Pondering energy on Independence Day
Whatever you may think of Thomas Jefferson, the Declaration of Independence
is an inspiring read. Proof that humans can rise above their limitations
and slave owners can declare all men equal, with inalienable rights. Indeed,
those assembled in Philadelphia in 1776 came tantalizingly close to abolishing
slavery. Adding to his list of other grievances, Jefferson accused King George
of waging a
cruel war against human nature itself, violating its most sacred
rights of life and liberty in the persons of a distant people who never offended
him, captivating & carrying them into slavery in another hemisphere or to
incur miserable death in their transportation thither… Determined to keep
open a market where Men should be bought & sold, he has prostituted his negative
for suppressing every legislative attempt to prohibit or restrain this execrable
commerce. Alas, the colony of Virginia was so adamant that these words be
stricken from the Declaration, that it endangered its passage.
Why? Agricultural economies of the 18th century needed vast amounts of energy, derived from human and animal muscles. So a quarter of all arable land was set aside to grow food for draft animals and thousands of human beings were enslaved to exploit their muscle power.
A person working hard can generate 60 to 300 watts of power, depending on the individual’s strength and the muscles used. 100 watts is good average. So, over an hour, a slave generated 100 watt-hours (0.1 kWh) of power. Laboring just eight-hour days five days a week for a year, with no holidays, this hypothetical hard worker could produce 208,000 watt-hours of useful work, or 208 kilowatt-hours per year. Not a great deal of energy – even when doubled by forcing the slave to work 14-16 hour days. Thousands of slaves were therefore needed, even in a world economy serving a human population of only 0.8 billion.
Since then we switched to a consumer economy and today’s world consumes about 153 billion megawatt-hours (520 quadrillion BTUs) of power each year. That would be the annual energy output of 734.4 billion humans doing 8 hours of manual labor daily – a hundred times the current global population – and the equivalent of 100 billion barrels of oil.
The Founders aimed at freedom in 1776 but we have not really become as independent as they envisioned. We only traded oppressors – a slave trader king for distant multinational corporations plying the modern energy-slave trade our economy still depends on. The 21st century’s “energy slaves” are fossil-fueled. They work mostly to benefit people in wealthy countries, some of whom waste much of their energy. The poorest still get by largely on muscle power and that unfortunate omission from Jefferson’s historic Declaration still haunts our national conscience.
But there is good news: over 1,000 times as much solar energy reaches Earth annually than we need to sustain our global human enterprise. We have the technology to make use of it. So, 240 years on, Independence, if we still aspire to it, is finally on the horizon.