As road freight transport levels continue to grow, concerns about the impact on the environment and human health come sharply into focus. Fossil fuel dependency makes it a leading source of greenhouse gas (GHG) emissions, but shifting freight to other transportation modes will prove challenging. Solutions that will improve the efficiency and performance of road freight transport are therefore essential to achieve defined environmental goals. In this blog, we will explore a potential solution that has been pioneered by Siemens - called eHighway. This combines the efficiency of electrified railways with the flexibility of trucks in order to form an innovative, next generation freight traffic system that is efficient, economical and environmentally friendly.
Road freight transport reached record levels in the UK during 2016, and across the EU, a five-year high was recorded in 2015. The International Transport Forum estimates that global CO2 emissions from road freight will grow from 1.36 Gigatons in 2015 to a staggering 2.4 Gigatons by 2050, with total emissions caused by freight transport expected to overtake those of passenger transport. In the UK, roads continue to be the primary method of transporting freight, with over three quarters of all goods moved by this method - and heavy goods vehicles (HGVs) contribute almost 20% of all GHG emissions from road transport, despite representing only 5% of the overall traffic.
Increased vehicle efficiency and alternative fuels help, but they do not deliver sufficient impact, with huge gaps between predicted emissions and reduction goals. And while companies like Tesla, alongside traditional automotive manufacturers, are proving the viability of battery-powered electric passenger cars, powering HGVs this way is far more difficult. Aspects such as cycle times, transported loads and distances driven constitute significant hurdles when it comes to the use of battery solutions for long haul transportation applications. The size and weight required for on-board storage of electrical energy would clearly impact on freight capacity, and charging such batteries would restrict operational availability. These problems can be solved by providing electrical power directly to the vehicle while it is driving.
The eHighway system consists of specially adapted hybrid trucks, supplied with electricity from overhead contact lines via an active pantograph (similar to those used on electric trains or trams), which can connect and disconnect with the contact line at speeds up to 90 km/h (56 mph). Based on safe and proven rail technologies, it provides continuous energy supply to heavy commercial vehicles, and can be integrated and operated within existing road infrastructure without prohibitive effort or cost.
Combining the efficiency of electrified railways with the flexibility of trucks, the eHighway system halves energy consumption while maintaining full mobility. It also enables trucks to use renewable energy, contributing significantly to reducing emissions. Both the ecological and economic advantages of the system will grow with increased use of the routes over time.
The trucks’ hybrid drive systems enable full electrical operation within the electrification infrastructure, but also allows switching between electric and hybrid modes when overtaking or to bridge non-electrified parts of the route. The system is also compatible with other alternative fuel technologies, such as biofuel, natural gas or fuel cells. Direct transmission of electric energy delivers outstanding efficiency - greater than 80% from sub-station infeed to the wheel (twice that of conventional combustion engines). During braking, the flow of energy is reversed, allowing otherwise unused braking energy to be fed into on-board energy storage or back into the grid to be used as needed by other eHighway trucks.
Central to the eHighway system, the active pantograph transmits energy directly from the overhead contact lines to the truck’s electric motor. Sensors verify whether the traffic lane is equipped with contact lines and the pantograph can be connected or disconnected at speed, either automatically or at the push of a button by the driver. Sensor and actuator technology also allow the pantograph to automatically adjust its position to compensate for lateral movements of the truck in the lane, ensuring that steering an eHighway truck connected to overhead contact lines is no different to driving a standard truck. This also minimises wear across the pantograph to ensure a long lifespan - and enables it to automatically disconnect in the event of evasive manoeuvres.
Constant power supply will be guaranteed by substations along the eHighway. For power distribution to the trucks, a two-pole catenary system ensures a level contact wire and reliable, stable and secure energy supply, even at high speeds. Crucially, eHighway infrastructure will allows for rapid, easy integration into existing road networks and won’t disrupt other road users. Furthermore, it can operate in all traffic and weather conditions.
The eHighway system is particularly applicable for heavily-used shuttle transport routes (for example, from ports or mines to freight and distribution centres), as well as for long haul road freight transportation. It can substantially reduce use of fossil fuels, noise and truck operating costs, at the same time as virtually eliminating local emissions (such as CO2, nitrogen oxides and particulate matter). In terms of potential impact, fuel savings of around €20,000 can be achieved by a 40tonne truck driving 100,000km on the eHighway - with potentially 6,000,000tonnes of CO2 savings per year being realised if 30% of truck traffic on German highways were electrified and supplied with renewables. Siemens has already partnered with governments, manufacturers and haulage operators in Sweden, the US and Germany to trial the technology on public roads.