Comments on: X-Prize Goes Energy—With “Crazy Green Idea” Prize to Debut at MIT Today http://www.xconomy.com/boston/2008/09/10/x-prize-goes-energy-with-crazy-green-idea-prize-to-debut-at-mit-today/ Business + Technology in the Exponential Economy Sat, 21 Nov 2009 22:30:41 -0600 http://wordpress.org/?v=2.8.6 hourly 1 By: Lawrence Zeitlin http://www.xconomy.com/boston/2008/09/10/x-prize-goes-energy-with-crazy-green-idea-prize-to-debut-at-mit-today/comment-page-1/#comment-29843 Lawrence Zeitlin Wed, 24 Sep 2008 15:59:59 +0000 http://www.xconomy.com/?p=4778#comment-29843 During a stint as a Fullbright Professor in India, I noted that a substantial amount of cooking in rural regions is still done with dried cow dung. The dung is hand shaped into pancake sized patties, air dried, and then used in small stoves. While an ecologically sound solution to the fuel problem, the fuel patties are less than optimum as a source of heat. The large surface area of a dried patty ignites and burns hot then emits less heat as the size and surface area is reduced. The cook will add more patties to maintain heat. This is wasteful. Back when I was in the aerospace industry we encountered a similar problem with solid fuel rockets. As the area of the propulsion core changed, the thrust would increase or decrease depending on the shape, making control difficult. The answer was to shape the fuel so that the burning area would remain constant during combustion. Correct design of a charge, either as a hollow cylinder or a thick cross would permit the surface area available for combustion to remain constant. Rather than shaping cow dung fuel patties by hand, a simple constant combustion area mold or press would permit the rapid production of fuel patties that would offer uniform heat throughout the cooking process. These could be made cheaply out of plastic and distributed to villages. Since about 1/2 of all energy used for cooking in rural India comes from cow dung, the process would offer immeasurable savings for the Indian economy. During a stint as a Fullbright Professor in India, I noted that a substantial amount of cooking in rural regions is still done with dried cow dung. The dung is hand shaped into pancake sized patties, air dried, and then used in small stoves. While an ecologically sound solution to the fuel problem, the fuel patties are less than optimum as a source of heat. The large surface area of a dried patty ignites and burns hot then emits less heat as the size and surface area is reduced. The cook will add more patties to maintain heat. This is wasteful.

Back when I was in the aerospace industry we encountered a similar problem with solid fuel rockets. As the area of the propulsion core changed, the thrust would increase or decrease depending on the shape, making control difficult. The answer was to shape the fuel so that the burning area would remain constant during combustion. Correct design of a charge, either as a hollow cylinder or a thick cross would permit the surface area available for combustion to remain constant.

Rather than shaping cow dung fuel patties by hand, a simple constant combustion area mold or press would permit the rapid production of fuel patties that would offer uniform heat throughout the cooking process. These could be made cheaply out of plastic and distributed to villages. Since about 1/2 of all energy used for cooking in rural India comes from cow dung, the process would offer immeasurable savings for the Indian economy.

]]>