21 December 2009

How Large is the Global Energy Economy?

Over at the Energy Tribune Robert Bryce has an interesting post discussing the fallout from Copenhagen. What I'd like to focus on are his estimates of the size of the global energy industry, which help to answer a question I've had for a while. He writes:
The global energy business dwarfs every other sector. It is a $5-trillion-per-year business, of which at least $4.4 trillion is derived directly from coal, oil, and natural gas. No matter how much the US and the rest of the world may desire a move away from those energy sources, the transition to renewable sources – and to no-carbon sources like nuclear power – will take most of the 21st century and require trillions of dollars in new investment.
I emailed Robert asking for details and he helpfully wrote back with the following:
Total global energy use in 2008 was 11.29 billion tons of oil equivalent.
At 7.33 bbls per ton, that works out to about 82.8B bbls.
Multiplied by $60/bbl = $4.9T (Source)
If the global economy is $61 trllion (2008, PDF)) then $5 trillion represents about 8.2% of the global economy. But surely Bryce's back-of-the-envelope calculation is a lower bound. I am posting this up in hopes that readers might help point to other estimates of the size of the energy industry in the context of the global economy. Thanks!