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Oahu homes are getting power from poop.
Since it began full operations May 12, a special intake station at Oahu’s waste-to-energy facility, HPOWER, has been producing additional power for Oahu’s homes with processed sewage known as sludge.
The sludge is added to the garbage burned at the city-owned plant to create additional energy. Mixing in the sludge has allowed the facility to process more garbage, increasing HPOWER’s energy production, said Lori Kahikina, director of the city Department of Environmental Services.
"With the additional sludge and bulky (waste), we generate 14,000 megawatt-hours of additional energy, resulting in $2.3 million in additional revenue to the city and enough to power up 6,500 homes," Kahikina said.
The intake station has the capacity to process 90 tons of sludge each day — adding to the 2,160 tons of garbage per day the entire plant processes.
HPOWER said it has taken steps to manage the smells that can come from its new energy source.
"Sludge is able to be received, stored and metered into the Mass Burn Boiler in a manner designed to manage odors by drawing them into the boiler through a biofilter, while feeding into the waste feed chute to avoid exposure. The odor control system is an enclosed system that provides negative pressure, preventing the sludge odors from escaping," said Markus Owens, spokesman for the city Department of Environmental Services.
The sludge is collected from seven of the nine county wastewater treatment plants and sent to the waste-to-energy facility at Campbell Industrial Park. Before the injection station was installed, the 20,000 tons of wastewater sludge HPOWER is using was taken to the Waimanalo Gulch Sanitary Landfill.
Trucks haul the sludge from the plants to the receiving station at HPOWER, and it is mixed with garbage.
"Sludge is like a mud-cake consistency," Kahikina said. "The sludge cannot just be dumped into the pit because it cannot be easily picked up with the grapple claw. We have to mix it with our bulky waste."
The total capacity of HPOWER is 88 megawatts, but the power producer only is on contract to send 73 megawatts to Hawaiian Electric Co., after using 15 megawatts to run the plant.
HPOWER sells its electricity to HECO for about 20 cents per kilowatt-hour under a 20-year power purchase deal with the utility.
After eight months of construction, Mayor Kirk Caldwell dedicated the $10 million sludge station in April.
The plant had been testing 60 tons of waste per day until May when it began full operations and increased the total waste it processes daily to 90 tons.
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