Blog - Solar Cooking

BLOG – Solar Cooking This blog is about solar cooking and attempts to provide a brief overview of the most commonly used solar cooking technologies. Main body The three most common types of solar cookers are heat-trap boxes, curved concentrators (parabolics) and panel cookers. Hundreds — if not thousands — of variations on these basic types exist.(Anon (1), 2009) Many large-scale solar cooking systems have been developed to meet the needs of institutions communities worldwide, eg. The Scheffler Reflector array used in various ashrams in India

1) Box cookers “Box cookers cook at moderate to high temperatures and often accommodate multiple pots. Worldwide, they are the most widespread. There are several hundred thousand in India alone.” (Anon (1), 2009) ◦Eg. “Designed by Uli Oehler of the ULOG -Group, are a technologically simple and easy to handle way for private people to cook without gas or wood. The filled cooking vessels are simply placed inside the thermally insulated glazed box and exposed to the sun. Within 2 to 3 hours, the contents gets deliciously cooked without stirring or any other attention to it. The box cookers work perfectly for baking and canning too.” (Anon (3), 2009)

2) Curved concentrator cookers “Curved concentrator cookers, or "parabolics," cook fast at high temperatures, but require frequent adjustment and supervision for safe operation. Several hundred thousand exist, mainly in China. They are especially useful for large-scale institutional cooking.” (Anon (1), 2009) •Scheffler Reflector ◦A remarkable project carried out over 25 years by an Austrian-born engineer by the name of Wolfgang Scheffler which originally began in northern Kenya (with the initial intention of building a cost-effective solar glass smelter) and resulted in a highly energy-efficient solar concentrating solar cooker aptly named the 'Scheffler Reflector'. The project has since spread to other African countries and India. There are probably now more than 950 Scheffler Reflectors in action around the world and the core design is currently being adapted for the Northern European culture and climate (Scheffler, 2009; Anon (3), 2009) ◦As well as huge energy and financial savings, if used at appropriate scales of size eg. A solar community kitchen, I would think that many of our sunny fossil-fuel dependent outback communities would embrace the technology if there was a cultural shift back to more communal living without the baggage of mission management. In some outback schools, communal kitchens are the norm. As mentioned in a previous blog, the transport and costs of diesel in the outback are clearly a problem for many communities, particularly those ones still powered by diesel generators whose residents are mostly using electric cookers to cook food – bad economics or just lack of good information? For example, at the world's largest solar-kitchen in Abu Road, Rajastan, built by the Brahma Kumaris, a 'Scheffler Reflector' array saves 400L of diesel fuel every day with a payback period of approximately 3.4 years, or 1.7 years with a 50% government subsidy. (Scheffler, 2009; Anon (3), 2009). •SK14

◦“Designed by Dr. Ing. D. Seifert and promoted by EG - Solar ( a foreign aid initiative of the State Technical College of Altoetting ). A 1.5 m² parabolic bowl concentrates the sunlight onto the black cooking vessel supported in its centre and heats its content to boiling point. A very efficient and easy to build solar cooker.” (Anon (3), 2009) In this setup the pot does not need to be moved over longer cooking periods – only the parabolic dish.

3) Panel cookers Panel cookers incorporate elements of box and curved concentrator cookers. They are simple and relatively inexpensive to buy or produce. •CooKit ◦The most widely used combination cooker manufactured by 'Solar Cookers International'. (Anon (2), 2009) Conclusion In all countries, underdeveloped and overdeveloped, renewable solar technologies are clearly underexploited in most areas of human activity – cooking food is one such area that uses a lot of energy and generally has high ecological and financial costs to the consumer. Solar cooking, using appropriate solar cooking technology for every situation, seems to be a highly effective way of using local resources, human and material, as well as freely available solar energy via capturing the sun as a diffuse pulse of energy during the daytime and concentrating the flow into a usable energetic input for cooking food resulting in a hot meal output! References •Anon (1), http://solarcooking.org/, last updated 2009 •Anon (2), http://solarcooking.wikia.com/wiki/How_solar_cookers_work, last updated 2009 •Anon (3), http://www.solare-bruecke.org, last updated 2009 •Scheffler, Wolfgang, http://podcast.beyondzeroemissions.org/audio/podcast-2009-04-0533994.mp3, BZE, Melbourne, 2009