Waste-To-Energy Plant

Aerial viewOur waste-to-energy plant, next door to the recycling facility on Blueberry Road, receives trash identified as un-recyclable and converts it at 2000 degrees Fahrenheit to energy in the form of electricity. The ecomaine Waste-To-Energy (WTE) plant processes about 175,000 tons of trash a year and, from that process, generates enough steam to create about 100,000 to 110,000 megawatt-hours of electricity annually — enough to power about 14,000 homes for a year! That’s enough electricity for all the homes in both South Portland and Gorham! The revenue from the sale of electric power in FY 2012 was $3.7 million.

Converting the trash to energy also benefits the communities we serve by reducing its volume by 90 percent, leaving only ash to be stored at the landfill site. (There are also statewide economic benefits from WTE plants; click here to read the results of a Maine study.)

ecomaine‘s state-of-the-art WTE plant opened in 1989 and operates around the clock, every day of the year, with the exception of an annual two-week shut down for planned maintenance. The building was designed with negative pressure to trap any odors inside and to re-circulate that air for boiler combustion. Because the air is filtered, office space for ecomaine staff is also located in the same building.

The emissions monitoring and control devices in place at ecomaine are second to none. Some of the devices we use to make sure our air is clean include an electrostatic precipitator and expensive injections of carbon, urea, and lime slurry. The effectiveness of these methods is carefully measured by staff and by independent specialists. Our efforts have been so successful that in 2002 the ecomaine WTE plant earned ISO (International Standards for Operation) 14001 certification for excellence in environmental management. To retain this certification, ecomaine has passed and continues to pass additional detailed examinations every six months. ecomaine was the first municipally owned waste management site in the nation to pass the rigorous examination.

In 2012, ecomaine also earned the OHSAS 18001 certification for health and safety excellence in the workplace. This was accomplished – and is renewed – using an almost identical system of rigorous examinations as in the ISO 14001 certification.

Waste-to-energy process diagram

Download process diagram (PDF 41KB)

WTE Revenue Chart /// WTE Tonnage Chart

Trash is collected by municipalities and independent haulers and, then, brought to the ecomaine plant at 64 Blueberry Road in Portland. Each truck bringing in trash is weighed at the scale house as it enters the facility and weighed a second time as it exits, empty; the difference is the net weight. The price per ton paid to ecomaine is applied to the net weight.

Trucks stop at the scale house and then enter the enormous garage area, known as the “tipping hall”, and back-up to one of seven bays in order to unload the collected trash into the holding “pit” or “bunker,” an enclosed seven story temporary storage area. A large indoor crane then continuously feeds that trash into each of our two boilers; this system operates around the clock, picking up two tons of material each time the claw is dropped into the pit.

Environmental Concerns

Though fiscal responsibility is certainly a priority to ecomaine, profit is not. The 21 communities that own and operate ecomaine are charged with making decisions that will best serve their residents for generations to come – and environmental stewardship is a high priority.

To minimize emissions, ecomaine has turned to public education and applied science-based systems. We have created printed materials, website pages with detailed information, educational presentations, and issued informational news releases to educate the public about the proper and legal methods for disposing of materials that cannot be converted to energy, such as medications, medical waste and chemicals, etc. To mitigate emissions from the small amount of hazardous materials that do make their way into the waste stream, ecomaine employs several state-of-the-art systems, such as urea injections, static particle precipitators, carbon injections, and lime slurry injections.

Though illegal for several years, many people continue to throw mercury-containing items (old thermometers, thermostats, florescent lights, etc.) in with their household waste, causing ecomaine to handle any clean-up problems through emissions control. Despite this situation, ecomaine has managed to eliminate about 90% of the mercury emissions.

Another factor in assessing the environmental impact of any waste-to-energy plant is its method of handling trash prior before the conversion process. ecomaine converts whole waste, without any front-end or pre-conversion processing. Without any prior processing of the trash, stack monitoring devices are able to record all emissions; virtually everything that enters the plant is accounted for.

By contrast, a front-end processing plant first shreds all waste, causing breakage and releases many pollutants before it reaches the boiler. These pollutants are not captured physically, nor are they captured in monitoring data. Comparing emission records from front-end processing plants to those of a mass-conversion facility like ecomaine is both misleading and inaccurate.

Proof of Environmental Excellence

Wire towerOur efforts have been and are successful. ecomaine was the first public waste-to-energy plant in the country to earn the International Standards Organization’s (ISO) 14001 certification for excellence in environmental management. ecomaine achieved this goal in 2002 and has successfully passed rigorous reviews every six months since then by ISO regulators. This highly regarded certification also applies to ecomaine‘s recycling facility and landfill/ashfill – a rare achievement.

The 7,500 member Solid Waste Association of North America (SWANA) named ecomaine the winner of its 2006 Waste-To-Energy Silver Excellence Award.

In 2009, ecomaine’s waste-to-energy plant was named by the American Society of Mechanical Engineers (ASME) as Small Combustion Facility of the Year. The award was based on success in several categories, including innovative and technical contributions to solid waste processing, environmental performance, and health and safety records.

The owner-municipalities of ecomaine invite you to visit this and any other of our facilities to see our environmentally conscious operations for yourself. Contact Shelley Dunn at dunn@ecomaine.org or 207-773-1738