5 votes

Ignoring initial construction costs, what takes less of a toll on the environment: a human-powered bike or an electric bike?

What’s up tildorans, This is more of a thought experiment then anything else, is the impact of consuming calories more or less impactful then producing the electricity needed to power the bike? And I also understand this is extremely affected by circumstance. Let’s say you eat beef 3 times a day and live in a part of the world where power is mostly generated via nuclear or hydroelectric. At that point, would the impact via electricity be less then the one via calories? What if you flip the spectrum and you’re a vegan living somewhere that produces all its energy via coal and oil, how does that affect the equation? Thanks

1 comment

  1. mftrhu Link
    TL;DR: no idea, but the electric bike will probably take less of a toll - muscles are just not very efficient. Most of what we eat requires quite a bit of energy to grow and/or process. We don't...

    TL;DR: no idea, but the electric bike will probably take less of a toll - muscles are just not very efficient.

    Most of what we eat requires quite a bit of energy to grow and/or process. We don't just eat random biomass, we can't even metabolize most of it (e.g. wood). Without even thinking about animals, growing grains, growing potatoes, fruit, leafy vegetables all require a fair amount of work - to get the ground ready, to plant them, to water them, to protect them from parasites and wild animals, to harvest them, to prepare them, to cook them.

    Animals, of course, need an order of magnitude more energy.

    (keep in mind that I'm just spitballing here, I'm not even sure what all the assumptions I'm making are)

    The efficiency of muscles themselves is pretty low, apparently between 18% and 26%. The efficiency of most heat to electricity conversion systems is not much better, but it's still better (30% to 40% for most systems, but it can get up to 90%), and that heat can be produced from biomass that an animal (and specifically, an human being) can't extract calories from.

    Even allowing for similar ranges - let's say that both systems have an efficiency of 25%, because maybe you are producing electricity with... hell, a wood-fired steam turbine - not using your muscles for it would still be better.

    (I'm assuming that you don't need to travel far to get wood - chopping down even a large tree for firewood is the work of just a couple of days for a small group of people if they have relatively modern equipment)

    (this of course does not apply if you are using coal or oil, I'm imagining a post-apocalyptic situation with little infrastructure built from the grounds-up)

    You'll still need to take in account the costs of maintenance, for both the human (if anything, you are going to put more clothes in the laundry if you bike vs having your bike carry you) and the machine. The batteries will need to be changed periodically, the generators will have to be cared for, the grid will have to be maintained.

    An argument could also be made that, not having to put in the effort to get to your workplace - and by getting there faster - you'll be able to get more work done, which might be good or bad. On the other hand, exercise is good for you. On the other, other hand, exercise could lead to injuries.

    4 votes