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Landfill Gas and Alternative Fuels
Posted By Jon Ellenbogen On December 7, 2009 @ 9:40 am In Ceramics Monthly Master Class,Daily,Gas Kiln Firing | No Comments
Engineering studies have predicted about twenty years of gas production from a typical landfill. For a project such as EnergyXchange, the savings in fuel costs for the resident artists and greenhouse activities at the site could total approximately $2 million. Naturally, the majority of this is attributable to the high energy demands of the glass studio.
Significant cost savings can be realized by potters without access to a landfill through a variety of strategies and fuel choices. These can be divided into categories and discussed in terms of benefits and difficulties. Solid fuels are difficult, liquid fuels are moderate, and gases are easier.
Besides traditional wood firing, numerous attempts have been made to use sawdust to fuel kilns. This fuel occupies large volumes, needs to be delivered to the site of the kiln, must be kept dry, and has to be fed to the firebox in a continuous and controlled manner. It’s the delivery system to the firebox that generally proves to be difficult. Professor Lowell Baker at the University of Alabama Art Department has developed a sawdust injection system. Information is available on his research page at http://bama.ua.edu/~wbaker/Main. Another source of information is the book Handbook of Homemade Power, published by Mother Earth News, and available on Amazon.com.
Many potters are utilizing a variety of liquid fuels such as french fry oil from restaurants, crankcase drain oil from automobiles and home heating oil. The simplest configurations can be described as drip systems, in which one of these liquids is dripped in a fine stream directly into a propane or natural gas burner flame, thus boosting the heat delivered to the kiln. Such systems are simple and inexpensive to build but require constant monitoring during use. Combustion is incomplete (possibly good for reduction firings) and therefore likely to contribute to global warming and cause some air pollution. Burning crankcase drain oil likely presents environmental hazards and cannot be recommended.
For efficient burning, liquid fuels must be precisely atomized and require complex mechanical pump-driven burner systems. Bakersville, North Carolina, potter Kent McLaughlin, among others, is successfully using an electrically driven mechanical burner to supplement a propane-fired Cone 10 reduction kiln with fry oil he collects from area restaurants (see “French Fried Pots“). Fry oil must be gathered, screened and preheated before it can be used in a pressure burner system. Though it is “free” right now, supplies will become squeezed as biodiesel fuel becomes more common.
Manufactured gaseous fuels remain the most practical for potters. Propane and natural gas are simple to store and to deliver, burn efficiently with inexpensive burner systems, and are generally trouble free. Renewable gaseous fuels, with landfill gas being only one source, present greater challenges. Composters can be constructed on almost any scale and the resulting gas utilized much like landfill gas, with the major challenge being the complexity of collecting compostable materials on a sufficiently large scale and the difficulty storing such gas production. Currently only municipalities can deal with composting on a scale sufficient to result in usable gas production.
Other Cost-Saving Strategies
Many studies have shown that lowering the firing temperature of a typical glaze firing from Cone 10 to Cone 5 could save 25-35% in fuel costs while reducing the impact on the planet. Consequently, such an adjustment would be both a socially responsible and economical choice.
Heat recuperation is another approach to fuel savings. This involves a heat exchanger built into the flue or chimney of a kiln to use the heat of the escaping flue gases to preheat the combustion air. Such processes are widely used in industry but not normally considered by studio artists. Interesting work is currently underway in Hawaii by glass artist Hugh Jenkins (check out a diagram of his volcano kiln heat recuperation). Since propane in Hawaii currently costs $3.20 per gallon the incentives for recuperation are obvious.
If you are interested in starting a landfill partnership project in your area, visit the Environmental Protection Agency’s Landfill Methane Outreach Program website at www.epa.gov/lmop.
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