One of the biggest problems for the survivalist is the lack of refrigeration, since the cost in energy is just prohibitive, especially in the multi-generational scenario. Normal refrigeration uses an electrically driven compressor to compress a refrigerant (a liquid that boils at room temperature) turning gas to a liquid. For the survivalist, ammonia is the refrigerant of choice, and at the proper pressure (since it is normally a gas), it will act as a refrigerant, although other chemicals may be added to improve performance, including water and salts. When the liquid boils it will cool the surface that the refrigerant evaporates from returning to gas again. (Note that you can change the pressure in the system to alter the temperature it will boil at)
Evaporative cooling [1] works the same in this case as it does when sweat evaporates into vapor cooling you. Ammonia [2] can be made from urine and was first derived from urea. “It was also used by dyers in the Middle Ages in the form of fermented urine” This is of particular interest for those who worry about the multigenerational scenario.
There are many plans available on the internet for experimental ice makers [3].
These ice makers for the survivalist may make the difference between life and death for those who need cooling for insulin that will work even after an EMP [4].
Further ice will have huge trade value when there is no other way to make ice post-crash.
Bleach is a great sanitizer but unless stored as a powder it loses potency over time, and there is a limit to the amount of powdered bleach you can rationally store. So the ability to make bleach from raw materials, water and salt, is worthwhile knowledge. Further with the advent of antibiotic resistant bacteria and pandemic viruses, sanitation is not an issue of social graces, but sickness and death. Further bleach made from salt is another potential use for the salt that should be stored for those who do not have access to bodies of salt water, it has innumerable uses, and this is just one more. The basic process is similar to the other electrolytic processes described on SurvivalBlog, like making colloidal silver [5]. Also see this site [6].
Alcohol is in many ways the wonder fuel for survivalists. It doesn’t spoil (like gas or diesel), it has been made since the dawn of civilization, so it is a robust and simple process the make it, and the ingredients are ubiquitous, plus it makes good trade fodder as more than just fuel. All you need is sugar, yeast and a sealed vessel. Yeasts digest sugar and make alcohol when there is no oxygen around, this is called fermentation. Yeasts are common enough that even without a culture you can just contaminate the vessel with saliva or expose it to air, and there will be enough yeast to ferment the sugars. This is not the most efficient way, or the most appetizing, but it can work. There are many sources for more information about making the mash, but to make a fuel or liquor rather than a semi-toxic mash you need to refine the product. This process is called distillation, and it works by using the boiling points of alcohol and water to separate them in a device called a still. This process is simple, but for efficient distillation, a well made device is required, and most are quite expensive. This is a good tutorial on how to make a quality one for a reasonable price. [7]