There is a lot of debate about whether rail really is greener than air or car travel. Some researchers have said the environmental damage caused by railway construction could offset the benefits, and that ridership needs to hit relatively high levels—and encourage switching from other modes—before the costs are worth paying. Still, on a per-passenger CO2-per-mile basis, trains generally do better than the rest. And, it seems likely that trains will make faster efficiency improvements than airlines (the latter’s emissions targets stretch well into the century).
Consider this recent announcement from a German engineering company called MTU Friedrichshafen. Working with Germany’s rail operator, Deutsche Bahn, the company has developed a hybrid locomotive that cuts energy use and carbon emissions by 25%. The system claws back kinetic energy that’s normally lost during braking, converting it to electricity that’s stored in a battery.
Spokesperson Mirko Gutemann says DB is currently testing the train on the Aschaffenburg to Miltenberg line in Bavaria. Based on 300 days service a year, with seven trips a day, he says it should save about 40,000 liters of diesel per year, or 105,000 tons of CO2. It will also be quieter and cleaner than diesel. When the train is in stations, drivers can shut off the fossil-fueled engine, and restart it using the electric battery. It only returns to diesel again once safely outside the station area, where the noise and fumes will cause less of an inconvenience. "It’s a parallel hybrid, which means you can use either the diesel engine, a combination of the diesel and the batteries, or just the batteries," Gutemann says.
The train is not taking passengers yet, and requires government approval before it can go into service. But the technology should help further make the case for rail, especially in countries with existing infrastructure.