Proponents of natural gas vehicles continue to point to their fuel of choice as a natural option in an effort to reduce unwanted emissions.
Power grids still need to be updated to support battery electric vehicles. But renewable natural gas (RNG) can be produced from waste – delivering a negative carbon intensity score that improves both renewable diesel, biodiesel and electric power, said Eric Bippus, senior commercial director of ‘Hexagon Agility, during a panel discussion at ACT Expo.
The fuel also offers an option for trucks that continue to rely on internal combustion engines, while compressed natural gas (CNG) prices are generally more stable than those associated with a barrel of oil, he said. he adds.
“There is a TCO [total cost of ownership] it’s very attractive, especially now,” Bippus said, referring to today’s diesel prices. And there’s no difference in operating ranges, eliminating a challenge with some alternative fuels that would require more trucks and drivers – resources that are also scarce.
The Los Angeles County Sanitation District has found a solution by producing RNG from waste collected within the jurisdiction.
“We’re actually carbon neutral,” said fleet manager Dave Bolderoff, who oversees 1,100 vehicles. “A big part of that is the production and use of that natural gas.” Its fleet now has 90 trucks running on RNG, with plans to double that number in five to six years, supporting everything from heavy-duty tractors to vacuum equipment. Contract carriers are also required to run on renewable natural gas.
“I think it’s very close to that point that it’s sustainable,” he said, when asked if incentives would be needed to support fuel transitions. Diesel is already triple the price of natural gas right now. “Some of this technology still needs to be improved, but the total cost of ownership is comparable to diesel today, even without subsidies. So [a grant is] not necessary, but nice to have.
Based on current costs, natural gas is available at 7 US cents per kilowatt hour, compared to 28 cents paid for an equivalent amount of full electric power and 83 cents for hydrogen.
There have certainly been some growing pains in the adoption of fuel. Staff using emergency response vehicles for overflowing sewers were reluctant to switch to alternative fuel, wondering if it would be reliable. But the first of these trucks arrived in 2015, and the last was online last September. During a major sewage overflow in Carson this Christmas, there were no downtime issues.
Maintenance costs can be controlled by changing fuel filters and spark plugs at the correct service intervals, he added.
Renewable natural gas also offers an option to divert organic waste from restaurants and grocery stores. The Los Angeles County Sanitation District uses a biological separator to create pumpable sludge, which is shipped 25 miles to a digester for sewage treatment plants. Anaerobic digestion creates biogas.
It’s like a modern version of using a banana peel to power a flux capacitor in Back to the futurehe joked.
Pollution becomes a charging solution
It’s a better option than letting the facilities burn the gas, said Thomas Healy, CEO of Hyliion. “We can take pollution and use it to charge a battery instead of letting that pollution go into the atmosphere…That’s what makes it a win-win for RNG.”
Hyliion, meanwhile, plans to use natural gas-powered engines to recharge batteries on board hybrid-electric trucks. The advantage is that the range is not compromised. Gas-powered generators can be turned off within city limits, and the hybrid system still offers batteries that provide 75 miles of range.
There are also financial benefits. Healy refers to a fleet that would need a $30 million upgrade to prepare a warehouse to support 50 battery-electric trucks.
There are also limits to the use of hydrogen, he said, referring to gray hydrogen made from fossil fuels rather than renewable sources. “We need to start making green hydrogen.”
“There is no one-size-fits-all solution,” said Tom Swenson, Cummins Director – Global Regulatory Affairs.
For its part, the engine manufacturer produces 6.7, 9 and 12 liter engines running on natural gas. A recently unveiled 15-liter design will deliver up to 500 hp and up to 1,850 lb-ft of torque. The goal is to have this integrated into a truck by 2024.
Such an engine is particularly important because it supports the driver’s experience. “If drivers hate it, they’ll find ways to make it not work,” he said. The 12-liter engine can be underpowered for many 80,000 lbs. apps. But its 15-litre counterpart offers a torque curve that essentially matches its counterpart.
A clear advantage over diesel is that natural gas engines can rely on a simple three-way catalyst that weighs only 100 lbs and is packaged as a muffler. It is maintenance free and has no filters to clean or replace. Unlike diesel, there are no active regenerations, SCR fluid or associated maintenance costs.
The X15N is also 200 pounds lighter than the existing ISC12N and 500 pounds lighter than today’s 15-liter diesel, he said. Fuel economy should also be 10% better than the 12-litre model.
But fleets adopting the engines will have to be prepared for some changes. They require a different engine oil than diesel models, for example. But some oil formulas have been developed for platforms as diverse as diesel, natural gas, gasoline, and propane.
Since the 15-liter engine is quieter than diesel models, Cummins has also received reports of it ticking. It turned out to be the sound of an air compressor that had traditionally been drowned out by diesel power.
It is admittedly 15% less efficient than a diesel engine, but Cummins expects to narrow the gap to a range of 5-10% when the model finally hits the market.
“I don’t think there will be a one-size-fits-all solution that will be, you know, kind of what diesel is today,” Hyliion’s Healy said. “Electrification is on the way. It happens… The reality is that it has to be practical.