The challenge of electrifying HGVs

The progress made in the electrification for passenger vehicles has led to an examination of batteries and charging technology for HGVs, observes Mark Patrick.

Good progress has been made with passenger vehicles offering multiple electric models in a variety of categories, ranging from ‘ultra-compacts’ to sedans and pick-up trucks. Recently, the automotive industry began to electrify vans and similarly sized vehicles of the type used in last-mile delivery. The biggest challenge remains in electrifying what are referred to as heavy goods vehicles (HGVs) in Europe and Class 8 vehicles in the US. These include long-haul trucks and other heavy-duty vehicles such as articulated lorries, tankers and large specialist vehicles such as logging trucks and cement mixers.

Mass is among the most consequential factors when electrifying vehicles. The larger the vehicle, the more power is needed to move it, which necessitates bigger, more complex batteries. Also, the farther a vehicle has to travel, the more power it needs, which again necessitates bigger batteries.

HGVs are required to traverse hundreds, and sometimes thousands, of miles on any single journey and therefore require large, powerful batteries.

Challenges impacting HGVs

The limitations associated with current battery technology force compromises between the range and the payload capacity of commercial vehicles. Insufficiently powerful batteries translate directly into more recharging stops, resulting in longer transportation times and increased expenses.

The necessity for larger and more powerful batteries to propel heavier loads amplifies both the cost and design effort associated with these vehicles, especially when compared to passenger equivalents.

Battery innovations

Manufacturers continue to gradually make batteries more efficient, smaller, lighter and able to hold a greater charge, which all serve to extend range.

However, incremental improvements are not resulting in batteries optimally suited for HGVs quickly enough. As a result, researchers are exploring different battery chemistries that might perform even better than Lithium-ion (Li-ion).

Other battery types are being pursued. One example is a new class of solid-state batteries, which are characterised by greater power density. Unlike conventional Li-ion batteries that use a liquid electrolyte, solid-state batteries employ a solid electrolyte. This solid structure not only enhances energy density, but also reduces risks associated with liquid electrolytes, such as leakage and flammability.

Another possible alternative is hydrogen batteries, once quite exotic but gradually becoming more practical. Hydrogen batteries, or fuel cells, generate electricity through a chemical reaction between hydrogen and oxygen, producing water as a by-product. In contrast to Li-ion batteries that store energy electrochemically, hydrogen batteries are renowned for their ability to produce energy on-demand and their high energy efficiency, making them ideal for rapid refuelling.

Recharging infrastructure is key

HGVs cannot use the same chargers as passenger vehicles. Even the newer, higher-power chargers designed to more quickly replenish passenger vehicle batteries are insufficient for recharging larger batteries designed for medium goods vehicles, let alone HGVs.

Several major industrial companies established a the Charging Interface Association to devise a set of standards for MW chargers suitable for larger vehicles. Versions of these chargers are becoming commercially available.

Charger infrastructure is lacking across the globe, even for passenger EVs, but especially for larger vehicles. The European Automobile Manufacturers’ Association (ACEA) predicts that by the end of 2025, only 40,000 charging points for medium- and heavy-duty trucks will be operational in Europe. The ACEA estimates that 270,000 will be needed by 2030.

Battery swapping

Another battery option for HGVs has nothing to do with the batteries themselves, but rather how they are managed. Battery swapping is being explored to determine if such schemes could be faster and/or easier than recharging. In 2022, half of the electric trucks sold in China, the largest market for EV trucks, were capable of battery swapping, according to the International Council on Clean Transportation (ICCT).

The swapping process is mostly automated and typically takes about three to five minutes, making it much faster than even the quickest truck chargers. Robotic arms detach and extract the battery packs from the truck’s cab, then install a newly charged pack while the depleted pack is connected to a rapid charger. Battery swapping significantly reduces the time and cost compared to the fastest truck chargers. Early assessments by the ICCT indicate that the infrastructure is effective in supporting electric trucks used for short-haul operations at ports, mining sites and urban logistics, which typically have an average journey of less than 100km.

Slow, but inevitable

Trucks of all sizes or classes are far outnumbered by passenger vehicles, but the category is responsible for a disproportionate amount of greenhouse gases, so there is a firm desire to phase out internal combustion engine trucks in favour of electric models sooner rather than later.

Though electric trucks are currently more expensive than diesel trucks, economics are beginning to tilt in EVs’ favour, too. The ICCT notes that operating costs for last-mile delivery vehicles, that is, lighter trucks, are already at parity with their diesel-powered counterparts in many European cities. Meanwhile, the costs of heavy duty vehicles are diminishing faster than expected, and might reach parity with their diesel counterparts as early as 2030, according to Energy Innovation, a policy firm that consults with the US Environmental Protection Agency

There is evidence that despite the cost disparity today, running and maintaining an electric truck fleet is already less expensive. According to Renault, energy and fuel costs are cheaper, so the total cost of ownership of electric trucks is lower.

Governmental incentives can make the use of electric trucks even more attractive.

While it may take years before it is practical to operate large fleets of electric HGVs, efforts to make the transition have begun. The electronics industry is continually improving electric powertrains (including inverters); creating more powerful batteries; designing more effective battery management systems; and building faster, powerful charging systems based on new GaN and SiC power ICs and DC/DC converters that operate at the necessary voltages.