastes down into volatile fatty acids. Proteins are broken down into amino acids and further into volatile fatty acids. Carbohydrates are broken down into simple sugars and then into volatile fatty acids. Fats and oils are broken down to long chain fatty acids and then to volatile fatty acids. 
Acetogenic bacteria use the volatile fatty acids and form acetic, propionic, and lactic acids. In addition, hydrogen and carbon dioxide gas can be released by the acetogenic bacteria. 
2. Methane Production Methane-forming bacteria (methanogens) use acids formed in stage 1 to produce methane. Other bacteria use hydrogen and carbon dioxide produced in stage 1 to form methane. 
Temperature The anaerobic digestion process is carried out by a delicately balanced population of various bacteria. These bacteria can be very sensitive to changes in their environment. Temperature is a prime example. It has been determined that 35 degrees centigrade (95 degrees Fahrenheit) is an ideal temperature for anaerobic digestion. 

## Anaerobic Plug-Flow Digester System Haubenschild Farms Inc., East Central Minnesota

## EERC Developments

**EERC Developments**

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

**Notes:**
Alternative Uses for Waste Potatoes
JR Simplot Company.
Project funding also provided through EERC Red River Water Management Consortium.
As much as 30% of potatoes processed can end up as waste.
Could be over 200,000,000-lb/yr waste stream.
Anaerobic treatment to produce methane gas.
Product gas averaged 44% methane content and a calculated heating value of 440 Btu/ft3.
Estimated 25% of the Grand Forks plant’s process heat could be provided from potato waste conversion to methane.
Estimated payback period of 4.5 years for full-scale implementation.
Recommend continuous-feed pilot-scale studies to develop engineering design and more reliable economic data.
Develop the Basic Landfill Site Parameters
Conduct a preliminary assessment (feasibility study) of the landfill site for gas production, and determine if the proposed gas recovery project will work at this site.
Develop the Basic LFG Characteristics
Use the existing passive well network to develop the gas extraction site plan, sample the gas, and develop a gas quantity and quality profile for the landfill site.
Preliminary gas analysis indicates:
52% methane
47% CO2
520 Btu/scf

Preliminary site profile indicates:
1.5–2 million tons of waste in place
500–600 scfm/day gas production potential
1–2-MW gross power generation potential

## 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.

**Notes:**
A new slide for your presentation. On the question on lack of digester implementation: Many municipalities with mechanical wastewater treatment plants incorporate anaerobic processes into their treatment scheme, as do industries such as American Crystal Sugar, Minnesota Dehydrated Vegetables, Cargill Sweeteners, etc. Widespread utilization of the technologies is not seen in smaller industries (JR Simplot, swine and dairy, ethanol production [Alchem], etc), most likely because of a relatively high capital investment. Many of these operations can get higher rates of return on other investments. Another issue is operations. Anaerobic treatment systems are living systems, and require daily monitoring to ensure optimal performance. This requires trained personnel and many small operations don’t have the time and resources to maintain them properly. The result is a bad name for the technology, which further hinders implementability. Feel free to call and discuss it further.

## What Is Gasification?

- Fuel

- Thermal Conversion

- Product Gas

- Gas Conditioning

- Utilization
- Boiler/Heat/Engine/ Generator

- Residues Charcoal Condensate

**Typical Product Gas:**  CO and H2 (15%–30%) Each
- Combustibles		CH4 (2%–10%)
- Diluents			CO2 and N2 (over 50%)
- Contaminants		Particulate, Organics

- Air, Heat, Steam, Oxygen

## Biomass Gasification Applications

- 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

- Gasifier

- Boiler

- Gas
- Burners

- Biomass

- Process
- Steam

- Grain Drying

- CatalyticReactor

- Power Generation

- Chemical Products/Fuels

## 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*

## 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

- Renewable Policies and Incentives
- Biodiesel and Ethanol Production
- Biorefinery Chemicals and Products
- Biopower Development for Heating
- Biopower Development for Electricity

**Biomass ’06**