STEEL WASHER MANUFACTURERS leave behind metal sheets perforated with washer-sized holes. They happen
to be perfect for creating the “Mewar Angithi”:
a simple, performance-improving insert for
cooking fires that costs about US$1 to make.
The grate, which was developed jointly by the
University of Iowa and NGOs Climate Healers
and the Foundation for Ecological Security,
recently underwent lab testing at Maharana
Pratap University in Udaipur, Rajasthan, India.
Across six rounds of tests, the lab boiled water
over a traditional three-stone cookfire—called a
chulha—with and without the grate. The grated
fires burned 63 percent less wood and produced
88 percent less soot, according to the lab.
“It took them a whole day to run the tests.
They repeated [them] the next day as well,
since they were surprised by the results,”
Sailesh Rao of Phoenix, Arizona-based
Climate Healers told E4C.
BEHIND THE NUMBERS
The lab tested the fuel efficiency of grated
and grateless chulhas by measuring their
thermal efficiency (the ratio of thermal en-
ergy delivered to the pot versus the amount
locked into the wood) and power rating (the
rate at which thermal energy is delivered to
the pot, in kilowatts.) The tests found that
grated fires have an average 24. 5 percent ef-
ficiency and 1. 35 k W power rating—more than
double that of chulhas without the grate.
As for soot emissions, grated fires emitted 5.97 grams of carbon monoxide per
megajoule of thermal energy delivered to
the pot, which is less than half of grateless fire emissions. The grated fires also
released about one tenth the amount of
A SIMPLE TEST FOR A SIMPLE DEVICE
Cookfire inserts like the Mewar Angithi are
not new. Crispin Pemberton-Pigott, a tech-
nical consultant to the World Bank works
on stove standards in Indonesia and has
seen another grate used there. But much of
the ingenuity of these devices—in addition
to the low cost—is that they do not require
cooks to learn how to use anything new or
change their habits. All of this gives grates
an advantage over other improved cooking
devices, like high-efficiency cookstoves.
To test for themselves, Rao’s research team
at the University of Iowa in the U.S. took the
Mewar Angithi for basic field testing. They
checked the grate’s performance against two
brands of improved cookstoves and grateless
fires by testing them in the homes of three
women who cook every day over chulhas in
the Mewar region of Rajasthan.
The team looked on as the women cooked,
accounting for differences in meal size by calculating the weight of wood required to cook
one corn roti, or flatbread. The grated chulhas
required 0.066 kg of wood to cook a roti.
Grateless fires required 2. 5 times the amount
of wood, while the two cookstoves required
1.85 to 1. 9 times as much.
“The Mewar Angithi outperformed
both high-efficiency cookstoves by a wide
margin,” Rao said. “As far as the women are
concerned, it is this real-world performance
WHERE TO IMPROVE
Opinions vary on the best ways to test
improved cookstoves, so E4C ran the Mewar
Angithi lab findings by Pemberton-Pigott. He
was not surprised by the results, though he
said fuel savings of 63 percent did seem high.
One way the grate could perform better is
if it covered a larger area of the chulha floor,
Pemberton-Pigott noted. He added that
enhancements for the chulha itself, like shortening the pot-holder walls or adding a hole at
the back of the stove so the grate can pull in
outside air, could also improve performance. •
These cheap, simple
devices do not require
people to learn any new
cooking tools or change
EDI TED B Y ROB GOODIER
A $1 cookfire insert cuts wood use and soot
pollution by more than half
Standardized laboratory tests have
shown that placing a cheap, steel
wedge grate into a traditional Indian
cookfire can greatly increase fuel
efficiency and cut soot emissions.