“Probably one of the most fuel efficient vehicles in existence” is one of the dumbest takes I’ve ever seen. The human body is a ridiculously inefficient machine.
I am not a chemical engineer so I am not sure how equivalent these two measurements are… I mean for starters I can eat 1000 calories… but I think if I tried to get 1000 calories by consuming gasoline; I would die.
Keep in mind how much CO2 gets emitted for the food you eat during it’s production. Being vegan helps.
Of course it’s still much between than driving a car, but an ebike would be even better. Even if you charged it with electricity from a coal power plant the CO2 emissions would be way lower
And generating heat. I believe motorcycles fail to beat bicycles with rereads to efficiency. Though there are significantly better than cars EVs included
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.
Well, per traveled distance with moderate speed it is not completely untrue.
But still outclassed by a similar, but electrically powered (or assisted) vehicle.
Something a lot of people have a hard time coming to accept…
Part of it is due to thermodynamics. A diesel engine works at a high temperature difference, with peak gas temperatures going somewhere in the >1000°C range.
High temperature differences lead to high efficiency >40%.
A human body can’t use high temperature processes, so has to stick to chemical workarounds which lead to additional losses.
A diesel car will typically run 20 km per liter. One liter of diesel is about 10 kWh. so if you put four people in the car, that’s 2.5 kWh per person. 2.5 kWh should allow you to walk for eight hours, or about 40 km. *quick edit: this is walking, cycling will get you further on 2.5 kWh!
Another thing is, diesel engines are water cooled, the heat is shed to the environment. This is about two thirds (varies 60-70%) of the energy produced, the > 40% efficiency you mention is only achieved by the highest performing engines around today.
Ok, lets assume an efficiency of 35%.
That means 3500Wh usable energy per liter of diesel.
A complete 500Wh charge of my ebike gets me ~70km at 20km/h without any pedaling (tried that out).
So the usable energy delivered by one liter of diesel would be sufficient to drive me and my bike a distance of 7*70km = 490km.
A person won’t be able to sustain 20km/h on a bike with the same low effort as walking at 5km/h, but even if that was the case, in 8h this would only get him 160km far.
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Edit:
Looked up some numbers for bicycling.
Driving 20km at ~20km/h burned energy is generally given in the range ~500kcal, meaning 580Wh.
That is better than I expected, as the 10kWh primary energy would get you ~350km far, so almost as good as the diesel engine.
(To be fair: this doesn’t yet take into account the CO2 footprint of food production, which is really abysmal. But that’s a different topic.)
“Probably one of the most fuel efficient vehicles in existence” is one of the dumbest takes I’ve ever seen. The human body is a ridiculously inefficient machine.
my BODY is a MACHINE that turns PIZZA into WHEEL ROTATION
sort of the human body is pretty inefficient but a 20 mile bicycle ride can burn around 1000 calories while a gallon of fuel contains 31,000 calories.
http://berkscountynature.org/calories_in_gallon.html
I am not a chemical engineer so I am not sure how equivalent these two measurements are… I mean for starters I can eat 1000 calories… but I think if I tried to get 1000 calories by consuming gasoline; I would die.
That really would be efficient!
But I guess you actually meant to say kilo calories ;-)
A moped would be the closest equivalent ~100mpg so 3,000 calories per mile, vs a bike at 50.
I think it’s more that the moped /ICE engines are very inefficient then bikes are efficient, as an electric scooter would be lower then both.
Keep in mind how much CO2 gets emitted for the food you eat during it’s production. Being vegan helps.
Of course it’s still much between than driving a car, but an ebike would be even better. Even if you charged it with electricity from a coal power plant the CO2 emissions would be way lower
being vegan would help if it effected production
I don’t eat more on days I cycle to work than on days that I take the bus or work from home.
It’s almost as if you burn all that fuel to move the car, the content of the car (people) is almost a rounding error.
And generating heat. I believe motorcycles fail to beat bicycles with rereads to efficiency. Though there are significantly better than cars EVs included
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.
Well, per traveled distance with moderate speed it is not completely untrue.
But still outclassed by a similar, but electrically powered (or assisted) vehicle.
Something a lot of people have a hard time coming to accept…
I’m really curious here, how so? I would expect energy inefficiency to be an evolutionary disadvantage.
Part of it is due to thermodynamics. A diesel engine works at a high temperature difference, with peak gas temperatures going somewhere in the >1000°C range.
High temperature differences lead to high efficiency >40%.
A human body can’t use high temperature processes, so has to stick to chemical workarounds which lead to additional losses.
A diesel car will typically run 20 km per liter. One liter of diesel is about 10 kWh. so if you put four people in the car, that’s 2.5 kWh per person. 2.5 kWh should allow you to walk for eight hours, or about 40 km. *quick edit: this is walking, cycling will get you further on 2.5 kWh!
Another thing is, diesel engines are water cooled, the heat is shed to the environment. This is about two thirds (varies 60-70%) of the energy produced, the > 40% efficiency you mention is only achieved by the highest performing engines around today.
Ok, lets assume an efficiency of 35%.
That means 3500Wh usable energy per liter of diesel.
A complete 500Wh charge of my ebike gets me ~70km at 20km/h without any pedaling (tried that out).
So the usable energy delivered by one liter of diesel would be sufficient to drive me and my bike a distance of 7*70km = 490km.
A person won’t be able to sustain 20km/h on a bike with the same low effort as walking at 5km/h, but even if that was the case, in 8h this would only get him 160km far.
============
Edit:
Looked up some numbers for bicycling.
Driving 20km at ~20km/h burned energy is generally given in the range ~500kcal, meaning 580Wh.
That is better than I expected, as the 10kWh primary energy would get you ~350km far, so almost as good as the diesel engine.
(To be fair: this doesn’t yet take into account the CO2 footprint of food production, which is really abysmal. But that’s a different topic.)