BURNABY, B.C.—According to the U.S. Department of Energy, 400 billion KW of hot water goes down the drain annually in the United States—roughly $40 billion worth of energy at an average cost of $.10/KW. A great deal of that energy loss occurs in hotels—where energy is uncaptured from greywater from showers and baths, sinks, dishwashers, laundry, etc. Energy is also lost in the blackwater coming from toilets. One company, International Wastewater Systems, has developed a system it calls SHARC (which stands for sewer heat recovery) to capture and reuse heat that typically is lost to the sewage system.
International Wastewater Systems, based in Burnaby, B.C., has installed its SHARC system in several buildings, including a 172-unit condominium complex in Vancouver, B.C. While International Wastewater Systems has not yet installed SHARC in a hotel, company founder and president, Lynn Mueller, said the system is ideal for a hotel building.
Green Lodging News asked Mueller how his system works and what equipment is required.
“A wastewater heat recovery system can be installed in a hotel much like any residential building,” Mueller said. “The equipment involved is modular and includes SHARC filtration and heat exchanger units, heat pump(s), pumps and piping that connects each module. Also required is a wastewater storage tank to ensure that energy is available when it is needed. The system has a control panel which is the brain that runs the system, and it has remote monitoring capabilities so that the status of the system can be observed from anywhere in the world.
“Water enters our buildings at approximately 7 degrees Celsius (44 degrees Fahrenheit) and leaves at 20 to 25 degrees Celsius (68 to 77 degrees Fahrenheit),” Mueller added. “Sewage heat recovery captures the heat in water leaving the building and uses it to re-heat hot water tanks and/or the building itself. It can also be used for building cooling. The SHARC is used to temporarily separate out solids, which make up about 2 to 3 percent of our sewage. Then, with the help of a heat exchanger, the heat from the sewer water is transferred into clean water and this warm, clean water supplies heat pumps with the energy required to produce potable hot water. At the end of the cycle, the clear sewer water picks up the solids that were extracted at the start and flushes them back into the municipal sewer system.”
Mueller said approvals are sometimes necessary in the case of a local district energy system which may have governing authority over the sources of energy which may contribute. He said maintenance involves three levels of service routinely performed on a quarterly schedule. The system comes with a two year warranty which includes parts and maintenance under normal operating conditions. After the two year warranty period the annual cost for maintenance varies based on the scale of the system installed.
When asked about cost and expected return on investment, Mueller said the cost varies greatly depending on the size of the system and what is included, in regards to the required equipment and whether this includes heat pumps and a wastewater collection tank.
“It can range anywhere from approximately $200,000 up to in excess of one million dollars,” Mueller said. “The typical return on investment is three to five years, but in some cases can be considered immediate. This would be in the case of an integrated geothermal and sewage heat recovery system. The inclusion of sewage heat recovery greatly reduces the geothermal loop drilling requirements, a costly portion of the geothermal system. The cost of a sewage heat recovery system can be offset by the savings from reduced drilling costs.
“Rebates differ depending on location,” Mueller added. “Some utility companies and municipalities have programs that encourage energy savings through incentives such as density bonuses, in which case a developer will be allowed to build more units than would normally be permitted by the city. Another benefit is the potential LEED points that a sewage heat recovery system achieves.”
A 60-unit condo development in North Vancouver, B.C., was able to achieve a LEED Platinum rating thanks in part to the SHARC system. The development experienced a 75 percent reduction in energy used for water heating.
Mueller said his company’s SHARC system is good for the environment. “It can eliminate the dependency on fossil fuel energy sources,” he said. “A typical building relies on natural gas for hot water production and heating while both of these tasks can be taken on by a sewage heat recovery system. This means significant carbon dioxide and other greenhouse gas emission reductions. There can also considerable water savings involved with the implementation of a sewage heat recovery system, in comparison with traditional technologies.
Click here to learn more about International Wastewater Systems’ wastewater heat recovery system.
Glenn Hasek can be reached at [email protected].
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