Hybrid technology could break into heavy-duty machines

Hybrid technology could start to find its way into a range of heavy-duty machines after a test of the technology almost halved fuel consumption and cut carbon emissions.

Finnish researchers at the University of Aalto’s HybLab team have been developing the technology for around six years, culminating in the trial at Helsinki harbour.

While the motor industry has driven the large-scale uptake of hybrid technology by targeting environmentally conscious consumers, sectors such as construction and goods handling have proved more difficult to persuade.

‘They are conservative and typically they are using their machinery in order to get profit — if you want to bring new technology you have to show them that they can really get savings in their process and so the lifetime cost has to be smaller,’ said Prof Jussi Suomela of Aalto who heads the HybLab team.

Heavy-duty machines are operated for long periods of time each day and so can rack up considerable total emissions and fuel consumption.

Traditional machinery uses so-called ‘diesel-mechanical transmission’ to hydraulically power various moving parts. Using lab-based drivetrains to simulate machinery, the research team investigated the feasibility of switching to a diesel-electric transmission, using actuators in place of hydraulic pumps.

Such a system has the advantage of being able to easily incorporate energy-capture features for the ‘recovery phase’ of certain machine movements.  

Taking their research into the field, the team modified a straddle carrier — which is essentially a 20m high mobile, rectangular frame capable of lifting and moving containers around harbours.

‘The straddle carrier is very attractive because its cycle is amenable for hybridisation. They typically accelerate while transporting the containers then decelerate to store the containers by piling them up. The containers might easily weigh 50 tonnes so there is huge potential energy to capture,’ Suomela said.

Tests showed that the hybrid machine consumed 16 litres of fuel per hour, compared with the 26 litres a conventional diesel carrier would consume.

The modified straddle carrier uses supercapacitors to store captured energy for short periods ready for re-use at peak demand, but the team is also investigating battery packs and hydrogen fuel cells.