by
Alexis Belonio and Edward Ligisan Glory to God!!
For several years of continuous research and improvement on clean energy source using
agro-wastes as fuel, the rice husk gas stove was proven to be a good alternative device for
cooking. This is basically because of its low CO
2
(i.e.,
0.6 kg CO2
per kg
of rice husks) and
black carbon (i.e.,
50 ug/m
3
)
emissions. Also,
the cost of
cooking is much
lower as
compared with
that of
conventional
cookstoves. With
an aim to further
simplify the design of
rice husk gas stove to
suit specific needs of rural households in the Philippines, a collaborative effort was carried out
between the Center for Rice Husk Energy Technology (CRHET) and the Biomass Energy System
and Technology Enterprise (BEST-e) in the Science City of Munoz, Nueva Ecija, Philippines.
Instead of continuous operation that allows it to operate for a longer period, the stove was
Pictorials of the Stove
Design and Performance Specification of the Stove
Solar and Battery for
the Stove
designed to operate just enough to cook one dish or boil water with one load of fuel. In this
way, women who do the cooking can easily use the stove not requiring much attendance to
reload fuel and to discharge char. In addition, the cost of construction of the stove is cheaper
hence making it more affordable to many.
As shown in the figure at the
right above, the stove consists
of the following: a 12-cm ΓΈ x
45-cm high reactor where rice
husks are gasified producing
combustible gases, which are
rich in carbon monoxide and
hydrogen; a gas burner where
the gas produced are efficiently
burned, giving a blue-to-pink
flame; a 12-volt, 0.3-amp DC
fan that supplies the air needed
in gasifying rice husks; a 1000-mA AC-DC adoptor which
energizes the fan; a heat shield
that protects the user from
accidental touching the hot
reactor; and a 2-cm high sleeve
that helps in keeping the heat intact and directs the flame to the
bottom of the pot during cooking.
Results of performance evaluation of the stove shown in table above
revealed that in one load, it consumes 0.4 kg of rice husks within 18 to
20 minutes, depending on the input voltage of the fan that controls
the flow of air through the fuel bed. Start-up time is almost 1 minute
using burning pieces of paper. Two liters of water can be boiled in the
stove within 12 minutes. A 200-g rice can be cooked within 15
minutes while 3 pieces of tilapia can be fried within 18 minutes.
Moreover, the computed specific gasification rate of the stove is 114
kg/hr-m
2
with a power output of 0.91 kWt. The stove has the
following advantages: (a) easy to operate; (b) controllable flame
intensity by simply adjusting the input voltage of the fan with the use
of a switch located at the adoptor; (c) with light-blue colored flame
indicating the gas burned is clean; (d) no smoke during operation; (e)
safe to operate since it operates in DC power and at almost ambient
pressure; (f) very minimal electrical consumption in running the fan;
and (g) very affordable. In cases where grid is not available, the stove
can still be used with a 12-volt battery or a 5-watt solar panel (see
photo right side above) to energize the fan. The by-product in burning rice husks in the stove
Model RHGS-12D
Fuel Rice Husk
Fuel Consumption Rate 400 grams per load
Flame Color Blue to pink
Power Output 0.91 kW
Fan 3 watt, 12 volt DC
Start-Up Time 1 min
Time to:
Rice 3 cups of rice in 15 minutes
Boil Water 12 min for 2 liters of water
Fry
3 pcs of tilapia in 15minutes
3 pcs of table egg in 5 minutes
Operating Time 18-20 min
Overall Dimension 20-cm W x 20-cm L x 50-cm H
Several Units of the Stove Ready for Use
Char with High Water Holding
Capacity
has a percentage char content of about 30% which is a good
source of material as soil conditioner. Tests conducted on
char have shown that it can hold water 5 to 7 times of its
weight.
The stove can be easily produced using locally available
materials such as metals sheet, bar, and wire mesh screens.
Basic tools and equipment that can be found even in some
remote places in the Philippines, such as arc welding
machine, hand drill, tin snip, grinding wheel, and others are
used in the production of the stove. Standard parts of the
stove like fan and adoptor can also be found in local stores
at a cheap price. Producing the stove in
volume basically can generate
employment and additional income for
the local people. Retail price of the stove
including the fan and adoptor is P1,500.00
(1 US$ = PHP 45) per unit. Distributors
price is P1,300.00 per unit with a
minimum order of 20 units. Users of the
stove can recover their investment within
2 months against LPG- and kerosenefueled stoves.
At present, BEST-e is mass producing the
stove in limited numbers for distribution
in Central Luzon region and in neighboring
provinces. BEST-e also engaged in helping communities by encouraging others to produce the
stove for the benefit of others especially in the Visayas and Mindanao Regions.
For further information, contact Engr. Alexis Belonio, Center for Rice Husk Energy Technology,
CLSU-CRHET Rice Husk Project, College of Engineering, Central Luzon State University, Munoz,
Nueva Ecija, Philippines or Email at atbelonio@yahoo.com.
Acknowledgment
We wish to acknowledge the Rolex Awards for Enterprise 2008 (www.rolexawards.com) and
The Tech Awards 2010 (www.techawards.org) for supporting this development project.
Released: June 2011
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