borne by the household and external effects, provide a conceptually solid base for comparing different options – options that have lower social cost for providing a given level of cooking services would be preferable to options with higher social cost. However, estimating a number of key influences on the costs of alternative cooking modes remains a significant practical challenge.

The paper discusses challenges in analyzing the social costs of household cooking methods (fuels and associated stove technologies) in lower-income countries. These challenges include valuation of household time, impacts of credit constraints on stove selection, preferences for stove characteristics, and the magnitude of health and environmental externalities. All of these influences on cost require consideration of local context.

Section 2 of the paper provides a categorization of fuel-technology options for household cooking. Section 3 provides a general framework for assessing the social cost of different cooking options. Section 4 discusses challenges in assessing social costs. Section 5 shows the wide potential ranges for social costs, depending on particular contexts. . Section 6 contains concluding remarks. The Appendix provides examples of social cost calculation in specific contexts.

# **2. Characterizing Fuel-Technology Combinations for Household Cooking**<sup>**3**</sup>

Different terminologies and definitions are used in categorizing household cooking energy types (Figure 1).<sup>4</sup> Different types of cookstoves are used by households and these stoves are associated with the availability of specific energy types. Biomass is used in rural areas for traditional cooking (with a pot supported on 3 stones over the fire), and with some simple enclosed stove designs. Kerosene is used for cooking as well as lighting in some areas, especially where it is subsidized. In contrast, cooking stoves using LPG, natural gas and electricity are more common in urban areas, though their direct costs in terms of stove and fuel are higher. In recent years, biogas cookstoves are also gaining popularity in rural areas of some developing countries, though the economics of biogas cooking depends on the availability of cattle dung and the capital cost of the manure digester. There are also efforts to expand the use of bio-ethanol for cooking.

The conversion efficiency of household cookstoves varies widely by stove design and energy sources, and it depends on a variety of site-specific circumstances in developing countries. More modern fuels have high energy content per kg of fuel used, while traditional biomass fuels have low energy content. Traditional fuels also can be much more polluting than modern energy sources, though this depends very much on the type of stove used as well. It is thus important to understand how and why these different types of energy sources and stoves are used for cooking in different parts of the developing world.

> 3 This section draws from Malla and Timilsina (2014).  See also World Bank and GACC (2015).

> 4 In the literature, "fuels" and "energy" are often used interchangeably. In this paper, fuel refers to any material which is used to produce heat or power by burning, and energy refers to heat and power.

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