Solar Notes

back to http://scratchpad.wikia.com/wiki/Sasecurity#Energy_notes

These are random scratchpad notes that will be structured later into coherenet sections.

Salt melting assembly


Hot 400deg salt is added from the mini-containers at the focul point of the Fresnel Array mirrors. Multiple containers is winched down from many Fresnel array mirror assemblies and manually emptied into the large hot molten salt container (1). This container is vacuum sealed allowing 24 hour operation. A heat exchanger is inserted into a smaller container(2),into which the 400degree salt is pumped from (1). The salt that cools down to 300 or 200degree is pumped to storage tank (3). (3) could also be the individual mini-containers taken down from the solar array to be reheated back to 400degrees celcius.

Micro and macro environments for Solar
Micro environments like residential homes makes it more difficult to safely convert solar energy.

Seven fresnel mirrors on roof top
Line up seven 1x1 or 2x2 m fresnel lenses on the top of the roof, each heating molten salts or mineral oil to 400degrees celcuis in its own miniboiler. Each boiler is connected to its own pump, pumping the salts or mineral oil to a main larger vacuum flask container or one cubic meter dome filled with glass beads if mineral oil is used. This larger conainer pumps the salts around a steam boiler driving a 1kwH steam engine.

From the main flask seven pumps or on large pump, pumps to each fresnel mini-boiler and the back to the main boiler.

Increase solar water heater by factors


Place silver reflective material under water heater borri silicate tubes.

Transfer energy to Stirling or Steam engine
Heat up MoltenSalt using a FMA(see solar links) in a boiler with heat exchanger inside. Flow mineral oil through the heat exchanger heating it to 400C and store in adjacent container. Run the hot mineral oil over the pistons of the StirlingEngine, steam engine or quasi turbine.

Fresnel lens array mounted on single metal grid
Take the fresnel solar furnace idea from SolarLinks and instead of an array of reflective mirrors(mounted on metal grid) spanning 4x4m or 16square meters setup an array of sixteen 1x1m Fresnel lenses over 4x4m square.

Each fresnel lens on the metal grid focusses its energy on a mini boiler(16 in total). All the boilers are connected to one central boiler/heat exchanger. It would be more cost effective and simpler to use mirror arrays instead of 16 fresnel lenses but mirror arrays are extremely dangerous in small enclosed micro-environments such as residential homes. They are more suitable for open areas around which a designated danger zone can be mapped such as farms or plots. For a 4meter focus point fresnel mirror array, a radius of 8m around the mirror array is needed to avoid being roasted.

If the mirror arrays are at an offset angle to the sun a burning hotspot will be created on the side of the soil in a radius of 8meters, instead of on the central boiler.

With 16 fresnel lenses mounted on the metal grid, each 1x1m lens would only be a danger in a 2meter radius. Focusing the metal grid on the sun would result in each fresnel lens focusing its energy on its boiler. Thus only one pan/tilt control mechanism would be needed for the metal grid, as opposed to sixteen control mechanisms.

Residential hot water generation


Use on large boiler filled with molten salts and heat-exchanger. Heat up boiler with FMA(SolarLinks) in the veldt 10km away from residents and then deliver a few units by truck. Mineral oil is pumped through Boiler2 until desired workting temperature is reached such as 80c. Cold water is then pumped through container2. Heat exchanger1 is permanently immersed in salt. The boiler is removed next morning to be reheated back to 400C. One small boiler will easily supply four adjacent homes with hot water.

With valves v1,v2 the oil flow is closed and Boiler1 removed to be reheated.



Array of Fresnel lenses on roof
In a micro environment place a series of 1x1m fresnel lenses on the pinnacle of the roof, each focusing its energy on a small boiler. All the boilers are connected with piping. Seven square meters generates 1kwh electricity with a 20% efficient steam engine, stirling engine or quasi turbine(hybrid between steam and turbine engine)

http://bit.ly/gB3x1w
 * See this Korean design for positioning a fresnel lens:


 * http://tinyurl.com/3yvu5tk (short url link to http://www.heliostat.co.kr)

Make Large Fresnel
http://translate.googleusercontent.com/translate_c?hl=en&sl=ko&u=http://www.heliostat.co.kr/fresnel-lens-boiler.htm&prev=/search%3Fq%3Dstirling%2Bengines%2Bkorea%2Bsite:.co.kr%26num%3D100%26hl%3Den%26lr%3D%26as_qdr%3Dall&rurl=translate.google.com&twu=1&usg=ALkJrhhErlTuNtc0sRD_9hzQcVzNKHY_HA

a large 3x3 meter lens is made by dividing it up into nine blocks. Each block is made in strips projecting towards the centre. With injection molding machine fresnel strips can be easily made. This would allow safer energy generation in a residential area.



Commercial solar boilers with molten salt
http://bit.ly/fhPBnu South Korea company(http://www.heliostat.co.kr). Shows pictures.

http://bit.ly/f63K4r

Concentrated sunlight on solar cells
http://bit.ly/i3lBGi and http://bit.ly/hkipSX we have

CTJ Terestrial by Emcore concentrating triple-junction(CTJ) solar cells

http://www.emcore.com/solar_photovoltaics/terrestrial_solar_cells_and_receivers

Power Solutions using EMCORE Concentrator Photovoltaic Arrays (CPV Using optical lenses and mirrors we concentrate the sunlight onto a very small, highly efficient Multi-Junction solar cell. For example, under 500-sun concentration, 1 cm2 of solar cell area produces the same electricity as 500 cm2 would, without concentration. This is particularly significant when considering the inherent efficiency advantage of the Multi-Junction technology over Silicon solar cells The use of concentration, therefore, allows substitution of cost-effective materials such as lenses and mirrors for the more costly semiconductor PV cell material.

GEN 3 CPV SYSTEM

GEN 3 CPV MODULE

EMCORE's Multi- Junction Solar Cell Technology Adapted to Terrestrial Power Generation High efficiency Multi-Junction cells have a significant advantage over conventional silicon cells in concentrator systems because fewer solar cells are required to achieve the same power output.

CPV solar arrays utilize accurate 2-axis sun tracking systems to capture even more of the available sun energy.The high energy output from a more efficient system, and the savings in costly semiconductor area make the application of CPV technology economically advantageous. As Concentrator PV arrays advance on their projected learning curve (high volume manufacturing, increased cell efficiency to > 40%) this technology will continue to dramatically reduce the cost of generating electricity from solar energy. EMCORE is favorably positioned in being vertically integrated in CPV solar cell and systems level capability. We have a substantial ongoing business, and the corporate resources and commitment to competitively bring CPV power to market.

Heat pipes
From this Korean site http://bit.ly/fpNXOw we have:

Thermacore

http://www.thermacore.com/search.aspx

http://www.thermacore.com/thermal-basics/heat-pipe-technology.aspx

Efective thermal conductivities (5,000 Watts/meter·K to 200,000 Watts/meter·K), energy-efficiency, light weight, low cost and the flexibility of many different size and shape options. As passive heat transfer systems, heat pipes offer simple and reliable operation, with high effective thermal conductivity, no moving parts, ability to transport heat over long distances and quiet vibration-free operation. Heat pipes transfer heat more efficiently and evenly than solid conductors such as aluminum or copper because of their lower total thermal resistance. The heat pipe is filled with a small quantity of working fluid (water, acetone, nitrogen, methanol, ammonia or sodium). Heat is absorbed by vaporizing the working fluid. The vapor transports heat to the condenser region where the condensed vapor releases heat to a cooling medium. The condensed working fluid is returned to the evaporator by gravity, or by the heat pipe's wick structure, creating capillary action. Both cylindrical and planar heat pipe variants have an inner surface lined with a capillary wicking material.

What is a Heat Pipe?

Heat pipes are the most common passive, capillary-driven of the two-phase systems.Two-phase heat transfer involves the liquid-vapor phase change (boiling/evaporation and condensation) of a working fluid. The heat pipe technology industry leader, Thermacore has specialized in the design, developmentand manufacturing of passive, two-phase heat transfer devices since 1970.

Heat pipes have an extremely effective high thermal conductivity. While solid conductors such as aluminum, copper, graphite and diamond have thermal conductivities ranging from 250 W/m•K to 1,500 W/m•K, heat pipes have effective thermal conductivities that range from 5,000 W/m•K to 200,000 W/m•K. Heat pipes transfer heat from the heat source (evaporator) to the heat sink (condenser) over relatively long distances through the latent heat of vaporization of a working fluid. Heat pipes typically have 3 sections: an evaporator section (heat input/source), adiabatic (or transport) section and a condenser section (heat output/sink).

Key Components of a Heat Pipe

The three major components of a heat pipe include: They all work together to transfer heat more efficiently and evenly. The wick structure lines the inner surface of the heat pipe shell and is saturated with the working fluid. The wick provides the structure to develop the capillary action for the liquid returning from the condenser (heat output/sink) to the evaporator (heat input/source). Since the heat pipe contains a vacuum, the working fluid will boil and take up latent heat at well below its boiling point at atmospheric pressure. Water, for instance, will boil at just above 273° K (0°C) and start to effectively transfer latent heat at this low temperature.
 * A vacuum tight, sealed containment shell or vessel
 * Working fluid
 * Capillary wick structure

Make Fresnel mirror with reflectech

 * http://www.google.com/patents?vid=USPAT4347834 Patent expired 2002

http://www.redrok.com/images/US4347834.gif

Variable entropy solar energy harvester (A Fresnel mirror composed of concentric rings of paraboloidal mirror segments focusing behind the array)

Look at full description of patent pretty good;

http://www.google.com/patents?id=Bzk2AAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

Mirror positioners
http://www.google.com/patents?id=9q4yAAAAEBAJ&pg=PA3&source=gbs_selected_pages&cad=4#v=onepage&q&f=false

Note the picture on creating a pan/tilt system. Patent has expired.

random construction notes
will structure later

Get back to the patented idea with fresnel lenses.

Four large fresnel lenses are mounted side by side to heat oil. The windspeed is monitored, lenses positioned vertically and assembly turned into the wind to minimize wind loading. This allows a light structure and large solar energy storage into molten salts and mineral oil during periods of wind calm.

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===================== scrap yard sells metal for R2/kg.

Large 2x1m fresnel lens can melt metal to pour into metal moulds to make steel tubes. plastic bottles are melted to make plastic pipe, recycled glass melted into 30x30cm square shapes. Mirrors are made by covering it with with reflectec Mirror Reflector material. ($20/m2)

Or melt plastic into rigid 30x30cmcx5mm squares, covering it in reflectec to form a mirror. Thus lightweight 1x1m fresnel pvc plastic mirrors array are created. Fit 25 of these on a 5x5m metal tube grid. / / / / / / / / / / / / / / / /

nine mirrors per meter 9 x 25 = 225 mirrors focusing all on one 30cm spot. Thus there are 225 suns on one 30cm spot.

the rigid plastic is painted with a UV protection paint. reflectech last 20years. cheaper mylar can be used but must be replaced each year.

Lighter drive gear is needed.

google make own steel tubes out of scrap metal..

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= clamping mirror what methods?

form square bracket or rectangular then. smeer one side with silicon and gluje mirror to it across the lenght. on hte back of the rectangle secure bolt with nut.

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= concentric ring fresnel lens down length of roof to minimize wind loading. or use indjecting molded fresnel lenses.

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===== build all plastic grid of say 1x1m fitted with small 5x5cm square mirror. each mirror c lamped into braket. a plastic stick is fused into the main plastic frame by meling it into the main plastic tube. insside the pasltic is thick wire.

the focused 5x5cm focused beam is put through a loupes lens to finally form a small 1cm focus point ab#le to cut throu0gh ah engine block.

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SOLAR cutting torch: focus a large solar furnace onto a small 30x30cm fresnel lens the resultant smaller focused beam will be like a cutting torch able to cut through an engine block.

Build a large frensel arry with conentric rings as per patent,,,, and swti.com page. note the patent has expired. svti.com

the larger fresnel assembly focus into a second fresnel lens.

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=============== wrap blou-draad around the pvc tube and then bend the wire to focus the fresnel lens.

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===================== plastic construction of 1x1m fresnel mirror array and not expensive metal. the bolts must be clamped to the pvc pipe as they are inserted through the pvc pipe, use thin bolts, handy bar non galvanised. or galvnsd. The clamp on top is hardened metal bolt bends in this. Very thin threaded bolts can be used, the weight of one square 30x30cm mirror isn't much. Drill a whole through 25cm pvc pipe and insert the bolt through this with washers on both sides of the pvc pipe.

To strengthen the pvc, should it be needed, a short round piece of metal is fitted over the pvc pipe, this allows the metal to bear the bending force when the botls are bended to focus each mirro on the focul point. The washers though should be suffiecent.

combine PVC with metal by mounting the 1x1 pvc frame on a 1x3m metal frame to reduce metal costs. or mount on one large 5x5m metal frame, thus 25 1x1 pvc frames.

five 5m tubes from left to right vertically. one at bottom and top = 7 tubes. Then one horizontally in the middle for total = 8 x 5m = 40m length.

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============ link is where? australian steam engine project: At 1kw thermal energy into australie they had 180m square for 25kwh electric at 20% conversion efficiency with steam engine. thus 7.2m square for 1kwh electric out. This means 2.7 x 2.6 m square fresnel mirror array.

variables that influence the the cost of creating 1kwh of electrical energy is solar radiation or thermal energy per square meter. In South Africa it is around 5kwh. Conversion efficiency of steam engine(15%), Stirling(30%), quasi or turbine(15%). Turbines are viable above 300Kwh only. Newer micro turbines uses refrigerator coolant, but they have patents that need to be hacked. Steam engines don't have patents. Patented commercial Stirling and turbine engines sell for around $30000/3kwh and are thus not viable. The quasi-turbine is competitive with Steame Engines3.

construction cost of heliostat fresnel mirror and driving motors.

The relion fuel cell 5kwh at $15000 is shared between five homes, $3000/residence for 1kwh. R21000 at 9% interest is R157,00 per month.

Hydrogen is made with an electrolyzer and electric power with the steam engine.

80% of this sun thermal energy converts to pressurized steam at the boiler due to reflective losses from the mirror. 15% of this converts to electrical power. Thus about 620watts electrical power is available per square meter of a Fresnel mirror array using a steam engine.

Ideally this 620kwh should be available directly at the residence by funneling it over the Eskom grid with the owner paying Eskom only for the grids usage. Since this won't happen the energy must be used to create hydrogen via the electrolyser which is stored in high pressure tanks.

Tanks are trasported to the Relion fuel cell at the five residences. Two tanks would thus be needed to assure 24hour power availability. Any piece of open veldt can be used to setup a solar furnance, the closer it is to residences the better.

Work out total capital cost, take out a loan at 9% and it seems that energy is available at about 30% what the municipalities is charging.

A household paying R2000 a month for electricity is in effect paying interest of 9% on an eternal debt of R266,666.00 to baas Eskom and its empowerment partners. If one can produce 1kwh of electricity for a capital amount significantly less than this using solar energy, it would make solar/hydrogen a viable alternative.

how much hydrogen volume can be generated with 1kwh of electricity. convrersion efficiency of hydrogen back to electriciy;

in going from electric->hydrogen->electric there will again be switching and conversion losses. it would be ideal to have the solar furnace on the roof, but the space constraints and danger of solar furnaces dont allow for this.As eskom hikes prices there will come a tipping point where hydrogen/solar will be superior.

it took one 1kwh electricity to generate x-cubic volume hydrogen. Going from hydrogen to electric for the same period at 25% efficiency means that the effectivre 620watts reduces even further to 150watts. Of an initial 5kw thermal energy we only have 150watts at the home away from the solar furnace plant.

Thousands of solar DIY solar plants could be setup across the country selling their power back to the Eskom grid, it probably won't happen.

using hydrogen to heat the geyser isn't cost effective due to the low conversion efficiency. Heating the geyser must be done with parabolic troughs on the roof resulting in heat->heat conversion. heat->electrical(generator)->hydrogen->electrical->heat is a huge wastage of resources. Residential roofs provides enough space for fresnel mirror or parabolic trough heat->heat conversion. Such conversion is around 80% efficient compared to an effective 5-10% in the alternative case.

the hydrogen eneryg must be used for lighting, computers and television. Stoves is also or the utility function is reduced.

Solar cookers won't really work on a mass scale because it involves lifestyle changes. People don't want hassels, they aren't goin go run around in the garden to boil water. Rather think of ways to generate power in such a way that it becomes transparant.