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Energy Saver: Cooking Techniques
(continued ...) as a purpose made lid but it is dramatically better than just wide open. Optimize the foil trick by letting it droop concaved slightly into the pot opening. This allows gravity to pull the condensed water to the center and drip freely back into the pot. And that is the general idea here: reduce, reuse and recycle energy that otherwise is wasted or lost energy. When you are finished cooking you can throw the used foil in the recycle bin.
Here's an experiment you can try. Get two identical pots; carefully measure a quart of water into each. Put them on the same size burner or element. Put a lid on one but not on the other. Turn on the heat equally and simultaneously. See which one gets to boil first. After both are up to boil, reduce the heat while maintaining a boil. See how low you can set the burner on each while maintaining the boil.
Waste heat energy is being lost from our cooking system in the form of conduction, convection, evaporation, phase change, radiation and inefficient combustion. There are some things that can be done to reduce these losses. Here you learned about the many reasons that barbequing in the summer not only tastes better but saves energy. In the winter, junk heat from cooking is actually beneficial. Never use cooking equipment to heat for comfort. Always put a lid on that pan, pot, skillet and just about every other cooking vessel; unless you actually want to lose water by evaporation. EnergyWrite.com