The Solar Still
Solar Stills operate on the same principles that produce rainfall. The sun is allowed into and trapped in the Still. The high temperatures produced destroy all pathogens. The water evaporates, and in this process, only pure water vapor rises in the Still, only to condense on the glass. The glass is sloped to the south, and the condensed water runs down the glass and is collected in a trough. The water is allowed out of the collector through silicone tubing, and is collected in 5 gallon glass jugs. There are no moving parts in the solar still, and only the sun's energy is required for operation.
Solar dish/Stirling
A solar dish/Stirling electric power generation system consists of a concave parabolic solar concentrator (or dish), a cavity receiver, and a Stirling heat engine with an electric generator or alternator
It was not until the oil embargo of 1973 that modern dish/Stirling systems came out of the laboratory and began being developed for commercial applications. Because dish/Stirling systems have high solar-to-electric conversion efficiency and can be mass-produced, they can be used in modular installations that produce 5 to 100,000 kW of electrical power from the sun (Stine, 1989). This chapter describes dish/Stirling systems that have been developed or that are currently being developed.
Photovoltaics
Photovoltaics are solid-state semiconductor devices that convert light directly into electricity. They are usually made of silicon with traces of other elements and are first cousins to transistors, LEDs and other electronic devices.
Virtually any electric power need can be met by an appropriately designed PV power system. This includes power for lighting, pumping, refrigeration, radio transmission, etc. The only limitation is the cost of the equipment and occasionally the size of the PV array, although this is rarely a factor.
Creating mineral-rich soil from your table scraps is finally convenient, clean and easy with a "living machine." The composter is a highly functional piece of appropriate technology.
The Composter is a truly solar-powered machine. The composting process is accelerated by the warm environment. Using conventional techniques a compost pile at least 3 ft. across is needed to obtain necessary elevated temperatures. To compensate, this device uses solar architectural techniques, glazing and insulation to attain elevated temperatures. The solar heat collected through the dome, along with the heat generated internally by the respiration of the composting microbes is trapped by the insulated walls of the composting chamber. A unique feature of this insulation is its ability to keep the heat in, while it allows oxygen to freely flow to the composting microbes.
Solar Ice Maker
During the day the solar collector focuses the energy of the sun onto the ammonia generator in the collector trough. Solar heat distills pure ammonia vapor from the water-ammonia solution in the generator. The vapor condenses in the cooling coils and collects as liquid ammonia in the receiving tank in the evaporator.
At the end of the day, the user switches three valves from the Day to Night position to allow the ammonia to evaporate in the ice compartment, providing the refrigeration to freeze the water. The resulting vapor is absorbed back in the generator. Critical to the operation of Isaac is a passive thermosyphon that operates in the Night mode to remove the heat from the generator and allow the ammonia vapor to absorb into the solution at lower pressure and temperature.
At the beginning of the day, the operator harvests the ice from the ice trays, operates a drain sequence to remove traces of absorbent from the evaporator, and places the unit back into Day mode to begin the next cycle.
Solar air-conditioning
One type of solar air-conditioning operating only with air and heat-exchangers, functions as follows: first the surrounding air is dried with the help of a drying agent, then the air is humidified with water resulting in a cooling-off effect. The trick: the whole process functions better the dryer the air is before the humidification step begins. To achieve this, they utilize a drying agent, silica gel, which is well known for its use in the area of packaging. The water is drawn out of the air by collecting it in the silica gel's molecular structure, which thereby adsorbs water until the gel is as wet as a sponge. The silica gel can be regenerated with heat so that it can repeatedly absorb water.
The driving power of the solar air-conditioning system, along with electricity for the ventilators, comes from the heat - about 80 degrees Celsius - derived from the solar collectors. Because the period of solar radiation and the
Solar Air Conditioning 2
A cooled liquid desiccant absorber, based on special exchanger surfaces, has been developed and built. It can be used in desiccant cooling systems for air dehumidification, air cooling, and cold water production. The open cycle cooled absorption technology offers several advantages compared to conventional desiccant cooling systems, e.g., lower regeneration temperature potential, higher COP potential, and high energy storage potential, which facilitate the utilisation of waste heat, cogeneration heat, district heating and solar energy for air conditioning purposes. Conditions are discussed under which these potentials can be realized, efficient energy storage up to (1000 MJ/m³) being the major objective. Solid and liquid desiccants have been compared. Experimental results using LiCl-H2O solution as desiccant are reported.
Solar Refrigeration
Molecular seive zeolite to obtain useful energy from low-grade heat sources such as solar energy. Molecular sieve zeolite and a low pressure polar gaseous fluid adapted to be adsorbed by zeolite in a closed container are in a circuit which includes gas condensing and expansion apparatus. In one embodiment, cooled gas is received in another zeolite filled container, upon cooling of the first container, is returned via condensing and expansion apparatus providing more cooling. In another embodiment, sintered zeolite forms a divider across a container; heating one side creates a temperature gradient across the divider which functions as a pump for adsorbed gas and a pressure as well as temperature differential develops across the divider whereupon the heated relatively pressurized gas, after giving up energy in a circuit which may include condensing and expansion apparatus, is returned to the container and again passed through the divider. In a further embodiment, water vapor is desorbed from a zeolite panel by daytime solar heat, condensed by ambient temperature cooling, and collected in a container. At night the vapor is adsorbed by the zeolite, lowering the pressure whereby more evaporates, is readsorbed, and ice forms in the container. In another embodiment, a solar heated liquid circulates through heat exchangers in zeolite filled pressure vessels with intervening liquid cooling apparatus. Nitrogen heated in one vessel is expelled at high pressure through an engine and adsorbed by a cooler low pressure vessel with valving determining which are the the high and low pressure vessels.
Alternative Solar Generator
Hybrid Solar
Turbine Generator based on an organic Rankine Cycle.
Unlike solar panels that generate electricity using visible light, the system captures heat using a solar collector and converts it into electricity through a micro turbine generator.
The Hybrid Solar
Turbine is also readily adapted to recover waste heat from
industrial processes for electricity generation. It can also
receive supplemental fuelling using any heat source, ensuring
electricity is provided 24 hours a day, 365 days a year in colder
climates.
Solar
detoxification of hazardous wastes
Heterogeneous
photocatalysis combined with solar energy photons has the
potential to break down hazardous substances into simpler
non-toxic products like CO2 and H2O.
Solar reforming
systems
Steam
reforming of natural gas (main component methane) is the most
important industrial process for the production of synthesis gas.
The solar-driven steam and CO2 reforming of methane for the
purpose of energy storage and transport is investigated jointly
in experiments being carried out at the solar tower facilities.
Solar Hydrogen -
Solar Metals
Water-splitting
thermochemical cycles based on metal oxides redox systems are
being investigated. The thermal reduction of metal oxides are
high-temperature highly endothermic reactions that can be driven
by concentrated solar energy. The metals produced can be used to
generate either high-temperature heat via combustion, or
electricity via fuel cells, or hydrogen via a water-splitting
reaction; the hydrogen may be further processed for heat and
electricity generation.
Direct absorption
/ conversion processes
These
activities, under investigation on the direct absorption concept
for conversion of concentrated solar radiation into transportable
and storable energy. Direct absorption provides efficient means
of heat transfer to chemical processes at the the reaction site
and, under proper conditions, photochemical enhancement of the
reaction.
Selective
photoreactions and materials development
Photochemical
reaction paths to generate chemicals of commercial value can
produce highly selective and pure products, but the artificial
light sources required lead to high power costs. Solar energy is
an alternative clean source of photons for certain photochemical
reactions.