According to the World Bank, 94% of the African rural population and 73% of
the urban population use fuelwood as their primary energy source.
Unfortunately, supplies of fuelwood are diminishing throughout the world. As
the cost and collection time for fuelwood increases, people are looking for
alternative energy sources.
In many sunny parts of the world, solar cooking is a viable option. The
HotPot is a newly developed solar cooker, which was adapted by the Florida
Solar Energy Center and by Energy Laboratories, Inc. from designs of a panel
oven by Dr. Roger Bernard and Solar Cookers International. This durable,
affordable, and portable solar cooker is easier to use, store, and maintain
than many other solar cookers. This study will show that the level of the
HotPot performance makes it an ideal solar cooker for citizens worldwide.
The following tests were conducted on the HotPot in the field in several
West African countries, including Burkina Faso, The Gambia, and Senegal:
-
The Stagnation Test
This test determines the maximum temperature
reached by an empty solar cooker. Measurements of the temperature inside
the HotPot, the ambient temperature, and solar insolation are recorded
every 10 minutes until a maximum temperature is attained.
-
The Water Heating Test
This test evaluates the thermal performance of
the solar cooker in heating water to 90°C (194°F). This is the temperature
where a slow boil can be observed. One liter of water was placed in the
HotPot and brought to a boil. Measurements of the water temperature, the
temperature inside the HotPot, the ambient temperature, and solar
insolation are recorded every 10 minutes until a rolling boil is attained.
-
The Cooking Test
This test determines the amount of time needed to cook
a certain quantity of food. Measurements of the food temperature, the
temperature inside the HotPot, the ambient temperature, and solar
insolation are recorded every 10 minutes until the food is completely
cooked.
These are standard methods used to evaluate solar cooker performance and
have been used by numerous studies (e.g., see Patel and Philip, 2000;
Suharta et al., 2001; Negi and Purohit, 2005). The results of these tests
demonstrate the utility of a solar cooker.
During the stagnation test, the HotPot reached a maximum temperature of
146°C (295°F). This temperature was attained in 50 minutes with initial
ambient temperatures ranging from 29 to 35°C (85 to 95°F).
During the water heating tests, one liter of water reached 90°C (194°F) in
60 to 90 minutes, depending on environmental conditions. Figure 1 shows the
results of one water heating test in The Gambia. The water temperature
increased along with solar insolation to a roiling boil at a temperature of
94.5°C (202°F). The outside air temperature fluctuated between 30 and 34°C
(87 and 93°F) during this 2-1/2 hour test.
Figure 1. HotPot water heating test in Serekunda, The Gambia
The cooking test is more subjective and dependent on variables such as what
kind of food is used, how much water is added, and to what extent the cooker
is filled. We cooked a medley of chopped vegetables in the HotPot. A cooking
temperature of 82°C (180°F) was attained in 50 minutes. The vegetables were
deemed cooked to taste within two hours.
These experimental results obtained from testing the HotPot in several West
African countries show that this simple solar cooker can provide efficient
cooking at high temperatures. Use of the HotPot helps users conserve
traditional energy sources, save time cooking and collecting fuel, reduce
their exposure to harmful smoke and particulate matter, as well as reduce
the amount of carbon dioxide released to the environment. Further tests in
these and other countries under a variety of environmental conditions will
lend further proof to the suitability of the HotPot as an alternative to
nonrenewable energy sources.
Melanie Szulczewski is an environmental scientist. To send her an email
click here.
Acknowledgements
Numerous thanks are extended to Christine Danton for the invaluable
fieldwork contributions to this study.
Works Cited
Negi, B.S. and I. Purohit. 2005. Experimental investigation of a box type
solar cooker employing a non-tracking concentrator. Energy Conversion and
Management. 46, 577.
Patel, N.V. and S.K. Philip. 2000. Performance evaluation of three solar
concentrating cookers. Renewable Energy. 20, 347.
Suharta, H., A.M. Sayigh, K. Abdullah, and K. Mathew. 2001. The comparison
of three types of Indonesian solar box cookers. Renewable Energy. 22, 379.
