It seems that the latest trend in train technology is hybrid powertrains. For a long time, diesel trains have used electric motors for smoother power but as battery improvements arrive, the powertrains are becoming more sophisticated and handle features such as regenerative braking.

Let's start with France. Last October, SCNF started a medium distance route between Paris and Troyes using the Canadian Bombardier AGC which can be powered by dual mode (either diesel or electric) or dual voltage (because some train lines have different voltage levels). Users don't perceive any change when switching from one energy source to another - although no batteries are installed.

Then there's Japan's Kiha E200 (pictured above) which uses both an 95 kW electric motor and a 300 kW diesel engine and lithium-ion batteries located within the ceiling of wagons, which is run by JR East. But there's more: JR East has also a concept model, called NE, that uses a hydrogen-powered fuel-cell which reaches 60 mph and is able to run 30 to 60 miles without refuelling, thanks to regenerative braking. The NE has also batteries within the ceiling and has an auxiliary diesel engine that helps the train climbing up slopes or when the batteries are too low. Three units from the latter are being tested in the UK and Australia as well.

Arriving from Canada, there's the 2004 Green Goat, an improved diesel locomotive with diesel electric and diesel hydraulic which is claimed to be cheaper to run and maintain and produces less pollutants.

But don't think that hybrid trains are new. Back in 1986, Czech's CZD company built a hybrid locomotive that used both a diesel engine and electric motors backed up with batteries which were recharged with regenerative braking or from the tender. Unfortunately, the project was discontinued because of the company's financial problems.

[Source: Consumer and Japan for Sustainability]