SNCF Research is exploring a whole range of ideas for reducing our energy consumption and carbon footprint, including hybrid drive systems.

The first focus is on eco-driving. The SNCF spends more than €900 million on powering its trains (with electricity and diesel) and is aiming to save 1% (8 million KWh) by fine-tuning its real-time eco-driving calculations.

A second focus is on braking energy recovery. Already, 20% of the power needs of double-decker Paris region trains and 6% on the TGV Est high-speed trains are supplied in this way. On our single-phase power lines (at 25,000V), braking energy is recovered and sent back to the EDF substation, but in the form of DC power at 1,500V and further studies are required. SNCF researchers are testing supercapacitors and inertia wheels as methods for storing energy in substations, so as to be able to reinject it into the grid at peak consumption times, for instance.

Alternative energies put to the test. Local TER trains are already running on B30 (a mixture of diesel with 30% vegetable oils) and SNCF are keeping tabs on the development of second-generation biofuels (biodiesel and other bio-oils). Solar power is already used in our stations, but experiments are still underway to look at uses in trains and other rail infrastructure. In the Poitou-Charentes region, SNCF researchers are testing the use of photovoltaic panels on the roof of local TER trains, to power lighting systems. Hydrogen appears to be another option, but it is not naturally occurring and requires a significant production, transport and storage infrastructure.

Promising possibilities with hybrid fuel usage. The SNCF's researchers think that the most plausible option is a mix of power sources and technologies. The PLATHÉE project (platform for energy-saving and environmentally-friendly hybrid trains) is exploring these options. The project brings together various energy supply or storage sources with "smart" energy management technologies, in order to draw from the most appropriate sources at the right time, reducing consumption and pollution. Measurements are being carried out to check whether the estimates are correct and results are due out in late 2010. Watch this space...