• Energy Research

The energy use of fruit tree pruning represents a current alternative to achieving an energy transition toward clean biomass resources, which can substitute for fossil fuels and mitigate polluting emissions. In Mexico, avocado is one of the most important fruit crops, with approximately 260,000 ha planted. The pruning of avocado trees generates large amounts of biomass that are not fully exploited, lacking studies that analyze in depth the energy potential of pruning. This study aims to determine the potential energy use of avocado pruning as densified solid biofuels. The physical, chemical and energetic properties of two pruning fractions defined as class B (branches) and class BAL (branches and leaves) were determined. From class B, pellets were made, and their physical and mechanical properties were determined. Subsequently, the evaluated parameters of the pellets obtained were compared to European quality regulations to determine their quality and identify their potential uses. The characterization of avocado pruning indicates that class B generally has better physicochemical characteristics than class BAL to be used as solid biofuel. It was found that class B has a high calorific value (19.61 MJ/kg) and low ash content (1.2%), while class BAL contains a high amount of ash (7.2%) and high levels of N (1.98%) and S (1.88%). The manufactured pellets met most of the quality requirements for immediate use in the residential, commercial and industrial sectors at the regional level.

Abstract The government of San Luis Potosi (SLP) in Mexico implemented the Ecological Cookstove Program (ECSP) during the period 2010–15, subsidizing over 60,000 improved cookstoves with the goal of addressing poverty in rural communities where people cook with fuelwood in open fires. As part of the comprehensive summative program evaluation conducted during 2014–2016, we assessed the implementation processes analyzing the regulations governing the program and contrasting them with the opinion of the officials and users involved in the program. The evaluation of the operation processes of the program was conducted using three qualitative techniques: documentary analysis, semi-structured interviews, and in depth interviews of stakeholders (government officials and beneficiaries). The processes of social marketing, selection of beneficiaries and follow up were identified as the critical nodes for the successful implementation of the program. There was no document detailing the overall process and this was reflected in a lack of standardization in the execution of each step of the process. This type of programs should go beyond a change in technology, i.e., they need to consider the state's social, cultural, and economic factors, and their difference among the different regions of the state. In summary, the evaluation presents eight recommended actions which should be considered during the design and implementation phases of these type of programs.

Improved cookstoves have been identified in Mexico as a key opportunity to advance sustainable local development priorities in disadvantaged regions while mitigating climate change. This paper reviews the Patsari Cookstove Project initiated in 2003 by an NGO, Interdisciplinary Group on Appropriate Rural Technology (GIRA). The project applied an interdisciplinary and participative user-centered approach to disseminate improved cookstoves in rural Mexico, with a special focus on indigenous and poor rural communities. To date, GIRA and the Patsari Network have disseminated thousands of stoves using a “training to trainers” model. Benefits from the project include tangible improvements in users’ health, as well as savings in time and money expended on fuelwood procurement and use. The project has also documented substantive environmental benefits from significant mitigation of greenhouse gas (GHG) emissions associated with traditional open fires. To sustain scaling up efforts over the long-term, two networks have been created: The Patsari Network, which includes several organizations promoting Patsari stoves for household users, and the Tsiri Network, which supports local food security and the empowerment of indigenous women through the promotion of institutional cookstoves. Through appropriately designed and implemented local interventions, the project demonstrates that the goals of advancing sustainable local development in rural areas and climate change mitigation may not be contradictory, and may in fact reinforce one another.

The authors would like to make the following corrections about the published paper [...]

There is a critical need for developing wood-burning cookstoves lab tests that better reflect their field performance, and that can be used to complement existing standard tests. This is particularly true for Plancha-type cookstove stoves, widely disseminated in Latin America, where existing tests, like Water Boiling Test (WBT) and Controlled Cooking Test (CCT), are either not well suited to these stoves or do not capture the simultaneous and sequential arrangement of local cooking practices –i.e., multi-pot cooking, pre-heating of meals, and use of residual heat. In this paper, we developed a “controlled cooking cycle” or “controlled burning cycle” (CBC) test to study the benefits, in terms of fuelwood and pollutants emissions savings, of multi-pot cooking arising from the integration of cooking tasks. Tests were conducted on the Patsari stove, a plancha-type stove that has been widely disseminated in Mexico and in other regions of Central America. We first used CCTs to evaluate the comparative energy and emissions performance of the Patsari stove relative to a traditional U-shaped open fire (U-type) for the most common cooking practices carried out in the Purepecha Region of Michoacan. We also compared results from the CBC multi-pot cooking with results from simply conducting the cooking tasks in series. All the CCTs and CBCs were carried out in a simulated kitchen at GIRA facilities in Patzcuaro, Michoacan, Mexico with two local cooks who performed all the cooking tasks in the traditional/typical manner of the region. Results from CCTs showed Patsari benefits relative to the open fires, in terms of fuelwood consumption and CO and PM2.5 emissions savings, vary among cooking tasks and range from negligible to 63% depending on the parameter and the task. The sequential cooking and integration of these tasks in a CBC result in average savings of 65% for CO, 65% for PM2.5 and 35% for fuelwood relative to the U-type, and of between 30% and 44% savings with respect to simply conducting the cooking tasks in series in the same stove. The CBC fuelwood savings obtained here are comparable with field results from Kitchen Performance Tests (KPT) conducted regionally by other authors. The results confirm that multi-pot cooking and a smart sequential integration of tasks developed by local users are key to achieve the maximum benefits from plancha-type stoves, and need to be much better reflected in standard lab tests.

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.

AbstractWhile plancha-type cookstoves are very popular and widely disseminated in Latin America, few peer review articles exist documenting their detailed technical performance. In this paper we use the standard Water Boiling Tests (WBT) to assess the energy and emission performance of five plancha-type cookstoves disseminated in about 450 thousand Mexican rural homes compared to the traditional 3-stone fire (TSF). In the high-power phase, average modified combustion efficiencies (MCE) for plancha-type stoves were 97±1% which was higher than TSF 93±4%, and reductions in CO and PM2.5 total emissions were on average 44%. Time to boil and specific fuel consumption, however, were increased in plancha-type stoves compared to the open fire as a result of the reduced overall thermal efficiency of the plancha during WBT. In the simmering phase, plancha-type stoves showed much more consistent performance reductions compared to the TSF. MCE for plancha stoves were on average 98±1% and 95±3% for the TSF, while reductions in CO and PM2.5 total emissions were on average 55%. In this phase 27% average savings in fuel use are achieved by plancha-type stoves. Removal of the plancha rings resulted in savings of specific fuel consumption (SFC), thermal efficiency (TE), and time to boil; however, CO and PM2.5 emissions increased significantly as flue air is drawn through the comal surface rather than through the combustion zone, resulting in suboptimal combustion conditions.International Workshop Agreement (IWA) energy performance Tiers for plancha-type stoves ranged from 0 to 1. However, these results contrast sharply with the well documented reductions in fuel consumption during daily cooking activities achieved by these stoves. IWA indoor emissions Tiers are 4 for both PM2.5 and CO using locally measured values for fugitive emissions. Optimization of combustion chamber design on these stoves in Mexico is desirable to further reduce indoor emissions and to reduce the impacts of neighborhood pollution that can re-infiltrate kitchens. Comparison of performance between plancha-type stoves and unvented stoves should reflect the substantial gains that are made by reducing indoor air pollution and exposures by venting pollutants.