Table 2. Thermal efficiency and emissions performance during laboratory testing of five semi-gasifier cookstove prototypes.
| Prototype | Thermal Efficiency (%) Mean ± St Dev | Emission Factors (g/MJda) Mean ± St Dev | ISO Tierb,c | ||
|---|---|---|---|---|---|
| n | PM2.5 | CO | |||
| I | 6 | 27 ± 3 | 0.230 ± 0.069 | 4.1 ± 0.7 | 2, 2, 4 |
| II | 4 | 16 ± 1 | 0.164 ± 0.044 | 2.9 ± 0.1 | 1, 3, 4 |
| III | 3 | 18 ± 1 | 0.351 ± 0.019 | 21.2 ± 2.2 | 1, 2, 0 |
| IV | 5 | 25 ± 1 | 0.121± 0.056 | 1.6 ± 0.4 | 2, 3, 4 |
| V | 10 | 41 ± 2 | 0.038 ± 0.013 | 2.2 ± 1.1 | 3, 4, 4 |
CO, carbon monoxide; PM, particulate matter
a
Mega-joules of energy delivered to the cooking pot; conversion from per-mass emissions multiplied by the caloric heating value of the fuel (= 17.1 MJ/kg) and the thermal efficiency of the stove
b
International Standards Organization (ISO) International Working Agreement tiered cookstove rating system, values from 0 (worst performance) to 4 (best performance) (ISO, 2012)
c
First value refers to thermal efficiency tier, second value refers to PM2.5 emissions tier, and third value refers to CO emissions tier