Think "well to wheel" around emission options
INDIANAPOLIS, IN – The trucking industry has to “put on the brakes” when it comes to its thirst for diesel if it hopes to meet targets to slash Greenhouse Gas emissions, according to Wilfried Achenbach, Daimler Trucks North America’s senior vice president – engineering and technology. But electric vehicles don’t yet offer the answer when the steps to produce electricity are considered.
Speaking at the NTEA’s annual Green Truck Summit, Achenbach stressed that diesel engines continue to be the industry’s “workhorse” because of their high torque and long-life, delivering 10 kwh of energy per kilogram in a format that is easy to refuel and readily available.
Gone are the days of black smoke belching from exhaust stacks, thanks to a steady rollout of tighter emissions limits since 1990 that have attacked smog-producing NOx, Particulate Matter, Greenhouse Gases and carbon dioxide, he explained. “We should not see it from any modern diesel engine.” In fact, a 1998 truck belches 35 times more NOx and 60 times more Particulate Matter than an EPA10 equivalent, he said. “What we’ve accomplished as an industry, we can be proud.”
But there is more to do. The 2016 Paris Agreement to reduce Greenhouse Gases requires more.
“We have to put on the brakes if we continue burning diesel as we do today, we will not be able to live up to those limits,” he said during a keynote address. Transportation accounts for 34% of the carbon dioxide emissions in the U.S. Trucks themselves account for 6%.
While accounting for a smaller share overall, long-haul heavy-duty trucks remain the most significant lever to shift carbon dioxide emissions, he said.
The good news is that gains have been made. “We are not starting from scratch,” Achenbach said, referring to the first phase of Greenhouse Gas regulations, and a second phase that begins to roll out in 2018. Combination tractors alone will see fuel efficiency boost 20, 23 and 25% in 2021, ’24 and ’27 model years.
“In the foreseeable future, 10 miles per gallon will become the new normal for tractor-trailer combinations,” he said, referring to the promise shown through SuperTruck programs. “We don’t have to wait 10 years. This is going to happen faster.”
The improvements, however, will involve looking at a broad range of systems. While 170 horsepower is needed to move 76,000 pounds 62 miles per hour, 85 horsepower is lost to aerodynamic drag and 74 horsepower is lost to rolling resistance, he said. Even a focus on tire pressure will make a difference. “Tire pressure, for me, is one of the underutilized levers we have today,” Achenbach says.
But the Daimler executive stressed that electric vehicles are not the answer on their own. Even those have a carbon footprint.
Electricity still has a carbon footprint. “Electricity is not free environmentally. Not as it is today,” Achenbach said, noting how 39% of electricity comes from burning coal, and 28% comes from natural gas. “If we want to change something, we need to change this.” In Germany, however, 30% of the electricity is from wind and solar. But that takes political will. And money.
When measuring well-to-wheel emissions, diesel and electric vehicles perform relatively the same, he says. A single kilowatt-hour of energy at a wheel end is generated with 1.7 pounds of carbon dioxide whether it involves electricity or diesel, he said. “Currently with our energy mix it doesn’t make any sense to go electric,” he added. Change that to solar panels, thermal power plants and windmills, the carbon dioxide begins to drop.
Surprisingly, the vehicle technology is available. It just comes at a cost.
A truck powertrain would require 720-volt batteries and the underlying power distribution, an inverter, and electric motor, he explained. The high-voltage batteries face the biggest issues because of cost and energy density. One day of driving more than 950 kilometers with diesel will require 450 liters of fuel, weighing in at 840 pounds and costing about $1,162. Looking at 2022, the battery pack would weigh 11,022 pounds and cost $156,239.
“Be careful that you take everything into the equation that might contribute to emissions,” he said.