an original design incorporating the efficiency of a rocket stove into the design of a pizza oven This will reduce the amount of fuel and time required to heat your oven and also stops the oven from spewing smoke out constantly. It burns almost perfectly clean. Check out my website (http://lhalfo011.wix.com/rocket-vs-oven) where I talk about the science behind how it does this.
The DutchTub, a "low-tech" jacuzzi that uses a very rudimentary heat exchanger coil to heat the water. This idea can be used for heating water via open flame, adjoining grills or stoves, coiling about exhaust stacks, generator exhaust tubes, solar heating units, or generally anything that generates a good amount of heat for any amount of time. In this way one can easily heat water, even large amounts of water, for survival, emergency or off-grid living conditions of any sort. weltevree.nl