MIT: Plug-in Hybrid Electric Trucks Are A Near-time Solution To Reduce Diesel Trucking Emissions

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Gepubliceerd op 4/16/19

Plug-in Hybrid Electric Trucks to the rescue?

Many automakers are trying to reduce emissions caused by diesel engines powering long-haul trucks. Automakers are trying two things: make diesel engines cleaner and develop full-electric trucks.

Today's heavy-duty diesel engines are significantly cleaner than older ones, while developing more power and requiring less maintenance. However, new regulations on truck emissions will make even those clean diesel engines too dirty. Furthermore, the image of diesel has been tainted due to recent scandals, making regulators even more strict towards diesel engines.

At the same time, automakers are also trying to make the jump to full-electric long-haul trucks, most notably Tesla, Daimler-Benz, and Volvo. But even with the latest battery technology these trucks are still better suited for short-haul transport, and not for long-haul transport, where trucks can be on the way for days. Charging the batteries multiple times on one journey simply takes too much time.

The renowned Massachusetts Institute of Technology (MIT) suggests there is a third way; a near-time solution that can start reducing emissions immediately, without having to wait until the technology for full-electric trucks is ready.

The solution: plug-in hybrid electric vehicles (PHEVs). These vehicles combine a combustion engine with an electric motor, allowing the vehicles to run on full-electric power for a limited time. This is the technology used in most ‘hybrid’ cars on the road today. MIT suggest using flex-fuel engines, that run on either gasoline or pure alcohol, or a mix of both.

Gasoline engines produce only a tenth as much nitrogen oxide (NOx) pollution as diesel engines do. Combining a gasoline engine with an electric motor will reduce emissions even further, while emitting less greenhouse gasses at the same time.

The gasoline engine could be further tweaked to run on ethanol or methanol. These kinds of fuel could theoretically be extracted from sources, such as agricultural waste or municipal trash. This solution could potentially bring greenhouse gas emissions to zero.

While MIT’s idea to combine a PHEV powertrain with flex-fuel is somewhat novel, the idea for hybrid long-haul trucks is certainly not. The problems with the technology are well-known: packing two motors in a truck would make a vehicle heavier, and the electric motor relies on batteries, which add even more weight to a truck. More weight means more power is needed to move the truck forwards, reducing some of the positive effects of the initial emissions reduction.

Furthermore; PHEV powertrains are complex, far more complex indeed than a diesel powertrain or a full electric powertrain, and therefore require more care and costlier maintenance. Finally, PHEV powertrains are more expensive than the diesel or electric alternatives, making them unpopular with fleet owners.

All of this means that PHEV trucks are so far only operating on short-haul routes within cities, where these disadvantages matter less. Better battery technology would help PHEV trucks, especially lighter batteries, but those would equally help the development of full-electric trucks.

The MIT solution may help reduce emissions, but it doesn’t take away the other downsides of a PHEV truck, even compared with a clean diesel engine, and especially compared with a full electric truck. Concluding: electric trucks are still the future, we just have to wait a little longer.  

Dutch moving startup ScanMovers.com is currently researching the potential of using electric trucks for the moving sector. Primarely results indicate that the currently available trucks are best suited for city environments, but that technology is evolving so fast that electric trucks will soon be able to operate on medium-haul distances, further reducing the need for a costly and complex interim solution. 

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