Do we have the energy to charge a cell phone using our blood sugar?
Recently I found myself wondering if it would be possible to charge a cell phone using only the blood sugar in a person's body, given we had some cool technology to convert glucose into electricity. This led me to a critical question: how much energy does our body use compared to cell phones?
To answer that question, we need to determine the power consumption of people and cell phones using a standard unit. Since people use about 2000 food Calories per day and a watt is about a Calorie an hour, we can estimate that a person runs at about 100 Watts. Mother Nature is pretty impressive, no? With only 100 Watts she powers a talking, walking, thinking machine, whereas Thomas Edison could only light up a room.
Next we need to determine the energy use of a cell phone, like an iPhone for instance. The calculation is not straight-forward as a phone uses different amounts of power depending on its usage. In the worst case scenario, browsing the web on 3g, Apple reports that the iPhone can last 6 hours. At this rate the iPhone is running at 3 watts. So Steve Jobs manages to produce a streaming, calculating, communication device for much less energy than Mother Nature uses on us. Pretty impressive too.
Taken together, we realize that a 100 W human could afford to power a 3 Watt cell phone given we could tap into our blood sugar and drink a little Kool-Aid when we want to watch Netflix.