Waste not, want not: Sewer gas may be fuel
A clean energy proposal by Grand Junction officials has all the makings of a public relations sensation.
Methane currently flaring off at the Persigo Wastewater Treatment Plant could be cleaned up, piped down Riverside Parkway, converted into compressed natural gas and used to fuel the city’s fleet.
The cost savings: thousands of dollars a year.
The reduction in air pollutants: tons.
“When we do this, there’s going to be a spotlight on Grand Junction,” said Jay Valentine, internal services manager for Grand Junction.
City leaders have been batting around the idea for years, initially considering working with Xcel Energy on the project. Xcel is hesitant to combine sewer gas into its natural gas lines, officials said, so leaders now are poised to present a plan to Grand Junction city councilors in January to build their own nearly 5-mile pipeline along Riverside Parkway to shuttle the gas. The cost is estimated at about $1 million and the project could be completed in 2014, said Don Tonello, Persigo’s wastewater systems manager.
Methane is a byproduct of processed sewage. Natural gas is composed mostly of methane.
“It’s exciting,” Tonello said. “It’s the opportunity to save money and do the right thing to save the environment.”
About 400 gallons of methane is burned off at Persigo each day. Roughly 300 gallons of CNG are used each day by the city’s fleet of trash trucks, dump trucks and utility trucks. As more CNG vehicles are purchased, all of Persigo’s gas could be used to fuel vehicles. Persigo also could produce more methane if the demand for the fuel increases, officials said.
Counting Grand Valley Transit busses, there are 18 CNG vehicles that fill up at 10 slow-fill stations at the city shops facility off Riverside Parkway.
On another front, Grand Junction is requesting $200,000 in a Department of Local Affairs grant to help purchase 10 more slow-fill stations and a backup compressor. GVT also is requesting two more CNG-fueled busses through a DOLA grant application. City officials should know in February or March whether their grant request is approved.
Even if the grant doesn’t come through, city officials say they plan to march ahead with efforts to use more CNG vehicles and add more fueling stations.
The city uses the slow-fill stations for its fleet, a process which can take hours.
A single, separate, commercial CNG pump is available for general community use at the site off Riverside Parkway. The infrastructure was created by the city, but the station is operated by Monument Clean Fuels. The station sells about 1,500 to 2,000 gallons of CNG a month, Valentine said. The listed price for a gallon of CNG is currently $2.59.
For each CNG refuse truck the city uses, “it’s as if 325 vehicles were taken off the road,” said Kathy Portner, neighborhood services manager for Grand Junction.
Emissions vary depending on the vehicle, but compared with diesel trucks, CNG trash trucks emit 75 percent less carbon monoxide, 95 percent less particulate matter and 49 percent less nitrogen dioxide and nitric acid, pollutants created by engine combustion.
Using trash trucks that run on CNG is especially helpful for keeping down pollutants because they burn about one to two gallons of fuel a mile. CNG fleet vehicles cost about $40,000 more to purchase than their diesel-fueled counterparts, but the city saves an estimated $10,000 a year using CNG compared to diesel fuel.
“The city has had a CNG Civic for about a year,” Portner said. “We’re starting to look at options for more CNG vehicles. It’s great for our air quality. It’s a drastic reduction in our emissions.”