The Value of Energy
An adult can exert about 100 watts of effort for a reasonably sustained period of time. Over a 10 hour work day, this would result in one kilowatt-hour output. At $5 per hour, that would be $50 per kwh. You probably pay about 10 cents for one kwh of electricity, or about 1/500th the price of human effort.
One barrel of oil is the same as 20,000 man-hours of labour (or $100,000 if you paid a $5/hour wage). 100,000 divided by 1500 = 66.666…
There are 3,412 BTUs in a kilowatt-hour and over 6,800,000 BTUs in a barrel of oil. If a barrel of oil were $67, this would be approximately 1/1500th the cost of human effort.
The comparison of energy costs above has been paraphrased from:
http://www.cleantechblog.com/2006/11/what-is-energy-worth.html
The potency of energy contained in oil and gas is of such a high concentration that it is essentially “free” energy, even at $2 per litre of gasoline. What we are paying for at the pumps is merely the cost of extraction and refining. We pay nothing for the material/fuel itself. That is what is meant by “free” energy.
