Is this the future of refrigerated transport? Wickham’s first Sunswap goes to work

Australia’s first commercially purchased Sunswap Endurance battery-electric refrigeration unit is heading into service with Wickham Freight Lines, and after months of real-world interstate testing, the question is no longer whether electric transport refrigeration can work. The more interesting question is how quickly operators will start asking why they are still pouring diesel into the little engine hanging off the front of the trailer.

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Key Points

• Wickham Freight Lines is the first Australian operator to commercially purchase a Sunswap Endurance battery-electric refrigeration unit.
• The Sunswap is battery powered, with roof-mounted solar acting as a range extender rather than the primary power source.
• During testing, the demonstrator completed about 1,671km and 38 hours of refrigeration operation, finishing with around 67 per cent battery remaining.
• Wickham’s tested the system in real freight work, including interstate runs, overnight operation, B-doubles, road trains and multi-drop deliveries.
• Protran Solutions says the Sunswap installation is around 100kg lighter than a comparable diesel refrigeration unit with a full fuel tank.
• Grant Turner says suitable operations could recover the higher purchase cost in under five years, with substantial diesel and maintenance savings after that.

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There’s a peculiar thing that happens the moment you put the words “electric” and “truck” in the same sentence. The conversation instantly bolts sideways into range anxiety, charging stations that don’t exist, government policy written by people who’ve never backed a B-double, and whether a battery truck will make it from Melbourne to Brisbane while dragging 68 tonnes into a headwind. All perfectly fair questions.

But while everyone has been concentrating on how to replace the big diesel engine at the front, another diesel engine has been quietly chugging away on the front of refrigerated trailers, burning fuel simply to keep the load cold.

That is where Wickham Freight Lines and Protran Solutions have taken a rather different approach. Instead of trying to electrify the whole combination in one heroic leap, Wickham’s has started with the refrigeration unit.

And after putting the Sunswap demonstrator through interstate work, overnight running, B-double and road-train applications, multi-drop deliveries and the ordinary indignities of life on a loading dock, the Queensland operator has become the first in Australia to buy one.

Which raises a rather uncomfortable question for the conventional diesel fridge: if the electric one can already do the job, how long before that little engine on the front starts looking decidedly old-fashioned?

Eighty years of doing it the same way

Protran Solutions Managing Director Grant Turner has spent around 30 years in transport refrigeration, and he points out that the basic principle behind a conventional transport refrigeration unit hasn’t changed much in decades.

There’s a small diesel engine hanging off the front of the trailer, it drives the refrigeration system, and while the rest of the truck industry has steadily filled itself with electronics, telematics and increasingly clever powertrains, that little engine has simply kept rattling away. Turner says a conventional refrigeration unit can consume somewhere around two to four litres of diesel an hour, depending on what it is doing.

Eventually, three engineers in the UK decided that rather than adding batteries and solar panels to an existing diesel refrigeration design, they would start again. Sunswap Endurance was developed as a battery-electric refrigeration system from the outset, rather than taking a conventional diesel unit and hanging a collection of electrical bits off it in the hope they all got along.

“When this technology came around, that’s what made me jump,” Turner told roadtrains.com.au. “People were putting bits and pieces together and didn’t really build anything from scratch. When someone built one from scratch, I thought, this is cool.”

Sometimes engineering breakthroughs begin with billions of dollars of research funding, and sometimes three blokes look at something that’s been done the same way for 80 years and simply ask why.

It’s battery powered, not solar powered

The solar panels covering the trailer roof inevitably attract most of the attention, but Turner says describing Sunswap simply as a solar-powered refrigeration unit misses the point. The refrigeration system runs from its onboard battery, while the solar array is essentially a range extender, continually feeding energy back into that battery whenever conditions allow.

The system operates independently of the prime mover, with no reliance on an e-axle or truck-derived electrical supply. It also answers the first question everybody asks: what happens when the sun goes down? Quite simply, it keeps working.

“What happens if it rains? What happens on a cloudy day? It’s a massive battery pack,” Turner says. “The technology is a battery pack that powers a refrigeration unit. It’s not solar. We see solar as the range extender.”

Before committing to Sunswap in Australia, Turner travelled to the UK to see the equipment operating in real fleets. Importantly, he says he wasn’t particularly interested in talking only to company owners or sustainability departments; he wanted to hear from drivers, loading dock staff and operations people who actually had to live with the equipment.

In some applications, operators told him they were plugging the units in only periodically to balance the batteries rather than routinely charging them between every run. And Britain, it should be remembered, is not a country generally famous for excessive sunshine, so Australia may have a slight advantage there.

Wickham’s decided to try to flatten it

Buying new technology is one thing. Handing it to an Australian transport operation and telling everybody to treat it normally is quite another, and Wickham Freight Lines Director Graham Keogh says that was effectively what they did.

“I put the Sunswap Endurance into the fleet and told the team to stretch it, treat it as a normal unit,” Keogh says. “We were genuinely impressed. I’m a true believer. I love the technology and I’m not a true tech person whatsoever. But you can just see that it’s a winner.”

That simple instruction to “treat it normally” is probably one of the most valuable parts of the entire trial, because normal transport operations are not laboratory conditions. Drivers stop, loading runs late, doors stay open longer than expected, plans change and refrigerated trailers spend hours backed against docks.

Occasionally someone also discovers at two o’clock in the morning that what the operations manual says should happen and what is actually happening have become distant relatives. Wickham’s encountered exactly that, with Keogh saying the Sunswap trial actually highlighted some of the company’s own loading practices.

They discovered occasions where a trailer could sit at the dock with its doors open for a couple of hours and the refrigeration unit running. The electric unit didn’t just survive it; it made everyone realise how much fuel the diesel units alongside it were quietly consuming while doing exactly the same thing.

A 1,671km argument

One of the more convincing exercises began as what Turner describes as a relatively gentle validation run, although it didn’t remain gentle for very long. The Sunswap demonstrator ultimately covered a Sydney-Warwick return operation of about 1,671km and around 38 hours of refrigeration operation, with Turner saying it finished with approximately 67 per cent battery remaining.

The demonstrators have subsequently worked across Queensland, New South Wales and Victoria, carrying loads ranging from chilled freight through to frozen product, with Turner saying the two units have now accumulated around 4,000 operating hours between them.

Wickham’s also helped put the technology through B-double and road-train applications rather than keeping it confined to short metropolitan work. That takes the Sunswap well beyond the sort of predictable metropolitan shuttle where an electric refrigeration system has a relatively easy life.

It becomes considerably more convincing when somebody hooks it behind a combination, sends it interstate overnight and, rather than wrapping it in cotton wool, simply treats it like another piece of working transport equipment.

“We just worked it,” Keogh says. “Left the doors open. Did everything wrong.”

It is possibly not the sentence the engineering department would choose for the brochure, but it might be the best endorsement in it.

The diesel bill nobody notices

The economics are where this gets interesting, with Turner estimating that a conventional refrigeration unit in some applications can consume around 8,000 litres of diesel a year. On an individual trailer that is noticeable, but across a substantial refrigerated fleet it becomes a number capable of getting the attention of somebody sitting in the accounts department.

And the waste is not always happening while the truck is hammering along the highway. Turner says a modern diesel refrigeration unit can be relatively efficient once the load reaches its set temperature, but sitting on a loading dock working hard can see consumption climb to around 3.5 to four litres an hour.

Multiply that by several trailers, then several nights, then an entire fleet, and suddenly the apparently insignificant little diesel engine on the front wall starts developing quite an appetite.

Sunswap obviously has a higher initial purchase price, something Turner doesn’t attempt to hide. His argument is that operators need to look at total operating cost rather than the initial sticker price.

Depending on the duty cycle, Turner says modelling suggests the additional capital cost can be recovered in under five years. From around year six, he says fuel savings in suitable applications could amount to roughly $15,000 to $20,000 annually.

Those are Protran’s figures, and naturally every operator will need to do the sums against its own utilisation, diesel price and refrigeration task. But at least there are sums to do, rather than relying entirely on a warm glow from having bought something electric.

And it doesn’t weigh more

One of the obvious objections to hanging a sizeable battery on the front of a trailer is payload, but Turner says that objection disappears fairly quickly. With its battery incorporated into the front wall and solar panels across the roof, he says the Sunswap installation is around 100kg lighter than a comparable diesel refrigeration unit once the conventional unit’s diesel tank and fuel are included.

There is also considerably less mechanical hardware to maintain. The refrigeration circuit itself remains familiar territory, but the small diesel engine, fuel filters, exhaust system and associated servicing disappear.

Turner describes the maintenance requirement on the electric drive side with a highly technical Australian engineering term: “Bugger all.”

He says the unit carries around 1,000 sensors monitoring operating parameters, allowing Protran to use the data for predictive maintenance rather than simply opening the doors at fixed intervals and looking around hopefully for something about to fall off. The same data can monitor door openings, power consumption, operating temperatures and route behaviour.

Drivers can also remotely start the refrigeration unit and monitor trailer temperature through their phones. That means they can be sitting at a servo an hour from the loading point, start the fridge remotely and see what is happening without climbing out of the cab, proving that technology occasionally does produce something more useful than another password.

The strange problem of being too quiet

Then there’s the noise, or rather, the distinct lack of it. Anybody who has stood beside a row of refrigerated trailers at two in the morning will understand that transport refrigeration units are not traditionally known for their contribution to serenity.

A diesel fridge starting in the middle of the night has roughly the calming properties of somebody firing up a concrete saw outside your bedroom. For urban deliveries, supermarkets, fast-food distribution and noise-sensitive areas, removing that diesel engine offers an advantage that has nothing to do with carbon accounting.

Turner says Sunswap is so quiet in operation they have encountered the opposite problem.

“We can’t hear the Sunswap unit running,” he says. “We’ve got to get some more operational lights on it to show that it is on because it is so quiet.”

There can’t be many pieces of heavy transport equipment whose development department has been asked to make them more obvious because nobody can hear them.

What about battery life?

Naturally, the next question is battery life. Turner says the Sunswap system uses a 48-volt battery architecture and Protran is currently offering five-year battery warranties, with Turner confident the technology has the potential to operate well beyond that period.

He says the company is considering extending warranty coverage towards ten years as operational data builds. The solar panels themselves are thin, flexible units bonded to the trailer roof with an air gap beneath them for cooling, with Turner saying the design also provides some flexibility against impacts such as hail and allows individual panels to be replaced if damaged.

Routine cleaning, he believes, should be little different from washing the rest of the trailer, with telematics showing operators how effectively the solar system is performing.

There are still applications where diesel will continue to make sense, and Turner freely acknowledges Australia is a very large country with freight tasks where operating conditions make electrification difficult. But that doesn’t mean every refrigerated trailer needs a diesel refrigeration engine simply because that is what refrigerated trailers have always had.

Perhaps start with the easy diesel engine

Australia’s road transport industry is going to spend years arguing about how, where and whether battery-electric prime movers fit into long-distance freight, and there are plenty of good reasons why that debate will continue. The distances are enormous, every kilogram of payload counts, charging infrastructure remains patchy and transport operators generally prefer equipment that earns money rather than equipment that makes a particularly handsome photograph at a government media event.

The Sunswap story raises a rather different question. While everybody is trying to work out how to replace the 600-horsepower diesel engine at the front of the combination, should we perhaps start with the little one hanging off the trailer?

Wickham Freight Lines appears to think so, and after interstate work, overnight running, loading docks, multi-drop work, freezer and chiller freight, B-doubles, road trains and what sounds suspiciously like a deliberate attempt to find out where the limits were, Graham Keogh has reached a fairly uncomplicated conclusion.

“I’m a true believer,” he admits. “I think it’s a fantastic idea and I love the technology. I’m not a tech person whatsoever, but you can just see that it’s a winner.”

And perhaps that is the most significant part of Australia’s first commercially purchased Sunswap. It hasn’t been bought because somebody needed another sustainability announcement; it has been bought by a refrigerated freight operator after they put it to work, and in trucking that remains a considerably harder test to pass.

Related Reading:

• How to Reduce Refrigerated Trailer Fuel Costs on Long-Haul Runs
• Solar-Powered Refrigerated Trailers on Australian Roads
• Why Cold Chain Logistics Is Starting to Ditch Diesel