Sunday, January 08, 2006

Daily Energy Use

I was thinking about how much energy I use to ride my bike to work and in other daily activities. When I ride my bike to work, I use roughly 450 calories (one way), which is really 450 kilocalories if you're talking about anything other than food and exercise. (The nutritional 'calorie' actually equals 1000 real calories. Genius system.) This happens to be equivalent to the energy in 1 litre of apple juice (about 4 cups). I want a single unit of energy to use for comparing my daily activities, and this 1 litre of apple juice just works out so well compared to my bike ride that I have to use it. One litre of apple juice also equals about 3 tablespoons of gasoline in terms of energy, but it isn't as tasty, so let's stick with apple juice.

Like I said, riding my bike to work uses 1 litre of apple juice.

If I look at other daily activities, there are the ones that aren't exactly optional, especially if you're riding a bike places, like taking a shower. Heating the water takes about 2.2 L of apple juice, but varies widely depending on how sleepy you are in the morning, how much you drank the night before, or if you like to combine your morning activities so as many as possible take place in the shower.

Using more rough numbers, if my apartment has 8 light bulbs, and all are old fashioned 60 W incandescent light bulbs on for say 8 hours per day, this uses 7 L of apple juice per day.

If I switch all my light bulbs to compact fluorescent, I use 1.8 L of apple juice per day.

Of course there's home heating and cooling. I'll have to leave that for another day. There are so many variables there.

If I decide to drive my car to work instead of cycle, it takes 62 L of apple juice.

Some numbers:
1 BTU = 1055 joules
1 kCal = 4186 joules
1 shower = 4000 BTU = 2.2 Litres of apple juice
My commute distance = 19 km one way

Darren J 1/08/2006 09:26:00 PM


What about the energy to draw your shower water from the lake, purify it, and pump it up to Lawrence? Plus the energy used producing your shampoo and soap? :) Just kidding man. This is a great post. I'll try to link it if I ever find time to post... I've been bookmarking news articles all over the place but haven't had a chance to "blog" them yet.
Wow- that is a really cool way of thinking about things. How much energy is required to power a bus filled with people? Do you divide the energy by the number of people transported? Any idea?
Joe, you cause me so much pain! It is true though; there are lots of costs I've left out, like car manufacturing and materials, etc.

That would be great to work out how much energy is used to take the bus or subway. It would take a lot more research and on buses and trains, but I guess that's what the internet is good for. I could look at it by my particular route to work or by the average public transit rider. Hmmm.
You should start an energy blog called "Apple Juice" or "Turn-On-The-Juice" or something. :) It's crazy when you start thinking about how much energy is involved in all parts of life.
Here's a table I got from from Bicycle Science (using gasoline):

A bike at 15 mph gets 840 mpg (357 km/l)

Do you mind if I copy one of your graphics for a link to this post from Cyclelicious?
Feel free Fritz! Thanks for asking.

Add a comment