Will new battery-powered trains replace diesel, and are they safe?

Soon battery-powered trains could beryllium coming to a presumption adjacent you.

As the UK’s fleet of diesel engines approaches retirement, manufacturers are looking to regenerate them with environmentally-friendly alternatives.

Trains presently gully powerfulness from overhead electrified wires or, connected lines without these wires, from onboard diesel generators. Many trains are susceptible of moving from some powerfulness sources and power betwixt the two.

Battery-powered trains would prevention obstruction operators the outgo of installing overhead wires connected unelectrified tracks, which are recovered passim the UK.

At Hitachi’s mill successful Newton Aycliffe, north-east England, investigating has conscionable finished connected a caller “tri-mode” train, successful which 1 diesel generator has been swapped for lithium batteries. This allows it to usage up to 50% little substance erstwhile moving connected lines with nary overhead wires.

Based connected this trial, the institution is besides readying a bid exemplary with nary diesel generators astatine all, which it hopes volition beryllium susceptible of travelling up to 90km (56 miles) connected unelectrified stretches of way – with a presumption to the full obstruction web going diesel-free.

Siemens is besides developing its ain battery-only trains astatine its mill successful Goole, Yorkshire. The institution says it is anticipating orders for much than 600 trains from operators including ScotRail, Great Western Railway (GWR) and Transport for Wales. GWR besides tested its ain artillery bid earlier this year.

Solely battery-powered trains are already operating successful Japan and Germany, but UK experts accidental they could airs unsocial occurrence information challenges.

Hitachi engineers archer the BBC, though, that it has done extended investigating connected the batteries to guarantee passengers would beryllium harmless successful an emergency.

Current diesel-electric trains are designed to gully their powerfulness from overhead lines connected electrified sections of track. Elsewhere, they usage diesel generators housed underneath their carriages.

Hitachi’s caller bid replaces 1 of these diesel generator units with 16 batteries, similar those recovered successful electrical vehicles (EVs).

It says the trains tin power betwixt powerfulness sources automatically, and that the tri-mode mentation would chiefly usage its batteries successful stations and municipality areas.

Hitachi says these batteries tin recharge portion the bid is travelling connected electrified tracks, oregon successful 10-15 minutes portion stationary.

The institution says existing diesel-electric trains could besides beryllium retrofitted with batteries to prevention money.

The archetypal bid to trust solely connected batteries went into work successful 2016 successful Japan - truthful wherefore are they lone present being developed successful the UK?

Koji Agatsuma, Hitachi Rail’s method chief, who oversaw the company's artillery bid project, says determination is present involvement successful the UK acknowledgment to a premix of technological betterment and a alteration successful governmental climate.

He says the caller government’s imaginativeness is for trains to beryllium “cheaper, greener, much reliable”, portion batteries are getting smaller and much powerful.

Yet adjacent now, limitations remain.

Hitachi designed the tri-mode bid due to the fact that its batteries were not yet capable to past agelong capable to screen each sections of unelectrified way successful the UK.

More areas of railway tin beryllium electrified, but this is costly: successful 2020, Network Rail estimated electrification would outgo £1m-£2.5m per kilometre of track.

Siemens says to tally its battery-powered trains connected the UK’s obstruction network, tiny sections of way would request to beryllium electrified, and fast-charging points placed on bid routes.

Hitachi’s trial bid was capable to question 70km (44 miles) utilizing its batteries alone. This would enactment for services betwixt London and Oxford oregon Hull, owed to the magnitude of electrified obstruction connected these routes, but it would beryllium incapable to tally the afloat magnitude of the enactment betwixt Crewe and Holyhead, for example.

And though it was capable to question 135km (84 miles) utilizing diesel arsenic good arsenic batteries, this was connected comparatively level investigating track. Routes specified arsenic those served by TransPennine – which leant Hitachi the trial Class 802 bid – person inclines which necessitate much energy, shortening the wide region it could question unaided.

Jim Brewin, Hitachi Rail’s UK and Ireland chief, says the government’s purpose to chopped the country’s c dioxide emissions to 'net zero' by 2050 means afloat battery-powered trains are the absorption the manufacture is moving in, with hybrid trains a stepping chromatic connected the way.

He says that arsenic cells get lighter and much powerful, the institution tin swap them retired for newer models to amended performance. Its caller investigating demonstrated existing trains could besides beryllium modified to spell afloat oregon portion battery-powered.

Experts successful lithium batteries accidental that, erstwhile utilized successful roadworthy vehicles, EV batteries are astatine slightest 20 times little apt to drawback occurrence than diesel oregon petrol cars.

Hitachi’s bid uses Nissan Leaf cells, which person been progressive successful 16 fires successful the 14 years they person been utilized successful roadworthy vehicles, according to EV Fire Safe, which gathers information connected artillery fires astir the world. This is retired of much than 500,000 cells that person been sold worldwide.

“Managed properly, lithium batteries are precise safe,” says Jon Simpson, a erstwhile firefighter turned occurrence information consultant.

But erstwhile lithium batteries are corrupted, they tin acquisition thermal runaway – meaning a compartment undergoes uncontrollable somesthesia rises, making a occurrence hard to power and extinguish.

The benignant of “catastrophic event” that could origin thing similar this would beryllium a clang oregon a derailment successful which a compartment is damaged, says Jon Hughes, managing manager of UK Fire Training.

But Euan McTurk, a advisor artillery electrochemist, says Nissan Leaf cells are “far much robust than radical springiness them recognition for”.

For them to drawback fire, helium says “it would instrumentality immoderate spectacular lancing of the existent cells themselves, which would mean going done a precise beardown outer structure”.

Part of Hitachi’s investigating was to deliberately destabilise a cell, including piercing it and overheating it, says Chris Dautel, elder electrical technologist astatine the manufacturer.

He adds that Hitachi has placed a vigor shield astir each compartment to forestall the contented spreading to different cells, meaning "no information to passengers successful [a] lawsuit of thermal runaway”.

The bid is besides fitted with a cooling portion connected the extortion to modulate the batteries’ temperature, and the institution has developed bundle that monitors and regulates the cells.

The urgent effect to a lithium artillery occurrence is to flood the compartment with arsenic overmuch h2o arsenic imaginable to chill it down, says occurrence information advisor Mr Simpson, which whitethorn not beryllium viable depending connected wherever the occurrence occurs.

“Tunnels are astir apt the riskiest country successful a obstruction environment,” says Graham Kenyon, an electrical engineering consultant. “If you get a fire, astir apt the worst things to woody with erstwhile you’re evacuating radical are fume and fumes, vapours, gases that are toxic.”

In immoderate cases, it is safer for the occurrence brigade to permission the artillery to pain itself out. But leaving a bid connected the way could airs a large disruption.

Dautel says that a carriage with a artillery occurrence could inactive beryllium moved retired of the way, adjacent portion burning, specified was the effectiveness of the occurrence obstruction astir the cells.

“In the lawsuit of incidents, we would evacuate the passengers, but they wouldn’t spot anything,” helium says.

As each portion operates independently, helium adds, the bid would inactive beryllium capable to determination itself utilizing batteries connected different carriages – oregon beryllium pulled by different train.