Colorado Community Benefits From Installing Waste Heat Recovery System

Abstract

The Town of Avon Colorado and the Eagle River Water and Sanitation District have partnered to design, construct, and operate a mechanical “Community Heat Recovery System” which extracts low-grade waste heat from treated wastewater and delivers this heat for beneficial use. Immediate uses include heating of the community swimming pool, melting snow and ice on high pedestrian areas in an urban redevelopment zone in order to improve pedestrian safety, and space heating for project buildings and an adjacent water plant pump station building. Points of use are located within one mile of the treatment plant. The initial system is sized to extract heat from 170 m3/hr (1.08 mgd) of wastewater plant effluent with a 298 kW (400 hp) heat pump. The heat pump will deliver 1,026 kW (3,500,000 BTU/hr) energy to the heat recovery system. A supplemental natural gas boiler provided to meet peak demands will provide an additional 1,026 kW (3,500,000 BTU/hr) energy. The system is expandable allowing the installation of a second heat pump in the future and roof-mounted solar thermal panels. Power for the waste heat recovery system is provided by wind-generated electricity purchased from the local electric utility. The use of wind power with an electric-powered heat pump enables the agencies to fulfill energy needs while also reducing the carbon footprint. The system will achieve a reduction in the temperature of the treated wastewater, which is currently discharged to the Eagle River during low river flow, fish-sensitive periods. The agencies expect to save tax payers and rate payers money as a result of this project as compared to other alternatives or the status quo because it results in a more sustainable long-term operation. At 2008 utility commodities pricing, delivery of heat generated from this system was estimated to cost about one-third less than that from a conventional natural gas boiler system. This facility is the first of its kind in the U.S. and received a “New Energy Community” grant from the State of Colorado. This project shows how local agencies can work cooperatively for mutual benefit to provide infrastructure which accommodates growth and urban renewal and simultaneously demonstrate strong environmental leadership. The potential application of this technology is broad and global. The installed system is expected to cost about $5,000,000; construction will be completed in 2010.

Pathways to Water Sector Decarbonization, Carbon Capture and Utilization

“…The town's largest municipal energy user is the town recreation center, which includes multiple heated pools and about 3700 square meters of heated space. By using waste heat from the wastewater to heat the pools, provide building heat, and to provide salt-free snow melting on town sidewalks, the town reduces effluent temperatures while simultaneously providing a low-cost heat source to offset fossil fuels used in the town facilities (Strehler et al, 2010). The town purchases wind power to offset the electric demand of the heat pump, ensuring the system is zero carbon.…”

Wastewater Heat Extraction for Commercial HVAC Applications: A U.S. Pilot Project

“…The system had a first-stage flow rate of 1003 m 3 /h through a wastewater filtration system and a heat transfer coefficient of 368 W/m 2 K between the building water and the sewage water in a shell-and-tube heat exchanger. A wastewater heat recovery system has been reported to extract heat from 170 m 3 /h of wastewater plant effluent with a 298 kW heat pump in Colorado (Strehler et al, 2010). The heat pump will deliver 1,026 kW of energy to supplement a natural gas boiler heating system.…”