Anyone who has ever got stuck behind an old milk float as it trundles down the street must find it hard to believe that it might be regarded as the future for modern delivery vehicles.
But increasingly companies are looking at electric trucks to provider greener and, in the longer term, cheaper, options for urban deliveries.
The past couple of years have seen the rise of Smith Electric Vehicles as well as Modec. Between them, the two companies have vehicles on trial with major operators such as DHL, TNT, UPS, Tesco and Marks & Spencer.
However, battery power is not the only technology available. There are various forms of dual fuel vehicles, diesel electric hybrids, hydrogen and fuel cell technology coming into play.
Volvo Trucks has been developing both gas-powered trucks and diesel electric hybrids.
The Volvo gas truck is based on a Euro-5 diesel engine with a separate fuel system using gas injectors in the inlet manifold. A small amount of diesel is injected and ignited by the compression, which in turn ignites the methane gas/air mixture. As a result, the power and driveability are identical to that of a conventional truck. Field testing will start in Sweden and the UK in 2010.
Efficiency
“This technology allows us to combine the advantages of gas with the diesel engine’s high efficiency rating, which is about 50 per cent superior to that of the spark plug engine,” says Lars Mårtensson, environmental director, Volvo Trucks. “As a result, this truck consumes about 30 per cent less energy than traditional gas trucks do.”
Volvo has also produced the FE Hybrid specifically for distribution trucks, city buses and refuse vehicles. It reckons the hybrid will reduce CO2 emissions and fuel consumption by 15-20 per cent depending on the application. It has a normal diesel engine and a gearbox, but in between the clutch and the gearbox sits the electric motor.
Henrik Kloo, who co-ordinated the project, says that starting the truck from standstill uses the electric motor because of its high torque. At higher speeds the diesel and electric engines can work together, or the diesel engine can take over.
A hydrogen bi-fuel hybrid conversion for petrol internal combustion engines is being pioneered by Revolve Technologies. Earlier this year it launched H2ICE – a hydrogen bi-fuel based on the Ford Transit 2.3-litre petrol panel van.
“Some people believe hydrogen fuel is a distant reality, but Revolve Technologies has a proven zero-emission hydrogen technology on the road today,” says managing director, John Mitchell.
Three vans have been produced, with two shortly to enter trial service with the Post Office. Revolve points out that they are not concept vehicles but essentially “production ready”.
Revolve argues that while the current focus might be on electric commercial vehicles, “which are undoubtedly preferable to standard petrol/diesel variants and provide zero emissions in use, the performance of the hydrogen-powered Transit is far superior to that of its electric counterparts”.
At the heart of the H2ICE conversion Transit is a traditional 2.3-litre petrol internal combustion engine. This is mated with separate fuelling, induction and electronically-controlled injection systems for compressed hydrogen gas. This enables drivers to swap between petrol or hydrogen should one source of fuel not be available.
While hydrogen fuel cylinders are needed in addition to a petrol fuel tank, these are under-floor mounted and do not restrict the payload area. Revolve argues that the cost of the H2ICE conversion is currently the cheapest option for low CO2 vehicles when compared against fuel cell and electric vehicles. In addition, it says hydrogen compares favourably with petrol from a safety point of view.
Electric vehicle suppliers are certainly aware of the threat of hydrogen power and are quick to point out the weaknesses – the most obvious being the lack of a distribution network for the gas.
But generally they are more keen to talk about the progress that is being made in developing battery technology. Axeon, which is based in Dundee, has played an important role in developing lithium-ion battery technology and supplies batteries to Modec.
Performance
Sales manager Mark Durrant points out that the performance of a lithium-ion battery is significantly better than lead acid, giving three to four times the performance. The development of AC motors, which are both lighter and more powerful than DC, have also helped.
In addition, lithium-ion is better at maintaining the voltage while delivering a high current. This means that it can, for example, support higher acceleration rates in vehicles. Lithium-ion technology cannot claim to be cheap at the moment, nevertheless, Durrant reckons it will give return on investment over five years and the period is going down – mainly as a result of rising oil prices. “The one caveat is that the price of electricity can be pushed up by a rise in oil prices.”
At the same time the performance of the technology is continuing to improve. Durrant says: “We have a road map that allows us to plot out the performance increase over the next three or four years.”
This road map suggests that capacity will increase three-fold over the period. In January a consortium led by Axeon was awarded almost £1m of government funding to develop new battery chemistries that will deliver high energy densities, thus making them ideal for use in plug-in electric vehicles.
The project aims to accelerate the introduction of next-generation batteries that will offer higher energy density combined with lower cost. Other members of the consortium include the University of St Andrews, Nexeon, a UK battery materials company developing silicon anodes for lithium-ion batteries, and Ricardo, the automotive technology specialist.
Over the next two years St Andrews will conduct research on potential new electrode materials. Nexeon will implement appropriate chemical engineering to scale up material synthesis and optimise electrode fabrication, resulting in prototype lithium-ion cells based on its proprietary silicon anode technology. The cells produced will be used by Axeon to construct a usable, plug-in hybrid electric vehicle-type battery, with cells engineered into a housing with electrical interconnects and harnessing. Ricardo will test the battery module integrated into a demonstrator vehicle.
Fuel cells are also starting to come into play. Smith Electric Vehicles, which produces both electric panel vans and light trucks, recently signed a deal with Proton Power to trial a fuel cell that could double the range of its vehicles.
The first prototypes, based on Smith’s Edison van, are due to be presented at the Hannover Fair later this month. The van will be fitted with a Proton Power PM200 fuel cell as a range extender. The fuel cell is used to top-up the batteries and support auxiliary vehicle functions such as air conditioning and heating.
Electric commercial vehicles have a maximum range of around 100 miles, which makes them suitable for low mileage urban operations. However, by adding the hydrogen fuel cell as a range extender, the vehicles will be able to achieve closer to 200 miles. Proton chief executive Thomas Melczer says: “Fuel cell range extenders are an attractive option for overcoming the current problems of electric vehicles.”
Tiny tubes promise 100 times the power
A battery one hundred times more powerful than lithium-ion – that’s the claim of researchers at the Massachusetts Institute of Technology, for a new phenomenon called “thermopower waves”.
The key to the technology is carbon nanotubes – sub-microscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms just a few billionths of a metre in diameter.
Heating pushes electrons along the tube, creating a substantial electrical current – much greater than that predicted by thermo-electric calculations, according to Professor Michael Strano of MIT. In theory, he says, such devices could maintain their power indefinitely until used, unlike batteries whose charges leak away gradually as they sit unused. And, while the individual nanowires are tiny, Strano suggests that they could be made in large arrays to supply significant amounts of power for larger devices. The researchers also plan to look at different reactive materials for the coating – allowing the wave front to oscillate, thus producing an alternating current.
How a fuel car works
A fuel cell uses a chemical process to generate electricity. At the anode of the cell hydrogen is broken down into protons and electrons. The protons diffuse through a membrane to the cathode.
However, the membrane is an electrical insulator so the electrons are forced to travel round to the cathode via an external circuit. This is the electric current generated by the fuel cell.
At the cathode, the protons and electrons react with oxygen to form water, the only emission.
