Thought of the day:
One barrel of oil contains about 5.8 million British thermal units (BTUs) of energy (1700 kilowatt-hours). That is roughly equivalent to the energy output of an adult human working 12.5 years worth of 40 hour weeks.
At present, the world uses about 31 billion barrels of oil a year. That is equivalent to the global population (6.7 billion people) working for 58 years.
While the theoretical capacity of renewables is even higher, it is a fair bet that they will take a lot more effort to harness. There aren’t many places where solar panels will spurt out of holes you make in the ground.
The last time I had to hire six strong lads to haul my Cadillac, it really cost me. I guess these high food prices make all transport options costly.
People subsisting on their own muscle power do not have the luxury of 40 hour weeks.
I think this is an unfair comparison. You have stated the theoretical heat energy of oil, presumably, the heat energy that would be released if it was burned with no unburnt fuel left over.
The fair comparison would be to the heat energy produced by the worker, not the effective work done.
To fairly compare with a worker I think you need to multiply 1700kwh by the efficiency of the most efficient (or averagely efficient) oil powered mechanical engine. Presumably, the number is less than 50%.
Wood and animal feed suppled more than 95% of the energy used in the United States in 1800. The population of the nation stood at just 5.3 million people, per capita GDP was about $1,200 (in real US$2000), dominant energy converters were human labor and draft animals (horses), and the population was overwhelmingly rural and concentrated near the eastern seaboard.
This query prompted an interesting discussion among the TOD staff on the comparison of human labour to oil.
This has been argued and debated often on TOD, mainly in response to some of my own quotes in media about 1 barrel equating to 25,000 hours of human labour (12.5 years at 40 hours per week). Ultimately the answer to this question depends highly on assumptions – but we can arrive at a good approximation. 1 barrel equates to 6.1 Gigajoules (5.8 million BTUs). Depending on the ‘job’, humans use roughly 100-700 Kilocalories per hour (Computer work requires an estimated 119.3 Kcals/hr). 1 kilocalorie (Kcal) = 4,184 joules. So 1 barrel of oil has 6.1 billion/4,184 = 1,454,459 kcals. Using a range of 100-700 kcals per human hour of work then results in a range 2078 and 14544 hours per barrel of oil. At 2000 hours per year (40*50), this is would then be 1.0-7.25 years per barrel. This was discussed in the comment thread here.
The average american uses 60+ barrels of oil equivalent(oil, gas and coal) per year (360 billion joules), which implies a fossil fuel ‘slave’ subsidy of around 60-450 ‘human years’ per person. Depending on assumptions another way to look at it is to take a midpoint of 10,000 hours per barrel. At $20 per hour average payroll compensation, that is $200,000 per barrel, not even quality adjusted….