Originally Posted by
cyccommute
Alcohol is less energy dense but it isn't heavier. Diesel weighs 0.83g/ml, gasoline weighs 0.75g/ml and white gas weighs from 0.75 to 0.78g/ml while ethanol and methanol weigh 0.78g/ml.
Thanks for those numbers.
What I had in mind was, heavier in the sense of heavier to carry (an equivalent cooking ability or capacity -- for an equivalent number of days).
The almost inevitable and often substantial water content of the various alcohols that are used also contibutes -- to some extent to the weight, and to a greater extent to the cooking capacity. And to the reduced heat output and speed, which results in longer cooking times and greater heat losses, and even more fuel requirements, which increase with cooler temperatures.
[The alcohol performance times are usually switched to 2-cup boil times (quite the tactic there), and often at higher room temperatures, to help the times look closer to the boil times for other stoves, which are traditionally given for boiling a full liter. Occasionally tests are done with a level playing field, and the alcohol boil times look much worse, even worse than the 2-cup times (and even-when-adjusted 2-cup times) would suggest. And at cooler temperatures (which are common for morning and evening outdoor camp usages) they are worse still, because the temperature-related and time-related heat losses need to be replaced by burning even more alcohol (alcohol + water actually). Extra time > extra heat losses > extra fuel.]