Hydraulic Hybrid Technology Could Rival Batteries

Plug-in hybrid, all-electric or fuel cell? Car-makers are hedging their bets on what will emerge as the next generation engine technology of choice – now it seems another alternative approach could well be set to enter the mix. Scottish engineering firm Artemis Intelligent Power has tested a hybrid system that it claims can cut carbon emissions by 30%, with the added advantage that it is better suited to inter-urban journeys than conventional hybrids like the Toyota Prius.

In common with other hybrids, the system employs a regenerative braking system that stores energy as the vehicle slows down, and feeds it back into the engine as it accelerates. The key innovation is that instead of storing the energy in a battery, the new system stores it in a hydraulic accumulator.

According to Artemis, the system, independently tested in a BMW530i prototype, records superior fuel efficiency because it is only a third of the size and weight of a battery hybrid. The tests also discovered that it doubled fuel efficiency and cut carbon emissions by around a third compared to cars powered by conventional engines.

The compressed-gas technology also beats battery-hybrids at capturing and delivering energy, especially on the open highway. Since conventional hybrids require frequent braking to capture enough energy for major improvements in fuel efficiency, they have sometimes been criticised for their limited value outside urban settings.

A further environmental advantage is that the Artemis system is mostly made up of benign materials such as aluminium, steel and rubber. This means that they contain less hazardous chemicals than batteries and are also cheaper to manufacture.

At the moment, Artemis have not announced any plans to bring the technology to the mainstream, but its chances have been given a significant boost following a move by components giant Bosch Rexroth to snap up the licensing rights. According to Wim Rampen, managing director at Artemis, “with market introduction, it’s Bosch’s territory and commercially sensitive.” Outside the car industry, an unnamed firm has also bought the rights to use the system in off-road agricultural and construction machinery.

Andrew Williams

is a writer and freelance journalist specialising in sustainability and green issues. He lives in Cardiff, Wales.