The unexpected scrapping of the WEZ (unexpected, that is, by anyone who hadn’t noticed that Boris was a Tory petrolhead) provoked a number of questions along the lines of ‘hang on, how will this affect the proposed cut in CO2 emissions by 2025, amounting to 60% reduction from 1990 levels?’. Well, at the time, there was some whiffle along the lines of ‘we’ll pay for it by reducing energy use in our spiffing new Overground and Underground trains’.
I was a bit sceptical for two reasons. First, this doesn’t actually reduce emissions, merely move them. Second, the Overground and Underground are seeing massive increases in capacity, by running longer trains closer together. Even with things like regen braking this should require an increase in energy use.
[Engineering Note - regen braking isn't all it could be on DC systems anyway, since have to use the reclaimed power on another nearby train that's accelerating, or burn it off in resistors. On AC you can happily shove it back in the National Grid. The Underground is exclusively DC. The East London Line is DC only, as well, as is the Euston-Watford Overground line, while the North London Line is mostly AC, with DC patches. The West London Line is AC as far as the A40, roughly, then DC to Clapham Junction].
Let’s remind ourselves of what TfL said at the time:
Although TfL estimates that traffic returning to the Western Extension would result in a small increase in emissions of air pollutants and carbon dioxide, this increase would be unlikely to have any material effect on measured air quality within the Western Extension or on the boundary route because of the number of different factors that affect local air quality. The ongoing investment in technology such as hybrid and hydrogen buses, encouraging the uptake of low-carbon vehicles and fuels, and reducing power consumption on the Underground and Overground are all helping us to tackle transport related emissions across the Capital
Now let’s see what TfL are saying about the Tube upgrade, in their highly interesting Environmental Report:
LU introduced plans for the Victoria line and sub-surface line (SSL) upgrades, which will halve the potential energy rises caused by increasing capacity on the line. The trains for both upgrades will have regenerative braking capability and the specifications for the new SSL signalling system will cap the energy increase at 30 per cent.
So, Boris and TfL appear to have the position that they’re going to cut emissions by increasing the pollution from cars and increasing emissions from trains. They’re going to try and make the increases quite small though, so that’s OK.
Is it just me or does this not add up? Greenery done properly, as I’ve said before, is just maths.
Tags: 4 Comments
4 responses so far ↓
The maths does add up and I’ll tell you why. Lets say we are in 2009 (we very nearly are). 2025 is 16 years away. In those 16 years zero emission cars will come on to the market in the form of electric and hydrogen fuel cell cars, leading to lower CO2 levels.
Hello! First time poster (great blog by the way).
Probably a really stupid question, but on the regen energy thing, couldn’t you set a flywheel spinning on the train with the braking energy? And then use that to help speed up the train later on? Or would that be hugely expensive and inefficient?
I don’t have an engineering degree, or anything, so I’m not claiming any special knowledge. I do have a physics degree, but I was rubbish at mechanics, so I know very little, really.
Also, what happens to the submit button on IE6 on this blog? It appears to be impossible to post comments in it… Something to do with the button being an image or something. Maybe it’s just my work firewall being weird.
Jack:
Relying on speculative future technology to cut carbon emissions is not the way to combat Climate Change; we need to make big steps forward now and adapt as new technology comes on the market.
What if the hydrogen fuel cell cars run into a PR problem (the Mail runs a scare story with the headline “H2O BOOM!” about unreliable fuel cells) and takeup is extremely slow? What if they run into a problem with getting the industry to take it up or in implementing a hydrogen infrastructure?
The current hydrogen bus trial uses hydrogen generated from natural gas in Holland, then shipped over. That’s not very green. Basically a hydrogen economy needs a plentiful source of secure electricity for electrolysis, which we don’t have and I doubt we’ll have much of in 2025 barring a massive expansion of nuclear power. Therefore, instead of whiffling about electric cars, Boris, we need to use what electricity we do have more efficiently, like in electrically powered railed vehicles.
Cars and cities don’t mix no matter what the car runs on - it’s a matter of density and the sacrifices you have to make in terms of liveability in order to accomodate a car-based society.
Charlie - what you’re suggesting is very like the Parry People Mover concept, but that’s only really suitable for smallish applications. Beyond that the flywheel engineering gets rather tricky. However, the recent Hayabusa trial using a High Speed Train power car set up to regen into batteries was quite successful, apparently. They could whack 1MW into them in quite short timescales, then dump it out when required.
It’s usually still better to run a proper electric train and regen into the wire - you see double-figure energy savings like that, and the figures I’ve seen (courtesy of Captain Deltic’s column) were in the order of 15-25%, which is big £££ these days.