Everybody Stacks: Lessons from household energy case studies to inform design principles for clean energy transitions.

Stove stacking (concurrent use of multiple stoves and/or fuels) is a poorly quantified practice in regions where efforts to transition household energy to cleaner stoves/or fuels are on-going. Using biomass-burning stoves alongside clean stoves undermines health and environmental goals. This review synthesizes stove stacking data gathered from eleven case studies of clean cooking programs in low/middle-income country settings. Analyzed data are from ministry and program records, research studies, and informant interviews. Thematic analysis identify key drivers of stove stacking behavior in each setting. Significant (28%-100%) stacking with traditional cooking methods was observed in all cases. Reason for traditional fuel use includes: costs of clean fuel; mismatches between cooking technologies and household needs; and unreliable fuel supply. National household surveys often focus on 'primary' cookstoves and miss stove stacking data. Thus more attention should be paid to discontinuation of traditional stove use, not solely adoption of cleaner stoves/fuels. Future energy policies and programs should acknowledge the realities of stacking and incorporate strategies at the design stage to transition away from polluting stoves/fuels. Seven principles for clean cooking system program design and policy are presented, focused on a shift toward "cleaner stacking" that could yield household air pollution reductions approaching WHO targets.

A follow-up study after an improved cookstove intervention in rural Mexico: Estimation of household energy use and chronic PM2.5 exposure.

The benefits of improved biomass cookstoves (ICS) depends on their adoption and sustained use. Few studies have documented if and how they are used more than five years after being introduced. We conducted a 9-year prospective cohort study among young rural women in the highlands of Michoacan, Mexico. Participants had received a Patsari ICS during a community trial either in 2005 or 2006. With retrospective information collected in 2012-13, we studied the households' energy use, ICS survival, and cooking practices during the follow-up period. Using an exposure model constructed with personal PM2.5 measurements in a subsample of homes at the time of the initial trial in 2005, we estimated the exposure associated with different energy use patterns during the follow-up period. The ICS had a mean lifespan of 4 years, after which more than half of the stoves were not in use; therefore, the use of open fire increased, particularly among the indigenous communities. ICS use peak was achieved two years after the initial trial, either exclusively or combined with open fire. Yearly household energy use and other variables were used to estimate chronic air pollution exposure. Mean PM2.5 exposure during the follow-up period ranged from 51 to 319 µg/m3; the median was 102 and 146 µg/m3 for mainly ICS and mainly open fire use, respectively. The ICS has a useful period after which it needs maintenance, repair, or replacement. Unfortunately, many programs have not afforded a follow-up component. Exposure to biomass smoke air pollutants can be reduced by using an ICS instead of the traditional open fire. Household energy strategies should ensure equitable access to clean energy options adapted to local needs and preferences with culturally appropriate technology implemented on a sustainable perspective.

Fugitive Emissions and Health Implications of Plancha-Type Stoves.

Plancha-type stoves have been widely disseminated in Mexico and Central America, but the contribution of fugitive emissions from these stoves to indoor air concentrations has been poorly quantified. In this study, fugitive emissions were measured for four plancha-type cookstoves most disseminated in Mexico (Patsari, ONIL, Ecostufa, and Mera-Mera). In controlled testing, fugitive emissions from plancha-type chimney stoves ( n = 15 for each stove) were on average 5 ± 3% for PM2.5 and 1 ± 1% for CO, much lower than defaults in WHO Guidelines (25 ± 10%). Using a Monte Carlo single zone model with locally measured parameters, average kitchen concentrations resulting from fugitive emissions were 15 ± 9 µg/m3 for PM2.5 and 0.06 ± 0.04 mg/m3 for CO. On the basis of these models, plancha-type stoves meet benchmarks for WHO Air Quality Guidelines (AQG) Interim Target I for PM2.5 and the 24 h AQG for CO, respectively, with on average 97% of homes meeting the guideline for PM2.5. Similarly, all four plancha-type stoves were ISO IWA Tier 4 for indoor emissions of CO and Tier 3 for indoor emissions of PM2.5. Three-dimensional computational fluid dynamics (CFD) analysis was used to estimate neighborhood pollution impacts of upstream chimney emissions. When chimney emissions were included as background concentrations combined with indoor contributions from fugitive emissions, plancha-type stoves would still meet the WHO AQG Annual Interim Target I for PM2.5 and the 24 h AQG for CO for the scenario modeled in this study.

Patterns of stove use in the context of fuel-device stacking: rationale and implications.

The implementation of clean fuel and stove programs that achieve sustained use and tangible health, environmental, and social benefits to the target populations remains a key challenge. Realization of these benefits has proven elusive because even when the promoted fuels-stoves are used in the long term they are often combined (i.e., "stacked") with the traditional ones to fulfill all household needs originally met with open fires. This paper reviews the rationale for stacking in terms of the roles of end uses, cooking tasks, livelihood strategies, and the main patterns of use resulting from them. It uses evidence from case studies in different countries and from a 1-year-long field study conducted in 100 homes in three villages of Central Mexico; outlining key implications for household fuel savings, energy use, and health. We argue for the implementation of portfolios of clean fuels, devices and improved practices tailored to local needs to broaden the use niches that stove programs can cover and to reduce residual open fire use. This allows to integrate stacking into diagnosis tools, program monitoring, evaluation schemes, and implementation strategies and establish critical actions that researchers and project planners can consider when faced with actual or potential fuel-device stacking.

Cleaner cooking solutions to achieve health, climate, and economic cobenefits.

Nearly half the world's population must rely on solid fuels such as biomass (wood, charcoal, agricultural residues, and animal dung) and coal for household energy, burning them in inefficient open fires and stoves with inadequate ventilation. Household solid fuel combustion is associated with four million premature deaths annually; contributes to forest degradation, loss of habitat and biodiversity, and climate change; and hinders social and economic progress as women and children spend hours every day collecting fuel. Several recent studies, as well as key emerging national and international efforts, are making progress toward enabling wide-scale household adoption of cleaner and more efficient stoves and fuels. While significant challenges remain, these efforts offer considerable promise to save lives, improve forest sustainability, slow climate change, and empower women around the world.

How much land-based greenhouse gas mitigation can be achieved without compromising food security and environmental goals?

Feeding 9-10 billion people by 2050 and preventing dangerous climate change are two of the greatest challenges facing humanity. Both challenges must be met while reducing the impact of land management on ecosystem services that deliver vital goods and services, and support human health and well-being. Few studies to date have considered the interactions between these challenges. In this study we briefly outline the challenges, review the supply- and demand-side climate mitigation potential available in the Agriculture, Forestry and Other Land Use AFOLU sector and options for delivering food security. We briefly outline some of the synergies and trade-offs afforded by mitigation practices, before presenting an assessment of the mitigation potential possible in the AFOLU sector under possible future scenarios in which demand-side measures codeliver to aid food security. We conclude that while supply-side mitigation measures, such as changes in land management, might either enhance or negatively impact food security, demand-side mitigation measures, such as reduced waste or demand for livestock products, should benefit both food security and greenhouse gas (GHG) mitigation. Demand-side measures offer a greater potential (1.5-15.6 Gt CO2 -eq. yr(-1) ) in meeting both challenges than do supply-side measures (1.5-4.3 Gt CO2 -eq. yr(-1) at carbon prices between 20 and 100 US$ tCO2 -eq. yr(-1) ), but given the enormity of challenges, all options need to be considered. Supply-side measures should be implemented immediately, focussing on those that allow the production of more agricultural product per unit of input. For demand-side measures, given the difficulties in their implementation and lag in their effectiveness, policy should be introduced quickly, and should aim to codeliver to other policy agenda, such as improving environmental quality or improving dietary health. These problems facing humanity in the 21st Century are extremely challenging, and policy that addresses multiple objectives is required now more than ever.

Impact of the improved patsari biomass stove on urinary polycyclic aromatic hydrocarbon biomarkers and carbon monoxide exposures in rural Mexican women.

BACKGROUND: Cooking with biomass fuels on open fires results in exposure to health-damaging pollutants such as carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), and particulate matter. OBJECTIVE: We compared CO exposures and urinary PAH biomarkers pre- and postintervention with an improved biomass stove, the Patsari stove. METHODS: In a subsample of 63 women participating in a randomized controlled trial in central Mexico, we measured personal CO exposure for 8 hr during the day using continuous monitors and passive samplers. In addition, first-morning urine samples obtained the next day were analyzed for monohydroxylated PAH metabolites by gas chromatography/isotope dilution/high-resolution mass spectrometry. Exposure data were collected during the use of an open fire (preintervention) and after installation of the improved stove (postintervention) for 47 women, enabling paired comparisons. RESULTS: Median pre- and postintervention values were 4 and 1 ppm for continuous personal CO and 3 and 1 ppm for passive sampler CO, respectively. Postintervention measurements indicated an average reduction of 42% for hydroxylated metabolites of naphthalene, fluorene, phenanthrene, and pyrene on a whole-weight concentration basis (micrograms per liter of urine), and a 34% reduction on a creatinine-adjusted basis (micrograms per gram of creatinine). Pre- and postintervention geometric mean values for 1-hydroxypyrene were 3.2 and 2.0 µg/g creatinine, respectively. CONCLUSION: Use of the Patsari stove significantly reduced CO and PAH exposures in women. However, levels of many PAH biomarkers remained higher than those reported among smokers.

New approaches to performance testing of improved cookstoves.

Monitoring and evaluation of improved cookstove performance is a critical factor in program success; however, consistent evidence indicates water boiling tests and controlled cooking tests are not representative of stove performance during daily cooking activities, and there is no ability to link these tests to kitchen performance tests during normal daily cooking activities. Since emissions from cookstoves contribute heavily to regional estimates of carbonaceous aerosols and other short-lived greenhouse species and given the current importance of stove performance tests as a basis for global climate prediction models and IPCC inventories, improvements in performance testing are critical to derive more representative estimates. Here real-time combustion efficiencies and emissions rates from daily burn cycles of open fires and improved stoves in Mexico are used to propose a new approach to stove performance testing, using simple and economical measurement methods, based on replication of the distribution of emission rates and combustion efficiencies seen during daily cooking activities in homes. This approach provides more relevant information for global climate models and inventories, while also providing a means to recreate representative emissions profiles in a laboratory setting for technical analyses. On the basis of emission rates and combustion efficiencies during normal daily cooking, we suggest performance criteria that can be used as benchmarks for laboratory testing of improved stoves in the absence of site-specific information, although requiring confirmation by field testing during daily cooking activities.

Improved biomass stove intervention in rural Mexico: impact on the respiratory health of women.

RATIONALE: Exposure to biomass smoke has been related to adverse health effects. In Mexico, one household in four still cooks with biomass fuel, but there has been no evaluation of the health impact of reducing indoor air pollution. OBJECTIVES: To evaluate the health impact of the introduction of an improved biomass stove (Patsari; Interdisciplinary Group for Appropriate Rural Technology [GIRA], Patzcuaro, Mexico) in Mexican women. METHODS: A randomized controlled trial was conducted in the Central Mexican state of Michoacán. Households were randomized to receive the Patsari stove or keep their traditional open fire. A total of 552 women were followed with monthly visits over 10 months to assess stove use, inquire about respiratory and other symptoms, and obtain lung function measurements. Statistical analysis was conducted using longitudinal models. MEASUREMENTS AND MAIN RESULTS: Adherence to the intervention was low (50%). Women who reported using the Patsari stove most of the time compared with those using the open fire had significantly lower risk of respiratory symptoms (relative risk [RR], 0.77; 95% confidence interval [CI], 0.62-0.95 for cough and RR, 0.29; 95% CI, 0.11-0.77 for wheezing) adjusted for confounders. Similar results were found for other respiratory symptoms as well as for eye discomfort, headache, and back pain. Actual use of the Patsari stove was associated with a lower FEV(1) decline (31 ml) compared with the open fire use (62 ml) over 1 year of follow-up (P = 0.012) for women 20 years of age and older, adjusting for confounders. CONCLUSIONS: The use of the Patsari stove was significantly associated with a reduction of symptoms and of lung function decline comparable to smoking cessation.

Ouantification of carbon savings from improved biomass cookstove projects.

In spite of growing interest, a principal obstacle to wider inclusion of improved cookstove projects in carbon trading schemes has been the lack of accountability in estimating CO2-equivalent (CO2-e) savings. To demonstrate that robust estimates of CO2-e savings can be obtained at reasonable cost, an integrated approach of community-based subsampling of traditional and improved stoves in homes to estimate fuel consumption and greenhouse gas emissions, combined with spatially explicit community-based estimates of the fraction of nonrenewable biomass harvesting (fNRB), was used to estimate CO2-e savings for 603 homes with improved Patsari stoves in Purépecha communities of Michoacán, Mexico. Mean annual household CO2-e savings for CO2, CH4, CO, and nonmethane hydrocarbons were 3.9 tCO2-e home(-1) yr(-1) (95% Cl +/- 22%), and for Kyoto gases (CO2 and CH4) were 3.1 tCO2-e home(-1) yr(-1) (95% Cl +/- 26%), respectively, using a weighted mean fNRB harvesting of 39%. CO2-e savings ranged from 1.6 (95% Cl +/- 49%) to 7.5 (95% Cl +/- 17%) tCO2-e home(-1) yr(-1) for renewable and nonrenewable harvesting in individual communities, respectively. Since emission factors, fuel consumption, and fNRB each contribute significantly to the overall uncertainty in estimates of CO2-e savings, community-based assessment of all of these parameters is critical for robust estimates. Reporting overall uncertainty in the CO2-e savings estimates provides a mechanism for valuation of carbon offsets, which would promote better accounting that CO2-e savings had actually been achieved. Cost of CO2-e savings as a result of adoption of Patsari stoves was U.S. $8 per tCO2-e based on initial stove costs, monitoring costs, and conservative stove adoption rates, which is approximately 4 times less expensive than use of carbon capture and storage from coal plants, and approximately 18 times less than solar power. The low relative cost of CO2-e abatement of improved stoves combined with substantial health cobenefits through reduction in indoor air pollution provides a strong rationale for targeting these less expensive carbon mitigation options, while providing substantial economic assistance for stove dissemination efforts.

Reduction in personal exposures to particulate matter and carbon monoxide as a result of the installation of a Patsari improved cook stove in Michoacan Mexico.

UNLABELLED: The impact of an improved wood burning stove (Patsari) in reducing personal exposures and indoor concentrations of particulate matter (PM(2.5)) and carbon monoxide (CO) was evaluated in 60 homes in a rural community of Michoacan, Mexico. Average PM(2.5) 24-h personal exposure was 0.29 mg/m(3) and mean 48-h kitchen concentration was 1.269 mg/m(3) for participating women using the traditional open fire (fogon). If these concentrations are typical of rural conditions in Mexico, a large fraction of the population is chronically exposed to levels of pollution far higher than ambient concentrations found by the Mexican government to be harmful to human health. Installation of an improved Patsari stove in these homes resulted in 74% reduction in median 48-h PM(2.5) concentrations in kitchens and 35% reduction in median 24-h PM(2.5) personal exposures. Corresponding reductions in CO were 77% and 78% for median 48-h kitchen concentrations and median 24-h personal exposures, respectively. The relationship between reductions in median kitchen concentrations and reductions in median personal exposures not only changed for different pollutants, but also differed between traditional and improved stove type, and by stove adoption category. If these reductions are typical, significant bias in the relationship between reductions in particle concentrations and reductions in health impacts may result, if reductions in kitchen concentrations are used as a proxy for personal exposure reductions when evaluating stove interventions. In addition, personal exposure reductions for CO may not reflect similar reductions for PM(2.5). This implies that PM(2.5) personal exposure measurements should be collected or indoor measurements should be combined with better time-activity estimates, which would more accurately reflect the contributions of indoor concentrations to personal exposures. PRACTICAL IMPLICATIONS: Installation of improved cookstoves may result in significant reductions in indoor concentrations of carbon monoxide and fine particulate matter (PM(2.5)), with concurrent but lower reductions in personal exposures. Significant errors may result if reductions in kitchen concentrations are used as a proxy for personal exposure reductions when evaluating stove interventions in epidemiological investigations. Similarly, time microenvironment activity models in these rural homes do not provide robust estimates of individual exposures due to the large spatial heterogeneity in pollutant concentrations and the lack of resolution of time activity diaries to capture movement through these microenvironments.

The impact of improved wood-burning stoves on fine particulate matter concentrations in rural Mexican homes.

To evaluate the impact of improved wood burning stoves on indoor air pollution, 53 homes in a rural town in Michoacán, Mexico, were selected from a health intervention study and monitored before and after receiving improved wood-burning stoves. Fine particulate matter--particles with aerodynamic diameter less than 2.5 microm (PM(2.5))--concentrations were measured in the central plaza of the community and in three microenvironments in the home (next to the stove, in the kitchen away from the stove, and outdoor patio). Forty-eight hour mean PM(2.5) concentrations in homes that burned wood in open fires were 693 microg/m(3) (95% CI: 246-1338) near the stove, 658 microg/m(3) (95% CI: 67-1448) in the kitchen away from the stove, and 94 microg/m(3) (95% CI: 36-236) on the patio. Mean ambient 24-h concentrations in the main plaza of the community were 59 microg/m(3) (95% CI: 29-92). Paired measurements before and after the installation of the Patsari improved wood-burning stove indicate a median 71% reduction in PM(2.5) concentrations near the stove and 58% reductions in kitchen concentrations, whereas patio and main plaza concentrations remain unaffected. Only 44% of participants reported to use their Patsari stoves exclusively during the transition period. Even with the predominant mixed use of the Patsari stove with open fires, estimated daily average personal exposures to PM(2.5) were reduced by 50%.