The energy efficiency of walking

Briskly walking up the incredibly steep hill on my way to university often makes me wish I had an electric scooter, bike, or even car. Of course, 5 minutes later once I've got my breath back, I disregard this idea as silly, but it got me wondering: how efficient am I compared to a motor vehicle? From a cost perspective, would it be cheaper for me to pay the ~£1 for an electric scooter ride compared to buying food to fuel the motor of my legs?

The boring answer is "it depends". On many things, particularly your body weight. It also depends on how and where you're walking. A leisurely walk on flat ground uses much less energy than speedwalking up a steep hill. The latter case is what I'm more interested in, as I'd never even be thinking about this if not for those hilly walks.

Walking

I weigh about 60 kg last I checked, so that'll be our baseline. The specific route I take has an elevation increase of ~42m over a ~0.32 km distance (according to Google Maps). That results in an overall gradient of approximately 13%. Given that this walk also takes me no more than 5 minutes, that means I walk at a pace of approximately 3.84 kph (This may seem quite slow but consider that it's up a steep as fuck hill). Overall, from the research I've done, I would estimate that walking at this pace and incline burns around 500 calories per hour, so for my 5 minute walk that's a measly 40 calories. Given I'm also carrying a backpack, we'll be generous and round up to 50.

Food

Any good machine / person needs fuel, and my body deserves the highest quality fuel. I'm going to estimate that the cost of a high-protein, nutrient-dense meal is around £3-5. We'll say that this meal provides 600 calories.

Final Calculations

At a walking rate of 50 cal/hr and £5/600 cal, this puts the cost of running my body at £0.0083333333/cal, and therefore ~£0.41/hr. The walk up the hill costs me a mere 3-4p in terms of energy burned. If we use lower quality "fuel" and I become entirely powered by slop like oats or rice, the cost drops even more to about £0.02/hr

All in all, here's the final breakdown:

Unfortunately, I have to conclude, as much as my body wants to disagree, that walking is the most efficient mode of transport for this particular journey... Until, of course, we consider the cost of moral support snacks :)