A brief search showed that the US mint used 694,462.4 gigajoules in 2011[1] (~0.2Twh). The US is ~25% of world GDP, so lets times this by 4 for a naive cost of minting across the whole world.
This gives a cost of ~1Twh annually for minting the entire world's supply of money, with a total Gross world product of ~$80 trillion[2].
Bitcoin is using ~1.3Twh[3] for a market cap of ~$35 billion[4].
Overall this means that bitcoins are ~3000x less efficient than physical money.
After writing this I've realised I should perhaps limit to the cash based economy.
The amount of US dollars in circulation is ~$1.3 trillion[5].
This gives a slightly better ratio of 222x less efficient.
Bitcoin is 222 times less efficient than a physical system of metal coins and paper/fabric/plastic.
[1] http://www.designlife-cycle.com/us-penny/ [2] https://en.wikipedia.org/wiki/Gross_world_product [3] http://blog.zorinaq.com/bitcoin-mining-is-not-wasteful/ [4] https://coinmarketcap.com/ [5] https://www.newyorkfed.org/aboutthefed/fedpoint/fed01.html