According to a new World Bank report, State of Access to Modern Energy Cooking Services, it's estimated that 2.8 billion people still rely on traditional polluting fuels and technologies as their primary cooking method, costing the world more than $2.4 trillion each year. Households in developing countries opt for cookstove and fuel 'stacking' along with their increased income. This blog shows how understanding household energy use can drive innovation for cleaner cooking programs.