technology transport

The energy sources of transport

The IEA and International Renewable Energy Agency (IRENA) released a global overview of renewable energy earlier this month, Renewable Energy Policies in a Time of Transition. It’s a useful guide to how countries are incentivising and supporting renewable energy, and I’d recommend it if you’re at all interested in how policy can support renewable electricity, heating and cooling, and transport.

For the purposes of this blog, this is the image that caught my eye: a well presented graph of transport fuels.

This is why we need to keep talking about transport. The percentage of global transport that can be called sustainable is a mere 3.1%, and that’s being generous to ethanol. Almost a quarter of the world’s CO2 emissions are from transport, and we’re barely making a dent in fossil fuels just yet.

On the other hand, highlighting the situation now provides us a baseline to observe from. Transport running on renewable electricity is only 0.3% right now, but it’s going to boom, and I look forward to being able to report those figures in future.


  1. This subject is trickier than is usually acknowledged. The overall cycle must be taken into account, including embodied energy in the construction of infrastructure and vehicles, thermodynamic losses, transmission losses, conversion losses and mechanical losses. An important way to reduce energy consumption is to go more slowly; on the railways there has been a general increase in speeds, which were formerly in the 30-45 mph range for freight and 50-90 mph for passenger services.

    The embodied energy in modern rail transport systems is horrendous, with the use of absurdly massive overhead gantries to support lightweight power lines, aluminium for passenger vehicle bodyshells,

    The shorter life of modern rolling stock is also a consideration. The first generation of Eurostar trains are going for scrap after 25 years of service, the BR mark 1 fleet was withdrawn with more than 15 years of remaining service life, the Irish railways scrapped a fleet of perfectly good coaches (almost identical to the BR mark 3 fleet) after just 20 years in use, when it could have been returned to use in Britain and regauged at relatively little cost, LUL withdrew its District Line fleet only ten years after a major rebuild.

    Steam locomotives typically had a service live of 50 years +, being designed so that wearing parts were small and easily replaceable, likewise older rolling stock.

  2. There is an interesting article on energy sources for rail by Roger Ford, in the current issue of Modern Railways (May 2018). He casts a sceptical eye on some of the ideas being floated, including hydrogen fuel, battery power and dual mode (electric+diesel) trains.

    Taking one thing with another, it will be hard to beat electrification for busy routes and diesel for quieter ones. Steam would be worth a look as fuel can be anything that will burn (including renewables) and it is actually easier to meet emission standards than with internal combustion.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: