Search results for: 'solar oven'

  • How to Desalinate Water

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    How to Desalinate Water

    Water is a dynamic resource. It depends on the season, the location, the temperature, and a host of other factors. But one thing you can always count on is that at any given time about 97% of the world’s water is tied up in the ocean. The other 3% is found in streams, lakes, groundwater, and ice. Looking at the numbers, it’s obvious that tapping into the ocean’s reserves opens a world of possibilities, especially when it comes to an emergency.

    Using ocean water in an emergency is an obvious possibility for people living in coastal or island areas. When one considers the number of vacation destinations in these areas, the application becomes much wider. Natural disasters, especially, have the ability to interrupt or cripple fresh water supplies in these areas.

    However, people cannot safely drink ocean water.  The reason for this lies in the kidneys.  As the kidneys process salt, they are only capable of producing urine that is less salty than ocean water.  This means it requires more water than that which is available in ocean water to rid the body of excess salt. So as a person drinks ocean water they become increasingly dehydrated, rather than rehydrated. This makes desalinating ocean water an appealing option.

    If removing salt from ocean water is part of your emergency preparedness plan, it will generally take a bit more effort and/or equipment than other water purification processes.  Describing the desalination process at some length emphasizes the fact that the key word here is preparedness. For desalination to be useable at home, some foresight will go a long way.

     

    Desalination: How does it Work?

    Desalination or Desalting is the process of removing salt from ocean water to produce fresh water. Desalinated water can be used for drinking water, or for agriculture, or industrial use.

    Desalination is an inherently energy intensive process. There is a reason why wells are drilled, treatment plants are used, and conservation efforts are exhausted before agencies, governments, and authorities consider using desalination. That reason is money. In many cases ocean water must be treated and/or filtered before the desalination process can take place. This means that aside from consuming a great deal of energy, it also requires equipment, facilities, and manpower. Ultimately, this results in expensive water.

    Despite the cost, removing salt from ocean water is still a useful process that is in use in many areas. Expensive water is much better than no water, and as technology advances, renewable energy sources such as wind or solar power make desalination more viable and affordable.

     

    Types of Desalination

    There are different ways that this process can take place. The two most common are distillation and reverse osmosis.

    • Distillation is the process of boiling ocean water and collecting the condensate which has left salt and other minerals behind.
    • Reverse osmosis uses pressure and a semi-permeable membrane to accomplish the same thing. Osmosis is a naturally occurring process in which a solvent (water) and a solution (salt water) equalize across a semi-permeable membrane. This occurs as the solvent flows from less concentrated to more concentrated water until equilibrium is achieved. Reverse osmosis, as the name implies, pushes the process the other way. Pressure is applied to the salt water side pushing water molecules to the less concentrated side producing clean, salt-free water.

    Ways to Desalinate Water in an Emergency

    There are several different techniques you can use to desalinate water during an emergency.

    • Home distillation is a possibility. It requires a lot of fuel, however. In an extended emergency this could become a problem. Fuels (propane, etc.) may not last and wood collection could become too labor intensive to be worthwhile.
    • Solar distillation may be used as well, but production from a solar still is generally small. If solar power is going to be used, preparedness will be the key. It would be a great idea to invest in something like a solar oven to make the process more efficient.
    • Reverse osmosis is a viable option in an emergency as well. It will, however, require some investment and planning.
    •  Purchase a Desalinator. For someone who lives in an area where using salt water in an emergency is their best option, there are some good products out there. There are a couple common types.
    1. Powered Desalinators: Battery or generator operated. Powered desalinators are capable of supplying a decent volume of water, but they will require ongoing maintenance of batteries, solar panels, or generators to be sure everything will function in an emergency. They’re also relatively expensive. A common model is the Katadyn PowerSurvivor 40E. It retails for around $4000.00. It runs on 12 volts and puts out 1.5 gallons per hour. There are other models as well, but this one is fairly typical of price and output. They go up or down in price based on options.
    2. Manual Deslinators: The Katadyn Survivor 06 is a good example of a manual desalinator. They are generally operated by pumping to supply pressure to force water through the membrane. These again highlight the large amount of energy needed for desalination. The Katadyn Survivor requires 40 pumps per minute to produce 0.89 liters per hour. That is 2400 pumps for less than one liter of water!  In an emergency you’ll be glad to have the water, but a small manual desalinator will only provide enough water for one or two people and it will take a lot of work to get it.

    There are many scenarios where desalination may be your best option for an emergency water supply. If this is the case, it’s critical that you do some planning. You may need to learn specific techniques and decide how to best accomplish the task. In some cases it requires a significant amount of equipment. More so than with almost any other emergency water supply plan, desalination requires planning and forethought in order to be prepared.

     

    Is a desalinator not in your price range for emergency supplies? For a step-by-step tutorial on how to distill your own water at home, check back for our upcoming article on home distillation.

    Also, check out some of our other water filters and purifiers, such as the Katadyn® Expedition. These filters and purifiers are a great way to clean water found in fresh water sources.

     

    -Joe

    Author Bio: Joe Huish has worked for the Central Utah Water Conservancy District’s drinking water treatment sector for 10 years.  He studied Geology at Utah State University where he earned a bachelor’s degree. He’s an avid outdoorsman and is a bit of a gear nut. He enjoys fishing, hunting, jeeping, and camping.

    Posted In: Insight, Uncategorized, Water Storage Tagged With: distillation, desalination, water storage, water

  • DIY Solar Still

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    If you were lost in the wild without any clean water to drink, making your own solar still could be a great way to get clean water until you can get back to civilization.

    But what is a solar still?

    A Solar still is a method of distilling (cleaning) water, using the heat of the sun to evaporate water from soil. Functionally, you’re turning the water from the soil into vapor, and then you collect the condensation to drink. Solar stills can range solar ovens to using a simple tarp over a hole in the ground.

    DIY Solar Still

    Distillation does a good job of removing many contaminants and pathogens.  It removes dirt, bacteria, viruses, and protozoa. It also removes metals such as lead, copper, and sodium. Distilling removes many things you are likely to find in the water, but not all.

    If something vaporizes at a lower temperature than water e.g. alcohol or gasoline, it will come out in the distillate. This means that distillation is not going to be useful for chemical contamination, especially in a do it yourself situation.

    DIY Solar Still Instructions

    Here’s what I did and what I learned when I made my own solar still. I decided to try a couple techniques for making a solar still that could apply in two different situations. Both techniques use the same materials.

    Materials:

    The Sun

    Bowl (about 12 inches in diameter, preferably larger)

    Mug or Plastic container (think Tupperware)

    Plastic Wrap or Sheeting

    A Weight (a rock, brick, box—anything heavy you can find to hold down the plastic wrap down)

    Shovel (or a tool or rock that can dig a hole)

    Plant Material (shrubs, grass, leaves, etc.)

     

    Solar Still #1: Coffee-Mug Still

    For the first one, I assumed a situation such as an earthquake or flood that leaves you in your home (sheltering in place), but causes a disruption in utilities. While normally you would have safe drinking water stored, in the event that you don’t—or it somehow became contaminated, you may need to make a simple solar still.  

    What I did:

    1. I put salt water in a bowl that is about 12 inches in diameter. I then put a coffee mug in the center of the bowl.  I placed the bowl on a table, directly in the sunlight.
    2. I covered the bowl in plastic wrap and put a weight on the center above the mug to direct the condensation toward the mug.  All that was left was to put it in the sun and wait.
    3. The contaminated water went into the bowl, then the condensation on the plastic wrap drips into an empty mug in the center, filling it with clean water.

    This method worked, but there were a couple major shortcomings.  The first time I tried it, the sky clouded up and I was rewarded with only a few drops of water for a whole day of waiting. The next try was better, but a day of sunlight still only yielded about one quarter cup fresh water. This would require a lot of bowls if you were relying on it for drinking water. I think an increase in surface area would make a big difference in how much water is produced.

     

    Solar Still #2: Pit-Style Solar Still

    The second method I used was more of a survival technique. You might use this type of solar still if you have to evacuate your home in an emergency and live off the land.

    What I did:

    1. I dug a shallow hole in my garden about 3 feet in diameter.
    2. I then filled the hole with plant material and placed a water collection cup in the center.
    3. Similar to the set-up described above, I once again covered the collection cup in a plastic sheet.
    4. I then placed a rock in the center to cause the condensate to run to the middle and drip into my collector cup.

     

    DIY Solar Still

    I did this on a hot sunny day, for the entire day, and collected around one third of a cup of water.

    DIY Solar Still

    What I learned

    The second method is energy intensive, both in terms of physical labor and in terms of the energy required to vaporize the water.  If you’re in a survival situation, you may want to weigh the outcome: the work required may not be worth the water produced. If you’re on the brink of dehydration, any amount of water could help you, so making a pit-style solar still could be well-worth it to you then.

    The Solar Still is a little tricky to get right, as well.  The clouds completely ruined my first attempt. On my second attempt I managed to get water, but it was disappointingly full of dirt from the plants I was putting in the pit.

    Given the right situation, however, I can imagine this process being fairly useful.  In a beach, swamp, or marshy area, the pit-style still would continually recharge with water from the soil. It would work passively and could be fairly productive.

    Since there’s so little water produced from the solar still, it’s important to use more than one method of water collection to make sure you have enough water to keep yourself hydrated. Check out the post “Finding Water in the Wild” for more water collection techniques to try out.

    --Joe and Angela

    Posted In: Insight, Skills, Uncategorized Tagged With: water purification, DIY

  • Cooking with the Sunflair Collapsible Solar Oven

    |4 COMMENT(S)

    Learning to cook with a solar oven is a useful skill to develop as you prepare for emergencies. It helps to have a variety of ways to cook your food in an emergency so that you’ll always be prepared to feed you and your family. A solar oven is the most self-sufficient method of outdoor cooking because the only fuel you need is an energy source that will never run out and can be used anywhere there is sunlight.

    Cooking with a solar oven, such as the Sunflair Deluxe Solar Oven Combo, allows you to cook your food while you’re off having other outdoor adventures. Sit back, relax, and let the sun do its job with the confidence that your food will never burn, but will come out moist, warm, and delicious. The Sunflair Deluxe is convenient, easy to use, and portable.

    Basic How-To:

    Cooking with a solar oven is similar to cooking with a slow cooker, so make sure you give yourself 3-4 hours (high-moisture foods will take longer) to cook your food before you plan on eating. The length of time it takes to cook your food depends on the amount of available sunlight, the season, and the type of food you’re trying to cook. Midday in the summertime (when the sun is higher in the sky) will cook your food faster than early or late in the day during wintertime. Slow cooker recipes are great to use in solar ovens where conventional recipes should have their cooking times doubled or more.

    The following recipes were cooked at 150 to 200 degrees. If the temperature of your oven gets hotter than that, your food won’t need to spend as much time in the oven.

    So the sunnier the day the better, but even with partial cloud cover or wind, your food will still cook through. Because this is a lightweight, portable oven, make sure to stabilize it with rocks if you’re in a high wind area.

    Before you begin preparing your meals, set up the oven according to the package directions and place the oven in the sun to preheat. Make sure to put the oven on a level surface, directly facing the sun (the oven’s shadow should be straight behind it). Place the included thermometer inside the oven and zip closed the clear, plastic cover.

     How to set up the Sunflair Solar Oven

    While the oven preheats, prepare your food. Once you start cooking your food, check it every hour to hour and a half, and rotate the oven as needed so it constantly faces the sun with its shadow straight behind. If the oven ever reaches a temperature too high for your meal, open the zipper to release some of the heat.

    For Best Results:

    • Use Sunflair bakeware—thin, dark pots that absorb heat and cook food best
    • Cook your food in high sun for faster cooking
    • Slightly tilt your oven back when the sun is directly overhead to get the most amount of sunlight in the cooking chamber
    • Wipe steam off of the plastic cover and vent by partially unzipping the oven.
    • Leave the oven zipped closed as much as possible
    • Avoid shadows in the cooking chamber

     

    What We Made:

    Solar Pork Chops with Apple Pear Cabbage (Approx. 4-5 hours)

     Solar Oven Pork Chops with Apple Pear Cabbage

    This sweet entrée combines the flavors of apples and pears with delicious pork chops. It makes a great meal for camping or in an emergency. Cooking it in the solar oven can also be a fun way to cook your dinner at home tonight.

    Spicy Roasted Cauliflower (Approx. 5 hours)

     Spicy Roasted Cauliflower

    The spice of this healthy dish will set a slight fire to your mouth—and will leave you craving more. Try using this great recipe as a side for dinner or a snack during a movie. Or add your own oils and seasonings to create a unique blend of flavors your family will love.

    Want to learn more about solar ovens? Check out Emergency Essentials’ Solar Oven Cook-offs:

    Do you have any tips for cooking with a solar oven?

    --Kim

    Posted In: Uncategorized

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