- THE MAGAZINE
Soaring natural gas prices have increasingly begun affecting the ceramic industry over the past several months. Some ceramic manufacturers have even had to temporarily suspended operations rather than pay the high gas prices and sell their products at a less than desirable margin. Even the recent drop in gas prices hasn’t helped much—in some areas, prices are still double what they were last year, and companies are only expecting the situation to get worse in the future. But what if you didn’t have to worry about high prices and possible service interruptions? What if you could operate as you normally do and be more profitable?
Landfill gas provides the opportunity to do just that. Landfills can free industries from today’s escalating fuel prices and their negative impact on profitability. Several related industries have worked with their suppliers to make design modifications to their burners to support this attractive fuel alternative, and an increasing number of ceramic manufacturers are starting to ask about the viability of using landfill gas in their plant.
What is Landfill Gas?Landfill gas (LFG) is generated from the anaerobic phase of the decomposition of waste products. As landfill waste decomposes, it produces a regenerative build-up of gas, which must be released from underground to prevent a possible fire or explosion. LFG is naturally emitted from landfill sites and is thought to be a contributor to global warming, nuisance odors and smog. Due to its environmental impact and potential hazard, the U.S. Environmental Protection Agency (EPA), under the Clean Air Act, announced new source performance standards and emission guidelines for landfills that received waste after 1987, have greater than 2.5 million metric tons of permitted capacity, and have annual emissions of NMOCs (non-methane organic compounds) greater than 50 metric tons.
At the very least, landfills meeting the EPA’s criteria are required to incinerate the collected gas through a ground flare, but this has been reported to contribute to local pollution. In addition, this scenario does not allow the landfill owner to recover the costs of the collection system. However, landfill gas is approximately 50% methane, a reliable and renewable fuel source—and this methane is fast becoming an additional revenue source for landfills. Many large and smaller landfills not affected by the EPA’s ruling have voluntarily participated in Landfill Gas to Energy programs. Many municipalities generate electricity from landfill gas through internal combustion engines, gas turbines or other means and then sell back any excess electricity to their local utility. Others have opted to supply LFG (after processing) directly to end users who use the gas in various forms of heat processing.
Landfills that have greater than one million metric tons of waste in place, are currently in operation or recently closed, have a waste depth of approximately 40 ft, and have more than 30 acres available for recovery can be cost-effective gas producers for years to come.
How Can I Use LFG in My Plant?Unfortunately, not everyone can take advantage of this regenerative resource. As a general rule, landfills bearing the cost to supply gas outside their premises are limited to a range of approximately five miles from their end user. However, as technology and demand in this field increases, economics may lead to longer distributive ranges. In many cases, an outside contractor who agrees to become the fuel supplier typically undertakes the costs associated with developing the necessary pipeline and processing equipment. Assuming you can take advantage of this resource and do find a landfill gas supplier, what steps should you take in your facility to assure quality production?
Landfill gas is inherently dirty and wet when first extracted from the landfill. Typically, the gas is extracted through a matrix of drilled wells held under vacuum via the intake side of a sufficiently sized blower. It is then filtered by several types of membrane separators, compressed and refrigerated to remove moisture. However, the key for efficient use in ceramic kilns is that it must be cleaned, dewatered and provided at the same consistent pressures as natural gas. Requirements are typically more stringent for ceramic manufacturing compared to other LFG applications because of the need to maintain a controlled high temperature environment.
Modifying your plant to accept landfill gas may require installing a booster pump as the gas enters your facility to ensure constant pressure to your system and eliminate problems with surge. Methane monitors are also suggested to track the consistency of the incoming gas. LFG has only about half of the BTU content of natural gas (~450-550 BTU/cu. ft.), which means that you have to supply approximately twice the volume of LFG to your burners to get the same heat input to your kiln in the same amount of time.
In addition to these modifications, larger capacity burners (or modified burners) may be required. If burners are already oversized, a larger orifice plate will be needed to provide the additional flow. Air demand should remain relatively unchanged since about 10 scf of air are still required to release 1000 BTU. Some commercially available burners* will supply 56M-1.2 MM BTU/hr LFG and have been used successfully in ceramic facilities. These burners are fully capable of burning either LFG or natural gas, or blends of both, and can be switched “on the fly” to avoid kiln shutdowns if one gas supply runs low. For plants that require something larger, perhaps for aggregate or raw material drying, burners that supply ~40 MM-150 MM BTU/hr have supported LFG for years of productive operation.** For these larger burners, a minimum base fuel (oil or natural gas) of 25% is recommended, with LFG making up the balance.
How Much Money Will I Save?How you choose to manage the incoming gas has the greatest bearing on your final cost. However, very conservative estimates put the cost of LFG at 75% that of natural gas, and that number can go much lower depending on your negotiating skills with the LFG provider.
For example, let’s assume that a given tunnel kiln operation produces 65 million building brick per year at an average weight of 4 lb per brick. The kiln averages 1200 BTU/lb. At 1000 BTU/scf natural gas, 312,000 Mcf or 3,120,000 therms would be needed to fire at the required level. Assuming a natural gas rate of $5.50/Mcf (or $0.55/therm), this operation would cost $1,716,000/year. Using LFG at a conservative 25% savings ($0.4125/therm) the final cost would be $1,287,000/yr—a savings of $429,000 annually.
Anyone who has examined kiln modifications within the last few years can agree that with this kind of savings, major improvements with paybacks of less than one year should be easy to sell to upper management. Additionally, most landfills are projected to be gas producers for upwards of 20 years.
A Reliable, Renewable AlternativeLandfill gas is a reliable and renewable fuel alternative. Because it produces little or no sulfur dioxide (SO2) or particulate matter, it is a much cleaner burning fuel than oil or natural gas. Landfill gas also produces less nitrogen oxides (NOx), and less volatile organic compounds during the combustion process.
Collection and distribution to industrial end users provides a win-win-win situation for the provider, user and the environment by producing additional revenue for the supplier, reducing fuel costs to the user and improving air quality. Local industries once tied to uncertain fossil fuel pricing and curtailments can now obtain a long-term, cost-effective fuel source—with fewer environmental consequences.
Editor's NoteFor a case study detailing how a company in the brick industry began using landfill gas, see the January 2000 edition of Ceramic Industry’s Brick & Clay Record, in print or online in the Editorial Archives.
For More InformationFor more information about modifying your kilns to use landfill gas, contact Hauck Manufacturing Co., Box 90, Lebanon, PA 17042; (717) 272-3051; fax (717) 273-9882; e-mail firstname.lastname@example.org; or visit http://www.hauckburner.com.
*Hauck’s RSVG line
**Hauck’s Starjet and Ecostar series
SIDEBAR: Did you know?According to the U.S. EPA, as of June 1999, there were in excess of 270 landfill gas recovery and use projects operational in the U.S. At that time, estimates projected an additional 500 sites prime for gas recovery and use.
Need to know more up-to-date information and find out whether you are near some proposed sites? Visit the EPA’s website at http://www.epa.gov/outreach/lmop. Here you will find a wide variety of information about the Landfill Methane Outreach Program, active and proposed landfill sites by state, and some case studies, as well as contacts by territory.
If you want to know what goes on at the landfill site, the U.S. Army Corps of Engineers wrote a comprehensive technical letter on this topic (ETL1110-1-10) in 1995. This letter is available online at http://www.usace.army.mil/inet/usace-docs/eng-tech-ltrs/etl1110-1-160/toc.html.