001-40_WC_144_SEPT-OCT25_PT - Flipbook - Page 31
WASTEWATER
Water’s Second Life
Markham’s WET project turns wastewater into heating and cooling for
thousands—with major lessons in partnerships and persistence
BY CHARLIE EVANS
Construction Manager, GHD
C
ONSTRUCTION IS NOW UNDERWAY
on the world’s largest wastewater energy transfer (WET) project in Markham, Ontario.
The system, led by Markham District Energy
(MDE), will capture heat from the region’s
wastewater to supply low-carbon heating and cooling
to nearby buildings, helping reduce greenhouse gas
emissions and conserving water. Wastewater energy
transfer is still relatively uncommon in North America, but its promise is significant: it turns waste into
a renewable energy source. By drawing heat from
the sewer system in the winter, facilities can avoid
burning natural gas in MDE’s boilers. In the summer,
discharging excess heat back into the sewer allows for
more efficient cooling than traditional chillers. And
because heat pumps are used instead of cooling towers, water use is significantly reduced.
“The project is well under construction and is
designed for 18.75 megawatts of heating capacity,” says
Peter Ronson, Chief Operating Officer of MDE. “This
is going to be our net capacity out of the facility which
ties reasonably well to the minimum flows through the
sewer. The project can also provide chilled water in the
summer to meet the area’s huge air conditioning load,”
he adds.
Historically, electrically driven centrifugal chillers
have been doing the work. In conventional big chilled
water facilities, or even building sized facilities, it is
necessary to get rid of that heat, typically with evaporative water cooling towers, which end up using a
tremendous amount of water to evaporate the heat out
into the atmosphere. “Because we have the sewer right
beside us, we can dump that heat waste right into the
sewer water and have it go off into the waste treatment
plant. So you’re saving water usage,” explains Ronson.
Charlie Evans is the
Associate Editor of
Water Canada.
WAT E R C A N A D A . N E T
Existing customers are already bene昀椀ting from the reduced greenhouse gas intensity
without needing to take action themselves.
WATER C AN ADA • SEP TEMBER/OCTOBER 2025
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