Gallery: Concept trucks of the future
THESE days our highways seem strewn with the wreckage of a car industry in crisis. Sales of gas-guzzlers have plummeted. Some of the world’s largest car-makers have all but gone to the wall. In the US, for the first time in a quarter of a century, the nation’s favourite SUV has been by a passenger car – a Japanese compact at that. No, life on the road ain’t what it used to be.
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So what of those kings of the road – the heavy trucks that move some 70 per cent of all freight in the US and a similar slice in the UK and much of Europe? With the global economy in recession, fuel prices still high and ever-tighter emissions laws ahead, you might imagine that they too would be heading at full tilt towards an economical, low-carbon future. You’d be wrong. “The truck industry has been stagnant for a very long time,” says energy-efficiency advocate Amory Lovins of the Rocky Mountain Institute (RMI) in Colorado.
While the average fuel efficiency of the US car fleet has almost doubled in the last 40 years, today’s (see graph). In 1990, America’s truckers burned the equivalent of 1.6 million barrels (254 million litres) of oil per day, about 10 per cent of the nation’s total consumption. By 2007, this had risen to 2.5 million barrels.
“Today’s heavy trucks guzzle the same amount of fuel that they did four decades ago”
This cannot go on, and truck-makers, freight companies and transport researchers are finally getting the message. Across the world, and especially in the US, they are taking a new look at ways to cut freight fleets’ fuel consumption.
Even small improvements can bring big benefits. A concept vehicle called the Innovation Truck unveiled in April by Daimler Trucks North America is designed to show what is possible by tweaking a vehicle’s aerodynamics. In wind tunnel tests it used 3 per cent less fuel than an unmodified truck – which rolled out across the entire US truck fleet would save annually. This translates into an annual cut in CO2 emissions of over 11 million tonnes.
More ambitious plans are afoot. Engineers and industry leaders at an RMI in April concluded that readily available and inexpensive technologies could boost efficiency by up to 23 per cent, and even doubling or tripling fuel efficiency might be within reach.
“Readily available and inexpensive technologies could double or triple fuel efficiency”
It has been half a century since the truck industry started experimenting with more efficient designs, and steady improvements to engines and modest aerodynamic advances have followed in the years since. Unfortunately, the gains have been undone by other factors that have increased fuel consumption, such as higher speeds, traffic congestion and excessive product packaging, which has cut the effective capacity of each truck. Meanwhile the cargo trailer – the box-on-wheels that is pulled by the tractor – has been virtually ignored. “It’s a dumb asset, and it has to get smarter than that,” says Bill Van Amburg of , a low-energy-transportation consultancy in Pasadena, California.
Yet there are ways of streamlining trailers. Skirts that cover the wheels and the open space under the trailer, and fairings covering the gap between the tractor and trailer, can improve fuel efficiency by 6 per cent. Rounded flaps or fins on the back of the trailer add a further 6 per cent. And simply blowing air through vents at the rear of the trailer cuts drag by up to 5 per cent (see “Go with the flow”). confirmed many of these improvements more than half a century ago. So why are they not commonplace?
Part of the problem is that with about four trailers to each tractor in the US, the trailers sit idle most of the time, reducing the payback from any investment aimed at enhancing fuel efficiency. To make matters worse, it’s the company operating the tractor unit that pays the fuel bill, while the trailer may well be owned by someone else. “It’s really a battle between logistics, practicality and cost,” says Ken Howden, director of the , a project to improve truck performance coordinated by the US Department of Energy.
One way around this is to look beyond the hardware for ways to save fuel. Shipping giant UPS uses routeing software that tries to avoid turns across the flow of oncoming traffic (left turns in the US and continental Europe; right turns in the UK and Australia) to cut down time spent idling. The company says that this and other tweaks to routeing saved it 11 million litres of fuel in 2007 in the US alone.
US superstore Wal-Mart, which maintains the country’s largest trucking fleet, claims to have done even better, with gains of more than 25 per cent helped by smart routeing software and keeping the packaging of its products to a minimum. With more measures like this, the company says it aims to .
Truck-maker Mercedes-Benz recently claimed a world record for one of its Actros trucks, which achieved a fuel efficiency of 19.4 litres per 100 kilometres (12.1 miles per US gallon) when hauling a 25-tonne payload on a test track. This represents a halving of fuel consumption compared to the average for trucks on the road in the US and Europe today. It was achieved in part by fitting “superwide” tyres in place of pairs of conventional tyres, which spreads the weight and minimises friction with the road. Aerodynamic smoothing also played a part.
Even more ambitious innovations are on the way. The first diesel-electric hybrid trucks are already cruising the highway (See “Electric juggernauts”), as are vehicles in which the diesel engine has been replaced by compact electric motors mounted inside the wheels (see “Drive wheel”). Other researchers want trucks to harvest energy from bumps in the road (see “Pothole power”) or from waste heat in the engine’s exhaust (see “Cool running”).
One thing is for sure: though driven by different priorities, policy-makers, truck-builders and freight companies realise that things are going to have to change. Last year, the American Trucking Association launched over the next decade by 318 billion litres through a combination of measures including streamlining and new engine technology.
If only we had started earlier, says Lovins. “I think we’ll look back in 2020 when we have tripled efficiency, and wonder what the heck took us so long.”
Gallery: Concept trucks of the future
Electric juggernauts
Petrol-electric hybrid cars have been around for years, saving their owners around 20 per cent at the pump, yet the technology has been slow to catch on in trucks. Even in the US, which ranks as a world leader in hybrid trucks, only about 1000 are on the road – and these aren’t big rigs but mid-sized delivery vehicles. In fact they mostly aren’t even full hybrids at all, but “power assist” hybrids. Most of the time, these trucks are powered by a conventional diesel engine and the electric motors just kick in to boost the power when needed.
Things took a step forward early this year when ArvinMeritor – whose main business is producing components and systems for truck manufacturers – unveiled a genuine diesel-electric hybrid long-haul truck, which can run solely on electric power at up to 75 kilometres per hour. It is expected to cut fuel use by up to 15 per cent on long journeys and 25 per cent in city traffic. It is being road-tested by the retailer Wal-Mart.
Cool running
Capturing the waste heat from the engine and using it to help power the truck is a sure-fire way to save fuel. Heat-recycling technologies that increase engine efficiency by 5 per cent will be on the road within the next five years, according Haoran Hu of engine technology company Eaton Corporation in Cleveland, Ohio. Efficiency improvements of up to 20 per cent are possible, he says, though they are more costly. Engineers are testing a variety of new thermoelectric materials capable of converting heat directly to electricity.
UK-based Clean Power Technologies (CPT) has developed a system that uses waste heat to generate steam. This is stored in an accumulator and used when required to help drive the engine itself, or to power auxiliary equipment such as the cooler of a refrigerated container. The technology is being tested by engine manufacturer Voith Turbo based in Heidenheim, Germany. CPT claims a 40 per cent increase in fuel efficiency, and is about to begin road tests with two Canadian freight companies.
Go with the flow
Turbulent airflow at the rear of a trailer can be a serious drag on fuel economy, and while rounded ends or tail fins can help, they can only improve things by a few per cent. A more radical solution is to combine geometric changes with a technology borrowed from the aerospace industry and surround the rear of the trailer with a stream of smooth air.
Robert Englar and his colleagues at Georgia Tech Research Institute in Atlanta have built a pneumatic system (New Scientist, 9 June 2001, p 36) that blows a gentle stream of air out of the rear of a trailer through a series of pipes and nozzles. This reduces airflow separation along the back of the truck (see diagram) that would otherwise create a pocket of turbulence and low pressure behind the vehicle, holding it back.FIG-mg27211102.jpg
Tests on a prototype in 2004 found by 5 per cent, on top of the 6 per cent savings offered by streamlining. Two airflow systems compatible with new and existing trailers have been completed in the past few months, and could retail for as little as $2000, Englar reckons. The device would pay for itself in about 161,000 kilometres, or less than three years, on average.
Smooth operator
If incremental aerodynamic improvements seem like a lot of effort for a small gain, the superstreamlined concept trucks by German designer Luigi Colani take aerodynamic enhancement to a whole new level.
In 2002 Colani unveiled a tanker truck that proved 41 per cent more fuel efficient than a conventional tanker of the same size. Then in 2007 Colani built a $1 million prototype “supertruck” that he says travelled 50 per cent further on a gallon of fuel than a conventional truck with the same engine. Colani says that mass-production would make his trucks more affordable.
Less spectacular, but possibly more cost-effective, simply increasing a vehicle’s length can improve efficiency in terms of fuel used per tonne carried. A recent study by the American Transportation Research Institute, based in Arlington, Virginia, found that attaching a second full-size trailer to the back of a conventional truck increased efficiency in these terms by up to 36 per cent. So-called “long combination vehicles” made up of four trailers behind a single tractor are allowed in parts of Western Australia. In many US states, even a second trailer is prohibited, as trailer trains can be unstable. Improved trailer design could overcome this objection.
More ambitiously, automated sensors and controls are being planned that allow “caravans” of trucks to form up and drive safely one behind another, with only a narrow gap between vehicles. Japanese researchers are planning highway tests of this technology in 2011. Based on trials by other groups, average fuel savings of 11 per cent per vehicle might be possible.
Pothole power
The smooth ride provided by a modern truck’s sophisticated suspension comes as a cost: it soaks up a lot of energy. Instead of letting this go to waste as heat, the system, developed by Levant Power of Boston, captures it and converts it to electricity, with fuel savings of up to 5 per cent.
The key component is a modified shock absorber or damper, which stops the vehicle bouncing after it hits a bump in the road. As in a conventional shock absorber, the suspension linkage connects the wheel to a piston, which is forced through a chamber containing viscous fluid when the wheel hits a bump. In the GenShock system, the motion of the piston forces fluid through a small turbine (see diagram) that drives an electrical generator.FIG-mg27211103.jpg
The electricity this provides charges the battery, which would otherwise take its power from the vehicle’s engine-driven alternator. The rougher the terrain, the more power the shocks produce, but even on smooth highways vibrations in the suspension system of a long-haul truck would generate useful amounts of power: 500 watts per unit, according to Levant Power’s tests. The company intends to start pilot tests on commercial trucks this year.
Drive wheel
The days of roaring juggernauts could be numbered. E-Traction, a company based at Apeldoorn in the Netherlands, has developed an electric motor for trucks and buses that , putting the power down right where it is needed (see diagram). By eliminating the heavy transmission and gearing that soaks up a significant portion of the engine’s power in a conventional truck, this delivers impressive efficiency savings. “We kick out all the mechanical parts,” says Arjan Heinen of E-Traction. “There is only one moving part: the wheel itself.”
E-Traction wheels have been working in experimental buses since 2005. Trials in the first freight vehicle, a 7.5-tonne diesel-electric hybrid, began last year. The truck, assembled by Dutch start-up , has a diesel generator that charges a bank of batteries, which in turn supply electricity for two motors, one in each rear wheel. The truck can go 40 per cent further on a litre of fuel than a conventional truck, and the E-traction wheel power provides a 10 to 15 per cent improvement over hybrids without in-wheel motors. The company plans to produce 10 of these delivery trucks next year and begin production of a 36-tonne hybrid truck in 2012.FIG-mg27211104.jpg
