Session H6: Invited Session: Energy Services for the Developing World I

Fuel efficient stoves for the poorest two billion

About 2 billion people cook their daily meals on generally inefficient, polluting, biomass cookstoves. The fuels include twigs and leaves, agricultural waste, animal dung, firewood, and charcoal. Exposure to resulting smoke leads to acute respiratory illness, and cancers, particularly among women cooks, and their infant children near them. Resulting annual mortality estimate is almost 2 million deaths, higher than that from malaria or tuberculosis. There is a large diversity of cooking methods (baking, boiling, long simmers, brazing and roasting), and a diversity of pot shapes and sizes in which the cooking is undertaken. Fuel-efficiency and emissions depend on the tending of the fire (and thermal power), type of fuel, stove characteristics, and fit of the pot to the stove. Thus, no one perfect fuel-efficient low-emitting stove can suit all users. Affordability imposes a further severe constraint on the stove design. For various economic strata within the users, a variety of stove designs may be appropriate and affordable. In some regions, biomass is harvested non-renewably for cooking fuel. There is also increasing evidence that black carbon emitted from stoves is a significant contributor to atmospheric forcing. Thus improved biomass stoves can also help mitigate global climate change. The speaker will describe specific work undertaken to design, develop, test, and disseminate affordable fuel-efficient stoves for internally displaced persons (IDPs) of Darfur, Sudan, where the IDPs face hardship, humiliation, hunger, and risk of sexual assault owing to their dependence on local biomass for cooking their meals.   

Solar Glitter: Low Cost, Solar Energy Harvesting with Microsystems Enabled Photovoltaics

The sun covers our environment with energy harvesting opportunities throughout the day. Although great progress has been made in developing low-cost, solar photovoltaic technologies to harvest the suns energy, the traditional silicon-based PV module format has remained unchanged for almost 40 years, thereby limiting energy harvesting to rooftops and large open spaces. Thin-film and building-integrated photovoltaics have increased the opportunity for energy harvesting, but suffer from low-efficiency. We have developed, based on micro-electro-mechanical systems (MEMs) and other microsystems technology, a new approach to solar photovoltaics applicable in a wide range of environments -- Microsystems Enabled Photovoltaics (MEPV). MEPV solar cells made from crystalline silicon or III-V compound semiconductors (for example, GaAs) are 5-20 microns thick and with lateral dimensions of 250 microns to 1 mm. These solar cells minimize the amount of expensive semiconductor used, but retain the high efficiency of crystalline materials, and allow novel module and system designs not possible with traditional approaches. This talk will outline the science and engineering of MEPV technology, and highlight several novel applications.