Currently, electric and driverless construction machines are still niche products or only at the prototype stage. However, market requirements and manufacturers’ commitment are driving development.
The international construction machinery industry is under increasing pressure to prevent both exhaust emissions and noise emissions. The Mayor of London, for example, has set a goal aiming to ensure that the center of the British capital is an “ultra-low emission zone” by 2020. This also means that construction machines will have to be either zero-emission vehicles or ultra-low emission vehicles. Construction work elsewhere, for example in our inner cities, in hospital areas and in enclosed spaces, will also have to be as quiet and involve as few air pollutants as possible. The increased use of electric drives could be one way of achieving this.
Electric versions of smaller construction machines in particular already exist bauma 2019 Electrically powered construction machines, such as this mini excavator, are ideal for environments where exhaust gas and noise need to be prevented. © Wacker Neuson
“Mechanical engineering companies have already launched e-solutions for smaller machines, such as vibratory plate compactors, small rollers and compact wheel loaders”, says Dr. Darius Soßdorf, Technical Regulations and Standardisation Consultant at the Construction – Equipment and Plant Engineering trade association of the German Mechanical Engineering Industry Association (VDMA e.V.). Wacker Neuson SE, for example, has been very active on the electrification scene for a few years now. According to the Munich-based company, its goal is to build up a full electric product portfolio, which already includes all essential e-devices and e-machines for developing inner-city construction sites, from battery-powered rammers through to wheel loaders.
Volvo Construction Equipment is also increasingly focusing on electrification. In September 2018, the Swedish company unveiled an electric compact wheel loader as a concept machine. The previous year, Volvo presented a fully electric compact excavator, also as a prototype.
Hybrid solutions for higher power ranges?
In contrast, manufacturers are currently still struggling with electric solutions for high-power-range machinery as the power required for the type of work in question is too high. “In order to supply a ‘normal excavator’ weighing approx. 15 tons with sufficient energy for a day shift, using current technology the necessary battery pack would weigh around eight tons,” calculates Wolfgang Lübberding. In light of this, the Business Unit Manager of the Association of the Construction Industry, Environmental Technology and Mechanical Engineering (VDBUM e.V.) sees hybrid vehicles as another future area for development. “The device would be electrically powered for light work, for example driving, and then a combustion engine would be engaged where maximum power is required” says Lübberding.
An opportunity for recuperation and storage systems
It is clear that when electric drive units are used, the machine’s available energy must be used extremely carefully. “As such, solutions focusing on energy recovery and storage will be increasingly in demand for electric and hybrid machines in particular,” says Prof. Dr. Eng. Frank Will with certainty. The current Endowed Chair of Construction Machines at the Technical University of Dresden continues: “Whenever a machine works largely intermittently, these systems can offer considerable potential to make savings.”