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‘Clean cold’ transport technologies come in from the cold

There’s an urgent need to develop sustainable transport refrigeration systems to replace the highly polluting diesel-powered TRUs that dominate the industry today, writes Professor Toby Peters

Artist's-impression-of-a-local-cold-economy-based-on-a-cryogenic-cold-chain-system-in-an-emerging-industrial-centreWhen the history is written, it is likely the 2014 SMMT Automotive Innovation Awards will be acknowledged as a tipping point. For the first time, the prestigious competition recognised the urgent need to develop sustainable transport refrigeration systems to replace the highly polluting diesel-powered Transport Refrigeration Units (TRUs) that dominate the industry today. Two of the six shortlisted companies are developing innovative cooling refrigeration technologies to reduce greenhouse emissions and local air pollution, and one, the Dearman Engine Company, was ‘highly commended’. With investment in cold logistics booming around the world, it is a timely recognition of the inevitable damage to the environment and human health if the exponential growth in diesel powered transport refrigeration goes unchecked, and of the arrival of a potentially $£multi-billion market in ‘clean cold’ technologies.

The diesel powered TRU is one of the trucking industry’s biggest challenges. While truck propulsion engines are tightly regulated in the EU and increasingly clean, the secondary ‘donkey engines’ used to power TRUs on many trucks and all articulated trailers are effectively unregulated and emit grossly disproportionate amounts of toxic air pollution. Over the course of a year, a modern trailer TRU emits six times as much nitrogen dioxide (NOx) and 29 times as much particulate matter (PM) as the Euro VI propulsion engine pulling it around. This kind of pollution is estimated to cause 29,000 premature deaths in Britain each year, and over 400,000 across the EU, according to the European Environment Agency. Refrigeration also accounts for around 20% of a truck’s diesel consumption and CO2 emissions.

Artist's-impression-of-a-rural-cold-economy-based-on-a-tank-of-cold-located-at-an-agricultural-'hub'On current trends, the environmental and health impact of diesel TRUs looks set to become dramatically worse. Online food shopping is growing fast, with the UK market alone set to double in value over the next five years to £13bn (US$20.5bn) according to market researchers IGD. If the additional refrigerated vehicles needed to deliver all this food are not made more eco-friendly, the impacts in urban areas could be serious. In the developing world, cold chains are growing even more rapidly to service the changing lifestyles and diets of the rapidly expanding middle classes – expected to swell by 3 billion by 2030. Some analyses suggest this means the global refrigerated truck fleet will more than double to 9 million in the next two decades, but others put the figure at almost twice as much again. Either way, in the short term India thinks it needs to invest US$15bn in cold chains over the next five years to keep up with demand. Booming investment in conventional TRUs can only worsen the appalling smog already afflicting Indian cities, which caused 600,000 premature deaths in 2010 alone.

Air pollution is rising rapidly up the political agenda, not least in Europe, where the European Commission has started enforcement action against the UK for persistently breaking legal limits on emissions of nitrogen dioxide, which could eventually result in fines of €300m (US$375m) per year. A separate ruling by the European Court of Justice in November 2014 also obliges the UK Government to clean up Britain’s air pollution, and applies equally to other EU member states. The issue goes back to the UK Supreme Court next year and the UK Government will then be forced to act more quickly.

Luckily, there are innovative, zero-emission and cost competitive technologies ready to solve the problem.

Liquid air energy system schematic
Liquid air energy system schematic

The liquid air refrigeration unit currently being developed by the Dearman Engine Company – based on the novel piston engine invented by Peter Dearman – is a significant advance on existing technologies since it exploits the phase change expansion of the cryogenic gas to produce both cooling and shaft power. First the cryogen is vaporised in a heat exchanger in the refrigeration compartment, so cooling the cargo down; then the high pressure gas is used to drive the Dearman engine, whose shaft power can be used to drive a conventional refrigeration compressor or for auxiliary power. Existing cryogenic cooling systems such as natureFridge and Frostcruise exploit only the cooling from evaporation. Since it is largely based on standard piston engine architecture, the Dearman refrigeration unit would cost little more than a conventional diesel TRU, and would repay its investment in under three months.

Because diesel TRUs are so polluting, the impact of even a modest fleet of Dearman units could be huge. A recent report found that a projected fleet of just 13,000 Dearman liquid air refrigerated trailers (about 15% of the total refrigerated vehicle fleet) would reduce NOx emissions by the same amount as taking 80,000 Euro VI trucks or 1.2 million Euro VI diesel cars off the road. It would be the PM equivalent of removing 367,000 such trucks from service – more than three times the entire UK articulated truck fleet today – or 2.2 million Euro VI diesel cars.

Liquid air is not yet produced commercially, but liquid nitrogen, which can be used in exactly the same way, is widely available throughout the industrialised world. In fact many countries have large amounts of spare liquid nitrogen production capacity because oxygen and nitrogen are separated by a process of refrigeration, and there is four times as much nitrogen in the air as oxygen. Britain, for example, has 2,200 tonnes of spare daily production capacity, enough to cool almost 9,500 refrigerated trailers, well over half the number of reefers operating on British roads in 2013. Liquid nitrogen is delivered to industrial users daily by road tanker, so the distribution system already exists, and can be supplied for as little as 4.5 pence per litre.

Liquid nitrogen or air could be supplied even more cheaply if we recycled the vast amounts of cold wasted during the regasification of Liquefied Natural Gas (LNG) at import terminals, which would reduce the electricity required to produce liquid air – and its carbon intensity – by two thirds. We estimate the waste cold from the projected global LNG trade in 2030 of 500 million tonnes could produce enough liquid air to cool more than 4 million refrigerated trucks – more than today’s entire global fleet!

But liquid air technologies are not just for the developed world; if anything, they will be even more important in the developing world, particularly in rapidly industrialising giants such as India and China, where the cold chains are growing fast but are far from fully established. These countries also have significant spare liquid nitrogen capacity and sharply rising LNG imports to support a new ‘Cold Economy’. Here liquid air transport refrigeration would not only reduce local air pollution and cost, but also post-harvest food losses of as high as 50%. One study has shown that if developing countries had the same level of cold chain as developed countries, they could save 200 million tonnes of perishable food annually, increasing the food supply by about 15%. This in turn would save huge amounts of water, labour and land which would otherwise be used to produce food that is never eaten; the water used to produce wasted food each year is estimated at 250km3, for example, or three times the volume of Lake Geneva.

Thus, the SMMT Awards mark not only the beginning of the end for the diesel TRU, but also the birth of a new global market in ‘clean cold’ technologies worth many billions of pounds. And it is a market in which Britain has a natural lead, with its enviable position in engine manufacturing and exports (2.6 million units built in 2013), and a hub of clean cold research and expertise centred in the Midlands.

The Dearman Engine Company is working with a number of partners including Hubbard to bring the technology to market. Following the start of on-vehicle testing with MIRA (formerly the Motor Industry Research Association) in 2014, commercial trials begin in 2015 and low volume manufacture in 2016. The Dearman engine is likely to break the orthodoxy that new technologies must be more expensive than established ones; based largely on standard piston engine architecture, it will be cheap to build, simple to maintain and contains no exotic materials. With local air pollution regulations set to become much stiffer in many jurisdictions, it will be an extremely cost effective way for logistics operators to eliminate NOx, PM and F-gas emissions from their refrigerated vehicles and achieve progressively larger reductions in CO2. The manufacturing capacity to produce the Dearman engine already exists in the UK, and a recent report found that by 2025, Britain could be making 173,000 engines a year, generating net revenues of £713m and creating or maintaining more than 2,100 jobs.

Clean cold technologies are not just coming in from the cold – they look set to create one of the hottest global markets of the 21st century.

This article appeared in the Q4 2014 issue of Automotive Megatrends Magazine. Follow this link to download the full issue.

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