Blazing Tube: Hybrid Solar Cooker
The Blazing Tube Solar Appliance was developed in Hawai‘i and incorporates the highest efficiency solar components available from around the world. Constructed of metal and glass with no moving parts, the Blazing Tube Solar Appliance has a long service life expectancy and is very stable in windy conditions. Its unique design and energy conservation characteristics allow it to operate at high altitude or under marginal weather conditions, during which most other solar cookers fail.
An exciting breakthrough in solar cooker design is now incorporated in every BlazingTube system. Intermittent solar conditions in many regions have led to a new backup option for users of BlazingTube cookers worldwide. Essentially, a unique hybrid BlazingTube now permits users to employ the sun exclusively, or when weather is too cloudy, the ability to add heat energy from solid fuels simultaneously.
John Grandinetti demonstrating the Blazing Tube Hybrid Solar Cooker
Overall, the BlazingTube solar cooking systems can function in three distinct modes,
(1) solar heat alone.
(2) hybrid operating with solar and wood heat simultaneously.
(3) wood backup alone. (In extreme multi-day rain episodes.)
Foods can be boiled, baked, steamed and fried throughout daylight hours, with operating temperature normally above 300°F/150°C. Hot serving temperatures above 160°F/72°C are maintained late into the evening hours, due to a well-insulated cook box.
This new BlazingTube is equipped with a rocket wood burner (and can also utilize gas burners), that gives a greater degree of reliability for the user, insuring fully cooked food everyday. BlazingTube can normally operate fully on sunlight alone, yet can instantly call upon the rocket stove as backup if sunlight is terminated by rain or extreme clouds. Overall, it is estimated that the BlazingTube system will achieve up to a 90% solar fraction annually. The rocket stove is an efficient and smoke-free backup device, which provides for the remaining 10% of heat input.
• Vacuum Tube: The core element is the 5"/12.7 cm diameter, all-glass, selectively coated, triple-cavity solar vacuum tube.
• CPC Reflector: An outdoor aluminum, mirrored reflector (97% reflectivity) surrounds the tube in a compound parabolic shaped metal frame.
• Cook Box: A highly insulated heat retention cook box, with hinged cover, houses a custom designed aluminum cook pan. The insulated heat retention cook box is round (as are cooking pots) to optimize the space needed for the hot air surrounding the cooking pot. It accommodates one cooking pot with a maximum capacity of 19 liter/5 gallon.
• Vegetable oil: 5 liters/1.321 US gallons of high temperature vegetable oil fills the tube and bottom section of the cook pan (which are tied together using a silicone hose coupling.)
• Reflector: The solar heat generated by the reflector (a compound parabolic curve) heats up the oil in the vacuum tube moving it upward into the round heat retention cook box with 12"/30 cm inside dimension.
• The operating temperature achieved within the cook box of 350˚F/177˚C, allows bread to bake, water to boil, autoclave to sterilize and even food to fry. Cook times are comparable to what gas or electric stove appliances require.
• Designed to last: readily assembled using hand tools, designed to be stable in an outdoor environment. Front wheels are incorporated into the frame structure allowing easy mobility. (Max. dimensions: 97" x 53"/2.46 m x 1.34 m)
• A high durability cover is included to cover and store the Blazing Tube Solar Appliance when not in use or the cooking is finished. Covering the unit will avoid overheating the oil when the cooker is not is use but could accidentally be exposed to direct sunlight.
SAFE Safe Access to Fuel and Energy
October 16, 2015
Lack of safe access to cooking fuel is a significant challenge for refugees worldwide. According to UNHCR’s first large-scale assessment of 3,308 refugee households in Chad, Ethiopia, Kenya, and Uganda, the vast majority (about 90%) rely on firewood for cooking. Members of these households spend an average of 31 hours per month on firewood collection – time that could otherwise be invested in more productive activities such as studying, working, and family care. Moreover, many of these refugees have experienced conflict with host community members while collecting firewood.
Since 2012, the United Nations High Commissioner for Refugees (UNHCR) and its partners - Caritas Burkina Faso (OCADES) and HELP - have been working to introduce renewable energy for cooking into Saag-Nioniogo, Mentao, and Goudoubo refugee camps in Burkina Faso. One solar-powered cooker, the Blazing Tube, has met with considerable success among the Malian refugees in the camps.
“Before the introduction of the stove, refugee women had to walk several hours a day to collect firewood,” says Olivier Lompo,UNHCR Environmental Officer in Burkina Faso. “Since we have a lot of sunshine, the stove allows them to cook without spending any more time on firewood collection. And, more importantly, it does not produce any smoke - they love it.”
In total, UNHCR delivered Blazing Tube cookers to 601 households (1 per household), ranging from two to eight family members each. Feedback from the families indicate that the cooker has reduced their firewood collection time by two to three times, enabling them to spend time on other tasks and to use distributed firewood sparingly.
Operation of a Blazing Tube initially requires 5 liters of vegetable oil. A solar reflector concentrates sunlight, which is transferred to an evacuated glass tube containing the oil. When heated, vegetable oil becomes more fluid and is more likely to transfer the energy it carries to aluminum objects. A portion of the oil overflows into a container, into which a cooking pot is placed, creating a bain-marie.
At its peak of operation, the vegetable oil can reach 200 °C or more, enabling fry cooking, as well as the ability to cook several different types of food. Moreover, ingredients can be added gradually instead of having to be cooked all at once. A cooking box incorporated into the unit enables heat retention, helping to keep food warm for hours.
UNHCR views the gradual introduction of renewable energy sources for cooking into refugee camps as an alternative to firewood distribution programs. Although providing firewood directly to refugees effectively reduces the risk of disease from uncooked food and the possibility of being subjected to violence while collecting fuel, it is not a sustainable strategy. Average firewood usage in Mentao camp alone, for example, reached approximately 33 tons per month. The environmental impact of firewood distribution could lead to irreversible land degradation if remedial measures are not taken.
Based on UNHCR’s monitoring process since 2013, the step-by-step strategy for introducing solar cookers into the camps has proven very beneficial, and enthusiasm for the technology among the refugees demonstrates a significant willingness to adopt solar energy as an alternative to firewood. UNHCR is targeting refugees who are already working with partners in domestic energy, as these individuals facilitate training in (and dissemination of) improved cookstoves among their peers.
Original Aritcle on safefuelandenergy.org
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