Thread by @25kV

@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies Lets look at that idea.

RTC were very good at learning from R&D done in other sectors. e.g. the APT having a body structure derived from aircraft design.

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies In this case they'd be looking at the work done by the automotive sector on EVs. Automotive has far larger buying power than rail.

With all of that R&D effort over the last 10 years, they have managed to create batteries with an energy density of ~1/5 that of diesel fuel

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies So that means that - to cover the distances a train does - an entire vehicle, maybe more, would need to be given over to batteries. And that affects the economic case because trains are all about BUMS ON SEATS and so the effective train length just reduced

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies Your claim that "It would be so much cheaper" is entirely untested and should not be taken as axiomatic. Against the one-off cost of electrification must be offset the increased costs of batteries due to weight, shelf life, poor efficiency, extra maintenance costs etc

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies But most importantly, you are missing the key advantage of electrification over *any* form of self-power. All self-powered trains are limited in how much power they can take, because that power is finite.

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies Electric trains effectively have infinite power available - or rather, so much power than the limit on their performance is not power, but adhesion at the rail. They can put down power right to the point where wheels are about to slip, and they can do it all day long.

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies That means they can accelerate more quickly than self-powered trains. Acceleration=capacity, because getting to linespeed more quickly means trains clear blocks sections more quickly and then the next train can go.

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies Batteries will undoubtedly play a part in some form or other, perhaps on very lightly-loaded branch lines which are short. But there is no technology on the horizon - even with all that automotive R&D spend - that will bring the energy density of battery down significantly.

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@alanlmsca @poggs @partialcontent @WillDeakin1 @petemashmorgan @jamesjefferies I hope that has helped!

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