Landfill Gas Utilization

Hayley EberlyDepartment of Chemical EngineeringThe University of Texas at Austin C, 2007

BASF, 2007

Agenda

Landfill Gas Overview Environmental Effects of Landfill Gas Life of Landfill Gas Landfill Gas Utilization Technological Changes Potential Problems Questions

Flare Image, n.d.

Landfill Gas Composition

Landfill Gas (LFG) Overview

1 million tons of waste produces 432,000 ft3/day of LFG

Produced by Bacterial decomposition Volatilization Chemical reactions

Composed of different gases Heating value of 500 BTU/SCF

Half the heating value of natural gas

Edgar, n.d.Landfill Gas Primer, n.d.

Environmental Effects

Landfills are the 2nd largest human source of methane Represent 23 % of all methane produced Methane absorbs 20X more infrared radiation by weight than CO2

LFG releases carbon dioxide Landfill gas also contains…

Volatile organic compounds (VOC) Contribute to ozone formation

Hazardous air pollutants (HAP) Affect human health when exposed

Frequently Asked Questions, 2008

Landfill gas is piped to a plant and partially displaces natural gas usage.

Life of Landfill Gas

Methane Generated From, 2008

Trash is delivered to landfill.

The waste decomposes and produces landfill gas.

Landfill Gas Utilization

Cheaper than natural gas Refineries and petrochemical

plants account for 14% of the natural gas used as fuel by industry in the U.S.

Significantly reduces the amount of carbon dioxide and methane released into the atmosphere by landfills

Can reduce NOx emissions when mixed with methane

No equipment changes downstream from burner

Edgar, n.d.Landfill Gas Direct, 2005

Schematic of LFG System

Technological Changes

Install separate fuel train and gas spuds for LFG

Dual fuel - fed by separate gas lines that connect at an intake flow regulator valve

Larger valve openings for higher volumetric flow

Maintain natural gas fuel train and gas ring

Replace internal parts with corrosion-resistant materials

Treat LFG before entering boilerto avoid condensation and corrosion

Edgar, n.d.Uses in Industry, 2004

Schematic of a Natural Gas Co-fired Boiler

Potential Problems

Adiabatic flame temperature (AFT) Natural gas – 2300 K Landfill gas – 2100 K 50/50 mixture – 2200 K

Flame stability and burning velocity With good mixing in the combustor, LFG has comparable stability to methane Install UV sensors

Stable zone of combustion Smaller for LFG than methane Must ensure constant heating value or mix with methane

Corrosion Use corrosion-resistant materials Maintain temperature above dew point of corrosive materials

Preheat combustion air Insulate the stack

Edgar, n.d.

References

BASF. (2007). Retrieved November 22, 2008, from Linde Engineering Web site:http://www.linde-india.com/customerreference/FrmPlantDetail.aspx?CatId=11&&Iid=5

C, C. M. (2007, October 30). The Macho Response. Message posted tohttp://themachoresponse.blogspot.com/2007/10/bully-for-you.h

Edgar, T. F. (n.d.). Evaluation of Environmental Emissions for Combustion of Landfill Gas in a Texas Petrochemical Plant. Retrieved from University of Texas Web site: http://texasiof.ces.utexas.edu/PDF/Reports/FINAL%208%2019%20Landfill

%20Gas %20Feasiblity%20Analysis.pdf Frequently Asked Questions About Landfill Gas and How It Affects Public Health, Safety, and the Environment . (2008, July 2).

Retrieved November 23, 2008, from U.S. Environmental Protection Agency Web site: http://www.epa.gov/lmop/faq-3.htm

Landfill Gas Primer - An Overview for Environmental Health Professionals [U.S. Department of Health and Human Services]. (n.d.). Retrieved November 23, 2008, from http://www.atsdr.cdc.gov/hac/landfill/html/ch2.htm

An Overview of Landfill Gas Energy in the United States. (2008, June). Retrieved November 18, 2008, from U.S. Environmental Protection Agency Web site: http://www.epa.gov/lmop/docs/overview.pdf

Flare Image. (n.d.). Retrieved November 24, 2008, from State Energy Conservation Office Web site: http://www.seco.cpa.state.tx.us/re_biomass-urban.htm

Methane generated from Sioux Falls Regional Landfill to provide energy for POET ethanol plant. (2008). Retrieved November 23, 2008, from POET Web site: http://www.poet.com/news/showRelease.asp?id=115

Landfill Gas Direct Use. (2005, May 6). Retrieved November 24, 2008, from U.S. Environmental Protection Agency Web site: http://www.epa.gov/stateply/documents/events/may2005/hildreth0505.pdf

Uses in Industry. (2004). Retrieved November 24, 2008, from http://www.naturalgas.org/overview/uses_industry.asp

Questions

Additional Slides

Modern Sanitary Landfill

An Overview of Landfill, 2008

Production phases of typical landfill gas