How green is your trailer?

The idea of ‘greening’ the non-motorised part of a commercial vehicle is not new. At the 2012 IAA, Schmitz-Cargobull revealed a sleek concept vehicle designed in collaboration with Mercedes Benz to improve on fuel consumption and CO2 output; while MAN and Krone teamed up to create the equally impressive Concept S study.

Both initiatives would have never happened if the companies involved didn’t already sense where European legislation was headed. In fact, the industry’s environmental consciousness had already been growing for a while at the time they were presented to the public in Hanover.

A team of students from a Dutch university had been developing special side skirts to improve the airflow underneath a common semi-trailer since 2010; and Californian start-up ATDynamics was already working on a so-called boat tail, a device designed to smoothen the airflow around the trailer and decrease drag.

But it was Schmitz’ and Krone’s eye-catching 2012 concept vehicles that elevated ‘environmental friendliness’ to become the buzzword it is today. On the back of the European Commission’s recent efforts to find out exactly which aspects of modern road haulage need improvement, industry experts now expect the arrival of a special eco-label rating the environmental performance of a trailer.

The label could inform both hauliers and their customers about the carbon footprint of each individual vehicle and boost demand for aerodynamically optimised transport equipment. After all, the most promising initiatives undertaken to reduce carbon emissions in the past focused on aerodynamic improvement.

It’s not for no reason that the European Parliament is currently discussing a proposal to allow for side-skirts and additional vehicle length to improve its aerodynamic performance.

However, it is actually quite hard to quantify just how much CO2 a commercial vehicle actually emits during transport, as weight, driver behaviour and wind direction all affect the outcome. In fact, some argue that complexity is exactly why France’s Écotaxe project has failed. The French have been exploring new ways to tax the road transport industry based on carbon emissions for a while now, but the project has not reached maturity just yet.

While there are certainly more reasons why the Écotaxe system failed, it is still a good example of how complicated it is to evaluate the environmental performance of a piece of transport equipment.

To get a hold of the topic, Global Trailer met Peter Sijs of TIP Transport to discuss the issue, and also asked Schmitz-Cargobull and Krone for a statement. Peter Sijs is responsible for all technical specifications on TIP’s vast trailer fleet, and he is not surprised aerodynamic improvement is high in the industry’s agenda at the moment.

“Aerodynamics certainly is an area we know quite well and where the best improvements can be made,” says Sijs, who has been involved with Delft University’s side-skirt project from the get-go. “Some of our customers have implemented these skirts and they have increased aerodynamics and led to a measurable decrease in fuel consumption.”

Research has shown that side-skirts can achieve a five per cent improvement on fuel consumption, while boat tails come in around the four per cent mark. Sijs says TNT recently executed an on-highway trial, where they reported at least six per cent in improvement. “That has to do with increased turbulence on the motorway caused by other vehicles,” he explains – indicating that the use of aerodynamic devices could in fact lead to a preferable environmental ranking.

Reflecting on the European Commission’s work, Sijs and his investigators found that increasing trailer length was just part of the solution, especially when it comes to using boat tails as they are already used in the US. “You need the right angle and you need the proper length to achieve the best outcome. We concluded that a boat tail should not exceed half the width of the trailer. We also determined the correct angle. The challenge is to keep the airflow as long and as close to the trailer body as possible. Yet at one point, you have to let go, but in such a way that as little as possible turbulence is being caused.’’

While boat tails and side-skirts traditionally take centre stage in the sustainability debate, there is a range of additional parts that could affect a trailer’s environmental performance. Sijs says that special mud flaps, which can hold spray water but let air pass through, could be one option. He also recommends mounting the fuel tank of a cooling engine lengthways instead of sideways underneath the chassis of a refrigerated trailer.

According to Sijs, the environmental optimisation of trailing equipment is still very much of a custom job. For example, not every company should opt for the side-skirt option, especially those operating intermodal. “To enter rail carriages damage-free, side-skirts need to be removed. But given only one per cent of trailers in Europe is also moved by train … there are still 99 per cent of the European trailer parc left that can be improved.”

While the aerodynamic improvement of transport equipment is still in its infancy in Europe, weight reduction is a well-studied field. But, would a lighter trailer automatically make for a better spot on the eco ranking, given the added payload would reduce the ‘CO2 emitted per tonne moved’ ratio?
Peter Sijs says while there is a correlation, the manufacturing industry should be careful not make next-generation equipment too light. “Saving weight is definitely a trend, but at some point, you risk tilting a trailer when a forklift enters it to put down a loaded pallet. Unfortunately this happened to some ultra-light trailers we have trialled ourselves.”
In line with that verdict, Sijs also doesn’t have high hopes for energy generating axles either. “Sure, they may help – but it doesn’t compare to a lowered riding height when the combination is on a motorway, for instance. With a slightly lower combination, aerodynamics increase significantly with all the positive side-effects you could imagine.’’  
The trailer’s environmental footprint – including the actual production process and future recyclability – could also be part of the new trailer label. That’s where refrigerated transport equipment could come under the microscope. 

“Those who can prove that they use clean technologies to reduce carbon emissions during the manufacturing process are going to be the winners in tomorrow’s market. If you also find a way to make it as recyclable as possible, you have the best chances of succeeding. Aerodynamic improvement, sustainable production and recycling is what trailer manufacturers will be judged on going forward,” he adds.

German trailer brand, Krone, is aware of the trend and was one of the first mainstream manufacturers to offer a side-skirt option, using Dutch supplier Optiflow, a Wabco subsidiary. In addition, the company can boast the Easy Tarp model, featuring a pneumatically tightening curtain for reduced wind-resistance. At this year’s IAA, it will also introduce a “more standardised trailer” to meet the requirements of sustainable production.

Schmitz-Cargobull, meanwhile, is producing its own range of side-skirts. “We measured a [fuel] advantage of 4.5 per cent, which equates to an 18 per cent of air resistance’’, a spokesman told Global Trailer. “[In regard to production processes,] we use bolting methods wherever we can to prevent unnecessary welding. Our trailer program is a modular offering, which means production is highly efficient. We also avoid waste and recycle whatever we can, albeit no complete trailers. We are preparing a project to re use materials from used trailers though.’’

If the eco-label does become reality, Germany’s top two seem well prepared. But it may take until the next IAA in September to gauge just how close we are to an environmental rating of transport equipment.

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