Solar cooking - rehdrating foods

Posted by: cruzenbye

Solar cooking - rehdrating foods - 05/27/08 05:49 PM

Has anyone had any experience with solar cooking for rehydrating dehydrated foods, where you simply need to warm up the water enough so that you can rehydrate?

We will be hiking in the grand canyon in a few weeks, and given the heat and the sun exposure there, I was contemplating about maybe eliminating some weight in fuel needs and using solar cooking instead. We will be using homemade dehydrated meals (freezerbag type meals - with many kudos to the poster in this group who has the website - its an awesome resource!).

I was thinking we could possibly even add water to a ziploc bag and wear it on the outside of our pack while hiking to hydrate up some foods, or, utilize aluminum foil or the space blankets as reflective materials to use at camp in the afternoon in order to cook with.

If anyone has experience or recommendations, please post. Thank you.
Posted by: Trailrunner

Re: Solar cooking - rehdrating foods - 05/27/08 07:43 PM

Just like solar battery charging, it's not worth the effort in most situations.

I experimented with solar cooking at home. Some of my tests were done in the summer in 90 degree+ temps. Unless you're going to purchase and carry specialized gadgets and you have the luxury of placing them in a stationary position oriented to the sun just right for much of the day you're not going to get very good results as far as actual cooking goes.

I was thinking we could possibly even add water to a ziploc bag and wear it on the outside of our pack while hiking to hydrate up some foods

And when you rest, what are you going to seek? Shade. If you're going to carry that extra water to heat your food why don't you just carry a far lighter amount of extra fuel to do the same job much better, without the hassle and the risk of leaks?

or, utilize aluminum foil or the space blankets as reflective materials to use at camp in the afternoon in order to cook with.

Have you actually done this? It's not as easy as it sounds. You'll need some sort of struts or frame. What if it's windy? Again, a little extra fuel is much lighter and simpler.

When you get to camp you can use what you already have e.g. Platys or water bottles. Just leave them out in the sun and they'll be warm soon enough.

Solar showers do heat water quite well under the specific conditions I listed above. But if you take one along for the sole purpose of heating water to save fuel, once again the fuel itself will be much lighter and simpler.

If you really want to save fuel, plan some no cook meals. When I kayak camp on lake Mojave during August in 100 degree+ temps the last thing I want in the evening is a hot meal anyway. You'll see, the heat and exertion will sap your appetite.

What you propose may make sense under ideal conditions on a very long trip with no resupply but not for the relatively short jaunt you have planned.
Posted by: NiytOwl

Re: Solar cooking - rehdrating foods - 05/27/08 10:46 PM

I have to agree with Trailrunner - solar cooking is not a good idea for backpacking. Leave the solar cooker/oven home. You'd have to spend more than a few weeks away from civilization before solar cooking would save you weight compared to the fuel used in a similar period.
Posted by: DavidD

Re: Solar cooking - rehdrating foods - 05/29/08 01:51 PM

I have been trying various foods--ramen, rice noodles, dehydrated mushrooms, and these at least rehdrate quickly at room temperature, no need for heat. I played with a pack mounted solar water heater--Had a black mesh bag that could be attached to top of pack, in it went an inflated gallon ziplock. a piece of the mesh was cut out so that light got in, but bag stayed in mesh. Got one of the twist top containeers with a dark blue top. Water went in it, upside down. Cut out black mesh draped over this inside inflated gallon bag, inside mesh bag. Slow in VA sun, and I don't nee hot food, just loose a little crunch and I am happy. Take a little piece of everything you might want to rehydrate in water and test at 30 minute intervals. david
Posted by: cruzenbye

Re: Solar cooking - rehdrating foods - 05/29/08 06:44 PM

I certainly wasn't planning to pack in a solar stove, but like David posted - I just want to rehydrate a couple of meals, they don't necessarily have to be "hot" but at least take the crunch out of the food and rehydrate it. But, we are still planning to take our rocket pocket and fuel to heat water for the 4am oatmeal start to the day.

I appreciate the input from all of you. My idea may not be that great. Was just trying to save a little bit of weight in the extra cans of fuel for the pocket rocket when we have to reheat water for 6 people.
Posted by: robi

Re: Solar cooking - rehdrating foods - 06/10/08 01:35 AM

I watched a kid take a drink of his cold water spit it out because it was HOT.

He had it oon the top of his backpack, wrapped in a black plastic garbage bag to avoid leaks.....

so.. as already posted is is possible to get water quite warm in the sun... Get a black plastic water bottle, warp it in black garbage bag, leave exposed to sun and it should get right hot.

Posted by: bulrush

Re: Solar cooking - rehdrating foods - 06/13/08 01:17 PM

If you take an 8x11 inch fresnel lens, it will heat up 2-3 cups of water in minutes on a sunny day.

Book stores might have full page plastic reading lenses, these are usually of the fresnel type. Just focus the sun's rays on your pot, like a magnifying glass. I've seen good glass lenses boil asphalt in 5 seconds on a summer day.
Posted by: goatpacker

Re: Solar cooking - rehdrating foods - 06/13/08 04:45 PM

In sunny locations I've heated water to well over 140F using these 3 items:

*Large Reynolds oven roasting bag
*black plastic bottle--half quart size works best
*Titanium (or Aluminum) stove wind screen (reflector)

Make a half-circle reflector with stove wind screen & place in oven bag. Add water bottle to bag--between reflector & sun location. Close/seal the bag & place in sunny spot 1-3 hours.

Caution: depending on location and "cook" time, water can get quite hot!
Posted by: Earthling

Re: Solar cooking - rehdrating foods - 06/15/08 05:08 PM

I wonder about these black bag hot water suggestions <img src="/forums/images/graemlins/confused.gif" alt="" /> Why not just use a Solar Shower it's pre-rigged for making water hot, as that is it's sole purpose.....oh yeah, the included directions say something specifically about not using it for 'heating potable water for consumption' <img src="/forums/images/graemlins/confused.gif" alt="" /> <img src="/forums/images/graemlins/tongue.gif" alt="" />
Posted by: finallyME

Re: Solar cooking - rehdrating foods - 06/17/08 06:35 AM

Fresnel lenses are also good at boiling the insides of ants. <img src="/forums/images/graemlins/shocked.gif" alt="" /> <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/smirk.gif" alt="" /> But, I wouldn't know anything about that. <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/wink.gif" alt="" />
Posted by: frank

Re: Solar cooking - rehdrating foods - 06/22/08 04:58 AM

I just completed a 760 mile hike on the PCT stoveless re-hydrating my food. I find that most dehydrated foods will re-hydrate with just cold water. Some grains like brown rice still need to be cooked. I used a plastic peanut butter jars for the rehydrating.

I carried six meals. Hummus (instant rehydration), Baba Ghanous (again instant), tabouleh (rehydrated in about 1.5 hours) a Quiona Salad (about 0ne hour) a Black Bean Chilli and a Red (kidney bean) Chilli (about two hours),

I would eat on on the instant meals for lunch and then soak and carry the meals that needed more time in the mesh pocket of my pack.

I made all the food from scratch. I found that Quoina that has been cooked and dehydrated is really one of the best whole grains to use. It really swells to a large volumn during rehydration. I am getting ready to do another 1000 + this time with an alcohol stove. I add some Quinoa to the black and Red Bean dishes for carbs.