United States Environmental Protection Agency Research and Development Water Engineering -~^1»" Research Laboratory 't jrj v Cincinnati OH 45268 EPA/600/S2-88/043 Nov. 1988 &EPA Project Summary Alternative Energy Sources for Wastewater Treatment Plants This technology assessment pro- vides an introduction to the use of several alternative energy sources at wastewater treatment plants. This document assumes that the reader has little or no knowledge of the technologies presented. The report contains fact sheets (technical de- scriptions) and data sheets (cost and design information) for the tech- nologies. Cost figures and schematic diagrams of the technologies are included. Case histories of seven treatment plants that have used one or more of the alternative technol- ogies are presented. Based on this assessment the fol- lowing alternative energy technol- ogies appear to be potentially cost effective: 1. Heat pumps which use influent or effluent wastewater as their heat source, for supplying process or building heat 2. Geothermal direct-use systems for large energy loads when geo- thermal source is adequate. 3. Wind power systems for large electrical loads when annual wind flux is adequate. 4. Passive solar systems where they can be cost-effectively integrated into the overall architectural design of a facility. 5. Low-head hydro systems may be appropriate for smaller plants which have an available head greater than three meters. This Project Summary was devel- oped by EPA's Water Engineering Research Laboratory, Cincinnati, OH to announce key findings of the research project that Is fully docu- mented in a separate report of the same title (see Project Report ordering Information at back). Introduction This technology assessment provides an introduction to the use of several alternative energy sources at wastewater treatment plants. This document as- sumes that the reader has little or no knowledge of the following technologies: 1. Heat pumps, 2. Active solar systems for heating and cooling, 3. Photovoltaic systems, 4. Geothermal—direct-use systems, 5. Wind power systems, 6. Low-head hydro systems, 7. Passive solar systems, 8. Geothermal—power generation systems, 9. Fuel cells, and 10. Active solar systems for power generation. For each of these technologies, the report presents a "fact sheet" that contains a description of the technology (including schematic diagrams), the current status of development and applications, design considerations, performance and reliability information, and a reference list. For the first six technologies listed above, simplified design and cost-estimating information is presented in "data sheets". Data collection for the report was done in 1982, therefore, the costs presented ------- should only be used to gauge the relative costs of the various technologies. Current cost information should be obtained from equipment vendors or other current sources for actual cost estimating. 1. Wilton, ME (active solar for process heating, passive solar, and heat pumps), 2. Lake Tapps (Bonney Lake, WA) sewerage project (Low-head hydro), 3. Newport, VT (active solar for process heating), 4. Hillsborough, NH (passive solar), 5. Livingston, MT (wind power), 6. Woodlawn, NY (Southtown plant) (wind power), and 7. Waynesburg-Magnolia, OH (photo- voltaic). Of the seven case histories, only Wilton, ME had been on-line long enough at the time the report was written to have meaningful operating data. Conclusions Heat Pumps Heat pumps are commercially avail- able. The temperature of the alternative energy source is the principal potential technical limitation on the application of these systems in POTW's; however, the use of the wastewater itself as the alternative energy source minimizes the impact of this limitation. The use of influent or effluent wastewater heat pumps is generally cost-effective in comparison to distilled oil, residual oil, and natural gas for supplying process or building heat to the POTW. Active Solar Heating and Cooling Systems Active solar heating and cooling systems are commercially available. The available solar insolation rate and system cost are the principal limitations on the application of these systems in POTW's. Active solar heating and cooling systems are not cost-effective alternatives to the use of conventional energy supplies in POTW's due to the high capital invest- ment. Photovoltaic Systems Photovoltaic systems are commercially available. The available solar insolation rate, system energy conversion effi- ciency, and system cost are the principal limitations on the application of these systems in POTW's. Because of the high initial capital investment, photovoltaic systems are not cost-effective alterna- tives to the use of conventional electrical energy supplies in POTW's. Geotherma/ - Direct Use Systems Geothermal direct use systems are commercially available. Geographical limitations associated with the geo- thermal temperature gradient and available well flow as well as site investigation and well construction costs, are the principal limitations on the application of these systems in POTW's. Geothermal direct use systems appear to be cost-effective in comparison with the use of conventional fuels for satisfying thermal energy loads greater than 108 kJ/d when the geothermal temperature gradient is approximately 45°C/km or greater, and when well flows are of a sufficient magnitude. Locations with geothermal gradients in excess of 45°C/km are predominantly limited to the Rocky Mountain states. Wind Power Systems Wind power systems are commercially available. Geographical limitations associated with the available wind flux regimes as well as overall system costs are the principal limitations on the application of these systems. Wind power systems appear to be cost- effective in comparison with the use of conventional fuels for satisfying energy loads greater than 1,000 kWh/d, when the annual wind flux is approximately 4,000 kWh/yr-m2 or greater. Locations with annual wind flux greater than 4,000 kWh/yr-m2 are predomin- antly limited to areas in the following states: • Maine • Vermont • New Hampshire • New York • Virginia • North Carolina • Kansas • Oklahoma • Colorado • Wyoming • Montana • Idaho • Utah • Nevada • Washington • California Low-Head Hydro Systems Low-head hydro systems are com- mercially available. Geographical limita- tions associated with the available head for these systems and the fraction of the total POTW energy requirements satisfied are the principal limitations on the application of these systems in POTW's. From the standpoint satisfying a significant portion of POTW's electrical requirement, the systems appear to be more approprie for smaller POTW's. The use of the systems should be seriously consider in any application that has an availat head greater than 3 m. Passive Solar Systems Passive solar systems are cor mercially available. These systems ha been used previously to reduce tl consumption of conventional heatir fuels in POTW's, as well as many oth architectural applications. The princip technical limitations of passive sol systems are possible site-specif limitations on available solar insolatk and the integration of the passive syste into the overall architectural pla Potential economic limitations a primarily associated with the increment costs for construction of the passive sol system instead of a convention architectural design. These increment costs must he considered, along with tl amount of alternative energy supplied, ( a case-by-case basis to potential justify the use of a passive solar syste in specific applications. In light of tt rising costs for conventional fuels, the; systems should be seriously consider* in future construction at POTW throughout the United States. Geothermal - Power System Geothermal power systems ai commercially available, however, curre technological limitations on minimu system size, as well as the limite availability of acceptable sites exhibitir the necessary geothermal characteristic will likely prevent the use of thes systems in POTW's. Fuel Cells Fuel cells are not expected to b commercially available until approx mately the year 2000. Active Solar Systems for Powt Generation Active solar systems for powe generation are not expected to b commercially available until the mi 1990's. In addition, these systems ce only use direct sunlight, and, therefor their applications would be primari limited to arid regions of the southwest. The full report was submitted i fulfillment of Contract No. 68-03-305 by Roy F. Weston, Inc., under th sponsorship of the U.S. Environment Protection Agency. ------- This Project Summary was prepared by staff of Roy F. Weston, Inc., West Chester, PA 19380. Francis L Evans was the EPA Project Officer (see below for present contact). The complete report, entitled "Alternative Energy Sources for Wastewater Treat- ment Plants," (Order No. PB 88-239 090/AS; Cost: $21.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 For further information, Donald S. Brown can be contacted at: Water Engineering Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 A Official Business Penalty for Private Use $300 EPA/600/S2-88/043 ------- |