Friday, April 18, 2008

Borneo Post 13 April 2008- Harnessing Solar Power for Cooking

Harnessing solar power for cooking
Posted By rajlira On 13th April 2008 @ 10:00 In TheSundayPost

GAZING at the blue sky, he thinks of applying solar power to apparatus that may help conserve vital natural resources. He is neither an environmentalist nor an inventor but his interests in using new technologies to preserve the Earth’s depleting resources havedriven him to start working on various types of solar cookers for preparing foods.

Electrical and telecommunications engineer Allen Liew says solar cookers work almost or just as fast as conventional gas or electrical stoves,depending on weather conditions. Over the years, he and his friends have been showing keen interests in “solar” cooking — a technology utilising the “native form of energy” from the sun and has been broadly favoured in several countries following heightened environmental awareness and acute scarcity of cooking fuel.

Last year, at long last, he came up with a few models. “Solar cookers work by harnessing energy from the sun in the form of light diverted to and trapped in a targetted spot to heat food,” he told
thesundaypost. According to him, solar thermal principles are used in making solar cookers — the solar energy is trapped to heat utensils and cook the food inside.

He explains that on reaching the Earth, solar radiation produces about one kilowatt per metre square … which is why a laboratory magnifying glass is able to generate enough solar energy to set a piece of paper on fire. “Solar rays may be collected by a funnel or a parabolic or a sheet of slender plate collector. The collector may be made of cardboard or plywood coated with a tinted reflec-tive sheet such as kitchen aluminum foil. Polished metal sheets or mirrors can also be used.”

Liew says solar energy is directed to the target by adjusting the angle of the reflector, adding that in Sarawak, situated almost right at the Equator, reflectors are not necessary. “Solar heat must be trapped. This is most effectively done by using a black object or a blackened surface. It’s equally important to provide an air insulator outside the cooking utensil to prevent the loss of heat.”

The Americans and North Africans are active promoters of solar cookers and major beneficiaries of this technology, he adds. Solar cookers are also widely used in the Middle East and the Indian sub-continent while Vietnam and Indonesia have also adopted the technology, he reveals.

According to Liew, through the perseverance of the Solarserver Organisation in Vietnam, a factory has been set up there to make solar cookers for the rural poor at cost. He says solar cooking, offering benefits like low upfront investments, no running costs, little mainte-nance and environmental friendliness, canbe a beneficial alternative for Sarawak in view of soaring living costs.

“There are little conversion losses against solar electricity and solar cooking can be very efficient. Solar power is used as a primary form of energy to heat the cooker and cook the food. “Furthermore, due to the nature of the heat in a solar cooker, food cooked in it tastes better and much nutrition can be retained,” he says, adding that the cooker can be left unattended because it will not burn.

He believes solar cookers can be significant labour-saving devices for interior Sarawak since they dispense with the time-consuming need to collect firewood from the jungle or transporting fuel from urban centres. Although there is the rural electrification scheme (RES) connecting grid electrical power to the rural resettlements, he notes that the people there do not use electricity to cook.

He reckons the electricity capacity in these settlements, allocated mainly for lighting, is not sufficient to fire up electric ovens or cookers. He also points out it is more expensive for RES participants to cook with electric cookers because they use a lot of power. “The high electricity bill can be a financial burden to the rural folks with low spending power. Thus, solar cookers can be a solution.”

Liew says solar cookers may be classified into three types — box cookers, panel cookers and parabolic cookers — with their own strengths and weaknesses. Box cookers — the simplest version — can be made with two cardboard boxes of different size. The smaller box should be put inside the bigger one to form a double insulated chamber.

“The inside of the cooker is lined with a reflective sheet like a kitchen aluminum foil to act as a reflector, and topped with a piece of double-glazed glass to allow the diffusion of sunlight but prevent the heat from escaping.” Liew adds that box cookers, which cannot generate enough heat, do not produce good results despite being the most used in the US. On the other hand, panel cookers or funnel cookers, though bigger and more complicated to construct, can have one or more reflectors and they appear to be the best performer of the lot.

According to Liew, funnel cookers consist of a cooker chamber made of plywood or cardboard, and the inner chamber wall is also lined with a reflective sheet. “Solar cookers are so designed that they can heat up immediately when the sky is clear. Funnel cookers work well because their heating chambers work in the same way as the steaming and boiling methods used in conventional stoves.”

He says parabolic cookers which focus solar energy onto a particular area, can produce intense heat to the cooking surface, thus making it possible to fry food and bake confectionery However, the reflectors can be rather glaring and one must avoid using this type of cooker without effective eye protection, he cautions. For identification, he adds, these cookers are named Solar In Actions Panel (SIAP) and they can heat up to about 120 degrees on sunny days. He discloses it takes around one hour to boil four eggs and 40 minutes to steam two eggs using these cookers.
“Solar cookers can also be used to bake cakes. In an experiment, an eight by two inch cake took about an hour to bake. These cookers can also be used to prepare many other Asian cuisine.”

About RM300 each, the solar cookers will cost less when produced in reasonable quantity, Liew says. “Solar cookers do not incur any running costs and there are no consumable parts. They also require low maintenance and spare parts are available locally.” Apart from cooking, solar cookers can be used to warm up food as they will not burn the food inside.

“For example, farmers can place a solar cooker in their hut near the paddy field … just leave it there to keep the food warm. “Also, solar cookers can work as a pasteuriser to make water safe for consumption,” he suggests. Pasteurisation is a process in which harmful micro organisms are destroyed without major chang es to the water chemistry. Alternatively, they can be used in disaster relief operations when basic amenities might be cut off or resources and cooking fuel could be scarce. In the US, he says, the people use their solar cookers for three to four hours during summer.

“In Sarawak, the weather is quite unpredictable and may reduce energy storage. I don’t claim my solar cookers to be established products yet — they are still prototypes.” Asked whether he will patent his solar cookers, he says: “I don’t think I can and I don’t intend to. There may be too many red tapes involved.”

Liew reveals an elected representative has shown keen interest in his cookers and requested him to build a prototype for testing. “I’m still working on it and hoping the government, through this YB, can provide funding for studies so that we can come up with a proper product.” He also suggests higher learning institutions such as Universiti Malaysia Sarawak (Unimas) play a bigger role in research and development by contributing ideas. “I read in the papers that Unimas students have done something similar. If the government can assist with funding, we will work on it and report back to the government.”

Liew says completed prototypes — at least 30 to 50 units — can be used in pilot projects in the remote areas and the data collected can be used to make the final product.

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