I would agree that depending on where you go small efficient stoves using locally scavenged biomass are often the most convenient and the most environmentally friendly and sustainable solution. Unless you are hiking in a particularly environmentally sensitive area, it is important to think of the total life cycle impact of your gear choices and methods on the entire globe and not just the trail you are on. Small efficient biomass stoves, using wood, bark, llama dung or whatever are very challenging to build and very rewarding to cook on. They are very tricky at times, and a homemade alcohol stove is an excellent backup.