Originally Posted by
mschwett
some “food” for thought for those who both advocate and are skeptical of bikes and eBikes as a means of transportation (setting aside recreational use)
approx calories burned to ride 20 miles, 0% electric assist: 800
calories in an ounce of beef: 70
ounces of beef to power a human on a 20 mile ride: 11
carbon footprint of 11 ounces of beef: approx 18 lb CO2e*
electricity required to cut the human demand in half: approx 140 watt hours.
carbon footprint of .14 kWh in the united states on “average” : .12 lb CO2e
this is an extreme example; most people aren’t eating a steak to offset the calories burned on a bike - but the point is clear. a human on a bicycle powered by beef has an enormously bigger carbon footprint of an electric bike per mile. the environmental impact of food is not as well understood as the impact of energy, but it needs to be addressed if one of the goals of getting on bikes is to reduce our carbon footprint as a society.
*i found wildly varying values for this and used the lowest one i found that appeared reputable - a prominent UK source was almost triple this
This is nonsense. First, on the ebike side, if you're going to count the production costs for food, then you need to count the production, distribution and storage costs for the electricity. Calculate in the energy costs of production of the battery and the engine, and probably want some accounting for the environmental costs of the rare earth mineral mining, and the disposal of the batteries.
On the human side, you really don't know whether people who stop pedaling are going to eat less. They may just put on weight, or they may just do some other aerobic activity for their exercise. People generally do some level of exercise, which is powered by food. Having that food-powered activity serve both the purpose of exercise and transportation may actually represent a net energy savings over riding your powered bike to the gym.