There is a good write-up in Wikipedia on Induction cooking &
efficiency and environmental impact.
To make a fairly succinct write-up even more brief, they differentiate between source energy used and site energy used. For instance, the source energy efficiency of an electric device is much lower, due to generation inefficiencies and transmission losses, than is site energy efficiency, where the generation and transmission losses are disregarded.
Gas Cooking Efficiency -- Source energy efficiency: 38%
- Site energy efficiency: 40%
Electric Non-Induction Cooking Efficiency -- Source energy efficiency: 22%
- Site energy efficiency: 74%
Induction Cooking Efficiency -- Source energy efficiency: 25%
- Site energy efficiency: 84%
Also stated was that induction cooking has a 12% efficiency advantage over non-induction electric cooking.
NOTE: Gas efficiency differences are very small because gas distribution pipe losses are also very small.
Bottom line, single counter top induction cooking units are becoming fairly inexpensive (< $100) but for some reason, full 4 burner induction cook tops are priced between $1000 and $2000. Since cooking consumes a fairly small amount of most home energy (around 4%), payback will be long, especially if a full 4 burner cook top is used (I calculated a breakeven of about 34 years for a $100 table-top unit, and about 340 years for a $1000 4-burner cook top). However, if on-site generated electricity is used for cooking, induction would be a clear winner.
Takaway: For those of us using grid power, the cost of an induction cooking device would be much better spent on home insulation.
Best,
-AC