Late last June, Sainsbury’s was revealed as the mystery “major UK commercial operator” that would be the first in the world to field trial a refrigerated truck chilled by a liquid nitrogen (LN) fuelled engine. The landmark zero-emission unit – developed under the Innovate UK-funded CoolE project – was to operate from the retail giant’s Waltham Point depot, we were told, delivering goods to stores across the London area.
This trial matters, particularly for Britain, with its increasingly laser focus on air quality. Why? Because most existing auxiliary diesel TRUs (transport refrigeration unit) are widely acknowledged to be heavily polluting since they are not subject to EU exhaust regulations. So, given that the new cooling unit promises not only to exceed Euro 6 standards but to eliminate CO2, NOx and particulate emissions altogether, it offers a once and for all solution.
Where are we now? In fact, by the time the Sainsbury’s news broke, a second generation LN engine refrigeration system had been supplied by ‘clean-cool technology’ specialist Dearman, along with partners Air Products, Dawsonrentals, Hubbard and Solomon. It had been installed under the chassis of a Mercedes-Benz Antos rigid, leased from Dawsonrentals. After commissioning, the truck and its new equipment had completed the requisite independent test procedures at Horiba Mira, verifying EMC (electro-magnetic compatibility), etc. It had also been approved by the VCA (Vehicle Certification Agency), and had been provided to Sainsbury’s ready to roll.
Dearman chief technology officer Nick Owen describes the installation as a near copy of the TRU developed for the earlier CoolE project, but subjected to “a detailed tidy-up”. Key components were relocated on the chassis rails, he explains, and the overall system integrated and re-engineered for real-world operation on-road at arm’s length by an important third party.
He also states that the Horiba-MIRA air curtain – also developed under CoolE, to minimise icing of Dearman’s ultra-cold evaporator (TE, July 2016, page 26) – was not implemented. “We’re still considering that technology for scenarios where there are frequent door openings. But for this trail that’s not the case,” he reasons.
Sainsbury’s has since started by testing the technology on single-drop missions, first delivering frozen and then chilled loads across London. It will next move on to operations involving more than one drop.
So how are trials going? Dearman commercial director David Sanders (formerly director of innovation at the Carbon Trust) says it’s too early to talk about carbon savings, although “they will be substantial whatever duty cycle”. He explains that to date Sainsbury’s testing has been about proving the reliability, robustness and performance of the equipment.
That said, he reports that the truck is performing at the high end of expectations. “It’s doing its job, albeit with a far greater level of monitoring and support than a production unit would receive,” he confirms. “The first few weeks have demonstrated that the technology works very well, in terms of achieving rapid pull-down times, and ensuring accurate temperature stability and control. In fact, it’s better than conventional equipment. It’s also very quiet. So the strengths we predicted are showing through.”
And his assertions are backed by serious data, according to Owen, who explains that instrumentation throughout the engine, thermodynamic equipment, LN injection system and the truck’s refrigerated compartment is logging all events. “On board telematics also mean we can see what’s happening here at our base in real time, and watch for developing problems.”
So far, there haven’t been any. Instead, the data has been helping Dearman’s development team to improve calibration around, for example, the temperature control algorithms. “Our system needs to be able to handle the differing demands of chilled versus frozen payloads, matching power delivery to the duty cycle. We’re learning how to tweak the controls in a way you just can’t in the laboratory environment or at a proving ground.”
What about refuelling? Owen explains that Air Products provided the temporary LN refuelling bay, which sits alongside Sainsbury’s diesel pumps at the Waltham Point depot. “Fuelling is designed to be automatic and the next iteration will use a near conventional nozzle to make the experience as intuitive as possible,” he says. And he adds that, although refuelling the truck’s insulated LN tank currently takes 45 minutes, that will more than halve with the development of a re-specified tank man enough not to trip safety systems at higher fuel flows. “The current tank was sized for a worst case scenario so has around five days’ capacity. For a normal duty cycle, we would go for two days.”
He concedes that, as with any cryogenic application, there are bound to be some LN losses – if only in terms of pre-cooling the refuelling pipes and on-board tank. “But that’s in line with expectations and accounted for in our economic models. There will be improvements for the next round of trials, but also, when it comes to large fleets there will be efficiencies of scale.”
So what does the future hold for Dearman? Sanders says the firm now has another generation of hardware under development, taking on board lessons from the trial as well as laboratory developments aimed at lightweighting and design-for-manufacture. Those should see the light of day before the close of 2017 ahead of full-scale production in 2018, he predicts. In the meantime, he says five more cold chain operators have signed up for trials this year – four UK-based and one on the continent – although he won’t reveal names.
“They will be using the next generation of equipment currently being durability tested, which will look more like finished product and fit within a standard Hubbard TRU enclosure. We’re still proposing to sling our equipment under the truck, but we can also mount it in the industry’s preferred position above the cab. The point is we don’t need an air intake or radiator. In fact, our equipment can be hermetically sealed. So there’s no requirement to mount it high. Going for our under-chassis approach makes servicing easier and eliminates working at height issues.”
For the rest of the industry, it’s a case of watch and wait. No prices are available yet, but Sanders insists that, when Dearman’s system is released for production, it will be “substantially competitive” against diesel TRUs “in terms of total cost of ownership”. And that’s without any kind of subsidy.
Taste the difference
Sainsbury’s estimates that during the initial three-month trial, its zero-emission truck will cut CO2 by up to 1.6 tonnes – the equivalent of more than 14,500km in a family car. It will also save 37kg of NOx and 2kg of particulate matter, compared to a conventional TRU (transport refrigeration unit).
“We recognise the importance of reducing emissions, which is why we’re working hard to cut carbon by 30% between 2005 and 2020,” comments Paul Crewe, head of sustainability for Sainsbury’s. “This trial with Dearman is just one of the innovations we’ve introduced. Their zero-emission system is really exciting: to be running a liquid air engine quite literally means our cooling is running on thin air.”
Drivers like it too. Dearman commercial director David Sanders reports that they find the new TRU just like any other – neither better nor worse. “Drivers don’t have to think about it. And, if it works better in terms of temperature control and pull-down, Sainsbury’s [and the planet] gets the benefit.”