- Thursday, June 19, 2014

Powering Life's Machines

Vis and viva are the latin words meaning energy and life. Together, vis viva is my phrase to describe the way evolution optimizes energy consumption for some of biology's most complex tasks.

Engineer Optimizing Electric Stoves

We like to think that humans are masters at energy efficiency right now. Well, I admit we're making astonishing improvements, but here's something that might blow your mind a little...

Trains are our most efficient form of overland travel today. They use less energy than cars or trucks or airplanes, but according to this post at Think Or Thwim they still use more energy than people walking (and not to mention the bicyclist).

Think or Thwim's graph is right about a lot, but I want to take this one step further to make a point. Let's compare how much energy a train would take to carry an average person the average distance a person walks in a day.

According to my calculations, a train would take 41 kWh to move a 185 pound person 5 miles. That's almost 16 times the total energy intake of a person in a day (2000 Calories = 2.5 kWh).

Now to account for the fact that a train has to navigate around, add in the 6 kWh you'd use running a desktop computer and another 6 kWh from running a video camera all day. That would come to 53 kWh.

So here's the real mind blower... Using the most efficient means of modern technology just to walk around would take 20 times more energy than you consume in a whole day. A human only burns as much energy in a day as a single incandescent light bulb. And people do all kinds of other stuff, like talking to people, eating delicious food, or playing tennis.

Yes, Maria Sharapova, that is something to celebrate! Biological organisms are super efficient!

Anyway, I'm using the term vis viva to represent the idea of this kind of biological energy efficiency. And I'm starting the VisViva series about looking to biological optimization when building new technologies with minimal energy waste. In the coming months, I want to write a few articles about newly discovered systems that try to capitalize on biology's natural efficiency. Here are the first ones I want to get to.

  • Whale fins improve aerodynamics
  • Photosynthesis for carbon capture
  • The genius of Velcro

I can't wait to get to these. So... coming soon.

My Calculations

The average Australian or Swiss person walks about five miles a day (Americans only walk 2.5, but we're considered "sedentary"). And the average human weighs 185 lbs. Since trains use 1 gallon of diesel to move 436 tons 1 mile and one gallon of diesel contains about 39 kWh of energy, we can say

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