Can you answer these questions?

•  From where and how do we collect methane gas?
•  Why is methane not a sustainable energy source? Why do some people continue to favor its use?
•  What are the advantages and disadvantages of using methane energy?

Join us on the field trip to find out!

Your bags of domestic trash may generate electricity! Wow! When your trash is piled with everyone else's trash at the landfill it is covered for a long period of time with no oxygen (anaerobic). The decomposition of the organic parts in this trash will produce gases. In most cases these gases are 50% or more methane.

Methane is a colorless, odorless, flammable hydrocarbon gas. A hydrocarbon is an organic compound containing only carbons and hydrogens. As organic matter anaerobically decays, methane gas and carbon dioxide are given off. Methane is also produced in such places as the bottom of marshes and reservoirs, mines, manure piles, and landfills. It is also emitted from rice fields, leaky natural gas distribution systems, and from the incomplete combustion of burning wood. Changes in temperature and moisture affect the quantity and quality of the methane gas. When present in the atmosphere, methane contributes to local smog and acts as a greenhouse gas, blocking the earth's radiant heat from escaping and thus raising the atmospheric temperature. According to Boyle (2004), methane is a greenhouse gas which is 30 times more potent than carbon dioxide, the gas most accused of increasing global warming. As of 1996 the US Environmental Protection Agency (EPA) requires landfills of certain sizes to collect and burn the methane emissions in order to reduce their presence in the atmosphere (EnviroGen 2004). Methane also presents health and safety hazards at landfills because it is a volatile gas that is easily ignited and can be explosive. Burning the methane reduces the incidences of potentially explosive pockets of gas within the landfill.

Instead of collecting and burning the methane gas, it is becoming more common to burn that methane to generate electricity. Methane does not require extensive processing to be ready to burn. It is an energy source that can significantly contribute to our electricity supplies, reducing the need to generate electricity from non-renewable sources. Although the production of methane gas at any landfill will eventually stop once the decomposition of all the organic waste is complete, it is a very reliable source because it is produced 24 hours a day, 365 days a year. Additionally, some small electric generation plants at landfills can be dismantled and moved to other sites when the existing supply of methane diminishes.

Landfill and coalmine gases are NOT renewable energy sources and are actually products of unsustainable activities. Also, combustion (burning) of landfill and coalmine gases releases toxins into the atmosphere. Therefore these are not considered sustainable energy sources. However, they are discussed here because those sources do currently exist and it is worthwhile to collect the methane for electricity generation until those sources of methane are no longer present in our society.

Here we discuss 3 possible sources of methane gas: landfills, coal mines, and farms.

Landfill Methane
Methane gas electric generation plants are being erected at landfills all across the country. One project in Ann Arbor, Michigan “removes 0.9 million cubic feet of methane per day and provides electricity for more than 1,600 homes” by producing 591 megawatts (MW) of electricity (ICMA 2002). Along with the elimination of methane, the Ann Arbor project has eliminated 125,000 tons of carbon dioxide since it started capturing methane in 1996. Three landfill generators run by Kentucky's Touchstone Energy cooperatives will soon be generating over 10 MWs of electricity, supplying the needs of 8,000 homes (Wolfe 2003). “According to E.P.A. estimates, if a 3 MW landfill gas electricity project starts up at a landfill with previously uncontrolled landfill gas, the project would have a direct methane reduction of approximately 6,000 tons per year" (EnviroGen, 2004, paragraph 7). This would be equivalent to removing the emissions from 28,000 cars, planting 38,000 acres of forest, or eliminating 630 coal-powered railroad cars (EnviroGen).

Coal Mine Methane
The Coalbed Methane Outreach Program (CMOP) is a U.S. Environmental Protection Agency voluntary program whose goal is to reduce methane emissions from coalmines. Their mission is to promote recovery and use of coalmine methane by working with coal companies and other related industries. Recovery of methane from coalmines can be done in advance, during, or after mining.

Degasification is a process used in advance of mining. In years prior to mining, vertical or horizontal boreholes are drilled into the underground coal seam to drain the methane gas, as shown below.

adapted from: www.epa.gov/coalbed/about.htm

The methane retrieved in this manner is very high quality (not containing other gases) and is acceptable to be piped into natural gas pipelines for domestic use. After the coal has been extracted the columns that were left for support of roof and walls are collapsed, filling the mine with debris called gob . Methane released into the mine as a result of this operation is called gob gas . Again, vertical and horizontal wells can be drilled to recover this gas. Initially this gob gas is of high quality. However, as the gas mixes with the surrounding air, the quality declines. This type of gas is a good choice for electric power generation and heating applications because they permit more variation in quality of gas than other applications (US EPA 2004).

Farm Methane
Unless you have worked with large quantities of animal manure you probably do not appreciate the meaning of farm methane. Farm methane is a continuous source. “Animals make manure while the sun doesn't shine, the wind doesn't blow and when there is not enough rain” ((L.T. Goodlife Publishing Company, Inc. 2004). Methane digesters use anaerobic bacteria to decomposes the manure. The resulting methane is called biogas. Biogas can be burned in internal combustion engines that turn turbines that produce electricity. After the methane has been removed, the remaining organic material from the manure can be used as fertilizer. Farm methane is very beneficial because it captures methane that would otherwise be released into the atmosphere. Collecting this methane kills pathogens, reduces farm odors, reduces fly reproduction, kills weed seeds, improves manure manageability, and simultaneously produces domestic renewable energy (L.T. Goodlife Publishing Company, Inc. 2004).


 
 
 
   
   
 

Our objectives for this field trip are to:

  1. learn specifics about the methane to electricity process at the Lakeview landfill
  2. learn how electricity is made from methane gas
  3. learn the advantages and disadvantages of methane electricity generation

 

 
 
 
   
   
 

We will visit the Lakeview Landfill in Erie, Pennsylvania. Methane collection at the Erie landfill started in May 1997.

There are three companies involved. Installation and operation is a joint effort between Caterpiller, who owns and installs the equipment, and Waste Management, who is in charge of the landfill gas production. Bioenergy Partners operates the electric generation system that turns methane into electricity.

 

 
 
 
   
   



Landfill Methane Gas

Our first stop will be at a reclaimed landfill. This is a landfill that has reached capacity and thus is completely covered with dirt. You will see tall grass on the site. You will see that a pipe has been placed down into the trash layer below ground to allow the gases to be collected above ground. Inside a processing plant, where the landfill gas is purified, you will learn about the chemical composition of landfill gas and see some of the technology required for purification and monitoring of the landfill gases.


 

 

Sequestering and Electricity Generation

Gas escaping from a landfill is a mixture of methane and other gases. These gases have negative safety and environmental effects. For these reasons, instead of allowing the gases to escape into the atmosphere, laws permit the gases to be burned off or burned to generate electricity. On this field trip you will learn that there are two different methods of sequestering the gases and two different methods of generating electricity from the purified gas.



Special thanks to the National Renewable Energy Laboratory (NREL)
for permission to use their photographs in the making of this video.

 

 

Heat for Goddard Space Center

Goddard Space Flight Center (GSFC) in Greenbelt, Maryland uses landfill methane from Prince George's County Sandy Hill landfill to heat 31 buildings at the Center. Texas-based Toro Energy built and operates the processing plant. Construction of the plant and the five mile pipeline was completed at no cost to the United States government. As a matter of fact, the process is expected to “save taxpayers more than $3.5 million over the next decade in fuel costs” (US EPA 2004).

The animation below depicts the GSFC's Landfill gas process.
from: Goddard Space Flight Center (NASA)


 

Advantages:

  • prevents the release of two greenhouse gases (methane and carbon dioxide) into the atmosphere
  • reliable source because it is generated 24 hours a day, every day of the year
  • reduces demand on fossil fuel and nuclear energy
  • reduces our country's economic dependence on fossil fuels

Disadvantages:

  • the non-methane portion of landfill gas consists of many compounds that are toxic. These are released into the atmosphere
  • methane gas production is a result of unsustainable activities
  • generation plants have to be moved when the gas is no longer produced at the site
  • discourages solutions to overwhelming waste problems

 

 

 
 
   
   
 

Methane present in the atmosphere as a result of landfills, manure, or coal mining activities, is a health and environmental hazard. When compared molecule to molecule, methane is a more potent greenhouse gas than carbon dioxide. It contributes to unhealthy smog over cities and presents safety hazards when it accumulates in underground pockets. From a health, environmental, and economic perspective it makes good sense to use this gas for a purposeful objective. Methane recovered from landfills, coalmines, and farm manure can generate electricity and, in some cases, supply gas that can be burned to heat buildings. Although methane is a much cleaner form of energy than coal or oil, landfill and coalmine methane are not renewable energy sources and are actually products of unsustainable activities. Therefore these sources are not considered sustainable energy sources. However since these sources of methane currently exist, it is worthwhile to collect the methane until those sources of methane are no longer present in our society. Farm methane is a renewable energy source because it is a natural byproduct of animal manure. This makes it a good source of renewable energy.


Recall our earlier questions:

•  From where and how do we collect methane gas?
•  Why is methane not a sustainable energy source? Why do some people continue to favor its use?
•  What are the advantages and disadvantages of using methane energy?

If you can't answer these, review the field trip again.



 
 
 
   
   
 

World Wide Web
National Renewable Energy Laboratory www.nrel.gov

U.S. Department of Energy www.eere.energy.gov

Energy for Keeps: Electricity from Renewable Energy. An Illustrated Guide for Everyone Who Uses Electricity. 2003. By Educators for the Environment, Tiburon California. www.energyforkeeps.org

Fuel Cells 2000 www.fuelcells.org

Sustainable Energy Coalition: Find an Expert www.sustainableenergy.org/experts.htm

U.S. Office of Energy Efficiency and Renewable Energy: Education Site. 2001. Operated by Midwest Research Institute www.eere.energy.gov/education

CREST Renewable Energy Educational Module solstice.crest.org

 
   
 

Special thanks to Melaney Williams, Community Relations Specialist for Waste Management at the Erie Landfill, for all her help obtaining a video and permission for us to use it, and for her generous informational support. Also special thanks to Tim Malesiewski, Technical Manager for Waste Management at the Erie Landfill, for the information he provided.

Boyle, Godfrey 2004. Renewable Energy Power For A Sustainable Future. Second edition. Oxford University Press Inc., New York.

EnviroGen. 2004. Use Renewable Energy for a Cleaner Future. EnviroGen...Your Green Energy Supplier. www.envirogen.net/aternative-energy-green-portfolio.html

International City/County Management Association. 2002. Landfill Methane Gas Project. Ann Arbor, Michigan www1.icma.org/main/sc.asp

L.T. Goodlife Publishing Company, Inc. Retreieved April 2004. www.rcmdigesters.com P.O. Box 1943 Ossining, NY 10562.

NASA (retrieved April 2004). Top Story Goddard Space Flight Center. www.gsfc.nasa.gov/topstory/2003/0508landfill.html.

U.S. Department of Environmental Protection. (retrieved April 2004). Coalbed Methane Outreach Program. www.epa.gov/coalbed/about.htm

Wolfe, Bill. 2003. Power plants ready to use methane from 3 landfills. The Courier Journal Louisville, Kentucky www.courier-journal.com/business/news2003/09/03/biz-front-landfill03-8844.html

Video clips are from:
Goddard Space Flight Center (NASA) www.gsfc.nasa.gov/index.html

Photographs from the National Renewable Energy Laboratory (NREL) www.nrel.gov/data/pix/pix.html. Video created by Deets, Majerik and Torgerson.

Renewable Power: Earth's Clean Energy Destiny. Courtesy of Hydrogen 2000, Inc
. www.hydrogen2000.com

 

 
 
 
 

 

Created by Lola Deets, Carla Torgerson, and Chris Majerik
Last updated March 6, 2006
© 2006 The Pennsylvania State University