How to prepare rice in a very real emergency - no boiling (no electricity or alternatives)?

Do not eat raw rice, you might get very ill. From LiveStrong:

Lectin is a protein that serves as a natural insecticide with a strong affinity for carbohydrates. Found on uncooked rice and beans, this protein is one of the top 10 causes of food poisoning and can lead to nausea, diarrhea and vomiting when eaten in abundance.

There are also Bacillus Cereus which is a bacteria that can be poisonous in a similar way and cellulose which is indigestible fiber. All of these make cooking rice a very important step for consumption.

Even if you wanted to ferment it, you'd still have to cook or steam it first. So I'd say you either pack pre-cooked rice or choose something else to eat.

On another hand, if you have access to electricity you can cook your rice in the microwave almost the same way as with conventional heat. Add rice and water to cover in a microwave-safe container, put a lid on it (leave a small opening so steam can escape) and turn it on for 10 or 15 minutes.

There is no way to prepare the rice without heating. If you don't have a heat source, your stored raw rice is almost useless. I say almost, because in an emergency, raw rice is preferable to eat over things like cardboard or shoe leather or leaves of unidentified plants, but in anything short of a starving scenario, it is not suitable for eating.

You can consider ways to prepare the rice first and store it, then eat that when the emergency happens. Pressed cakes of puffed rice are a modern option, but I am pretty sure there must be durable breads made from rice flour too. The results are shelf-stable and can be kept for years as an emergency supply.

Another solution would be to store a camping gas stove and use it for cooking during an emergency. Then you can prepare your rice. This can present some practical problems though (will users remember to not use them inside, are you allowed to store gas where you live, do you have the storage space for a sufficiently large gas bottle to cook for a family for several days).

Rice uncooked is not the best to eat for health reasons. But I have seen the very poor. Grind it between 2 flat rocks. Add water & let set for 2 hours before eating. Or make a rice mush this way over a fire of scrap plastic bottles & such. In a tin can. Not the best but you do see such in 3rd world Countries. That is Hunger. So how hungry are you at the time? Raw rice can be ate. On the other hand you have not led a life to adapt to such in life. So not cooking rice may prove fatal to some.

Even in Asia, I'm sure you've heard of Minute Rice which is a brand name of instant rice. Instant rice is rice that's already been cooked and then had the water removed (dehydrated). It tastes pretty bad/bland unless you're someone who was raised on it. A person is meant to add boiling water to it, stir and cover (without cooking it) and it's supposed to be reconstituted in a minute or less.

Since it's already cooked, the boiling water is only meant to make it hot for eating. Cold water would also work but take longer to rehydrate.

You can make instant rice yourself, dehydrate it and properly store it for emergencies. You'd need to make sure it's throughly dry before storage and that your containers are completely water and air tight. A glass container with a snug lid would suit but I'm not sure if glass containers might not be broken during a catastrophic event. Metal or very good quality plastic would be safer.

I'd not plan on storing your instant rice longer than a year (or less) but then most food stored as emergency supplies need to be cycled yearly. Since instant rice doesn't have the best flavour, I'd use the old supplies to make congee where long cooking is best for it anyway. This site explains how to make your own instant rice. http://thehomesteadinghippy.com/make-instant-rice/

I don't have a dehydator but I use my oven to dry herbs. The oven setting doesn't go below 200° F (94-5° C) but I found that using a 100 watt incandescent bulb instead of the oven light bulb and leaving it on brought it close to the temperature a dehydator gives. I'd stir the rice around every few hours to make sure it dried evenly.

This is about the best solution to eating rice without any means of cooking it. Maybe not ideal but enough to provide your needs in an emergency. Instant rice only takes up a little more space than dried raw rice. You might even look into getting some of those food-safe silica gel packs for food products to absorb any moisture to be extra safe and add them to each container in storage.

Edited for further cautions It doesn't matter how much food you have to eat if your water supply isn't safe. A suggeston I read years back given by the UN has stuck with me so I did some digging to find it in order to provide a credible reference. You can sterilize your emergency water supplies without boiling or treating it with bleach or iodine as long as it's sunny.

Since the information is I'm a PDF file, I'll give the link but summarize it here. Essentially, the UV rays from sunlight will kill any pathogens present. If contaminated with chemicals from a spill, I won't work, of course. Containers used need to be clean and be clear plastic. Used pop or water bottles work well. Please look over the link given to find the simple steps needed. In many places in the world, safe water is hard to come by and even clean water can be germ-laden. This method ensures almost anyone can have access to safe water. In extremely dire circumstances, muddy water could be filtreed through cloth a few times and let stand to take the clear water off and then sterilized. Water can mean the difference between life and death. One should always be prepared for the worse case scenario.

Water Sterilization link Household Water Treatment and Safe - World Health Organization http://www.who.int/household_water/resources/emergencies.pdf

The answer as as you've seen from the others is "no." But since you are preparing for it then a simple inexpensive camp stove that runs on propane, butane, or liquid fuel is good for an emergency kit. The small ones for backpackers are very small and easy to store in house or car. Get a good pot and lid to make it work most efficiently.

Pro for jet stove: small & cheap.
Con: fresh air/ventilation required, flames make fire (though some have a safety shut off if knocked over).

Other choices for an all around power outage kit could be an Uninterruptible Power Supply (UPS) battery (though running a cooker would require a large, expensive one) or building a 12 volt system: a deep cycle battery, LED lights, charge phones, and 12v burners, stove, rice cooker, whatever you want. The battery and maintenance charger will cost some money, $100 USD or so depending on the size needed to meet your needs. The cookers are not expensive, but I'd test them to make sure they'll work for your needs.

Pro: All around solution for cooking and lights, radios, charge phones, etc. Can be solar charged.
Con: Requires some electrical knowledge and setup, expensive (about 300USD for all around system), bigger/heavier/less portable.

Update: since looking into this question I discovered more: lectin in the rice and other agglutinins have been increased in modern rice varieties, which have had their natural antibacterial and anti-fungal properties engineered to be stronger (fewer pesticides, longer shelf life); they rely on full high heat cooking for edibility and safety.

I had one idea - though it's not very practical.

I know rice can be cooked, specifically popped, with heated sand - I've seen it done. So no boiling water required. (salt may be an alternative to sand, but that's speculation). It may be that soaking the rice beforehand will produce something closer to puffed rice, if the moisture will start to steam the rice before it dries out and pops/puffs - though that might also let sand stick better to the rice

The sand is usually heated with a fire, or some other heat source with which you could directly boil water. Even if not, that heat source - or the hot sand - can probably be used to heat up other things (rocks, etc) which can be used to indirectly boil water. So, fireless and waterless preparation is a very contrived situation.

If you wanted to try anyway, I would think it would work best with very dark sand - I know colored sands are available for craft purposes, though I don't know how food-safe they are. And to use it, solar heat seems like the best choice absent fire, electricity or other alternatives. If the sun is very strong, a thin layer may soak up enough heat to pop the rice (aka fry-an-egg-on-the-sidewalk heat). The heat may be concentrated with magnifying glasses or other lenses (even clear water-filled containers, aka plastic water bottles, supposedly), or with mirrors or other reflecting surfaces.

Of course, this is basically a solar cooker, and can almost certainly be set up to heat water or cook other kinds of foods. Or possibly start a fire, with which you can boil your water.

Yes. But first, you must grind the rice until it turned into powder. Then put a bit of water, just enough to make it like you are making a bread. Then let it ferment, slice like a bread, put in a flat wood or anything you can find that is clean enough to set it. Then let it sit under the sun for awhile. Couple of hours will do.

Rice is a well known desiccant, so it's always tricky to keep rice safe and dry. And also it's not recommended to can rice as well. However, shelf-stable rice products are available on the market. It might need some tooling and extra ingredients, but it should be possible to create shelf-stable rice portions at home.

I believe the commercial producers follow a similar process to canning and they make sure they acidify the product (most probably using lactic acid) in order to make it shelf-stable.

I'm not an expert on food safety, so I won't be giving a recipe and I never recommend getting a recipe online as well. Food preservation is a serious matter, and should be approached with utmost care and the guidelines should be strictly followed.

A parabolic rice cooker. You can make one at home using aluminum foil to create a reflective surface:

Video on youtube using a parabola and a pressure cooker: https://www.youtube.com/watch?v=oyIT_iAtpH4