GWR's battery-electric train--the verdict

 I talked about this before.  This new video gives more useful detail.

• GWR has been investigating battery-electric trains to replace diesel on branch lines.
• Straight-out electrification is expensive.  The overhead wires and the catenary posts are costly.  On high volume routes, this cost is worth it. But on less-used lines it is not.
• On this route, the diesel train produces 960 kg of carbon dioxide vs 235 kg per day for the battery units (a 75% reduction)  With renewable energy sources for the electricity, this could be reduced to 26 kg/day (a 97% reduction)
• The charging rail is on the ground, but is only activated when the train is over it (much safer!)
• It reaches full charge in 4 minutes (for 5 miles of travel).  The charger is connected to a bank of batteries (on the ground) which is connected to the national grid.  This stops the massive drain of power from tripping the local grid.
• So, unlike an overhead-wire electrification, it's just one charging station, which means there is no need for catenary posts and adjacent electrical infrastructure.  It's all off-the-shelf equipment, and can be installed with ease, even while services are running.
• Even with current battery technology, the batteries only need to be swapped out once in the unit's operating life, and can then be recycled.
• It's been tested under all sorts of conditions: rain, ice, leaves on the line, snow and baking heat, with full heating on, and it's worked without problems.
• It's far more efficient than diesels in terms of power usage, with 79% efficiency, with an electricity consumption of 2.4 kW per carriage per mile, and is obviously much quieter than a diesel.
• Diesels are more expensive on fuel and maintenance, but were cheapest on infrastructure. Overhead electrification was most expensive on infrastructure, but on a par with battery-trains on other costs.  Costs per train-mile:  £5/ train-mile, diesels £4/train-mile, battery-trains £2.52/train-mile.
• The batteries have a possible range of at least 80 miles (130 km).  [Though, by my calculations, that would take an hour to charge].  It is possible, though less efficient, to charge the batteries via the overhead cable, i.e., this battery-electric train could run along mixed electrified and unelectrified track.

Land transport contributes +-20% to CO2 emissions, and more to NOx, which are much more potent greenhouse gases.  Cars and light trucks make up most of this, but diesel for rail is not insignificant.  And it's horribly polluting.   

See also my articles on battery-electric trains.