Solar ovens sometimes fall short of their promise as the gold standard of clean cooking, despite producing zero emissions (see L. S. Brown and W. F. Lankford Nature 521, 284–285; 2015).
In a solar-oven project funded by the Central American Solar Energy Project (CASEP) in Nicaragua, participants generally reported large fuel savings. Yet objective measurements found that savings were not significant, and surveys indicated that users continued to cook on biomass-burning stoves. Data from thermometers inside solar ovens confirmed that oven usage was widely over-reported (see go.nature.com/oqff6a).
Furthermore, although the 77 Nicaraguan women interviewed in 2014 (by S.V.) found CASEP's empowerment training helpful, this did not result in self-sustaining community action after the project ended.
In parts of Latin America, preparing tortillas accounts for more than half of cooking fuel usage (O. Masera et al. Energy Sustain. Dev. 11, 45–56; 2007), but tortilla preparation is impossible with most solar-cooker designs because they are not hot enough. And in areas with a rainy season, solar cooking is impractical for half of the year. Improved biomass stoves and biogas might be more effective solutions in such regions.