is provided by other information in Bensch and Peters (2015) indicating that the ICS reduced firewood use per dish cooked by around 48%.

Notwithstanding any rebound effect, however, Table 6 indicates that the increased thermal efficiency of the ICS significantly reduced time spent cooking (by almost one-quarter). Information from WageIndicator Foundation (Tijdens et al 2012) suggests that a relevant hourly value for this time (based on wage rates for informal sector work) would be $0.40 – $0.80 per hour. This would put the weekly value of time saved from the ICS at $3.60 – $7.20 per week, implying a very fast payback on the stove cost in terms of the opportunity cost of time alone.

Finally, Table 6 indicates that households with an ICS in the experiment report a sharp decline in the occurrence of respiratory illness symptoms (a decline of almost half in the frequency of symptom reporting within a household, relative to the baseline). To carry out the calculations for the economic value of health benefits shown in Tables 4-5 of the main text, we would need to have figures on typical household size, baseline occurrence of acute respiratory illness, and cost of an episode of illness.

# **_Ethanol, LPG, and Fuelwood_**

A study by Practical Action et al. (2014) examines possibilities for improved fuels and/or stoves in several different parts of Senegal. We focus here on the part of the study concerned with the possibility of introducing ethanol fuel and stoves in the Saint-Louis region (chapter 5 of the report). Ethanol is of interest in this area because the country’s main sugar producer is located there, and is already producing significant quantities of ethanol for non-fuel markets.

The study focuses on the possibility of ethanol fuel penetration in the _urban cooking energy market_ within Saint-Louis, and so we begin with that here. According to figures supplied by Practical Action et al. (2014), the urban population in 2010 was about 394,000, about 44% of the total population. About 60% of the region’s urban population already are using LPG. However, many of them also use charcoal as a secondary fuel, and charcoal is used as the primary fuel by the majority of the other households; about 75% of all urban households have a simple charcoal stove, while 16% have an improved charcoal stove.

As noted, the cost comparison between ethanol and LPG for cooking needs to take into account a variety of factors including fuel cost differences and differences in their thermal content, differences in amortized stove cost and thermal efficiency, and differences in environmental impacts. The Practical Action et al. (2014) report indicates that both ethanol and LPG stoves have a conversion efficiency of about 50%. It provides a range for potential ethanol stove costs of $30$60, but does not provide information on LPG stove costs.

To look more deeply into this, we drew upon information in a review of clean cooking alternatives for all of Sub-Saharan Africa (World Bank, 2014). Appendix 1 of that report indicates that more sophistical ethanol stoves would cost on the order of $50-$80 (cheaper but less durable stoves using gel alcohol cost less). Multiple burner LPG stoves would cost on the order of $50-$90 (less convenient single burner ones, $10-$50). Figure 44 in the main body of the report indicates that the LPG stove is typically costlier than an ethanol stove, but only modestly so – and such a cost difference likely would be even smaller in Senegal given an established urban market for LPG.

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