By Rob Goodier

Solar cookers solve real problems in health and conservation—they promote better air quality in the kitchen and healthy forests around a community. The problem is that they don’t work at night.

The aid organization Climate Healers stumbled on the issue last year after handing out solar cookers to women in two rural Indian villages. The broad, reflective parabolas that work so well to cook rotis, rice and dhal by day were useless when the sun went down, just when the women began to prepare their families’ dinner. And they were equally useless for cooking breakfast in the early morning.

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By Rob Goodier

A new forced-air stove design intended to make clean stoves burn even cleaner could double as a wood-powered electricity generator in the home. The generator may be the only means of charging cell phones and operating radios in homes that need clean cook stoves most.

The device is a fan that attaches to the side of a “Rocket Stove,” one of the most widely distributed clean-burning stoves in the world. With the fan attached, the Rocket becomes a forced-air stove that mixes the smoke back into the flame to burn away soot.

Forced-air stoves burn cleanest
On their own, Rocket Stoves reduce fuel use by 40-50% and burn about 50-75% cleaner. With the fan, they burn 95% cleaner. That’s according to lab tests by Biolite, a stove-technology development organization, in partnership with Approvecho Research Center, which designed and helped distribute its Rocket Stoves since the 1980s.

To power the fans, the designers considered energy sources such as batteries, solar power, or simply a wall outlet, but those options either added to the cost or just seemed impractical. Rather than require cooks to pay for electricity, the design team figured that the stove should generate its own using a thermoelectric generator.

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Thirty-four experts, academics, and entrepreneurs from Laos, Cambodia, Vietnam, and Thailand gathered to discuss how to create a cleaner, more efficient stove during the Stove Design & Testing Workshop in Vientiane, Laos on March 14-16. Participants shared methods to design, evaluate, and commercialize improved-stoves that use less fuel and produce less smoke.

Exposure to smoke from traditional cookstoves and open fires—the primary means of cooking and heating for nearly three billion people in the developing world—causes 1.9 million premature deaths annually, with women and young children the most affected. Cookstove smoke contributes to a range of chronic illnesses and acute health impacts such as early childhood pneumonia, emphysema, cataracts, lung cancer, bronchitis, cardiovascular disease, and low birth weight. In Laos, diseases caused by cookstoves kill more people per year than car crashes or malaria.

Governments and NGOs across the Lower Mekong Region are increasingly aware of the links between cookstoves and health and productivity, with Thailand and Cambodia already actively invested in more efficient cookstove projects, and a key objective of the Vientiane workshop was to build networks between major regional stakeholders in this issue. The workshop was the also the first step in a phased process that will eventually lead to the distribution of 500,000 improved stoves over the next eight years in Laos.

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It may come as a surprise to know that half of the global population uses biomass (wood, agricultural wastes and dung) and coal for cooking.

For Sub-Saharan Africa where electrification rates outside of South Africa are only 28 percent, biomass and coal are the primary cooking fuels for over three fourths of the population. Combustion of unprocessed biomass fuels, especially in open or poorly ventilated stoves, emits high concentrations of pollutant mixtures – particulates, and carbon dioxide, methane, and carbon monoxide – associated with a number of respiratory and other diseases and is the leading cause of death among infants and children worldwide.

Since the task of cooking is mainly done by women and girls, it is they who face daily exposure to levels of pollution which are estimated to be the equivalent of consuming two packets of cigarettes a day (Kammen, 1995; Ezzati and Kammen, 2001).

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Int J Tuberc Lung Dis. 2011 Mar;15(3):391-8.

Wood smoke exposure, poverty and impaired lung function in Malawian adults.

Fullerton DG, Suseno A, Semple S, Kalambo F, Malamba R, White S, Jack S, Calverley PM, Gordon SB.

duncan.fullerton@liverpool.ac.uk

BACKGROUND: Household air pollution from burning biomass fuel is increasingly recognised as a major global health concern. Biomass smoke is associated with chronic obstructive pulmonary disease (COPD) in Asian and Central American countries, but there are few data from Africa.

METHODS: We hypothesised that reported wood smoke as compared to charcoal smoke exposure would be associated with a reduction in forced expiratory volume in 1 second in Malawian adults. Volunteers from urban and rural locations performed spirometry and completed a questionnaire assessing lifestyle, including smoke exposure and symptoms.

RESULTS: In total, 374 adults were recruited; 61% were female; 160 cooked using charcoal and 174 used wood. Individuals who used wood as their main domestic fuel had significantly worse lung function than those who used charcoal. Significant factors associated with impaired lung function in the multivariate model were age, sex, height, wood smoke exposure, poverty, smoking and previous tuberculosis.

CONCLUSION: Our data suggest that wood smoke and poverty contribute to reduced lung function in rural Africans and that COPD is common in this population. The use of charcoal in rural populations may be relatively protective, and this idea merits further study. The risk factors for impaired lung function in Malawi are multiple and require more detailed characterisation to plan appropriate health interventions.

Environ Sci Tech, March 29, 2011

Climate Change Impact of Biochar Cook Stoves in Western Kenyan Farm Households: System Dynamics Model Analysis

Thea Whitman, Charles F. Nicholson, Dorisel Torres, and Johannes Lehmann

Cook stoves that produce biochar as well as heat for cooking could help mitigate indoor air pollution from cooking fires and could enhance local soils, while their potential reductions in carbon (C) emissions and increases in soil C sequestration could offer access to C market financing.

We use system dynamics modeling to (i) investigate the climate change impact of prototype and refined biochar-producing pyrolytic cook stoves and improved combustion cook stoves in comparison to conventional cook stoves; (ii) assess the relative sensitivity of the stoves’ climate change impacts to key parameters; and (iii) quantify the effects of different climate change impact accounting decisions.

Simulated reductions in mean greenhouse gas (GHG) impact from a traditional, 3-stone cook stove baseline are 3.50 tCO2e/household/year for the improved combustion stove and 3.69−4.33 tCO2e/household/year for the pyrolytic stoves, of which biochar directly accounts for 26−42%.

The magnitude of these reductions is about 2−5 times more sensitive to baseline wood fuel use and the fraction of nonrenewable biomass (fNRB) of off-farm wood that is used as fuel than to soil fertility improvement or stability of biochar. Improved cookstoves with higher wood demand are less sensitive to changes in baseline fuel use and rely on biochar for a greater proportion of their reductions.

Microfinance Intervention for Financing Solar Cooking Technologies –Financing with Savings, 2011.

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Gunjan Gautam

The findings of this analysis are consistent with findings of Kandpal and Mathur(1986).The discount rate has insignificant effect on NPV. When estimations are carried out with interest rates reasonably below the critical interest rates, regardless of the discount ratethe solar cooker generates positive NPV for the user. Use rate and price of the solarcookers significantly affect the NPV. For given interest rate, decrease in either of theseparameters leads to negative NPV.

Further, at lower user rates and prices the user wouldnot be able to pay the loan with savings from use of solar cookers.As in the case of the borrowers, the effect of discount rate for the lending MFIs isinsignificant. However, changes in prices and in use rate have implications on determination of critical interest rate at the time of financing and on the incentive compatibility constraint at the time of payment collection. The decrease in use rate or inthe price of the substituted fuels diminishes the savings for the borrowers and therefore reduces the maximum repayment that MFIs can collect.