Cooking with the sun
by Alice Martinez
In many energy-poor areas of the world, solar energy provides a potential
hose of us fortunate enough to live in the industrialized
world don't spend much time thinking about cooking. Flip a switch, turn
a valve - presto - instant heat, clean, fast and always available.
The picture in poor nations is radically different. Heat for cooking is
generally only available by gathering and burning some local fuel: wood,
charcoal, dung, leaves, etc. The direct and indirect consequence of this
simple daily necessity are dramatic:
- Environment: Even though the third world consumes little energy compared
to the first world, 90 percent of its energy is used for cooking food. Currently,
one-quarter of humanity is affected by a fuel wood shortage; by the year
2000 the shortage will affect at least 2.4 billion people (UN/FAO estimate).
The ensuing deforestation causes soil erosion, water pollution, a loss of
soil fertility, and ultimately, desertification. Sub-Saharan Africa is a
graphic example of this process.
- Economics: Many families are forced to spend more on cooking fuel
than they are able to spend on food. As the world's population climbs, the
availability of these fuels decreases and the gathering of fuel becomes
a major occupation. Almost universally, the poor of the world, and especially
the women, are enslaved to the processes of fuel collection and cooking.
- Air quality: Cooking in smoky conditions can be equivalent to smoking
10 - 20 packs of cigarettes a day. Many suffer chronic respiratory and eye
ailments due to these conditions. The global effects of billions of people
burning organic fuel sources on a daily basis contributes substantial greenhouse
gasses to the atmosphere.
- Clean water: Billions of people suffer regular bouts of diarrheal
illness due to lack of clean water. A simple and direct solution would be
to heat the water to 150° F. to kill microbial pollution - if a cheap,
reliable source of heat were available.
Here comes the sun
Fortunately - almost unbelievably - there is a simple
solution that could have a profound impact on these problems: the solar
box cooker (SBC).
At noon on a clear, sunny day, each square yard of the
earth's surface receives about 1100 watts of solar energy. Of course, there
are may factors that reduce the amount of available energy, including latitude,
time of year, time of day and atmospheric conditions. Nevertheless, even
on an overcast day, the amount of energy reaching the ground is substantial.
The SBC traps this energy as heat and makes it available
for cooking. The structure of the SBC is simplicity itself: an insulated
box with a transparent lid (to let sunlight in) that is black on the inside
(to absorb the solar energy). Reflectors outside the box direct sunlight
onto the lid and into the box. You just point the box at the sun, and the
inside gets hot. If you've ever gotten into a car parked in the sun that
has had its windows rolled up, the principle should be familiar.
An SBC can be constructed from a wide variety of materials,
often using what is on hand or easily available. The box can be constructed
from any material with decent insulating properties; wood works well, but
a demonstration unit can be built with cardboard. A sheet of glass is preferred
as a lid, but plastic sheeting can be used. Non-toxic black paint can be
used to make the inside absorb heat, but so can soot from a smoky fire or
fire-darkened clay. Workable reflectors, to reflect sunlight onto the lid,
can be made from aluminum foil wrapped over any rigid, flat material.
An SBC with excellent cooking characteristics can be constructed for about
$20 in materials. In many parts of the world, this is less than a family
will spend for fuel in two weeks.
The SBC can improve health in the third world in numerous
ways. It can be used to pasteurize water, thereby reducing the incidence
of diarrheal illnesses. Since the SBC is smokeless, its use will reduce
the incidence of respiratory and eye ailments. It could even be used to
disinfect medical instruments. Several pots of food can be cooked simultaneously,
permitting separate preparation of weaning foods for babies. Breadstuffs
can be baked in an SBC, yielding foods which have some degree of stability.
Use of the SBC will reduce dependence on fuel wood and
charcoal. Reduced rates of deforestation will yield reduced rates of soil
erosion. In many villages there is a complete lack of fuel wood and the
people have resorted to burning dried animal dung or crop residues. These
practices deprive the soil of much of its potential fertility. Use of the
SBC minimizes the burning of dung and crop residues, thereby permitting
those materials to be used as natural fertilizers.
Lastly, the SBC is a significant labor-saving device
since less time would need to be spent in accumulating and transporting
fuel wood or dung.
Two key organizations advocating the SBC are Solar Cookers
International (SCI) and Solar Box Cookers Northwest (SBCN). These are primarily
volunteer-based organizations - the spread of solar cooking is basically
people-to-people. They provide a number of ways that you can participate,
including: giving demonstrations at public or private events, advocacy with
leaders and policy makers, membership, and fund-raising. In addition, they
need help translating educational materials from English to other languages.
If you are fluent in another language, they would appreciate your help.
Please see the sidebar below for contact information.
The SBC is no panacea - it isn't going to eliminate
poverty, hunger or disease. But it could provide a solution to some traditional
problems that will make these conditions a little more tractable.
Call to action - What You Can Do
f you are interested in volunteering to help spread
the word about solar cookers, please contact SCI or SBCN at the addresses
below. If you have access to the World Wide Web, the Solar Cooking Archive
can be found on the internet at: http://www.accessone.com/~sbcn/index.htm.
This is an excellent source of information about all aspects of solar cookers.
Solar Cookers International (SCI) has published
a directory of 500+ solar cooking experts and advocates in 63 countries.
Along with contact information, other pertinent info is provided, such as
activities, funding, and number of cookers in the local area. The directory
is available for $9.20 (includes postage) from SCI, 1724 11th St., Sacramento,
CA 95814 USA.
Solar Box Cookers Northwest (SBCN) is now offering
a compact, light-weight kit that brings together hard-to-find materials
needed in international projects. They ask a donation of $60 or more to
pay their costs. Everything is neatly packed inside a mailing tube ready
for easy transport. The kit includes:
To order a kit, write to: Solar Box Cookers Northwest/
7036 18th Ave. NE/ Seattle, WA 98115.
Sol Food is a 56-page cookbook of healthy solar cooker recipes such as Solar
Stew, Sun Lasagne, Pasta Solar Salad, Zucchini Sun Feast, Elegant Cherry
Pie, and Oatmeal Raisun Cookies. Author Harriet Kofalk also gives brief
illustrated directions for building a solar cooker. Available from Peace
Place, 175 East 31, Eugene, OR 97405 USA ($7.95 includes postage).