Using electricity to power road freight

The ‘eHighway’ ,it's concept uses electricity delivered via overhead lines to electrify road lanes and provide clean and efficient power to trucks - enabling the use of renewable energy and can result in lower CO2 emissions.

The first real-world demonstration project of the technology will take place in California near the Ports of Long Beach and Los Angeles, the two largest ports in America, and is due to begin operation in July 2015. Working with the South Coast Air Quality Management District, Siemens is to install an eHighway system along one mile of a highly-travelled corridor near the ports. Up to four trucks will be running in the one-year demonstration, making multiple trips each day. As this is the first operational trial of the technology there are no official projections regarding savings on emissions and running costs, so the project’s findings will act as benchmark of what the technology can achieve.

Using technology similar to trolley systems or street-cars with overhead contact lines, the eHighway system will use an active pantograph to conduct direct current (DC) electricity to an electric and/or electric-hybrid truck. The drive system will enable full electric operation when connected to the contact line while retaining an engine, or other form stored energy, supplies power when outside of the contact lines.

Unlike rail technology the eHighway contact line system is designed with two poles (one to handle the power in-feed and the other the out-feed) because the current return circuit cannot flow via the road in the same way it can through a rail. Overhead contact lines provide a secure energy supply at speeds up to 96kmh (60mph). A substation connected to the medium voltage grid located near the eHighway provides power to the overhead contact lines and can collect and feed it back energy from regenerative braking system to further increase the efficiency achievable from the technology.

An active pantograph atop the truck transfers the energy from the overhead lines to the electric motor and can connect and disconnect with the contact line automatically at statutory speeds. As soon as the truck-mounted optical scanner recognises an overhead line, the pantograph is ready to connect and it can also be extended automatically or manually from inside the vehicle. This allows significant flexibility as the eHighway trucks can easily switch lanes or pass other vehicles without being permanently fixed to the overhead systems like a street-car.

Each truck will be equipped with either an all-electric or a hybrid drive systems comprising a drive motor, generator, inverter, on-board energy storage and DC/DC converter. The eHighway system could be combined with most other technology, be it diesel, natural gas (CNG/LNG), battery or fuel-cell for powering the vehicle outside of the catenary.

While details are yet to be finalised the eHighway technology being demonstrated in California looks set to feature a hybrid diesel/electric truck, one powered by a compressed natural gas/electric hybrid drive train and an all-electric truck that runs on battery power outside of the contact line. The option remains for a fourth vehicle with a different configuration to be added to the trial.

Already under development for the project is a diesel-hybrid demonstration vehicle which is being built a partnership between Siemens and Mack Trucks, a subsidiary of Volvo. The vehicle will be based on a conventional Mack Pinnacle highway chassis and equipped with a proprietary and fully integrated hybrid electric drive-line. It will be fitted with the fuel-efficient 11-liter Mack MP7 engine which drives the vehicle mechanically through a modified Mack mDRIVE automated manual transmission, and a 150kW integrated AC electric motor/generator.

Mack’s 11-liter engine develops 302kW (405hp) and 2,115Nm (1,560lbft), which is mid-range for this type of vehicle and work. According to Jan Hellaker, Volvo Group vice president of transport solutions: “Besides further reducing exhaust emissions and fuel usage without compromising performance, the MP7 engine delivers a significant weight advantage and helps offset the weight of add-on components required for the eHighway.”
The trucks will operate in full-electric mode when on the eHighway routes and will automatically switch to the diesel/mechanical drive system where there is no overhead line.

Benefits of eHighway

Siemens expects adopting eHighway technology to result in a number of environmental and economic benefits due to the increased efficiency an electric motor has in comparison with a diesel engine.
Using electricity also eliminates the local emissions associated with diesel engines, greatly improving the local air quality. At the same time, the eHighway concept allows the use of renewable electricity in heavy duty road freight, opening up the possibility to greatly reduce the green house gas emissions caused by the freight industry. It is also possible that roadside solar panels and wind turbines could be used to feed the overhead power lines which would reduce the carbon footprint still further.

Contact line systems have been proven to work reliably and cheaply across the world for more than a century, strengthening the case that this technology can be used successfully for other modes of transportation. Furthermore, the system can be installed along existing roads, greatly reducing investment and maintenance costs, and without disrupting traffic – an important consideration in severely space constrained and heavily trafficked areas like ports.

Electrifying Applications

The California eHighway project focuses on heavy-truck transport in key logistical hubs like ports but there are a number of other potential applications for electrified road freight. Mining is another example of trucks transporting goods on a small but regularly travelled route that may not warrant a separate rail connection. An eHighway concept in this setting could result in similar reductions in costs and emissions as the port demonstration.

Electrification is potentially applicable for almost any routes highly-travelled by trucks or other heavy-duty vehicles and over the coming decade will provide an ever increasing market for eHighway vehicles. Economies of scale will reduce prices and open the way for truck operations on moderate or diverse duty cycles. Regional or national highways may be considered for eHighway applications and with the expected standardisation of the vehicle technology, the challenge will shift to the traffic management.

This would include organising the billing and enforcement required to operate an eHighway system open to all suitable vehicles. Looking to the Future

The California project is crucial to understanding how electricity can answer today’s transportation challenges and to demonstrate zero emission road freight. Installing the technology in a real-world scenario allows it to be evaluated with a view of how it can be scaled up beyond connecting the ports to possibly the surrounding freeways and other cities.

In the future it might then be possible to electrify the highway network. These electric trucks would be able to charge their on-board storage from the power-line while on the move to make deliveries away from the electrified route – a concept that could have significant potential in densely populated nations. It also may not be so far off that we’ll see highway signs for HOV, Exit Ramps and also an ‘E’ lane.

Meeting greenhouse gas reduction targets and efficiently serving the transportation needs of a dynamic economy can only be achieved with new solutions. Using electricity is a key way to bring the transportation systems of yesterday into the present and to test the ideas of tomorrow.

This article is from ITS International magazine