Originally published on CleanTechnica
We understand what’s involved in recovering renewable heat from the Earth by deployinggeothermal recovery technologies. Now it’s time to become familiar with another untapped renewable energy resource: wastewater thermal energy.
Sewage happens to be an energy source flowing beneath the surface of almost all modern cities. Not only is it plentiful, it’s free and mostly untapped.
That is, unless you’re Lynn Mueller, CEO of Canada-based International Wastewater Systems (IWS). His company has developed an innovative heat exchange system which recycles heated wastewater and returns it as a heat source.
With a payback that happens over a short time, a growing number of building developers are inquiring after the installation of IWS’s SHARC (sewage heat recovery) and Pirahana systems. IWS offers heat recovery solutions for space and domestic water heating in the winter, as well as for air conditioning systems in summer.
The company also provides engineering assistance, project feasibility assessments, cost estimates, and technical support, as well as third-party energy analysis studies to evaluate the capability of incorporating sewage heat recovery into a project.
“When you think of sewage, you think it’s just a cost for everybody involved to deal with it, but about 30% of the energy in the world ends up going down the sewer pipes every day,” he said in a January 6 interview with MidasLetter. “So our system has developed a cost-effective way to recover that energy. I like to refer to it as the world’s most ultimate renewable energy, because you really use the same energy every day: you use it, it goes down the drain, you recapture it and you use it again.”
This is not a new undertaking for IWS. In 2014, the company announced it had been selected to provide its state-of-the-art sewage heat recovery technology as a component of the Sechelt sewage treatment facility.
At the time, the LEED gold standard Wastewater Treatment Plant was slated to be be the first of its kind in North America. This video shows the SHARC unit being installed at the Sechelt Sewage plant.
Case studies show the SHARC system allows for significant energy and water savings over the life of the plant by recapturing energy that would have otherwise have been wasted and would have just gone down the drain.
About that project, Sechelt Mayor John R. Henderson said, “This will be the largest infrastructure project in the District’s history. The facility will ensure wastewater treatment capacity for Sechelt for the next 20 years (with provision to add capacity incrementally for up to 50 years more!). The facility will meet the highest Provincial standards for water quality, energy efficiency and resource recovery. It will be the first of its kind in North America, giving Sechelt opportunities to demonstrate and market to others.”
How SHARC Works
IWS’ Sewage SHARC uses raw sewage as a medium to produce hot water, heat, and cooling for large residential and commercial buildings. The sewage is used before it gets to the plant, with all of the solids removed. It is put through a heat exchanger and utilized to produce 140°F water for domestic potable use.
Mueller said this process is 500% efficient; every dollar spent gets $5 worth of efficiency. The SHARC system will last for about 30 to 40 years, thereby becoming extremely valuable over its lifespan. In fact, he said buildings can recover the money spent on the systems in three to 10 years.
PIRANHA Retrofit System
In addition to the SHARC, IWS also offers a retrofit version of the technology known as the PIRANHA. While the SHARC is custom-built or constructed with new buildings, Mueller said the PIRANHA is a prepackaged unit that comes in 50-kw-per-hour and 100-kw-per-hour models. This version can easily be put into a building’s mechanical room and have the sewer line looped into it. Mueller said it was originally produced to help the European market improve its energy footprint by 25 percent, something it legally must do with each update of a building.
Mueller’s background in geothermal heat pump technology helped him understand it was possible to use sewage as a source of energy instead of using holes in the ground. IWS has now been at it for five years and marketing its SHARC product for two. In the last two years, IWS has made installations across three continents—Australia, Europe, and North America.
Current Project: Gateway Theater
Richmond, Vancouver, BC: at the Gateway Theater, a 50,000-sq-ft public facility. The city had a carbon-reduction plan in place and needed to reduce the facility’s emissions by 50 tons per year. It chose to use the SHARC, thus becoming the first wastewater recovery system at a public facility in Canada.
“Levi Higgs, the city’s corporate energy manager, told HPAC Engineering that before adopting the SHARC, the city undertook a couple of studies and found there was a large amount of potential for a heat- recovery system at the Gateway. This was attributed to the large pumping system next to the theater. Mueller made a proposal that Higgs called “very cost competitive,” and the city has seen some great savings since the installation in April 2013.
““Right off the bat, we saw about a 30% reduction in our natural– gas use with the SHARC system,” Higgs said. “We did some upgrades at the facility … and those coupled with the SHARC, we were able to push savings to about 45%.””
This YouTube video tour shows some of the Gateway Theater installation.
“We can produce all the domestic hot water without using a gas boiler,” Mueller said to HPAC Engineering. “Cost is comparable to a gas boiler, and it’s more efficient than the best gas boiler on the market. To give you an example, we did a roughly 200-unit building here in Vancouver, B.C. The greenhouse-gas savings amount to about 900 tons of carbon a year, just by cycling that heat from 200 units. We use heat-pump tech to move the heat.”
The infrastructure may be pricey, but the ROI is fabulous.
Images and video via IWS