Jun 17, 2015 - By Eric Blom, Staff WriterGFS making dual-fuel conversion on some globe's biggest trucks
One Florida company is showing how two Wyoming energy products can work better together.
The company, GFS Corp., has been converting haul trucks at Powder River Basin coal mines to run on liquified natural gas as well as diesel.
"The bottom line is it's fuel savings," GFS vice president of operations Kerry Hackney said.
After their conversion, the trucks run on both fuels at once.
"When our system is operational you're running on both fuels," Hackney said. "If the LNG runs out, or our system fails, it automatically converts to diesel only."
He said it takes 1.7 gallons of natural gas to replace 1 gallon of diesel, but natural gas has been cheap enough recently that companies can still come out ahead.
The amount of savings depends on price difference between the fuels and the life of the truck, Hackney said.
GFS has a background in converting stationary diesel power generators and train locomotives to run partially on natural gas, but the company now has developed a method of converting large trucks as well.
"This isn't something new from the engine side," Hackney said. "It's new that it's on the mine truck."
GFS's first truck conversion was in the Power River Basin with a pilot program converting three Caterpillar 793 haul trucks, which are 240-ton class trucks, for Alpha Coal West in 2012. Eventually the coal mining company ordered 13 more conversions.
Since then, the business has expanded.
GFS next received an order from Arch Coal to convert two Komatsu 830 haul trucks, also 240-ton class trucks, Hackney said. Arch also came back wanting more conversions, this time on four Komatsu 930 haul trucks, in the 320-ton class.
GFS is now working on a third order for converting 10 more Komatsu 930s for Arch. Seven went online in late April.
"We're actively engaged with lots of mines around the world but these are the only two that are doing it right now," Hackney said.
A large part of the conversion is fitting a liquified natural gas tank on the haul truck, but the original diesel engine can burn the natural gas.
"It's the exact same engine. There's no modification to the engine itself whatsoever," Hackney said. "We put the natural gas into the air stream right before the turbo chargers."
The main piece of the modification is adding a tank to hold the natural gas.
GFS puts a liquified natural gas tank on the upper deck of the Caterpillar trucks. It is more complicated for the Komatsus.
On the Komatsu 830 trucks, GFS replaces the cylindrical 240-gallon hydraulic fluid tank with a rectangular one that also contains a cryogenic compartment for natural gas. To keep the gas liquified, the tank is kept at W22;260 degrees Fahrenheit.
The company switches out the diesel tank on Komatsu 930. GFS replaces the original 1,200-gallon tank with one that holds 1,200 gallons of diesel along with natural gas.
The so-called bi-fuel trucks use more natural gas when they work harder, either carrying a load or going up hill. So how much natural gas it uses in place of diesel fuel, and in turn how much it saves in fuel costs, depends on the mine it operates in, Hackney said.
On average, however, he believes about 70 percent to 75 percent of the haul trucks' power comes from natural gas, the balance being from diesel.
Diesel is cheap now, making bi-fuel conversions less advantageous, Hackney said, but he still thinks the future is bright for his company.
"Right now in the current diesel environment the value proposition isn't as good as it was, but everyone doesn't believe diesel prices are going to stay where they are," he said. "They're going to go back up."
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