Here are a few metrics:
- A liter of fresh water is about 2.2 lbs. A quart is 2.1 lbs.
- Going from 50F to 212F is a 162F increase, which requires 357 BTU.
- For argument's sake, let's say the stove is 50% efficient (in reality, it's probably less), so 714 BTU worth of fuel must be burned.
- To do this in 3 minutes, burner output would be 14,280 BTU per hour.
- Ethanol is rated about 600 BTU per ounce, so it would take about 1.2 ounces of fuel.

For comparison sake, the burners on my gas range are rated at 13,500 BTU per hour and 9,000 BTU per hour.