Yesterday, I was reading that new book titled “Energy for a Sustainable World: From the Oil Age to a Sun-Powered Future” by Nicola Armaroli and Vincenzo Balzani.
The book looks pretty interesting, and the figure from “De Rebus Bellicis”( http://en.wikipedia.org/wiki/De_rebus_bellicis) is quite interesting. However what was the funny and witty(or weird) thing was the human-energy algebra done by the writers.
In Chapter 3, “Energy in History”, the writers compare the Roman society and modern society.They first assume human power like a traditional source of power in Watts(http://en.wikipedia.org/wiki/Watt) , like Watts in CFL or light bulbs. They claim:
- A (slave) people can work constantly at a rate of 50-80 W (in short bursts 800W momentarily p.29)
- Working animal ranges from 300W (oxen) to 700-800W (for good horse, p.27)
So what is the cost of modern life in terms of slaves? Answers are:
- Washing machine: 800W : 10 human slaves
- Electrical heating: 2.5 kW: 30 human slaves
- A small European Cutter: 3.5kW (work done with this cutter for one hour equals to a work done by 4 human slaves in whole day-10-12 hours I guess)
- A medium sized car: 80 kW consumes the energy equivalent to 1000 human slaves
- A Boeing 747-400 needs 80 MW to take off = 1 000 000 human slaves
And it claims, an average Italian citizen has as many as 55 energy slaves 24/7.
They also carried out a cost of energy by slave and gasoline. Since a slave can produce an amount of 800Wh in one day (in 10 hours constantly) and one liter of gasoline’s energy content is 12.9 kWh. So 1 liter of gasoline’s energy = 16 human slaves in all day. That means €0.03 for one human slave/day.
See how cheap the services granted by fossil fuels and modern technology.
Energy for a Sustainable World, Nicola Armaroli and Vincenzo Balzani, Wiley -VCH. , 2011