Ecomarsho's
Projects - Solar Energy Designs
Water Purification Using Photovoltaics
- Project-Design #1.3.4.EGZ.
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Design and Intent of Project:
This design for a desalination unit uses the Peltier principle to cool
moisture-laden air with the result of potable water collected
from condensation. Electrical power for the Peltier plate is generated by the photovoltaic (solar-
powered) panel.
The design is suitable for situations with high insolation, such as on islands affected by
a tsunami, where the lens of underground water was polluted by sea water.
Water collected may be sterilised by means of a UV light
source. As regards the wider scope for actual implementation of this project idea, larger desalination
plants would require suitable refridgerants and extensive ducting.
Spiritual devotees inspired by appeals such as Live8 would of course be able to suggest
further applications. Further practical info on such water supply units may be found on UN websites.
Note that Peltier plate must be supplied potted, and
fitted by slotting, cold side down, into base of saline tank -
using suitable sealant to prevent any leakage.
Click for more design-info.
Info on Peltier plates (Electronic semi-conductor design cooling unit).
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Extending the Possibilities of Harvesting Solar Energy.
Early passive absorbtion solar panel designs used the direct energy-transfer method to bulk heat
water, and blackened metal plates under glass were quite useful even on frosty winter days
in northern climates where a supplement to hot water supplies was needed. Simple black
plastic panels with water channels were all that was needed for summer use swimming pools.
A later improvement for water heating was the evacuated tube collector patented by Thermomax.
In contrast, the now quite common Photo-voltaic solar panels generate an electric current,
which can be used to charge a battery, whenever the sun excites the semiconductor layer (silicon
wafers) enough to give a higher potential voltage than the battery-voltage. A simple electronics
component, the silicon diode, has the right characteristics to enable forwards charging current
when the sun is out, but to prevent reverse flow which would discharge the battery.
Modern awareness of environmental problems, and their political and economic consequences, means
that there is a competitive drive in quest of improved solar panel efficiency (such as the
light-sensitive chemical photovoltaics by Graetzel of switzerland - instead of expensive to purify
silicon based panel designs), and better, more flexible, longer lasting energy storage facilities (a
lead-acid accumulator, such as used very frequently in the automotive industry, has a
limited service life before replacement is needed).
Find out more...
What's new? Battery design has improved by using alternative chemicals - from Nickel-Cadmium
to Nickel-Hydride, & Lithium based cells, and also Sulfur-mixture for automotive applications. But
what of photo-voltaic solar panels? What chemical is Graetzel currently proposing for his lower-cost
system of generating electrical energy?
