Copy of a letter sent to the Bristol Evening Post's letters page tonight (all figures in it come from the Open University course 'Working with our Environment: Technology for a Sustainable Future'):
Dear Open Lines
Given the recently announced plans to turn the most popular cycle route in the UK (from Bristol to Bath), with 2.4 million journeys per yr, into a major bus route, its well worth reminding ourselves of just how ultra-efficient, healthy and green that great piece of technology - the bicycle - is.
Primary energy use in cycling amounts to just 0.03 megajoules per kilometre, nearly 50 times less than a single decker bus! Even walking, which consumes 0.14 megajoules, is not this efficient. The average for a car with average occupancy is 2.1 megajoules per passenger kilometre whilst domestic air travel is also 2.1 due to its higher occupancy rates.
Public transport fares better with figures of 1.1 per passenger kilometre for the average rail (about the same as a double decker bus) and 1.4 for a single decker bus, depending on occupancy rates. The most efficient forms of public transport, such as London Underground trains or certain forms of tram might achieve figures as low as 0.2 megajoules when fully occupied - still no match for the bicycle.
This makes the bicycle 70 times more energy efficient than the average car and 6 or 7 times more efficient than even the very best forms of public transport running under the most efficient conditions. So, in terms of efficiency its vital to invest much more in cycling and try much harder to create a cycling culture.
More is also needed for public transport but not at the expense of cycling - the plans to turn the Bristol to Bath cyclepath into a bus route simultaneously cut the capacity for cycling and walking there as well as destroying a large amount of pleasant, quiet and wildlife-rich green space.
We need a cycling culture for our health as well as our environment - a 10% increase in the number of people riding a bike regularly would lead to a 4% reduction in people with heart disease, saving hundreds of millions a year in healthcare. And it would create a more pleasant, greener environment.
Yours sincerely
Glenn Vowles
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An interesting piece. When you say "primary energy use", would this be the energy required to propel a bike or the energy required to keep a bike running? From your comparison with walking I assume it's the energy the user needs to expend in order to travel. If this is the case then this is not a particularly sound argument, as as a society we need to be expending more "personal" energy (ie through exercise) and less "external" energy (ie from fuels). Doubtless cycling is a very efficient mode of transport, and one I enjoy using, but a full energy analysis would reveal that the embodied energy of a bicycle and all the consumables (lubrication, tyres etc) would make cycling far less energetically efficient than walking.
ReplyDeleteBy primary energy I refer to the 'first' or 'original' energy. Its a life cycle approach for fuel.
ReplyDeleteThe main point of the post is the comparison between non-motorised and motorised transport. The amount of fossil fuel used to manufacture a bicycle and the land to accomodate walking and cycling is pretty insignificant in global terms - making them both very efficient in energy use terms.
If you are interested the original sources are: Wood (1995) Energy use by dufferent passenger modes, Norwich: Transplan; CEC (1992) Green Paper:The impact of transport on the environment:a community strategy for sustainable mobility, Luxemborg: Commission of the European Communities (Office for Official Punblications), Tables 1 and 2; Joosung et al
(2001).
There may be other sources that give figures comparing cycling and walking that back up your point about embodied energy - I'd be interested in looking over them if you have any.