Which powertrain will conquer the future?
Let’s look for clues: Where is the path of truck powertrains leading? Can electric motors crowd diesel out of the picture? Or will completely different kinds of powertrains and fuels come into play?
At the moment, a host of technologies for long-distance trucking are under discussion, with some already in testing - all in a bid to achieve climate targets. For example, Germany’s Federal Ministry for the Environment is currently trialing overhead cabling for trucks on certain sections of the country’s highways. However, there’s no detour around diesel. “Looking at availability and what holds up in practice, the latest generation of diesel engines are the most efficient and therefore also the most environmentally friendly powertrain technology in long-distance truck transport. And they are likely to stay that way for some time,” says Stefan Hohm, Corporate Director, Corporate Solutions, Research & Development at DACHSER. He adds that the high energy density of diesel fuel makes it possible to drive very long distances with useful payloads. Moreover, the fact that global infrastructure is already in place for this vehicle technology makes deploying diesel trucks efficient. Nevertheless, to cut greenhouse gas emissions 30 percent by 2030 and reduce them to virtually zero by 2050, it will be necessary to gradually replace diesel vehicles. Electric trucks, powered by a hydrogen fuel cell directly on board, offer great potential.
The potential of fuel cells
Today there are already truck engines powered by natural gas. Yet when taking the full picture of greenhouse gas emissions into account, the use of CNG and LNG (both of them fossil fuels) offers no significant advantages over a modern Euro VI truck. “Taking a well-to-wheel perspective, we’re talking about a range of minus 10 to plus 10 percent compared to a state-of-the-art diesel truck,” Hohm says. The only way to achieve significant greenhouse gas reductions with CNG and LNG trucks is if the natural gas is synthetically manufactured using sustainable electricity.Hohm continues, “There is still some technological progress to be made to be able to produce methane this way economically.” Using biomass to generate natural gas would be one solution, but the existing quantities of waste and residual biomass are much too small to supply the whole transportation sector with sustainable fuels.
When it comes to long-distance trucking, fuel cells offer the most potential. These convert hydrogen (H2) and oxygen into electricity, leaving water as the only emission. In many ways, this sustainable technology directly addresses the needs of the logistics industry—for example, short refueling times. Initial pilot vehicles have demonstrated that fuel cells can work in heavy-duty transport. Still, manufacturers will have to get to grips with a whole series of problems over the next few years. “The technical challenges of fuel-cell powertrains for trucks are still high. Above all, these concern vehicle range and thus the placement and energy density of the tanks. In turn, it’s about the costs of the fuel cells and their service life as well as—very importantly—the efficiency of manufacturing hydrogen using sustainable electricity,” Hohm says. For the foreseeable future, trucks powered solely by batteries will be used only for short-distance transports; their smaller ranges and payload mean, they are not practical for long hauls. As part of its innovative City Distribution project, DACHSER has already deployed all-electric short-distance trucks along with cargo bikes in several cities.
Ultimately, the Corporate Director, Corporate Solutions, Research & Development sees a mixed picture: “There’s still a huge amount of research to be done here. With today’s batteries, electric drives are not feasible for heavy-duty transport, which is why we believe there is considerable potential in further research on hydrogen fuel cell technology. A stronger focus on the use of alternative fuels would be desirable—to date there has been too little discussion of synfuels, meaning fuels such as methanol that can be synthesized using green power. However, in our view, they offer major potential.”
We will keep an eye on this topic, with a further report planned for an upcoming issue of the DACHSER eLetter.