The drive to decarbonise is now at the top of the political agenda in many countries around the world and the transport sector, which is responsible for a substantial proportion of emissions, is only at the beginning of the decarbonisation journey. This is particularly challenging to road freight transport which still relies on the diesel-fueled internal combustion engine. Electric vehicles may not be the answer for heavy goods vehicles and innovation is required to develop workable solutions in this important segment.

Mark Bartholomew spoke to Simon Brewster and Nick Owen from Dolphin N2 about the alternatives to electric vehicles, including the recuperated split cycle engine being developed by their company and the potential contribution that such technology has to make in driving down carbon levels.

What are the existing challenges with electrification?

Although batteries and electrified roads have been demonstrated in use with heavy-duty goods vehicles, they are not without their challenges.

Simon explained that, for vehicles making long haul journeys, batteries can be inconvenient and result in the loss of load capacity. In order to accommodate the batteries, vehicles have to compromise payload, resulting in more vehicles being needed to shift the same amount of goods. For this reason, batteries typically work better for urban deliveries over shorter distances. Battery-powered trucks would also require a network of heavy-duty charging stations.

An alternative might be electrified roads involving either overhead lines to which the truck connects via a pantograph or a series of electric cables and electromagnetic transmitters buried underneath the road surface, which generate electromagnetic fields and in turn charge a vehicle's battery as it travels. Although this would reduce the size of batteries required and offer a solution to the large charging ports that would otherwise be needed for charging trucks, it would still require expensive infrastructure to be built on all main roads.

What are the alternatives to battery-powered vehicles?

Hydrogen fuel cell

One of the existing alternatives that is seen as viable for the freight industry, is the hydrogen fuel-cell. Hydrogen refueling is a more familiar process (it is closer to petrol or diesel in terms of time taken) and therefore it could use existing forecourts, although new and widespread infrastructure would be needed to dispense it.

Hydrogen and fuel cells remain costly and economic viability on a larger scale faces a 'chicken-and-egg' type challenge. Accordingly, it may be some time before fuel-cells are in widespread usage and accelerating near term decarbonisation whilst enabling additional demand for hydrogen is a priority.

Recuperated split cycle engine

Dolphin N2 is developing another solution for the sector, in the form of a recuperated split cycle engine. This is a form of internal combustion engine designed specifically for use in long haul trucks and achieves very high efficiency by recycling waste exhaust heat.

One of the big advantages of this technology is that it can operate using diesel and therefore has the potential to achieve a substantial reduction in emissions in a very short timeframe through widespread adoption.

The Dolphin engine can also operate on hydrogen, which might help to accelerate infrastructure investment, or biofuels. By running on biomethane produced from wastes that would otherwise rot and release methane into the atmosphere, the Dolphin engines would help to reduce not only carbon but also methane - a much more damaging greenhouse gas. As a result, it would provide an overall 'carbon negative' effect.

Are there any barriers to rolling out this technology?

Dolphin N2 is confident that there is little to prevent the roll-out of their technology, however, they do perceive a tendency for policy-makers to try to pick winners, rather than leaving it to the market and the engineers to come up with the most effective solutions.

The promotion of battery-powered electric vehicles and the ban on the use of the internal combustion engine in passenger cars is potentially quite unhelpful; in reality it is the non-sustainable fuel and deviation from existing regulations, not the device used to propel the vehicle, which is the problem.

It would also be helpful if policy-makers and regulators looked at full life-cycle costs rather than focusing on 'tail-pipe' emissions. Too often the carbon impact of supposed low emission technologies is ignored or exported.

The importance of innovation

Given the scale of change required to achieve decarbonisation in the transport sector, it seems likely that a range of solutions will be required. Road freight transport has its own particular challenges and there is not one specific technology that will achieve the policy goals across the sector. It will therefore be important for policy-makers and those regulating the sector maintain a level playing field and an open mind, to avoid the risk of stifling innovation.

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