Archive for May 1st, 2008

I’ve heard before that walking a mile emits more carbon than driving a mile so decided to investigate for myself.

A 190lb human walking at 3 miles per hour would expend 302 kCal. Therefore, covering a mile would take 20 mins and approximately 100 kCal. Apparently it takes 7-10 kCal of fossil fuel to produce 1 kCal of food. The upper end of the range assumes a diet of highly processed food and meat being transported long distances. The lower end of the range assumes a more vegetarian-centric diet and locally produced food.

Therefore,  a 1 mile walk requires 700 – 1,000 kCal of fossil fuel energy.

Driving a 30 mile per gallon car for one mile at 60 mph takes 1 minute and 1/30th of a gallon of gas. One gallon of gasoline contains approximately 30,000 kCal of fossil fuel energy.

Therefore, a 1 mile drive requires approximately 1,000 kCal of fossil fuel energy.

Depending on where you source your food and what you eat, it doesn’t make much difference in terms of carbon emissions. Driving a car one mile is far cheaper than walking a mile. But the health benefits of walking a mile far outweigh the cost.