Save Energy By Cooking With Your…Thermos?

[social_buttons]A friend recently hipped me to thermos cooking, which takes advantage of the thermos’ insulation to trap and use food’s residual heat for cooking. I was intrigued and immediately starting looking for more information on the subject. Here’s what I learned.

Thermos or vacuum flask cooking is an easy way to save energy. It’s as simple as using a crock pot but requires a fraction of the energy.

You can cook either in a regular old thermos or invest in a vacuum flask. The vacuum flask retains heat a bit better, but they’re on the pricier side. It’s a two part situation, where the food vessel goes inside a vacuum seal that helps retain the heat.

The basic method for cooking dry pasta and grains is to bring the grains and water to a boil on the stove, then pour the boiling food into your preheated thermos. To preheat the thermos, you just pour boiling water into it, so the insides are warm and won’t cool the food. Then you seal it, give it a shake, and let it steep until you’re ready to eat! Since you’re cooking at lower temperatures, it takes longer than making food on the stove, but the energy savings make the planning seem totally worth it. Cooking times seem to range from a just under an hour to overnight, depending on what you’re cooking.

Resources has some really helpful information, including recipes and cooking times for common grains.

I found an incredibly helpful article from Kurt Saxon that includes recipes, tips for planning your day’s thermos-cooked meals, and saving money on food in general.

Several folks recommended Aladdin Stanley as a good brand for thermos cooking.

If you’re looking to make big batches with this method, you might look into this thermal cooker over at Amazon.

Have any of you tried your hands at thermos cooking? I’d love to hear your stories!

Image Credits:
Steel Cut Oats. Creative Commons photo by dlifson
Aladdin Stanley Thermos. Photo via Amazon

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10 thoughts on “Save Energy By Cooking With Your…Thermos?”

  1. What a fascinating idea, I never thought of cooking in a thermos. Though to play devils advocate, I have to wonder how difficult the cleanup would be. Thanks for the cool article.

  2. I handle the marketing for Stanley and can verify that the Stanley vacuum bottles work great for cooking everything from oatmeal to hot dogs to pasta. We love to hear how else you guys cook w/ your bottles. Share more! We’re always amazed at how innovative you all are. Thanks for the post.

  3. That Thermos has a very narrow opening. How does a person get the stuff out? Oatmeal can get thick sometimes and pasta can be sticky.

  4. Thanks, John! Cleanup is a great point…maybe a bottle brush?

    JoAnne – Thanks for the information!

    La Donna – Great question! A little patience and a fork, spoon, or pair of chopsticks should do the trick. :)

  5. Jonathan Eyler-Werve

    This is a great idea in summer months, and dumb in the winter.

    In the prime oatmeal & soup season (winter), there’s no energy gain from this vs. my gas stovetop.

    Here’s why: as a resident of a cold climate who heats the house with gas, I’m already converting lots and lots of gas into heat. Heating stuff on my stove (with the same gas that would be burning in my furnace) converts that gas into heat AND food at the same time. Since the thermostat is in the kitchen, the furnace runs less in balance, keeping the electric fan turned off. By running the stove, you’re harvesting utility from an existing energy stream.

    For electric stoves and microwave users who heat with gas, there’s some energy savings from this.

    Where this makes sense, is in the summer, when you’re paying (in energy use) to COOL the house. Any reduction in overall heat output has double savings: less gas out, less A/C running to compensate.

  6. Thanks for the nice mention of the Thermos Cooking web site ( I’m just getting started and am totally fascinated by thermos cooking. We’ll have video and a lot more recipes up on site in the coming weeks.

    @ LaDonna – I really like the Thermos Sportsman brand thermos sold at Wal-Mart, Target, Ace Hardware and a few other places. It has a much wider opening and it’s a lot easier to get the food out – especially things like quinoa or millet. It’s not available online yet, but Thermos says it’s a newer model that’s still arriving at different stores. Costs about $20 at Wal-Mart. It’s also easier to clean.

    @ Becky – I use a long handled cleaning brush I found at Target. Works great on all of my thermoses except for the 61 oz jumbo Thermos. Going to need to find something with a longer handle for that.

    @ Jonathan – the energy savings isn’t really a big selling point to thermos cooking. Yes, it is more efficient, but you’re really only talking a few pennies either way. To me, it’s more about being efficient with your time. You don’t have to stand at a stove watching and stirring your food. It’s ready when you are and you can leave the rest in the thermos where it will stay hot.

    I’d also say that using a thermos to cook would come in handy in an emergency situation where your energy options might be limited.

  7. Kurt Saxon’s site got me going on this idea too and it led me to the thermal cooker option mentioned above. I started collecting information on the concept and created a blog to hold recipes, videos and other information on the broader idea of retained heat cooking. The method has been used for hundreds of years but the vacuum thermos and thermal cooker has made it much easier and much more reliable.

    The blog is the thermal cooker thermal cooking weblog at you may also be interested in which has a number of thermal cookers and thermoses that would work.

    One example I use when showing the efficiency of using a thermal cooker is cooking a pot of chili beans. To do it without a thermal cooker you would place a big pot filled with water and beans on the stove and let it simmer for about 3-4 hours. Using a thermal cooker, you soak the beans for 16-24 hours, pour off the water and rinse add more water and bring the water and beans to a boil and then let it heat through at a simmer for about 25-30 minutes. Place the boiling hot water and beans into the vacuum thermal cooker and let it sit for 3-4 hours the whole time it’s cooking in it’s own heat. Comparing the two methods, you are using ~35 minutes of fuel/power with the thermal cooker vs 3-4 hours using the stove or slow cooker/crock pot. That’s an 85%-90% savings in fuel and/or power use.

    Clean up is also much easier using a thermal cooker because the pot that holds the food is a separate easy to clean pot.

  8. I just heard of this idea a few days ago. The late Dr John Christopher, a well known herbal healer, said cooking whole grains this way is the healthiest way to cook and preserve nutrients. This, is low heat cooking, according to him. Whole grains cost less because they are unprocessed, and are actually healthier. I can get hard red winter wheat for $.99 a pound. that’s a lot of nutrition ‘ban for your buck’. I like the idea of saving energy and having warn grains ready. I usually let it cook over night.

    “The best food to start the day is fresh fruit or a good low heated whole grain. This should be a cereal in its wholesome state (with life in it). It can be prepared in a thermos bottle: Take a thermos bottle, fill in the early afternoon or evening one-third full of grain, then finish filling the thermos bottle with boiling water. Turn the thermos over two or three times to mix the grain and water. The next morning the grain is ready for consumption.”

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