DISTRICT ENERGY SYSTEMS POWERED THROUGH THE COMBUSTION OF MUNICIPAL SOLID WASTE Gregg Tomberlin & Brad Moorman Barlow Projects, Inc. 2000 Vermont Drive, Fort Collins, CO 80525 (970) 226-8557 email@example.com ABSTRACT Utilizing garbage as the fuel to power district energy systems makes sense on a number of levels. District Energy systems provide a centralized, efficient means of providing heating and cooling to a community, college campus or local institutions. Waste that is generated locally can be used to provide the fuel to power the district energy system. Fuel costs are predictable and do not fluctuate like natural gas and fuel oil. The waste-to-energy industry has proven itself to be an environmentally friendly solution to the disposal of municipal solid waste and the production of energy. Recovering energy from the waste we throw away is a good idea and Waste-to- Energy facilities can be used to provide a reliable, sustainable source of steam to District Energy systems. Key Words Waste-to-Energy, District Energy, Steam, Garbage, Fuel DISTRICT ENERGY SYSTEMS POWERED THROUGH THE COMBUSTION OF MUNICIPAL SOLID WASTE THE CONCEPT Using local resources to generate heat and energy is as old as gathering wood to burn in the fire to boil water. Yet as humanity has grown more advanced and sophisticated, that hasn’t been necessary. Fuel in the form of natural gas, coal and fuel oils has been readily available and relatively cheap. Regrettably, this reliance on importing these resources has gotten us into a bit of a bind and many governments, municipalities and industries are now looking for alternative means of generating energy. One of those alternative means that utilizes a locally produced, plentiful, sustainable source of fuel is the Waste-to-Energy process. Recovering energy from waste isn’t a new idea either, but it has evolved over the years from the simple incineration of waste in an uncontrolled, environmentally unfriendly way, with very little energy recovery, to the controlled combustion of waste with energy recovery, materials recovery and sophisticated air pollution control equipment insuring that emissions are within US and EU limits.1 This process took over 50 years of development and many improvements in design and technology, but the waste-to-energy industry has now proven itself to be an environmentally friendly solution to the disposal of municipal solid waste and the production of energy. A DUAL SOLUTION Communities considering District Energy or CHP systems may primarily be concerned with the economical generation and distribution of steam, but the majority of communities are also concerned with the disposal of their municipal solid waste. Unfortunately, most never realized they could use a locally generated fuel (garbage) to provide that centralized power. This solution can, in effect, kill two birds with one stone. Modern WTE facilities reduce the volume of incoming municipal solid waste (MSW) by 90%-95% creating energy in the form of steam and/or electricity in the process. Historically, due to the cost of the specialized equipment, only large cities could afford a WTE facility. This has left smaller communities with few waste disposal options and many end up trucking their waste to distant la ndfills at great expense. To meet this need, Barlow Projects has commercialized an innovative combustion system and facility design tailor made for those smaller communities with as little as 150 tons a day of municipal solid waste. As an example of the energy this waste can produce, a 200 ton per day facility could supply approximately 43,000 lbs/hour of saturated steam. This steam could be supplied to a District Energy system at a predictable price and, simultaneously, provide the local area with the capacity to process and dispose of 66,000 tons of garbage every year. The steam can be provided at a price discounted from that of natural gas, or some other fuel, and the tipping fee would be competitive with modern landfills. EXAMPLES OF DISTRICT ENERGY FACILITIES Each of the three WTE facilities currently using the Barlow technology sells Steam as one of its energy products. The Pope-Douglas WTE facility in Alexandria, MN supplies 38,000 lbs/hour of low temperature, low pressure saturated steam to a 3M plant and to the local hospital. This facility burns approximately 80 tons a day of municipal solid waste (garbage) as the fuel to supply this steam. The Harrisonburg, Virginia WTE facility has the capacity to supply 60,000 lbs/hour of steam to the J ames Madison University central heating & cooling system. The Perham WTE facility in Perham, MN supplies 30,000 lbs/hour of steam to a local pet food manufacturer and a creamery. The Harrisburg, Pennsylvania facility, when re-built, will supply an average of 50,000 lbs/hour of steam to the Harrisburg Steam Works and generate 23 MWs of power. Many other WTE facilities around the world, particularly in northern European countries like Norway, Sweden and Finland, are built as CHP systems providing steam to District Energy systems, greenhouses and producing electricity. Steam can be supplied from a WTE facility at whatever temperature and pressure needed by the industry, institution or District Energy system. Condensate returned to the WTE facility can be re- used in the boiler or as cooling water for the condenser. SIZING THE FACILITY Like any power plant, a WTE facility needs a ready supply of fuel and a market for the energy produced. Unlike most power plants, a WTE facility actually charges for the fuel instead of buying the fuel. This is referred to as the tipping fee. This fee is used to cover the operational costs of the facility and usually contributes at least 50% of the revenue. The other source of revenue comes from the sale of energy whether it is steam, electricity or both. Under normal circumstances, the minimum practical size for a modern WTE facility is around 150 tons a day, depending on the BTU value of the fuel, the price the energy can be sold for and the tipping fee. Therefore, a WTE power plant is generally only feasible (economical) for a community that has at least 50,000 tons of waste a year. In the United States a community, or group of communities, with a population of 75,000 would easily generate this much waste. There is no ma ximum limit to the size of a facility as the equipment can be scaled up quite easily and there are WTE facilities in the 1000, 2000 and 3000 ton per day range, but sizing the facility correctly is dependent on the amount of readily available waste. Communities investigating WTE facilities must take this into consideration. Determining the amount of waste available is generally as easy as making a call to the city or county solid waste manager. PUBLIC ACCEPTANCE Public acceptance of a WTE facility is largely dependent upon being able to demonstrate that the facility is safe and an “environmentally friendly” addition to the community. Fortunately, the air pollution control equipment being used is up to the task and modern facilities are meeting stringent new EPA emissions requirements. Additionally, EPA has done exhaustive studies to determine the safe exposure levels of the constituents that could potentially be emitted from a WTE facility and independent studies have determined that the actual amounts emitted do not present a significant threat to human health.2 There are WTE facilities located in the middle of small communities, in large cities, on college campuses and near hospitals. Those who tour WTE facilities are often amazed that no ‘smoke’ is coming out of the stack and that odors are minimal. Public opposition usually comes from well meaning environmentalists that rely on old data and unsound waste management concepts. Concepts like “zero waste” which advocate unrealistic recycling levels. And what about recycling? Can’t we just recycle everything so that there isn’t anything left for landfilling or incineration? Don’t WTE facilities compete with recycling and burn up valuable resources? With all the talk about recycling and the progress that’s been made toward source reduction, composting and other forms of diversion, American’s still send about 130 million tons of garbage to landfills every year.3 Even the most efficient recycling programs are only diverting 50% of the waste stream leaving the other 50% to be managed in some other way. The bottom line is that some forms of waste are just not suitable for recycling because it isn’t economical to do so. By removing those items from the waste stream that can and should be recycled you improve the quality of the fuel and improve the efficiency of the combustion system. This does not mean that we shouldn’t keep trying to manufacture goods in such a way that makes them more amenable to recycling and that we shouldn’t continue to work towards higher diversion rates, but at best, only a portion of the problem is addressed. As a species, we are currently entombing millions of tons of fuel in the earth in the form of refuse that could be used to generate heat or electricity through the WTE process. This fuel has a heating value approaching ½ that of coal.4 Why wouldn’t we take advantage of that? CONCLUSIONS Waste-to-Energy systems and District Energy systems are complimentary to one another. Waste that is generated locally can be used locally to provide the fuel to power a district energy system. The District Energy system provides a centralized, efficient means of supplying heating and cooling to a community, college campus or local institutions. Fuel costs are predictable and do not fluctuate like natural gas and fuel oil and the steam demand is predictable. Recovering energy from the waste we throw away is still a good idea and, despite some misconceptions, Waste-to-Energy is now a clean, reliable, sustainable source of energy, and a common sense alternative to landfilling. Communities, industries or institutions considering District Energy systems should also consider building a WTE facility to provide the steam for that system. References:  Hickman, H. Lanier, “A Brief History of Solid Waste Management During the Last 50 Years”, MSW Management, September/October 2001  Rao, Chaudhuri, Garcia, Stormwind and Ruffle, “Multiple Pathway Health Risk Assessment of a Municipal Waste Resource Recovery Facility in Maryland”, EM, August 2003  U.S. E.P.A. “Municipal Solid Waste in The United States: 2001 Facts and Figures Executive Summary”  ASSURE, “Energy from Waste Fact Sheets”, www.assure.org Biography: Mr. Tomberlin has 21 years of experience in the design of power generation facilities having served in various design and design management roles for one of the largest architectural engineering firms in North America. He holds a Bachelor of Science degree in mechanical engineering. He has been responsible for the management of the Aireal™ combustion technology development, including the prototype and commercial installations. He is responsible for the research & development of all new WTE projects for BPI and advances in the Aireal™ Combustion technology.
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