Originally Posted by
cooker
The person riding 70 miles a day (!!) will need an extra 3000 kcal/day to fuel that cycling, on top of the basic 2500 kcal diet. The energy in that extra food is about the same energy as 1/10 gallon of gas. If the other person harvests the potatoes by hand without using gasoline or diesel powered equipment, and no petrochemical fertilizer or pesticide, and they store them in a root cellar, eat them on site and use solar power or sustainable fuel to cook them, then yes, you can travel more miles per potato on a bike than in a car.
For the 7th time, the energy from the potato itself adds nothing, zero, zip, to the net carbon in the atmosphere. If the cyclist did not eat the potato, and it rotted in the field, it would emit exactly the same amount of carbon--through the process of decomposition--as if it had been eaten by the cyclist. If the cager ate the potato instead of the cyclist, again, same amount of carbon is later re-emitted into the atmosphere. If the potato burned up in a wildfire, also same carbon back into the atmosphere.
The only way to effect long-term removal of the potato's carbon is to bury it in such a way that it will turn into petroleum or coal. If this happens, the plant's carbon will be safely sequestered for incredibly long periods of time. That is, until somebody digs it up and uses it as liquid fuel to power a conventional car or as coal or natural gas to produce electricity for an electric car.
Originally Posted by
cooker
However most modern agriculture uses a lot of energy to produce the food - several times more input than the energy yield from the food. Plus people need to eat a diet that is more varied than potatoes,and can’t all be grown locally, so your food usually requires energy for fertilizing, pest control, harvesting, transportation, packaging, refrigeration etc. That’s why it ends up taking more energy to provide you with the extra food you need to bike 70 (or even 35) miles a day, than if you used that energy to drive an efficient car 35 miles a day.
Good point. But the take-away should not be that it's better to drive an electric car than to bike. The real lesson is that the way we produce and transport food is wasteful, unsustainable, and just plain stupid. We're using a lot more carbon, and especially a lot more water, than we have any business doing. We need to take a lesson from the potato plant: use solar power, grow up not out (vertical agriculture), and grow food in places where it needs less energy and water inputs.