In
1834 Jean Peltier noted that when an electrical current is applied across the
junction of two dissimilar metals, heat is removed from one of the metals and
transferred to the other. This is the basis of thermoelectric refrigeration.
Thermoelectric modules are constructed from a series of tiny metal cubes of
dissimilar exotic metals which are physically bonded together and connected
electrically. When electrical current passes through the cube junctions, heat
is transferred from one metal to the other. Solid-state thermoelectric modules
are capable of transferring large quantities of heat when connected to a heat
absorbing device on one side and a heat dissipating device on the other. The
Koolatron's internal aluminium cold plate fins absorb heat from the contents,
(food and beverages), and the thermoelectric modules transfer it to heat
dissipating fins under the control panel. Here, a small fan helps to disperse
the heat into the air. The system is totally environmentally friendly and
contains no hazardous gases, nor pipes nor coils and no compressor. The only
moving part is the small 12-volt fan. Thermoelectric modules are too expensive
for normal domestic and commercial applications which run only on regular
household current. They are ideally suited to recreational applications because
they are lightweight, compact, and insensitive to motion or tilting, have no
moving parts, and can operate directly from 12-volt batteries.
 |
| Jean Peltier |
Tom
Mancini
If want to do is heat or
cool, using solar energy this way is probably more efficient and
certainly cheaper than converting it first into electricity. "That
approach ought to be comparable to photovoltaics, or a little better. Traditionally
solar-powered refrigerators and vaccine coolers use a combination of solar
panels and lead batteries to store energy for cloudy days and at night in the
absence of sunlight to keep their contents cool. These fridges are expensive
and require heavy lead-acid batteries which tend to deteriorate, especially in
hot climates, or are misused for other purposes.[3][4] In addition, the
batteries require maintenance, must be replaced approximately every three
years, and must be disposed of as hazardous wastes possibly resulting in lead
pollution.[3] These problems and the resulting higher costs have been an obstacle
for the use of solar powered refrigerators in developing areas.
The use of solar energy to power
refrigeration strives to minimize the negative impacts refrigerators have on
the environment.[1][2] Fishermen in the village
of Maruata, which is located on the Mexican Pacific coast, have no electricity.
But for the past 16 years they have been able to store their fish on ice: Seven
ice makers, powered by nothing but the scorching sun, churn out a half ton of
ice every day.
Solar refrigeration can also be
inexpensive and it would give the electric grid much-needed relief. Electricity
demand peaks on hot summer days—150 gigawatts more in summer than winter in the
U.S. (A gigawatt equals on billion watts.) That's almost 1.5 times the generating
capacity of all the coal-fired power plants west of the Mississippi River.
Further, solar is plentiful. The solar energy hitting 54 square feet (five
square meters) of land each year is the equivalent of all the electricity used
by one American household, according to data from the National Renewable Energy
Laboratory and Energy Information Administration, both part of the U.S.
Department of Energy.
Adam Grosser
More than a billion
people lack access to electricity and refrigeration, which means they also lack
access to important vaccines that need to be kept cool. Nonprofits are pouring
millions into developing vaccines that don't need refrigeration, but tech
venture capitalist Adam Grosser has a different idea: change the fridge.
Working with a
thermodynamics team at Stanford, Grosser built a thermos-sized device that
contains a refrigerant that's triggered when the device is heated and left to
cool. It then acts like a powerful cold pack, turning anything from a jug to a
hole in the ground into a twenty-four-hour minifridge. At roughly fifty dollars
apiece, Grosser's device could potentially bring people in the developing world
high-maintenance medicines -- and the simple pleasure of a cold drink on a hot
day.
