,how to ,make and ,use ,the ,,byu ,solar ,cooker_/,cooler by ,steven ,e4 ,jones1 ,professor of ,physics at ,brigham ,young ,university 7,,byu71 with ,colter ,paulson1 ,jason ,chesley1 ,jacob ,fugal1 ,derek ,hullinger1 ,jamie ,winterton1 ,jeannette ,lawler1 and ,seth1 ,david1 ,nathan1 and ,danelle ,jones4 ,copyright 7c7 #bjjb by ,steven ,e4 ,jones stevejonesbyu4edu ,original web site with this article3 http3_/_/solarcooking4org_/funnel4htm ,image3 #ja4;jpg -- ,photo description this image shows a cardboard box being used to support a silvery funnel1 roughly #c feet high4 ,the funnel is placed within the box so that the sides of the box hold the funnel upright4 ,sitting within the base of the funnel is a black jar inside a clear plastic bag4 ,the plastic bag is inflated like a balloon to seal an insulating air pocket around the jar4 ,contents ,i4 ,introduction ,,ii4 ,how it works ,,iii4 ,how to ,build ,your ,own ,solar ,funnel ,cooker - ,what ,you will ,need for the ,funnel ,cooker - ,construction ,steps ,,iv4 ,final ,steps ,v4 ,after ,cooking ,,vi4 ,tests - ,tests in ,utah - ,tests in ,bolivia ,,vii4 ,water and ,milk ,pasteurization ,,viii4 ,safety ,,ix4 ,cooking with the ,solar ,funnel ,cooker ,x4 ,how to ,use the ,solar ,funnel as a ,refrigerator_/,cooler ,,xi4 ,conclusion3 ,why ,we ,need ,solar ,cookers ,,xii4 ,answers to commonly-asked questions ,,xiii4 ,recipe for wheatpaste ,,xiv4 ,updates - ,rabbit-wire base - ,reduced angle - ,save-heat cooker - ,funnel-cooling during the day - ,hot-and-cold running water - ,conclusion ,i4 ,introduction ,a few years ago1 ,i woke up to the fact that half of the world's peoples must burn wood or dried dung in order to cook their food4 ,it came as quite a shock to me1 especially as ,i learned of the illnesses caused by breathing smoke day in and day out1 and the environmental impacts of deforestation -not to mention the time spent by people 7mostly women7 gathering sticks and dung to cook their food4 ,and yet1 many of these billions of people live near the equator1 where sunshine is abundant and free4 ,as a ,university ,professor of ,physics with a background in energy usage1 ,i set out to develop a means of cooking food and sterilizing water using the free energy of the sun4 ,first1 ,i looked at existing methods4 ,the parabolic cooker involves a reflective dish that concentrates sunlight to a point where the food is cooked4 ,this approach is very dangerous since the sun's energy is focused to a point which is very hot1 but which cannot be seen4 7,,byu students and ,i built one which will set paper on fire in about #c seconds67 ,i learned that an altruistic group had offered reflecting parabolas to the people living at the ,altiplano in ,bolivia4 ,but more than once the parabolas had been stored next to a shed -- and the passing sun set the sheds on fire6 ,the people did not want these dangerous1 expensive devices1 even though the ,altiplano region has been stripped of fuel wood4 ,the box cooker3 ,basically an insulated box with a glass or plastic lid1 often with a reflecting lid to reflect sunlight into the box4 ,light enters through the top glass 7or plastic71 to slowly heat up the box4 ,problems3 energy enters only through the top1 while heat is escaping through all the other sides1 which have a tendency to draw heat away from the food4 ,when the box is opened to put food in or take it out1 some of the heat escapes and is lost4 ,also1 effective box cookers tend to be more complicated to build than the funnel cooker4 ,while studying this problem1 ,i thought again and again of the great need for a safe1 inexpensive yet effective solar cooker4 ,it finally came to me at ,christmastime a few years ago1 a sort of hybrid between the parabola and a box cooker4 ,it looks like a large1 deep funnel1 and incorporates what ,i believe are the best features of the parabolic cooker and the box cooker4 ,the first reflector was made at my home out of aluminum foil glued onto cardboard1 then this was curved to form a reflective funnel4 ,my children and ,i figured out a way to make a large card-board funnel easily4 7,i'll tell you exactly how to do this later on47 ,the ,solar ,funnel ,cooker is safe and low cost1 easy to make1 yet very effective in capturing the sun's energy for cooking and pasteurizing water -- ,eureka6 ,later1 ,i did extensive tests with students 7including reflectivity tests7 and found that aluminized ,mylar was good too1 but relatively expensive and rather hard to come by in large sheets4 ,besides1 cardboard is found throughout the world and is inexpensive1 and aluminum foil is also easy to come by4 ,and individuals can make their own solar cookers easily1 or start a cottage-industry to manufacture them for others4 ,prototypes of the ,solar ,funnel ,cooker were tested in ,bolivia1 and outperformed an expensive solar box cooker and a ,solar ,cookit-- while costing much less4 ,brigham ,young ,university submitted a patent application1 mainly to insure that no company would prevent wide distribution of the ,solar ,funnel ,cooker4 ,,byu makes no profit from the invention4 7,i later learned that a few people had had a similar idea1 but with methods differing from those developed and shown here47 ,so now ,i'm trying to get the word out so that the invention can be used to capture the free energy of the sun - for camping and for emergencies1 yes1 but also for every day cooking where electricity is not available and even fuel wood is getting scarce4 ,,ii4 ,how it ,works ,the reflector is shaped like a giant funnel1 and lined with aluminum foil4 7,easy to follow instructions will be given soon47 ,this funnel is rather like the parabolic cooker1 except that the sunlight is concentrated along a line 7not a point7 at the bottom of the funnel4 ,you can put your hand up the bottom of the funnel and feel the sun's heat1 but it will not burn you4 ,next1 we paint a jar black on the outside1 to collect heat1 and place this at the bottom of the funnel4 ,or one can use a black pot1 with a lid4 ,the black vessel gets hot1 fast4 ,but not quite hot enough to cook with444 ,we need some way to build up the heat without letting the air cool it4 ,so1 ,i put a cheap plastic bag around the jar--voila1 the solar funnel cooker was born6 ,the plastic bag1 available in grocery stores as a poultry bag1 replaces the cumbersome and expensive box and glass lid of the solar box ovens4 ,you can use the plastic bags used in ,american stores to put groceries in1 as long as they let a lot of sunlight pass4 7,dark-colored bags will not do47 ,i recently tested a bag used for fruits and vegetables1 nearly transparent and available free at ,american grocery stores1 that works great4 ,this is stamped ,,hdpe for high-density polyethylene on the bag 7ordinary polyethylene melts too easily74 ,a block of wood is placed under the jar to help hold the heat in4 7,any insulator1 such as a hot pad or rope or even sticks1 will also work47 ,a friend of mine who is also a ,physics ,professor did not believe ,i could actually boil water with the thing4 ,so ,i showed him that with this new solar funnel cooker1 ,i was able to boil water in ,utah in the middle of winter6 ,i laid the funnel on its side since it was winter and pointed a large funnel towards the sun to the south4 ,i also had to suspend the black cooking vessel--rather than placing it on a wooden block4 ,this allows the weaker sun rays to strike the entire surface of the vessel4 ,of course1 the ,solar ,funnel works much better outside of winter days 7when the ,,uv index is #g or greater74 ,most other solar cookers will not cook in the winter in northern areas 7or south of about #ce degrees1 either74 ,i thought that a pressure cooker would be great4 ,but the prices in stores were way too high for me4 ,wait1 how about a canning jar8 ,these little beauties are designed to relieve pressure through the lid--a nice pressure cooker4 ,and cooking time is cut in half for each #aj degrees ,celsius we raise the temperature 7,professor ,lee ,hansen1 private communication74 ,i used one of my wife's wide-mouth canning jars1 spray-painted 7flat7 black on the outside1 and it worked great4 ,food cooks faster when you use a simple canning jar as a pressure cooker4 ,however1 you can also put a black pot in the plastic bag instead if you want4 ,but don't use a sealed container with no pressure release like a mayonnaise jar--it can break as the steam builds up6 7,i've done it47 ,,iii4 ,how to ,build ,your ,own ,solar ,funnel ,cooker ,what ,you will ,need for the ,funnel ,cooker3 #a4 ,a piece of flat cardboard1 about #b feet wide by #d feet long4 7,the length should be just twice the width4 ,the bigger1 the better47 #b4 ,ordinary aluminum foil4 #c4 ,a glue such as white glue 7like ,elmer's glue71 and water to mix with it #ej-ej4 ,also1 a brush to apply the glue to the cardboard 7or a cloth or paper towel will do74 ,or1 some may wish to use a cheap spray adhesive available in spray cans4 ,you can also use wheat paste4 #d4 ,three wire brads--or small nuts and bolts1 or string to hold the funnel together4 #e4 ,for a cooking vessel1 ,i recommend a canning jar 7,ball wide-mouth quart jars work fine for me2 the rubber ring on the lid is less likely to melt than for other jars ,i've found4 ,a two-quart canning jar is available and works fine for larger quantities of food1 although the cooking is somewhat slower474 #f4 ,the cooking jar 7or vessel7 should be spray-painted black on the outside4 ,i find that a cheap flat-black spray paint works just fine4 ,scrape off a vertical stripe so that you have a clear glass window to look into the vessel1 to check the food or water for boiling4 #g4 ,a block of wood is used as an insulator under the jar4 ,i use a piece of #b,x#d board which is cut into a square nominally #d x #d by about #b thick4 7#aj;cm square x #e;cm thick47 ,one square piece of wood makes a great insulator4 #h4 ,a plastic bag is used to go around the cooking-jar and block of wood1 to provide a green-house effect4 ,suggestions3 -,reynolds ,oven ,bag1 ,regular ,size works great3 transparent and won't melt4 7,cost about #be cents each in ,u4,s4 grocery stores47 -,any nearly-transparent ,,hdpe bag 7,high-density ,polyethylene74 ,look for ,,hdpe stamped on the bag4 ,i've tested ,,hdpe bags which ,i picked up for free at my grocery store1 used for holding vegetables and fruits4 ,these are thin1 but very inexpensive4 ,tested side-by-side with an oven bag in two solar funnels1 the ,,hdpe bag worked just as well6 7,caution3 we have found that some ,,hdpe bags will melt should they contact the hot cooking vessel4 ,for this reason1 we recommend using the oven-safe plastic bag wherever possible47 -,an idea attributed to ,roger ,bernard and applied now to the ,,byu ,funnel ,cooker3 place a pot 7having a blackened bottom and sides7 in a glass bowl1 and cover with a lid4 ,try for a tight fit around the bottom to keep hot air trapped inside4 ,the metal pot or bowl should be supported around the rim only1 with an air space all around the bottom 7where the sunlight strikes it74 ,put a blackened lid on top of the pot4 ,then simply place this pot-in-bowl down in the bottom of the funnel--no plastic bag is needed6 ,this clever method also allows the cook to simply remove the lid to check the food and to stir4 ,i like this idea - it makes the solar cooker a lot like cooking over a fire4 ,see ,photographs for further details4 ,image3 #jb4;jpg -- ,photo description3 ,this photo shows a ,pyrex glass measuring cup -- looking like it might hold one-half gallon4 ,inside the measuring cup is a chrome or stainless steel dish1 fitting the sides of the cup very tightly4 ,the shiny dish is blackened on the outside and still shiny on the inside4 ,a man is holding the lid for the dish1 similarly blackened4 ,construction ,steps #a4 ,cut a ,half-circle out of the cardboard1 along the bottom as shown below4 ,when the funnel is formed1 this becomes a full-circle and should be wide enough to go around your cooking pot4 ,so for a #g diameter cooking pot1 the radius of the half-circle is #g4 ,for a quart canning jar such as ,i use1 ,i cut a #e radius half-circle out of the cardboard4 ,image3 #jc4;jpg -- ,photo description3 ,this photo shows a man kneeling beside a rectangular sheet of cardboard on the floor4 ,he is using a plastic bucket as a pattern to cut a half-circle from the center of a long edge of the triangle4 #b4 ,form the ,funnel4 ,to form the funnel1 you will bring side ,a towards side ,b1 as shown in the figure4 ,the aluminum foil must go on the ,,inside of the funnel4 ,do this slowly1 helping the cardboard to the shape of a funnel by using one hand to form creases that radiate out from the half-circle4 ,work your way around the funnel1 bending it in stages to form the funnel shape1 until the two sides overlap and the half-circle forms a complete circle4 ,the aluminum foil will go on the ,,inside of funnel4 ,open the funnel and lay it flat1 inside up1 in preparation for the next step4 ,image3 #jd4;jpg -- ,photo description3 ,a man is holding the sheet of cardboard1 with the long edge against his stomach1 the other long edge with the circle cut out on the opposite side4 ,he is using the edge of his hand for a hard edge to bend and crease the cardboard4 ,he is creasing the cardboard to form triangular sections2 the points of each triangular section are missing -- the points of all the triangles would have come together in the circular cut out area of the other long side1 across from the man4 ,side ,a is the side to the left of1 and directly adjacent to the half-circle4 ,side ,b is the other half of the edge1 to the right of the half-circle4 ,image3 #je4;jpg -- ,photo description3 ,this is looking strait down into the mouth of a cardboard funnel4 ,a man grabbed what was the long edge of the sheet of cardboard1 now divided in two by the half circle cut from it4 ,the two now separate edges are now brought together to form a cone4 ,the cone has no tip because of the cut-out half-circle4 #c4 ,glue ,foil to ,cardboard4 ,apply glue or adhesive to the top 7inner7 surface of the cardboard1 then quickly apply the aluminum foil on top of the glue1 to affix the foil to the cardboard4 ,make sure the shiniest side of the foil is on top1 since this becomes your reflective surface in the ,funnel4 ,i like to put just enough glue for one width of foil1 so that the glue stays moist while the foil is applied4 ,i also overlap strips of foil by about #a 7or #b cm74 ,try to smooth out the aluminum foil as much as you reasonably can1 but small wrinkles won't make much difference4 7,if even cardboard is not available1 one can simply dig a funnel-shaped hole in the ground and line it with a reflector1 to make a fixed solar cooker for use at mid-day47 ,image3 #jf4;jpg-- ,photo description3 two men are spreading a sheet of aluminum foil across a rectangular sheet of cardboard4 #d4 ,join side ,a to side ,b to keep the funnel together4 ,the easiest way to do this is to punch three holes in the cardboard that line up on side ,a and side ,b 7see figure74 ,then put a metal brad through each hole and fasten by pulling apart the metal tines4 ,or you can use a nut-and-bolt to secure the two sides 7,a ,b7 together4 ,be creative here with what you have available4 ,for example1 by putting two holes about a thumb-width apart1 you can put a string1 twine1 small rope1 wire or twist-tie in one hole and out the other1 and tie together4 ,when ,a and ,b are connected together1 you will have a funnel with two wings4 ,the wings could be cut off1 but these help to gather more sunlight1 so ,i leave them on4 ,image3 #jg4;jpg -- ,photo description3 ,this photo shows the outside edge of the cone where the edges of the cardboard meet4 ,two people are securing the edges together4 ,tape or glue a piece of aluminum foil across the hole at the bottom of the funnel1 with shiny side in4 ,this completes assembly of your solar funnel cooker4 ,for stability1 place the ,funnel inside a cardboard or other box to provide support4 ,for long-term applications1 one may wish to dig a hole in the ground to hold the ,funnel against strong winds4 ,image3 #ja4;jpg -- ,photo description this image shows a cardboard box being used to support a silvery funnel1 roughly #c feet high4 ,the funnel is placed within the box so that the sides of the box hold the funnel upright4 ,sitting within the base of the funnel is a black jar inside a clear plastic bag4 ,the plastic bag is inflated like a balloon to seal an insulating air pocket around the jar4 ,,iv4 ,final ,steps ,at this stage1 you are ready to put food items or water into the cooking vessel or jar1 and put the lid on securely4 7,see instructions on food cooking times1 to follow47 ,place a wooden block in the ,,inside bottom of the cooking bag4 ,i use a piece of #b,x#d board which is cut into a square nominally #d,x#d by about #b thick4 ,then place the cooking vessel containing the food or water on top of the wooden block1 inside the bag4 ,next1 gather the top of the bag in your fingers and blow air into the bag1 to inflate it4 ,this will form a small greenhouse around the cooking vessel1 to trap much of the heat inside4 ,close off the bag with a tight twist tie or wire4 ,important3 the bag should not touch the sides or lid of the cooking vessel4 ,the bag may be called a convection shield1 slowing convection-cooling due to air currents4 ,place the entire bag and its contents inside the funnel near the bottom as shown in the ,photographs4 ,place the ,solar ,funnel ,cooker so that it ,faces the ,sun ,remember3 ,sunlight can hurt the eyes3 ,please wear sunglasses when using a ,solar ,cooker6 ,the ,funnel ,cooker is designed so that the hot region is deep down inside the funnel1 out of harm's way4 ,image3 #jh4;jpg -- ,photo description3 ,this is a close-up photo of a black canning jar1 sitting on top of a block of wood4 ,the wood and the jar are sitting on the ground1 inside a clear plastic bag1 which is full of air1 like a balloon and tied at the top so that the air in the bag keeps the bag from touching the jar4 ,put the ,solar ,funnel ,cooker in the sun pointing towards the sun1 so that it captures as much sunlight as possible4 ,the design of the funnel allows it to collect solar energy for about an hour without needing to be re-positioned4 ,for longer cooking times1 readjust the position of the funnel to follow the sun's path4 ,it helps to put the ,solar ,funnel ,cooker in front of a south-facing wall or window 7in the ,northern ,hemisphere7 to reflect additional sunlight into the funnel4 ,a reflective wall is most important in locations farther from the equator and in winter4 ,in the ,southern ,hemisphere1 put the ,solar ,funnel ,cooker in front of a ,north-facing wall or window to reflect additional sunlight into your cooker4 ,v4 ,after ,cooking ,remember that the cooking vessel will be very hot3 ,use cooking pads or gloves when handling6 ,if you are heating water in a canning jar1 you may notice that the water is boiling when the lid is first removed - it gets very hot6 ,open the plastic cooking bag by removing the twist-tie4 ,using gloves or a thick cloth1 lift the vessel out of the bag and place it on the ground or table4 ,carefully open the vessel and check the food1 to make sure it has finished cooking4 ,let the hot food cool before eating4 ,helpful ,hints #a4 ,avoid leaving fingerprints and smudges on the inside surface of the cooker4 ,keep the inner surface clean and shiny by wiping occasionally with a wet towel4 ,this will keep the ,solar ,funnel ,cooker working at its best4 #b4 ,if your funnel gets out-of-round1 it can be put back into a circular shape by attaching a rope or string between opposite sides which need to be brought closer together4 #c4 ,for long-term applications1 a hole in the ground will hold the ,funnel ,cooker securely against winds4 ,bring the funnel inside or cover it during rain storms4 #d4 ,the lids can be used over and over4 ,we have had some trouble with the rubber on some new canning-jar lids becoming soft and sticky4 ,ball canning lids do not usually have this problem4 ,running new lids through very hot water before the first use seems to help4 ,the lids can be used over and over if they are not bent too badly when opened 7pry off lid carefully74 #e4 ,the jar can be suspended near the bottom of the funnel using fishing line or string 7etc471 instead of placing the jar on a block of wood4 ,a plastic bag is placed around the jar with air puffed inside1 as usual1 to trap the heat4 ,the suspension method allows sunlight to strike all surfaces of the jar1 all around1 so that it heats faster and more evenly4 ,this suspension method is crucial for use in winter months4 #f4 ,adjust the funnel to put as much sunlight onto the cooking jar as possible4 ,look at the jar to check where the sunlight is hitting1 and to be sure the bottom is not in the shadows4 ,for long cooking times 7over about an hour71 readjust the position of the funnel to follow the sun's path4 ,during winter months1 when the sun is low on the horizon 7e4g41 in ,north ,america71 it is helpful to lay the funnel on its side1 facing the sun4 ,,vi4 ,tests ,tests in ,utah ,image3 #ji4;jpg --,photo description3 ,this is a picture of the funnel sitting tilted at an angle between two stands4 ,the funnel has no hole at the bottom2 where there should be a hole is solid and shiny like the rest of the funnel4 ,a crossbeam connects the two stands1 above the funnel4 ,hanging by string from the crossbeam so that it rests near the shiny bottom of the funnel is a black canning jar1 surrounded by a clear plastic bag4 ,the bag appears to be blown up1 full of air1 and not touching the jar4 ,i have personally used the ,solar ,funnel ,cooker to cook lunches over many weeks4 ,my favorite foods to cook are potatoes 7cut into logs or slices7 and carrot slices4 ,vegetables cook slowly in their own juices and taste delicious4 ,i also make rice1 melted cheese sandwiches1 and even bread in the ,solar ,funnel ,cooker4 ,i usually put the food out around #aa3cj and let it cook until #ab3de or #a pm1 just to be sure that it has time to cook4 ,i've never had any food burn in this cooker4 ,i have also cooked food in the mountains1 at an altitude of around #h1cjj feet4 ,if anything1 the food cooked faster there--the sunlight filters through less atmosphere at high altitudes4 ,i find that people are surprised that the sun alone can actually cook food4 ,and they are further pleasantly surprised at the rich flavors in the foods which cook slowly in the sun4 ,this inexpensive device does it6 ,students at ,brigham ,young ,university have performed numerous tests on the ,solar ,funnel ,cooker along with other cookers4 ,we have consistently found much faster cooking using the ,solar ,funnel ,cooker4 ,the efficiency_/cost ratio is higher than any other solar cooking device we have found to date4 ,mr4 ,hullinger also performed studies of transmissivity1 reflectivity and absorptivity of alternate materials which could be used in the ,solar ,funnel ,cooker4 ,while there are better materials 7such as solar-selective absorbers71 our goal has been to keep the cost of the ,solar ,cooker as low as possible1 while maintaining safety as a first priority4 ,tests in ,bolivia ,the ,,byu ,benson ,institute organized tests between the ,solar ,funnel ,cooker and the old-fashioned solar box oven4 ,the solar box oven cost about #gj and was made mostly of cardboard4 ,it took nearly two hours just to reach water pasteurization temperature4 ,the ,bolivian report notes that food gets cold every time the pots are taken from and into the oven4 ,the solar box oven failed even to cook boiled eggs4 7,more expensive box cookers would hopefully work better47 ,an aluminized-mylar ,solar ,funnel ,cooker was also tested in ,bolivia1 during the ,bolivian winter4 ,water pasteurization temperature was reached in #ej minutes1 boiled eggs cooked in #gj minutes1 and rice cooked in #ge minutes4 ,the ,bolivian people were pleased by the performance4 ,so were we6 7,la ,paz1 ,bolivia1 ,august1 #aiif74 ,i also donated two dozen solar funnel cookers for people in ,guatemala4 ,these were taken there by a group of doctors going there for humanitarian service4 ,the people there also liked the idea of cooking with the sun's free energy6 ,for an aluminized-,mylar ,solar ,funnel ,cooker kit1 please contact ,,crm 7licensed manufacturer7 at #a 7#hja7 #bib-ibaj4 ,image3 #aj4;jpg -- ,photo description3 ,this photo shows what looks like the same style of funnel as in the above pictures except that it doesn't look homemade but something produced by a factory4 ,the photo shows something which looks like a machined metal_/shiny plastic funnel4 ,,vii4 ,water and ,milk ,pasteurization ,contaminated drinking water or milk kills thousands of people each day1 especially children4 ,the ,word ,health ,organization 7,,who7 reports that #hj percent of illnesses in the world are spread through contaminated water4 ,studies show that heating water to about #fe degrees to #gj degrees ,celsius 7#aej degrees ,fahrenheit7 is sufficient to kill coliform bacteria1 rotaviruses1 enteroviruses and even ,giardia4 ,this is called pasteurization4 ,pasteurization depends on how hot and how long water is heated4 ,but how do you know if the water got hot enough8 ,you could use a thermometer1 but this would add to the cost1 of course4 ,when steam leaves the canning jar 7with lid on tight7 and forms dew on the inside of the cooking bag1 then the water is probably pasteurized to drink4 7,the goal is to heat to #afj degrees ,fahrenheit for at least six minutes47 ,with a stripe of black paint scraped off the jar1 one can look through the bag and into the jar and see when the water is boiling - then it is safe for sure4 ,think of all the lives that can be saved simply by pasteurizing water using a simple ,solar ,cooker6 ,,viii4 ,safety ,safety was my first concern in designing the ,solar ,funnel ,cooker1 then came low cost and effectiveness4 ,but any time you have heat you need to take some precautions4 -,the cooking vessel 7jar7 is going to get hot1 else the food inside won't cook4 ,let the jar cool a bit before opening4 ,handle only with gloves or tongs4 -,always wear dark glasses to protect from the sun's rays4 ,we naturally squint1 but sunglasses are important4 -,keep the plastic bag away from children and away from nose and mouth to avoid any possibility of suffocation4 ,,ix4 ,cooking with the ,solar ,funnel ,cooker ,what do you cook in a crock pot or moderate-temperature oven8 ,the same foods will cook about the same in the ,solar ,funnel ,cooker --without burning4 ,the charts below give approximate summer cooking times4 ,the solar cooker works best when the ,,uv index is #g or higher4 7,sun high overhead1 few clouds47 ,cooking times are approximate4 ,increase cooking times for partly- cloudy days1 sun not overhead 7e4g41 wintertime7 or for more than about #c cups of food in the cooking jar4 ,stirring is not necessary for most foods4 ,food generally will not burn in the solar cooker4 ,,vegetables 7,potatoes1 carrots1 squash1 beets1 asparagus1 etc47 ,preparation3 ,no need to add water if fresh4 ,cut into slices or logs to ensure uniform cooking4 ,corn will cook fine with or without the cob4 ,cooking ,time3 ,about #a4e hours ,,cereals ,,and ,,grains 7,rice1 wheat1 barley1 oats1 millet1 etc47 ,preparation3 ,mix #b parts water to every #a part grain4 ,amount may vary according to individual taste4 ,let soak for a few hours for faster cooking4 ,to ensure uniform cooking1 shake jar after #ej minutes4 ,,caution3 ,jar will be hot4 ,use gloves or cooking pads4 ,cooking ,time3 #a4e-b hours ,,pasta ,,and ,,dehydrated ,,soups ,preparation3 ,first heat water to near boiling 7#ej-gj minutes74 ,then add the pasta or soup mix4 ,stir or shake1 and cook #ae additional minutes4 ,cooking ,time3 #fe-he minutes ,,beans ,preparation3 ,let tough or dry beans soak overnight4 ,place in cooking jar with water4 ,cooking ,time3 #b-c hours ,,eggs ,preparation3 ,no need to add water4 ,note3 ,if cooked too long1 egg whites may darken1 but taste remains the same4 ,cooking ,time3 #a-a4e hours1 depending on desired yolk firmness4 ,,meats 7,chicken1 beef1 and fish7 ,preparation3 ,no need to add water4 ,longer cooking makes the meat more tender4 ,cooking ,time3 ,chicken3 #a4e hours cut up or #b4e hours whole2 ,beef3 #a4e hours cut up or #b4e-c hours for larger cuts2 ,fish3 #a-a4e hours ,,baking ,preparation3 ,times vary based on amount of dough4 ,cooking ,times3 ,breads3 #a-a4e hours2 ,biscuits3 #a-a4e hours2 ,cookies3 #a hour ,,roasted ,,nuts 7,peanuts1 almonds1 pumpkin seed1 etc47 ,preparation3 ,place in jar4 ,a little vegetable oil may be added if desired4 ,cooking ,time3 ,about #a4e hours ,,mre's ,,and ,,prepackaged ,,foods ,preparation3 ,for foods in dark containers1 simply place the ,container in the cooking bag in place of the black cooking jar4 ,cooking ,times3 ,cooking time varies with the amount of food and darkness of package4 ,x4 ,how to ,use the ,solar ,funnel as a ,refrigerator_/,cooler ,a university student 7,jamie ,winterton7 and ,i were the first to demonstrate that the ,,byu ,solar ,funnel ,cooker can be used--at night --as a refrigerator4 ,here is how this is done4 ,the ,solar ,funnel ,cooker is set-up just as you would during sun-light hours1 with two exceptions3 #a4 ,the funnel is directed at the dark night sky4 ,it should not see any buildings or even trees4 7,the thermal radiation from walls1 trees1 or even clouds will diminish the cooling effect474 #b4 ,it helps to place #b 7two7 bags around the jar instead of just one1 with air spaces between the bags and between the inner bag and the jar4 ,,hdpe and ordinary polyethylene bags work well1 since polyethylene is nearly transparent to infrared radiation1 allowing it to escape into the heat sink of the dark sky4 ,during the day1 the sun's rays are reflected onto the cooking vessel which becomes hot quickly4 ,at night1 heat from the vessel is radiated outward1 towards empty space1 which is very cold indeed 7a heat sink74 ,as a result1 the cooking vessel now becomes a small refrigerator4 ,we routinely achieve cooling of about #bi degrees ,fahrenheit 7#aj degrees ,celsius7 below ambient air temperature using this remarkably simple scheme4 ,in ,september #aiii1 we placed two funnels out in the evening1 with double-bagged jars inside4 ,one jar was on a block of wood and the other was suspended in the funnel using fishing line4 ,the temperature that evening 7in ,provo1 ,utah7 was #gh degrees ,fahrenheit4 ,using a ,radio ,shack indoor_/outdoor thermometer1 a ,,byu student 7,colter ,paulson7 measured the temperature inside the funnel and outside in the open air4 ,he found that the temperature of the air inside the funnel dropped quickly by about #ae degrees1 as its heat was radiated upwards in the clear sky4 ,that night1 the minimum outdoor air temperature measured was #dg4e degrees--but the water in both jars had ,,ice4 ,i invite others to try this1 and please let me know if you get ice at #ee or even #fj degrees outside air temperature 7minimum at night74 ,a black ,,pvc container may work even better than a black-painted jar1 since ,,pvc is a good infrared radiator--these matters are still being studied4 ,i would like to see the ,funnel ,refrigerator tried in desert climates1 especially where freezing temperatures are rarely reached4 ,it should be possible in this way to cheaply make ice for ,hutus in ,rwanda and for aborigines in ,australia1 without using any electricity or other modern tricks4 ,we are in effect bringing some of the cold of space to a little corner on earth4 ,please let me know how this works for you4 ,,xi4 ,conclusion3 ,why ,we ,need ,solar ,cookers ,the ,,byu ,funnel ,cooker_/,cooler can3 -,cook food without the need for electricity or wood or petroleum or other fuels4 -,pasteurize water for safe drinking1 preventing many diseases4 -,save trees and other resources4 -,avoid air pollution and breathing smoke while cooking4 -,use the sun's free energy4 ,a renewable energy source4 -,cook food with little or no stirring1 without burning4 -,kill insects in grains4 -,dehydrate fruits1 etc4 -,serve as a refrigerator at night1 to cool even freeze water4 7,try that without electricity or fuels67 ,the burden for gathering the fuel wood and cooking falls mainly on women and children4 ,joseph ,kiai reports from ,dadaab1 ,kenya3 ,women who can't afford to buy wood start at #d am to go collecting and return about noon444 ,they do this twice a week to get fuel for cooking444 ,the rapes are averaging one per week4 ,from ,belize3 ,many times the women have to go into the forest dragging their small children when they go to look for wood4 ,it is a special hardship for pregnant and nursing mothers to chop and drag trees back to the village444 they are exposed to venomous snakes and clouds of mosquitoes4 7,anna ,k47 7,quoted by ,solar ,cookers ,international from a newsletter47 ,and the forests are dwindling in many areas4 ,edwin ,dobbs noted in ,audubon ,magazine1 ,nov4 #aiib1 ,the world can choose sunlight or further deforestation1 solar cooking or widespread starvation444 ,americans should be prepared for emergencies1 incident to power failures4 ,a ,mormon pioneer noted in her journal3 ,we were now following in their trail traveling up the ,platte ,river4 ,timber was sometimes very scarce and hard to get4 ,we managed to do our cooking with what little we could gather up444 7,eliza ,r4 ,snow7 ,now there's someone who needed a light-weight ,solar ,cooker6 ,here's another reason to use a solar cooker4 ,many people in developing countries look to see what's being done in ,america4 ,i'm told that if ,americans are using something1 then they will want to try it1 too4 ,the more people there are cooking with the others will want to join in4 ,a good way to spread this technology is to encourage small local industries or families to make these simple yet reliable solar cookers for others at low cost4 ,i've used this cooker for three summers and ,i enjoy it4 ,cooking and making ice with the funnel cooker_/cooler will permit a significant change in lifestyle4 ,if you think about it1 this could help a lot of people4 ,the ,,byu ,solar ,funnel ,cooker uses the glorious sunshine -- and the energy of the sun is a free gift from ,god for all to use6 ,,xii4 ,answers to commonly-asked questions ,will the cooker work in winter 7in the ,united ,states78 ,as the sun moves closer to the southern horizon in the winter1 the solar cooker is naturally less effective4 ,a good measure of the solar intensity is the ,,uv index which is often reported with the weather4 ,when the ultraviolet or ,,uv index is #g or above--common in summer months--the solar cooker works very well4 ,in ,salt ,lake ,city in ,october1 the ,,uv index was reported to be #c4e on a sunny day4 ,we were able to boil water in the ,solar ,funnel ,cooker during this time1 but we had to suspend the black jar in the funnel so that sunlight struck all sides4 7,we ran a fishing line under the screw-on lid1 and looped the fishing line over a rod above the funnel4 ,as usual1 a plastic bag was placed around the jar1 and this was closed at the top to let the fishing line out for suspending the jar47 ,the solar minimum for the northern hemisphere occurs on winter solstice1 about ,december #bast each year4 ,the solar maximum occurs six months later1 ,june #bast4 ,solar cooking works best from about ,march #bj to ,october #a in the north4 ,if people try to cook with the sun for the first time outside of this time window1 they should not be discouraged4 ,try again when the sun is more directly overhead4 7,one may also suspend the jar in the funnel1 which will make cooking faster any time of the year47 ,it is interesting to note that most developing countries are located near the equator where the sun is nearly directly overhead all the time4 ,solar ,cookers will then serve year-round1 as long as the sun is shining1 for these fortunate people4 ,they may be the first to apply fusion energy 7of the sun7 on a large scale6 ,and they may accomplish this without the expensive infrastructure of electrical power grids that we take for granted in ,america4 ,how do you cook bread in a jar8 ,i have cooked bread by simply putting dough in the bottom of the jar and placing it in the funnel in the usual way4 ,rising and baking took place inside the jar in about an hour 7during summer74 ,one should put vegetable oil inside the jar before cooking to make removal of the bread easier4 ,i would also suggest that using a #b-quart wide-mouth canning jar instead of a #a-quart jar would make baking a loaf of bread easier4 ,what is the optimum opening angle for the funnel cooker8 ,a graduate student at ,brigham ,young ,university did a calculus calculation over two years ago to assess the best shape or opening angle for the ,solar ,funnel4 ,jeannette ,lawler assumed that the best operation would occur when the sun's rays bounced no more than once before hitting the cooking jar1 while keeping the opening angle as large as possible to admit more sunlight4 7,some sunlight is lost each time the light reflects from the shiny surface4 ,if the sunlight misses on the first bounce1 it can bounce again and again until being absorbed by the black bottle47 ,she set up an approximate equation for this situation1 took the calculus- derivative with respect to the opening angle and set the derivative equal to zero4 ,optimizing in this way1 she found that the optimum opening angle is about #de degrees1 when the funnel is pointed directly towards the sun4 ,but we don't want to have to track the sun by turning the funnel every few minutes4 ,the sun moves 7apparently7 #cfj degrees in #bd hours1 or about #ae degrees per hour4 ,so we finally chose a #fj-;degree opening angle so that the cooker is effective for about #a4b hours4 ,this turned out to be long enough to cook most vegetables1 breads1 boil water1 etc4 with the ,solar ,funnel ,cooker4 ,we also used a laser pointer to simulate sun rays entering the funnel at different angles1 and found that the #fj-;degree cone was quite effective in concentrating the rays at the bottom of the funnel where the cooking jar sits4 ,,xiii4 ,recipe for wheatpaste ,prepare #a cup 7#b4d dl7 of very hot water4 ,make a thin mixture of #c tablespoons 7#de ml7 of white flour and cold water4 ,pour the cold mixture slowly into the hot water while stirring constantly4 ,bring to a boil4 ,when it thickens1 allow to cool4 ,smear on like any other glue4 ,for slightly better strength1 add #a tablespoon 7#ae ml7 of sugar after the glue is thickened4 ,after using a portion1 reheat the remaining in a covered jar or container to sterilize it for storage or keep refrigerated4 ,if wheat flour is not available1 other flours will work4 ,,xiv4 ,updates compiled by transcribists ,rabbit-wire base ,in later experiments ,steven ,e4 ,jones and ,christopher ,mc,millan of ,brigham ,young ,university tested different bases for the cooking pot used in the ,solar ,funnel1 published on the web in the article ,tests of the ,solar ,funnel and ,bowl ,cookers in #bjja4 ,according to ,jones1 the rabbit-wire stand they tested has proven to be much better than the wooden block detailed in this article4 ,we found immediately that raising the vessel off the bottom of the cooker using a rabbit-wire stand provided more rapid and even heating than the wooden block used previously4 ,placing the jar or pot on a wire stand allows as much reflected light onto the cooking vessel as possible4 ,this allows even the bottom of the cooking container to absorb thermal energy that is reflected off the lower portion of the funnel4 ,image3 #aa4;jpg -- ,photo ,description3 ,this photo shows two different sized cylinders1 made of rabbit wire -- fencing material for rabbits1 made of crossed wires tacked together1 so to make a single sheet4 ,a black pot is being lowered into the cylinders1 and will come to rest on a wire cross1 inside the cylinder1 made from wires going from one side of the cylinder to the other4 ,reduced angle ,the original report describes a large solar funnel1 having a #fj-;degree opening angle4 ,our ongoing experiments show that a reduced angle of approximately #de degrees allows about #aj faster solar cooking4 ,such a funnel is shown in the photograph4 ,start with the funnel described in the original report1 then simply bring the sides ,a and ,b together with a #bj-;cm overlap at the top of the funnel4 ,this makes a funnel with steeper sides4 ,save-heat cooker 7a retained heat cooker for canning jars heated using the sun or fire7 ,the photograph shows the ,save-,heat ,cooker which we have designed and built4 ,the box is made from a polystyrene cube1 #cj cm on a side4 ,we have drilled #d holes each about #aj cm in diameter into this block1 so that each holds a canning jar4 ,then a lid fits over the top to hold in the heat4 ,when a jar is placed in the solar funnel cooker1 a maximum temperature of about #aaj degrees ,c is reached in approximately #de minutes 7depending on solar conditions74 ,then steam is released around the rim of the canning jar1 which becomes an inexpensive pressure cooker4 ,but the jar will not get hotter1 so one takes the jar out of the cooker 7with a gloved hand7 and places it into the ,save-,heat box4 ,our experiments show that the temperature drops slowly in this box1 about #e degrees ,c per hour1 so that cooking continues for #d hours or so1 without a heat source4 ,in this way1 one can prepare up to four quarts of food per ,save-,heat ,cooker at mid-day1 and have the food cooked and hot for the evening meal6 ,or1 if desired1 the food will keep in the box overnight and be ready for eating the next morning4 ,thus1 a solar cooker can supply food for mid-day1 evening and the next morning1 as desired4 7,another design of the ,save-,heat ,cooker holds up to seven quart-sized canning jars47 ,the ,save-,heat ,cooker is particularly useful for foods such as beans which take a long time to cook4 ,food heated using a wood fire could likewise be placed in a jar1 and then this jar placed in the ,save-,heat ,box1 in order to save fuel-wood consumption1 and cooking time and effort4 ,the box can be cheaply molded out of polystyrene or styrofoam or other material1 so long as it is a good insulator and capable of withstanding temperatures of around #aaj degrees centigrade4 ,funnel-cooling during the day ,we noted in the original report that the funnel works as a cooler at night1 by reflecting heat out of the canning jar and up to the cold sky4 ,we have found that this works during the day also1 when the funnel is pointed to a region of the sky away from the sun 7and buildings1 etc474 ,we found cooling of about #ab degrees ,f41 compared with about #bj degrees cooling at night4 ,to achieve this1 the jar was placed on a rabbit-wire support as described above1 and housed in two cheap1 clear polyethylene bags1 such as used for vegetables in the ,united ,states4 ,hot-and-cold running water4 ,by placing a large funnel around a water barrel1 it will be solar-heated during the day1 or cooled at night4 ,thus1 having two barrels each with a funnel-like reflector around it1 and covering one when not sunny and the other whenever it is sunny1 one can have hot and cold water4 ,these barrels could be placed on a platform or roof to provide hot-and-cold running water6 ,conclusion ,we are hopeful that these developments will help many people1 especially those in areas of the world where electricity or even wood or gas are in short supply1 if available at all4 ,these ideas are offered freely to all4 ,prof4 ,steven ,e4 ,jones1 ,colter ,paulson1 ,jason ,chesley1 ,will ,shakespeare and ,jacob ,fugal4 ,for questions regarding the complete ,solar ,funnel ,cooker kit using aluminized ,mylar and a jar for the cooking vessel1 please contact ,,crm at #a 7#hja7 #bib-ibaj4 ,recent updates to this project can be found at http3_/_/physics#a4;byu4edu_/jones_/rel# dia_/solarbowl4htm4