## How Much Energy do We Use Driving?

Everyone knows that we are so dependent on cars nowadays and everyone knows that we use a lot of energy driving, just to get ourselves around. But exactly how much energy are we talking about here? Here is my simple calculation.

Say a typical American family has two cars and each car would be driven about 40 miles each day. Let us assume that each car has 150 horse powers, and in normal driving conditions, 75 horse powers are needed. We also know that one horse power equals 735 Watts (note, for mechanical horse powers the conversion is 746, but it is quite similar and to keep things simple we use the former). And we assume that it takes about an hour to cover the 40 miles everyday. So for an average family the energy used by driving is:

.2*1*75*735= 110250 (WH) = 110.25 (KWH)

So, how much energy is 147 kilo-watts-hour? Let’s compare that number with the energy we use in a typical family. Say a typical house has 6 rooms, and each has two 100 watts light bulbs. Suppose that we use all the lights three hours each day. The lighting would attribute to 6*2*100*3 = 3600 (WH). Washer, dryer, water heater and the range, they average out to be 1000W each and in our rough estimation, let us say we use them 1 hour per day. That’s another 4000 (WH). For other appliances and electronics let us add another 4000WH (which includes refrigerator, TV, etc.). Now we have a rough estimate of how much power is needed in a typical house:

3600 + 4000 + 4000 = 11600 (WH) = 11.6 (KWH)

From the simple calculations above, we can see that the energy we used driving cars in day to day life is much more than that needed to power a house, roughly 10 times as much.