Fuel efficiency is measured in litres per distance travelled, which is basically energy used per distance travelled.
I have a power meter on my bike, so I can get pretty accurate numbers for calories burned, by measuring the total kilojoules of energy used. On my road bike it takes roughly 1700kcal to travel 100km on a mostly flat course. According to Google there are approximately 8000kcal in a litre of petrol and a Smart Fortwo (a very small car) burns 6 litres per 100km on the highway. That’s 48000kcal to travel 100km, being generous.
Now let’s consider that the human body can convert roughly 20% of the energy consumed as food into useful work. That’s still only 8500kcal worth of food to travel 100km. So even with a full car with 5 people in it, 5 people on bikes are still going to need less fuel to travel 100km. Not to mention that producing the food will release much less carbon into the atmosphere (but that’s another topic).
In addition, the fuel that goes into a car is this ultra-refined blend of chemicals that is produced in a refinery. You have to extract oil from the ground, ship it to a refinery, use heat and various additives to transform it into automobile fuel, then ship it to a service station. I would imagine that the process of refining oil into gasoline is probably not 20% efficient.
Your body works on stuff that literally grows on trees. If you have a back yard, or even a decently sunny balcony, you can grow a tomato plant. Then, you eat that tomato, and voila, bike fuel. So, even if the calorie efficiency of a human body converting food into fuel isn’t great, the human body is the refinery. It can theoretically even be fuelled by foraging, no crops necessary.
Fuel efficiency is measured in litres per distance travelled, which is basically energy used per distance travelled.
I have a power meter on my bike, so I can get pretty accurate numbers for calories burned, by measuring the total kilojoules of energy used. On my road bike it takes roughly 1700kcal to travel 100km on a mostly flat course. According to Google there are approximately 8000kcal in a litre of petrol and a Smart Fortwo (a very small car) burns 6 litres per 100km on the highway. That’s 48000kcal to travel 100km, being generous.
Now let’s consider that the human body can convert roughly 20% of the energy consumed as food into useful work. That’s still only 8500kcal worth of food to travel 100km. So even with a full car with 5 people in it, 5 people on bikes are still going to need less fuel to travel 100km. Not to mention that producing the food will release much less carbon into the atmosphere (but that’s another topic).
In addition, the fuel that goes into a car is this ultra-refined blend of chemicals that is produced in a refinery. You have to extract oil from the ground, ship it to a refinery, use heat and various additives to transform it into automobile fuel, then ship it to a service station. I would imagine that the process of refining oil into gasoline is probably not 20% efficient.
Your body works on stuff that literally grows on trees. If you have a back yard, or even a decently sunny balcony, you can grow a tomato plant. Then, you eat that tomato, and voila, bike fuel. So, even if the calorie efficiency of a human body converting food into fuel isn’t great, the human body is the refinery. It can theoretically even be fuelled by foraging, no crops necessary.