how many cyclists does it take to replace a light bulb?

Cyclists reduce carbon emissions. Light bulbs increase carbon emissions. In each case, how much? Though the comparison is frivolous, Cycling England has asked: if commuters switched to bikes for Bike to Work Week, what would be the saving in CO2 emissions? Here's what they found.

A June 2007 report commissioned by Blue Rubicon for Cycling England (unfortunately not available online) says that if all the car and bus commuters in England were to switch to bicycles for one week, each would save on average 33 kg of CO2 over the week. That's a total of 341,154 tonnes of CO2. Of course, it's not reasonable to expect all commuters to switch, so they calculated that those who travel less than 5 miles per commuting journey could still produce savings of over 44 thousand tonnes of CO2 emissions in a week, which is equivalent to the emissions from heating 16,740 houses for a year.

Oh yes, the lightbulbs. A 60 W incandescent lightbulb burning continuously for 5 days uses 7.2 kWh. If the electricity it uses is generated using natural gas (much cleaner than coal) then the bulb is responsible for just over 3 kg of CO2 emissions for the week. A commuter using an average petrol car to travel 1 mile produces nearly 3 kg of CO2 emissions per week. So there's your answer: a commuter travelling a mile to work who switches to cycling would replace one lightbulb. A random statistic, if ever there was one.

The average Briton is responsible for producing 11 tonnes of CO2 a year, and 21% of this is from using cars and buses. Commuters currently using bicycles in England save an estimated 5 thousand tonnes of CO2 emissions a week. But the number of cyclists is going down. Another report from Blue Rubicon (this one online) shows that in England:

In the last ten years, the average number of bike trips has fallen by more than a fifth - from 18 to 14 trips a year. 69% of people cycle less than once a year. Only 43% of people aged over 5 own bikes.

The challenge is to pass on the enthusiasm for cycling from parents to children. Nearly half of all mothers have never cycled regularly, and 91% of children have never cycled to school. Increased distances from home to school may be part of the reason for the decline, but the report suggests that the biggest obstacle is parents' fear for their children's safety - despite government statistics that show a decline in the number of road accidents involving children.

Cycling England has launched a programme to improve cycling in six demonstration towns. One of them, Aylesbury, reported an increase of 25% in cycling in the first three months of 2006 compared with the same period in 2005. Part of the project is improving cycling infrastructure, which is an important component of any efforts to improve safety for cyclists. And they are building some cycle routes in new housing areas before the houses are built, sending a clear signal to homeowners that there is an alternative way to get to the town centre. Cycle Aylesbury - an online resource for cyclists - reports that cycling is now the main mode of transport for over 10% of residents.