Doing something as simple as heating water in an emergency can be problematic. In winter one can cook on the wood stove you use for heating. In summer this solution could be a toasty one. You could use the barbeque if you have propane or bricquets. There’s always a campfire. However, the Rocket Stove seems like a useful, low cost appliance to have on hand. For $45 you can heat things up quickly with minimal use of fuel and very little smoke.
My friend Dave on Whidbey Island just bought a Stovetec Wood Stove and here is his report:
“I fired it up today with a bit of paper and very few scraps of wood from the garage — I’m talking about three little pieces of wood. A bit of smoke when it first gets going but then the smoke all but disappears when it heats up. 5 minutes to heat a quart of water for tea. It heats almost as quick as a gas stove. Almost smokeless. Just a little ash left. The kettle/pot will, of course, be blackened on the bottom: the easy solution is to keep a dedicated pot to use just for the rocket stove since it can only handle one pot at a time. Rating: 5 stars (of a possible 5) absolutely performs as advertised.”
If you are handy, they are supposed to be easy to make.
Back to Stovetec, they are involved in a project donate stoves to people who cook over open fires. They claim that 3 billion people around the world cook at an open fire and that there are a 1 million and a half deaths annually caused by breathing this smoke. For $9 you buy one of them a stove .
This video review of the Stovetec Rocket Stove answers all your questions: