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- | cbhytmjcbszoui, http://cialisinspector.com/ Cialis, yJfkNgS. | + | |
+ | |||
+ | ==== organic photovoltaic notes ==== | ||
+ | |||
+ | |||
+ | copypaste mess from the [[Luminous Green Notes]] | ||
+ | |||
+ | Objectives/ | ||
+ | |||
+ | The objective is to compare the performance of home made natural dye based organic photovoltaic devices with commercial inorganic silicon based photovoltaic devices in sunlight and colored artificial light. | ||
+ | |||
+ | |||
+ | Method/ | ||
+ | |||
+ | Chlorophyll and anthocyanin organic dyes extracted from citrus leaves, raspberries and blackberries were absorbed onto nano-crystalline titanium dioxide coated on conducting glass slides. Photovoltaic devices were made with an iodide/ | ||
+ | |||
+ | |||
+ | Conclusions | ||
+ | Organic dye based photovoltaic cells can be made at home using chlorophyll and anthocyanin dyes. | ||
+ | These cells capture energy from sunlight and indoor light of sufficient intensity. Commercial silicon cells | ||
+ | are considerably more efficient than the home-made photovoltaic devices. | ||
+ | Natural organic dyes can be used to make home made cells for the capture of solar energy. | ||
+ | Dr. Greg Smestad, creator of the dye-sensitized solar cell kit, provided tips by e-mail. Mr. M. P. Reidy | ||
+ | gave conductive glass plates. Applied Films sent heat shield glass and Drs. Kaustav and Sonali Das gave | ||
+ | Triton X 100. Mother took notes during outdoor measurements. Father helped wire the circuit board and | ||
+ | |||
+ | |||
+ | Solvents | ||
+ | |||
+ | |||
+ | Apart from water nearly all solvents in which dyes are dissolved are | ||
+ | flammable, | ||
+ | highly toxic (irritants, narcotics and/or anestetics, carcinogen [dioxane]) | ||
+ | and some solutions are dangerous by skin contact by expediting the movement of dye through the skin [DMSO]. | ||
+ | Solvents | ||
+ | Methanol | ||
+ | Ethanol | ||
+ | Ethylene Glycol | ||
+ | DMSO (!) | ||
+ | Dioxane (!) | ||
+ | Benzyl alcohol (!) | ||
+ | Cyclohexane | ||
+ | Hexane | ||
+ | Toluene | ||
+ | Dichloromethane | ||
+ | Dichoroethane | ||
+ | [[/ | ||
+ | |||
+ | Ethylene glycol | ||
+ | From Wikipedia, the free encyclopedia | ||
+ | Properties | ||
+ | | ||
+ | | ||
+ | General | ||
+ | Name | ||
+ | Ethane-1, | ||
+ | | ||
+ | | ||
+ | | ||
+ | 62.068 | ||
+ | Synonyms | ||
+ | Ethylene glycol | ||
+ | Monoethylene glycol | ||
+ | MEG | ||
+ | 1, | ||
+ | | ||
+ | OCCO | ||
+ | | ||
+ | 107-21-1 | ||
+ | Phase behavior | ||
+ | | ||
+ | 260.2 HYPERLINK " | ||
+ | | ||
+ | 470.4 K (197.3 °C) | ||
+ | Thermal decomposition | ||
+ | ? K (? °C) | ||
+ | | ||
+ | 256 K (−17 °C) | ||
+ | ? kPa | ||
+ | | ||
+ | 720 K (447°C) | ||
+ | 8.2 MPa | ||
+ | | ||
+ | 9.9 kJ/mol | ||
+ | | ||
+ | 38.2 J/ | ||
+ | | ||
+ | 65.6 kJ/mol | ||
+ | | ||
+ | Miscible with water | ||
+ | Liquid properties | ||
+ | | ||
+ | −460 | ||
+ | | ||
+ | 166.9 J/ | ||
+ | | ||
+ | 149.5 J/ | ||
+ | | ||
+ | 1.1132 g/cm³ | ||
+ | | ||
+ | 21 HYPERLINK " | ||
+ | Gas properties | ||
+ | | ||
+ | −394.4 | ||
+ | | ||
+ | 311.8 J/ | ||
+ | | ||
+ | 78 J/ | ||
+ | Safety | ||
+ | Acute effects | ||
+ | Nausea, vomiting. CNS paralysis. Kidney damage. | ||
+ | Chronic effects | ||
+ | Kidney damage | ||
+ | | ||
+ | 111 °C | ||
+ | | ||
+ | 410 °C | ||
+ | | ||
+ | 1.8–12.8% | ||
+ | More info | ||
+ | Properties | ||
+ | | ||
+ | |||
+ | | ||
+ | | ||
+ | | ||
+ | | ||
+ | Ethylene glycol (monoethylene glycol (MEG), | ||
+ | [[/ | ||
+ | |||
+ | History | ||
+ | Ethylene glycol was first prepared in HYPERLINK " | ||
+ | When first introduced it created a minor revolution in aircraft design because when used in place of water as an HYPERLINK " | ||
+ | Production | ||
+ | Ethylene glycol is produced from HYPERLINK " | ||
+ | | ||
+ | This HYPERLINK " | ||
+ | This molecule has been observed in space by Hollis et al. (The | ||
+ | Journal, 571: | ||
+ | Uses | ||
+ | The major use of ethylene glycol is as a coolant or antifreeze in, for example, automobiles and personal computers. Due to its low freezing point, it is also used as a HYPERLINK " | ||
+ | Minor uses of ethylene glycol include the manufacture of HYPERLINK " | ||
+ | Ethylene glycol' | ||
+ | Ethylene glycol is also used in the manufacture of some HYPERLINK " | ||
+ | Ethylene glycol is commonly used in laboratories to precipitate out proteins in solution. This is often an intermediary step in fractionation, | ||
+ | Ethylene glycol has seen some use as a rot and fungal treatment for wood, both as a preventative and a treatment after the fact. It has been used in a few cases to treat partially rotted wooden objects to be displayed in museums. It is one of only a few treatments that are successful in dealing with rot in wooden boats, and is relatively cheap. | ||
+ | [ HYPERLINK " | ||
+ | The major danger from ethylene glycol is following ingestion. Due to its sweet taste, children and animals will sometimes consume large quantities of it if given access to antifreeze. Ethylene glycol may also be found as a contaminant in unlawfully | ||
+ | Ethylene glycol poisoning is a medical emergency and in all cases a HYPERLINK " | ||
+ | Symptoms | ||
+ | Symptoms of ethylene glycol poisoning usually follow a three-step progression, | ||
+ | Treatment | ||
+ | Initial treatment consists of stabilizing the patient and gastric decontamination. As ethylene glycol is rapidly absorbed, gastric decontamination needs to be performed soon after ingestion to be of benefit. | ||
+ | The HYPERLINK " | ||
+ | In addition to antidotes, | ||
+ | Industrial hazards | ||
+ | Ethylene glycol can begin to breakdown at 230° – 250°F. Note that breakdown can occur when the system bulk (average) temperature is below these limits because surface temperatures in heat exchangers and boilers can be locally well above these temperatures. | ||
+ | The HYPERLINK " | ||
+ | The basis for all photovoltaic devices is the separation of charge at an interface of two materials that have different conduction methods (Grätzel M., 2000). In conventional cells, this is between n- and p- type semiconductor: | ||
+ | The dye-sensitised solar cell (DYSC) was developed by Gratzel and coworkers (O’Regan & Gratzel, 1991) and uses the principle of [[photosynthesis]] to generate power; the boundary in a DYSC is between a wide band gap semiconductor and electrolyte solution. In solid-state devices light absorption and charge movement both occur on the semiconductor, | ||
+ | |||
+ | |||
+ | In a conventional solar cell, electron-hole pairs must travel a considerable distance without recombining to contribute to the current in the external circuit. As a result, expensive high-purity materials must be used to avoid premature recombination (Hart, J. 2003). Conversely, a DYSC alters the wide band gap semiconductors by chemically attaching a redox dye. This dye absorbs light, and positive and negative charge separation occurs across the dye/ | ||
+ | With these limitations in mind, research has turned to the nature for inspiration: | ||
+ | |||
+ | |||
+ | Using a photosynthetic mechanism, a plant converts the Sun’s radiant energy into the chemical into carbohydrates (Knox et al., 2005), by directing an electron through a transport system and extracting useful energy as the electron falls from an excited state back to ground. Despite its complexity, photosynthesis can be summarised by the following equation: 6H2O + 6CO2 + light → C6H12O6 (glucose) + 6O2 (BIOL1101 Lab Notes, 2005). A photosynthetic pigment absorbs a specific wavelength of light and uses this energy to excite an electron. In turn these electrons synthesise dihydro-nicotinamide-adenine-dinucleotide phosphate (NADPH), a molecule that eventually produces a carbohydrate (fig 2). To regenerate the pigment to its original state, an electron is donated in the oxidation of water to produce oxygen (Bering, 1985). | ||
+ | |||
+ | Essentially a DYSC is photoelectrochemical cell containing an electrolyte and two electrodes that produce electrical current by redox reactions that are driven by light. The operating principles of the DYSC in some respects parallel those of photosynthesis: | ||
+ | However, the key difference between the DYSC and plants is that plants store the energy in the form of starch for later use, whereas the DYSC cannot store energy. Currently research is being directed at inventing a device that incorporates both photoelectric and storage functions in a single cell structure or photocapacitor (Miyasaka & Murakami, 2004). | ||
+ | |||
+ | |||
+ | HOW THE DYSC WORKS: blueberry electricity | ||
+ | |||
+ | |||
+ | A redox dye is chemically attached to the surface of the DYSC (fig 3), and the absorption of incident light is determined by the number of dye molecules attached per unit volume of the semiconductor. If the dye is attached to a flat surface less than 1% of incident light is absorbed, and the conversion efficiency of light into useful energy is low (Sommeling et al.,, 2000). Light absorption is maximised by the use of sintered nanometre-sized anatase titanium dioxide; the surface area is increased by two or three orders of magnitude above the projected area of the film (Heij, 2002). This structure has pores in the range 20-500Å in diameter, and provides a huge surface area where absorption processes and electronic conduction can occur (fig 4). It is advantageous to use titanium dioxide because it is abundant, cheap, biocompatible and non-toxic (Gratzel & Hagfeldt, 2000). The anatase phase of titanium dioxide is used because it has a suitably wide band gap that it is transparent to visible light – this ensures that light is only absorbed by the dye – and can provide a useful cell voltage (Hagfeldt & Grätzel, 1995). The ideal titanium dioxide film thickness is between 5 µm and 20 µm (Grätzel, 2000): this is a compromise between maximizing surface area, and minimizing recombination losses. A larger film thickness means that the electrons must travel a greater distance before transferring to the conductive layer of the titanium dioxide. On the other hand, the film must be thick enough to give a sufficient surface area for good light absorption. | ||
+ | A photo-induced electron from the dye is injected into the semiconductor conduction band; this induces a charge separation. The electrons travel in this conduction band, via an external circuit (where they can do work) to the electrolyte solution or ‘charge collector’ (fig 5). To restore the original state of the dye, and prevent the electron recapture by the oxidized dye, an electron is donated by the electrolyte solution: 3I-+◊I3-+e-. Often this solution consists of an organic solvent containing a redox system, such as the iodide/ | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | DYSC DYES: a healthy alternative | ||
+ | [[/ | ||
+ | |||
+ | Commercially produced DYSC use ruthenium bipyridyl–based dyes (N3 dyes) and typically achieve conversion efficiencies of 10% (Nazerruddin, | ||
+ | It is also possible, and significantly cheaper, to generate a significant photocurrent using natural anthocyanin dyes that are extracted from berries as natural water-based substitutes (Tennakone, 1995, 1997a, 1997b). Such dyes are responsible for the red and purple colours of fruit, and biologically serve to attract insects and protect leaves from UV damage (Martin, 1995). The adsorption of cyanin to the surface of | ||
+ | is a rapid reaction; an OH- counterion is displaced from the Ti(IV) site that combines a proton donated by the anthocyanin molecule (fig 6). This strong chemical affinity is one reason that the fruit dyes work effectively in the DYSC. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | METHODS AND RESULTS: DYSC construction | ||
+ | |||
+ | |||
+ | A commercially bought titanium dioxide coated glass slide was stained with a berry dye (e.g. raspberries, | ||
+ | All cells produced a photocurrent when a voltage was applied (fig 8), but its magnitude varied between the dyes; the region of negative current and positive voltage represents photocurrent activity. It was found that blueberries were most efficient –they produced a photocurrent of 0.2mA (~0.02% efficiency) - followed by raspberries, | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | DISCUSSION: what’s going on? | ||
+ | |||
+ | |||
+ | The 2nd half of figure 9 – the degradation process – is hard to predict since many factors such as electrolyte degradation, | ||
+ | | ||
+ | Turning to the orange cell, the conduction band of the orange cell lies beneath that of the titanium dioxide (fig 13). Few electrons can transfer to the titanium dioxide, and a small photocurrent is produced. Even when placed underneath light, and the concentration of the electrolyte increases, this has no effect since the electrons still cannot make the transfer from the dye to the titanium dioxide. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | | ||
+ | |||
+ | CONCLUSION: moving towards the light | ||
+ | |||
+ | |||
+ | In choosing materials to construct a solar cell it is important to consider the energy levels of such components. A cell that produces a large photocurrent has a dye that is energetically well suited to the titanium dioxide with a conduction band energy level that is slightly higher than the titanium dioxide conduction band level. Similarly, the concentration of the electrolyte solution is energetically well suited to the dye (Bisquert et al., 2004). For future work on anthocyanin dyes such as raspberries, | ||
+ | A significant shortcoming of the DYSC is leakage of the electrolyte, | ||
+ | |||
+ | |||
+ | The DYSC has the potential to become an economically viable method of using solar energy commercially. Advantages of the DYSC over conventional solar cells include that it: does not need ultra-pure substances; uses low-cost materials and processes that have little environmental impact; achieves reasonable efficiencies which are expected to improve with more research; long-term stability of 10-20 years (Grätzel, 2000, Grätzel, 2001). There is flexibility in the choice of material for each component, allowing the properties to be adjusted and optimised for particular applications. | ||
+ | As fossil fuel resources dwindle, other methods such as solar energy must be considered: with improvements to increase their efficiency, extend their lifetime and reduce costs, the DYSC provides an economically viable solution, and could direct us to using solar power regularly. | ||
+ | |||
+ | ACKNOWLEDGEMENTS | ||
+ | |||
+ | |||
+ | Special recognition must go Dr Nicholas Ekins-Daukes, | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | REFERENCES | ||
+ | |||
+ | |||
+ | Bignozzi, C.A., Argazzi, R., Kleverlaam, C.J., 2000. Molecular and supramolecular sensitization of nanocrystalline wide band-gap semiconductors with mononuclear and polynuclear metal complexes. Chem. Soc. Rev., 29, 87-96. | ||
+ | |||
+ | |||
+ | Bisquert, J., Zaban, A., Greenshtein, | ||
+ | |||
+ | |||
+ | Bolton, J. R. Hall, D. O., 1991. Photochem. Photobiol., 53, 545. | ||
+ | [[/ | ||
+ | |||
+ | Cherepy, N.J., Smestad, G.P., Gratzel, M., Zhang J.Z., 1997. Ultrafast Electron Injection: Implications for a Photoelectrochemical Cell Utilizing an Anthocyanin Dye-Sensitized | ||
+ | Nanocrystalline Electrode. J. Phys. Chem. B, 101, 9342-9351 | ||
+ | |||
+ | |||
+ | Cotal, H.L., Lillington, D.R., Ermer, J.H., King, R.R., Karam, N.H., Kurtz, S.R., Friedman, D.J., Olson, J.M., Ward, J.S., Duda, A., Emery, K.A., Moriarty, T., 2000. Triple-junction solar cell efficiencies above 32%: the promise and challenges of their application in high-conceniration-ratio PV systems. Photovoltaic Specialists Conference, 2000. Conference Record of the Twenty-Eighth IEEE | ||
+ | |||
+ | |||
+ | Grätzel M., 2000. Perspectives for Dye-sensitized Nanocrystalline Solar Cells. Progress in Photovoltaics: | ||
+ | |||
+ | |||
+ | Grätzel M., 2001, Journal of Sol-Gel Science and Technology, 22(1-2), 7 | ||
+ | |||
+ | |||
+ | Gratzel, M., Hagfeldt A., 2000. Molecular Photovoltaics. Acc. Chem. Res, 33, 269-277 | ||
+ | |||
+ | |||
+ | Green, M.A., Emery, K., King, D.L., Igari, S., Warta, W., 2002. Solar cell efficiency tables (version 21) Progress in Photovoltaics: | ||
+ | |||
+ | |||
+ | Gregory, R.P.F., 1977. Biochemistry of Photosynthesis. John Wiley and Sons, Ltd. pp.30-37. | ||
+ | |||
+ | |||
+ | Hagfeldt, A., Grätzel, M., 1995. Light-induced redox reactions in nanocrystalline systems. Chem. Rev. 95, 49-68 | ||
+ | |||
+ | |||
+ | Hart, J., 2003. Dye-sensitised solar cells – the future of photovoltaics? | ||
+ | |||
+ | |||
+ | Heij, E. G., 2002. Nanotechnology – big action on little devices. CSIRO SUSTAINABILITY NETWORK. Update 8E: 5 April 2002 | ||
+ | |||
+ | |||
+ | Kubo, W., Murakoshi, K., Kitamua, T., Yoshida, S., Haruki, M., Hanabusa, K., Shirai, H., Wada, Y., Yanagida, S., 2001. J Phys. Chem. B, 105, 12809 | ||
+ | |||
+ | |||
+ | Longo, L., Nogueira, A. F., De Paoli, M.A., Cachet, H., 2002. Journal of Physical Chemistry B, 106(23), 5925. | ||
+ | |||
+ | |||
+ | Martin, H.-D. Chimia 1995, 49, 45. | ||
+ | |||
+ | |||
+ | Kang, M.G., Park, N-G., Kim, K-M., Ryu, K.S., Chang S.H., Kim, K.J., 2003. Highyl efficient polymer gel electrolytes for fye-sensitized solar cells. 3rd World Conference on Phorovolroic Emru Conversion . May 11-18, 2003 Osnh, Japan | ||
+ | |||
+ | |||
+ | Miyasaka, T., Murakami, T.N., 2004. The photocapacitor: | ||
+ | |||
+ | |||
+ | Nazeeruddin, | ||
+ | [[/ | ||
+ | |||
+ | Nogueira, A.F., De Paoli, M.A., Montanan, I., Monkhouse, R., Nelson, Durrant, I., 2001. J. Phys. Chem. B, 105,7417 | ||
+ | O' | ||
+ | films. Nature 353, 737-740. | ||
+ | Ren, Y., Zhang, Z., Gao, E., Fang, S., Cai, S., 2001. J. Appl. Electochem., | ||
+ | |||
+ | |||
+ | Smestad G.P., Gratzel. M., 1998. Demonstrating Electron Transfer and Nanotechnology: | ||
+ | |||
+ | |||
+ | Smestad, G., Bignozzi, C., Argazzi, R, 1994. Sol. Energy Mater. Sol. Cells, 32, 259. | ||
+ | [[/ | ||
+ | |||
+ | Smil, V. In General Energetics, Energy in the Biosphere and | ||
+ | ; Wiley: New York, 1992; p 53. | ||
+ | |||
+ | |||
+ | Sommeling, P.M., Rieffe, H. C., van Roosmalen, J. A. M., Schonecker, A., Kroon, J. M., Wienke J. A., Hinsch, A., 2000. Solar Energy Materials and Solar Cells, 62, 399. | ||
+ | |||
+ | |||
+ | Späth, M., Sommeling, P. M., van Roosmalen, J. A. M., Smit, H. J. P., van der Burg, N. P. G., Mahieu, D. R., Bakker, N. J., Kroon, J. M., 2003. Reproducible Manufacturing of Dye-Sensitized Solar Cells on a Semi-automated Baseline. Prog. Photovolt: Res. Appl. 11, 207–220. | ||
+ | |||
+ | |||
+ | Spiekermann, | ||
+ | |||
+ | |||
+ | Tennakone, K., Kumara, G. R., Kumarasinghe, | ||
+ | |||
+ | |||
+ | Tennakone, K., Kumara, G. R., Kottegoda, I. R., Wijayantha, K, 1997a. Semicond. Sci. Technol., 12, 128–132. | ||
+ | |||
+ | |||
+ | Tennakone, K., Kumara, G. R., Kumarasinghe A., Sirimanne, P., Wijayantha, K., 1997b. Photochem. Photobiol. A: Chem., 108, 193–195. | ||
+ | |||
+ | |||
+ | Zweibel, K., 1993. Am. Sci., 81, 362. | ||
+ | |||
+ | |||
+ | Zweibel, K. In Harnessing Solar Power; Plenum: New York, 1990; p 101. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | WEBSITES | ||
+ | |||
+ | |||
+ | | ||
+ | |||
+ | |||
+ | Dysol supply a ruthenium bipyridyl–based dye for $220,000! [2] | ||
+ | |||
+ | Blueberry Power; | ||
+ | Photosynthetic Electricity | ||
+ | |||
+ | |||
+ | Photovoltaics (technology that produces electric power directly from sunlight), once dominated by solid-state junction devices is now being revolutionised by the dye-sensitized solar cell (DYSC). Based on nanocrystalline materials and conducting polymer films, it is the only serious alternative concept (both technically and economically) to p-n junction photovoltaic devices. Not only are such cells cheap to produce, but they have little environmental impact. Already these cells produce 11% conversion efficiencies, | ||
+ | |||
+ | Blueberry Power; | ||
+ | Photosynthetic Electricity | ||
+ | |||
+ | |||
+ | By Helen Smith | ||
+ | |||
+ | |||
+ | Figure 1: Australian Government, Bureau of Meteorology: | ||
+ | |||
+ | Figure 9: Short circuit Current vs. Time | ||
+ | for a typical blueberry cell | ||
+ | |||
+ | |||
+ | Figure 8: Short circuit Current vs. Voltage | ||
+ | for a typical raspberry cell | ||
+ | |||
+ | |||
+ | Figure 7: A blueberry DYSC | ||
+ | |||
+ | |||
+ | Figure 6: Chelation process of dye to Titanium dioxide | ||
+ | |||
+ | |||
+ | Figure 5: How the DYSC works | ||
+ | |||
+ | Figure 4: Electron micrograph of Titanium dioxide in the nanocrystalline form | ||
+ | |||
+ | |||
+ | Figure 3: DYSC construction | ||
+ | |||
+ | |||
+ | Figure 2: Photosynthesis | ||
+ | |||
+ | |||
+ | Chloroplast envelope | ||
+ | |||
+ | |||
+ | stoma | ||
+ | |||
+ | |||
+ | Starch | ||
+ | |||
+ | |||
+ | CH2O | ||
+ | |||
+ | |||
+ | Carbon dioxide | ||
+ | |||
+ | |||
+ | NADP+ | ||
+ | ADP + Pi | ||
+ | |||
+ | |||
+ | ATP | ||
+ | NADPH | ||
+ | |||
+ | |||
+ | oxygen | ||
+ | |||
+ | |||
+ | Light | ||
+ | |||
+ | |||
+ | thyla-koids | ||
+ | |||
+ | |||
+ | Water | ||
+ | |||
+ | |||
+ | Figure 10: Model to predict improvement and degradation of DYSC. In red is the predicted improvement if degradation was absent | ||
+ | |||
+ | |||
+ | Figure 11: Energy levels associated with the different components of the DYSC | ||
+ | |||
+ | |||
+ | e- | ||
+ | |||
+ | e- | ||
+ | |||
+ | |||
+ | Electrolyte | ||
+ | |||
+ | |||
+ | Dye | ||
+ | [[/ | ||
+ | |||
+ | |||
+ | |||
+ | Figure 12: Energy levels in a blueberry DYSC | ||
+ | |||
+ | |||
+ | e- | ||
+ | |||
+ | e- | ||
+ | |||
+ | |||
+ | Electrolyte | ||
+ | |||
+ | |||
+ | Dye | ||
+ | [[/ | ||
+ | |||
+ | |||
+ | Figure 13: Energy levels in an orange DYSC | ||
+ | |||
+ | |||
+ | INTRODUCTION: | ||
+ | |||
+ | |||
+ | FURTHER READING | ||
+ | |||
+ | |||
+ | Kang, M.G., Park, N-G., Kim, K-M., Ryu, K.S., Chang S.H., Kim, K.J., 2003. Highyl efficient polymer gel electrolytes for fye-sensitized solar cells. 3rd World Conference on Phorovolroic Emru Conversion . May 11-18, 2003 Osnh, Japan | ||
+ | |||
+ | |||
+ | Miyasaka, T., Murakami, T.N., 2004. The photocapacitor: | ||
+ | [[/ | ||
+ | |||
+ | O' | ||
+ | films. Nature 353, 737-740 | ||
+ | |||
+ | |||
+ | Smestad, G., Bignozzi, C., Argazzi, R, 1994. Sol. Energy Mater. Sol. Cells, 32, 259. | ||
+ | |||
+ | |||
+ | Smestad G.P., Gratzel. M., 1998. Demonstrating Electron Transfer and Nanotechnology: | ||
+ | |||
+ | THE DYE SENSITISED SOLAR CELL (DYSC): | ||
+ | a fruitful future? | ||
+ | |||
+ | PHOTOSYNTHESIS: | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | HOW THE DYSC WORKS: blueberry electricity | ||
+ | |||
+ | |||
+ | DYSC DYES: a healthy alternative | ||
+ | |||
+ | METHODS AND RESULTS: DYSC construction | ||
+ | |||
+ | DISCUSSION: what’s going on? | ||
+ | |||
+ | CONCLUSION: moving towards the light | ||
+ | |||
+ | ACKNOWLEDGEMENTS | ||
+ | |||
+ | REFERENCES | ||
+ | |||
+ | WEBSITES | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | [1] | ||
+ | |||
+ | [2]https:// | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | " | ||
+ | [ HYPERLINK " | ||
+ | Ethylene glycol may also be used as a protecting group for carbonyls during synthesis. Acid catalysis, and a ketone or aldehyde with ethylene glycol will form a cyclic structure at the carbonyl. Other chemistry can then be done to the molecule before more acid will break open the protecting ring and restore the carbonyl. | ||
+ | Work procedureTuesday, | ||
+ | Solar Cells for Cheap | ||
+ | Not everyone gets a solar cell named after them: but Michael Gratzel did. He says his novel technology, which promises electricity-generating windows and low manufacturing costs, is ready for the market. | ||
+ | By Kevin Bullis | ||
+ | |||
+ | |||
+ | Michael Grätzel, chemistry professor at the Ecoles Polytechniques Fédérales de Lausanne in Switzerland, | ||
+ | Grätzel is now working on taking advantage of the ability of nanocrystals to dramatically increase the efficiency of solar cells. | ||
+ | Technology Review asked him about the challenges to making cheap solar cells, and why new technologies like his, which take much less energy to manufacture than conventional solar cells, are so important. | ||
+ | Technology Review: Why has it been so difficult to make efficient, yet inexpensive solar cells that could compete with fossil fuels as sources of electricity? | ||
+ | Michael Grätzel: It's perhaps just the way things evolved. Silicon cells were first made for [outer] space, and there was a lot of money available so the technology that was first developed was an expensive technology. The cell we have been developing on the other hand is closer to photosynthesis. | ||
+ | TR: What is its similarity to photosynthesis? | ||
+ | MG: That has to do with the absorption of light. Light generates electrons and positive carriers and they have to be transported. In a semiconductor silicon cell, silicon material absorbs light, but it also conducts the negative and positive charge carriers. An electric field has to be there to separate those charges. All of this has to be done by one material--silicon has to perform at least three functions. To do that, you need very pure materials, and that brings the price up. | ||
+ | On the other hand, the dye cell uses a molecule to absorb light. It's like chlorophyll in photosynthesis, | ||
+ | The real breakthrough came with the nanoscopic particles. You have hundreds of particles stacked on top of each other in our light harvesting system. | ||
+ | TR: So we have a stack of nanosized particles... | ||
+ | MG: ...covered with dye. | ||
+ | TR: The dye absorbs the light, and the electron is transferred to the nanoparticles? | ||
+ | MG: Yes. | ||
+ | TR: The image of solar cells is changing. They used to be ugly boxes added to roofs as an afterthought. But now we are starting to see more attractive packaging, and even solar shingles (see " HYPERLINK " | ||
+ | MG: Actually, that's one of our main advantages. It's a commonly accepted fact that the photovoltaic community thinks that the " | ||
+ | [With our cells] the normal configuration has glass on both sides, and can be made to look like a colored glass. This could be used as a power-producing window or skylights or building facades. The wall or window itself is photovoltaicly active. | ||
+ | The cells can also be made on a flexible foil. Could we see them on tents, or built into clothing to charge iPods? | ||
+ | MG: Absolutely. Konarka has a program with the military to have cells built into uniforms. You can imagine why. The soldier has so much electrical gear and so they want to boost their batteries. Batteries are a huge problem--the weight--and batteries cost a huge amount of money. | ||
+ | Konarka has just HYPERLINK " | ||
+ | TR: When are we going to be able to buy your cells? | ||
+ | MG: I expect in the next couple of years. The production equipment is already there. Konarka has a production line that can make up to one megawatt [of photovoltaic capacity per year]. | ||
+ | TR: How does the efficiency of these production cells compare with conventional silicon? | ||
+ | MG: With regard to the dye-cells, silicon has a much higher efficiency; it's about twice [as much]. But when it comes to real pickup of solar power, our cell has two advantages: it picks up [light] earlier in the morning and later in the evening. And also the temperature effect isn't there--our cell is as efficient at 65 degrees [Celsius] as it is at 25 degrees, and silicon loses about 20 percent, at least. | ||
+ | If you put all of this together, silicon still has an advantage, but maybe a 20 or 30 percent advantage, not a factor of two. | ||
+ | TR: The main advantage of your cells is cost? | ||
+ | MG: A factor of 4 or 5 [lower cost than silicon] is realistic. If it's building integrated, you get additional advantages because, say you have glass, and replace it [with our cells], you would have had the glass cost anyway. | ||
+ | TR: How close is that to being competitive with electricity from fossil fuels? | ||
+ | MG: People say you should be down to 50 cents per peak watt. Our cost could be a little bit less than one dollar manufactured in China. But it depends on where you put your solar cells. If you put them in regions where you have a lot of sunshine, then the equation becomes different: you get faster payback. | ||
+ | TR: Silicon cells have a head-start ramping up production levels. This continues to raise the bar for new technologies, | ||
+ | MG: A very reputable journal [Photon Consulting] just HYPERLINK " | ||
+ | Yes, people are trying to make silicon in a different way, but there' | ||
+ | And mankind doesn' | ||
+ | TR: Why does producing your technology require less energy? | ||
+ | MG: The silicon people need to make silicon out of silicon oxide. We use an oxide that is already existing: titanium oxide. We don't need to make titanium out of titanium oxide. | ||
+ | TR: An exciting area of basic research now is using nanocrystals, | ||
+ | MG: When you go to quantum dots, you get a chance to actually harvest several electrons with one photon. So how do you collect those? The quantum dots could be used instead of a [dye] sensitizer in solar cells. When you put those on the titanium dioxide support, the quantum dot transfers an electron very rapidly. And we have shown that to happen. | ||
+ | TR: You are campaigning for increased solar-cell research funding, and not just for Grätzel cells. | ||
+ | MG: There' | ||
+ | I am excited that the United States is taking a genuine interest in solar right now, after the complete neglect for 20 years. The Carter administration supported solar, but then during the Reagan administration, | ||
+ | Friday, July 07, 2006 | ||
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+ | Beyond the Solar Panel | ||
+ | The U.S. government plans to produce a buyer' | ||
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+ | Photovoltaic shingles (in blue) can be installed in the same way as conventional shingles. About 500 square feet of them produce three kilowatts during peak sunlight, enough for most residences. Currently, they' | ||
+ | [[/ | ||
+ | |||
+ | The government tests cars for gas mileage. Now it's testing roof tiles for wattage. | ||
+ | Homeowners have long been able to partially power their homes with sunlight, but it meant clumsily mounting photovoltaic (PV) panels on the roof. Now the latest generation of PV panels look and act much like ordinary roofing tiles or shingles. And the National Institute of Standards and Technology (NIST) is HYPERLINK " | ||
+ | "A lot of people are considering the use of PV products on their homes and businesses, and in order to make decisions on whether it's a worthwhile investment you need to predict their performance," | ||
+ | The roofing materials, which use various types of solar-to-electricity conversion, are being tested for 15 months. Fanney hopes to use the data to build a computer program and database with, among other things, average flat-surface solar radiation readings for neighborhoods across the United States (as measured by the weather service at the nearest airport). Punch in the performance characteristics of the roofing product you want to use, plus your location, roof orientation and slope, and other data, and -- bingo -- you'll know what kind of wattage you can expect from your roof. | ||
+ | According to Fanney, roofing tiles and shingles with embedded solar converters have been on the market for about three years. They look like regular roofing materials, keep out the sun and rain, and can be installed in much the same way. But by generating electricity, | ||
+ | Around 500 square feet of PV tiles can produce three kilowatts of electricity, | ||
+ | "A south-facing roof on a three-bedroom home could supply 20 to 30 percent of the home's electrical needs," | ||
+ | Without subsidies and incentives, such as those in California, PV power costs about twice as much as utility power, says Thomas Leyden, vice president of east coast operations for HYPERLINK " | ||
+ | , a PV systems integrator in Berkeley, CA. That difference, however, is shrinking. "PV hardware prices have gone down tenfold in the last 15 years, thanks to new technologies, | ||
+ | Maycock is even more optimistic, projecting that the installed price will fall from today' | ||
+ | Meanwhile, Guha maintains that PV roofing is already economical at certain times of the day, in places where utilities charge extra for peak daytime usage. There, he says, it can be used to avoid paying those surcharges, a practice called "peak shaving." | ||
+ | Historically, | ||
+ | I would think there is data from current installations in Europe and | ||
+ | Japan?? Also, I understand the top surface may be a fluoropolymer film, maybe that would help to reduce adhesion of city grime? Or perchance create a new industry (chimney sweeps to roofing sweeps)? | ||
+ | Suppose for a moment that you treat these panels just like a car - say wash them once in a while with soap and water. Then rinse. With newer nano surfaces that repel water they may even be semi-self cleaning. GE has a new plastic that has this capability. | ||
+ | As you clea your eves, you can hose your PV's now and then. | ||
+ | As for slope: for best results you want to have the sun light coming perpendicular to your panels. Sloped roofs work better than flat roofs (get more light). | ||
+ | And this changes with latitude. | ||
+ | If builders start including this in their desings, house orientation and roof shapes and slopes will be designe for the local condition to optimally make use of the sun in each particular location. | ||
+ | One company makes both solar roofing tiles and PV panels. | ||
+ | site is www.openenergycorp.com . There is some other interesting things there as well. | ||
+ | do these shingles hold up well in the deep south of the east and coast areas, is humidity an issue? | ||
+ | they do, if i understand you right. as a matter of fact, normally coastlines have more sunhours that on the land, so for solar coast is perfect. it depends a little whether you place the panels very near by the sea or not. very near means a salty film on the panels which should be affoided to my believe. | ||
+ | |||
+ | PV solarpanels are good to use anywhere, don't understand me wrong. even in canada or norway. i live in the netherlands where we have very diffuse light now and then, but no problem for solar, using poly-crystalline solar modules. these are perfect for that kind of conditions. | ||
+ | |||
+ | a rule of thumb is; the hotter (not about light) a climate is the better you should use thermal-electro solar power, since PV panels don't like their working surface very (VERY) hot. at the end, its all about efficiency and how much you want to matter with that, because we are talking about percents power more or less... writing this, i think i wouldn' | ||
+ | Solar power for our homes sounds great...until you start to add all the other expensive items. | ||
+ | It would be helpful to know the full expense plus all the maintenance needs and failure rates. Also, in the tropics (like Guam), air conditioning is the real energy hog. A solar system for this might be unaffordable for most people. And then there are the typhoons.... | ||
+ | concerning solar-energy in the tropics; it is known that photo-voltaic solar panels (PV) are less efficient when the working temperature is high (that is the temp on/in the panel itself). for tropical conditions it is, efficiency-wise, | ||
+ | You have mentioned temperature being a factor on the use of solar shingles for electricity. | ||
+ | for anyone interested in new energytech, including foil-solar and stuff, but also many different other projects and ideas, go to; HYPERLINK " | ||
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+ | Tuesday, April 25, 2006 | ||
+ | Holographic Solar | ||
+ | A novel approach to concentrating sunlight could cut solar panel costs. | ||
+ | By Prachi Patel-Predd | ||
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+ | Rows of silicon solar cells alternate with rows of transparent holograms in Prism Solar' | ||
+ | Other readers liked: | ||
+ | • | ||
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+ | 7/14/2006 | ||
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+ | 6/23/2006 | ||
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+ | [[/ | ||
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+ | The main limitation of solar power right now is cost, because the crystalline silicon used to make most solar photovoltaic (PV) cells is very expensive. One approach to overcoming this cost factor is to concentrate light from the sun using mirrors or lenses, thereby reducing the total area of silicon needed to produce a given amount of electricity. But traditional light concentrators are bulky and unattractive -- less than ideal for use on suburban rooftops. | ||
+ | Now Prism Solar Technologies of Stone Ridge, NY, has developed a proof-of-concept solar module that uses holograms to concentrate light, possibly cutting the cost of solar modules by as much as 75 percent, making them competitive with electricity generated from fossil fuels. | ||
+ | The new technology replaces unsightly concentrators with sleek flat panels laminated with holograms. The panels, says Rick Lewandowski, | ||
+ | The system needs 25 to 85 percent less silicon than a crystalline silicon panel of comparable wattage, Lewandowski says, because the photovoltaic material need not cover the entire surface of a solar panel. Instead, the PV material is arranged in several rows. A layer of holograms -- laser-created patterns that diffract light -- directs light into a layer of glass where it continues to reflect off the inside surface of the glass until it finds its way to one of the strips of PV silicon. Reducing the PV material needed could bring down costs from about $4 per watt to $1.50 for crystalline silicon panels, he says. | ||
+ | The company is expecting to pull in another $6 million from interested venture capitalists and start manufacturing its first-generation modules by the end of the year, selling them at about $2.40 per watt. Next-generation modules with more advanced technology should bring down the cost further. | ||
+ | In their ability to concentrate light, holograms are not as powerful as conventional concentrators. They can multiply the amount of light falling on the cells only by as much as a factor of 10, whereas lens-based systems can increase light by a factor of 100, and some even up to 1,000. | ||
+ | ut traditional concentrators are complicated. Since the lenses or mirrors that focus light need to face the sun directly, they have to mechanically track the sun. They also heat up the solar cells, and so require a cooling system. As a result, although they redirect light with more intensity than the hologram device, " | ||
+ | Holograms have advantages that make up for their relatively weak concentration power. They can select certain frequencies and focus them on solar cells that work best at those frequencies, | ||
+ | Also, different holograms in a concentrator module can be designed to focus light from different angles -- so they don't need moving parts to track the sun. | ||
+ | Prism Solar' | ||
+ | CEO Lewandowski says the holographic modules will cost about $1.50 per watt in a few years, using their second-generation technology, which will have solar cells sandwiched between two glass panels containing holograms. At that price, they' | ||
+ | The modules' | ||
+ | Although the idea of holographic solar concentrators has been around since the early 1980s, no one has developed them commercially yet, according to Professor Stojanoff, who has investigated the technique extensively. His company, Holotec | ||
+ | in Aachen, Germany, researches and manufactures holographic materials. Also, Northeast Photosciences, | ||
+ | So, if all goes according to plan, Prism Solar could be the first company to manufacture and sell holographic solar concentrator modules. | ||
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+ | Friday, July 14, 2006 | ||
+ | How To Build a Solar Generator | ||
+ | Affordable solar power using auto parts could make this electricity source far more available. | ||
+ | By Kevin Bullis | ||
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+ | Demand for solar power is rapidly heating up (see " HYPERLINK " | ||
+ | During a stint in the Peace Corps in Lesotho in southern Africa, Matthew Orosz, an MIT graduate student advised by Harold Hemond, professor of civil and environmental engineering, | ||
+ | The basic design of Orosz' | ||
+ | The refrigerant is then cooled in two stages. The first stage recovers heat to make hot water or, in one design, to power an absorption process chiller, like the propane-powered refrigerators in RVs. The solar-generated heat would replace or augment the propane flame used in these devices. The second stage cools the refrigerant further, which improves the efficiency of the system, Orosz says. This stage will probably use cool groundwater pumped to the surface using power from the generator. The water can then be stored in a reservoir for drinking water. | ||
+ | The design uses readily available parts and tools. For example, both the feed pump and steam turbine are actually power-steering pumps used in cars and trucks. To generate electricity, | ||
+ | As a result, the complete system for generating one kilowatt of electricity and 10 kilowatts of heat, including a battery for storing the power generated, can be built for a couple thousand dollars, Orosz says, which is less than half the cost of one kilowatt of photovoltaic panels. | ||
+ | "You can't afford something that's designed for solar. You have to buy something that's mass-produced for something else -- that way the cost is reasonable," | ||
+ | Repurposed auto parts aren't the only way to go. Amy Sun, a graduate student in MIT's Media Lab, has designed an inexpensive system that uses heat from a solar concentrator to drive a type of turbine originally patented by Nicola Tesla. Rather than making complex, difficult-to-manufacture bladed turbines, Sun turned to the Tesla turbine, which consists of simpler flat disks stacked like records on a central shaft. The disks are carefully spaced to allow steam to flow between them. As the steam flows, friction between the steam and the surface of the disks causes them to rotate. "Once I have rotational shaft work, I can couple it to almost anything -- an air pump, compressor, fan, mixer, grinder, sewing machine, refrigeration compressor, and, to power those very few things that are truly electric in nature, an electric generator." | ||
+ | Of course the overall economics of these solar generator systems depend on how long they will last and how much maintenance they will require. The lifetime for Orosz' | ||
+ | Having already built a working prototype, Orosz' | ||
+ | Although their system was originally designed for Lesotho, Orosz and his colleagues believe it might appeal to amateurs elsewhere. " | ||
+ | |||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | I'm now standing in IRL's Christchurch laboratories looking at their prototype wave energy device, which has been dubbed the 'Wave Wobbler' | ||
+ | |||
+ | Alister, can you explain how this device generates electricity from ocean waves? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Well this, of course, is an experimental device -- but basically it's quite simple. The large monolithic hull you mentioned [floats] vertically in the water just below the waterline. The float sits horizontally on top of the water, and the motion of the waves oscillates the float up and down. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Okay, so the monolith is sitting in the water [and] effectively it hardly moves at all. But the float follows the surface of the waves, and the difference in the motion enables you to generate electricity [via a suitable mechanism]. | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Fundamentally, | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | And you've obviously done quite a lot of modelling to explore that? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Yes, we spent two years developing some complex [mathematical] engineering models to develop the whole concept and come up with an optimized [design]. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So I know you've had this prototype in Lyttelton harbour, which only has tiny waves. In your further testing -- when you actually get it out into the real ocean -- what sort of power output do you expect from it? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | With the larger scale version which we'll be heading towards commercialization we're expecting round about 100 kilowatts. Which is enough power to keep round about a hundred houses going. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Okay, right, it wouldn' | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Yes, that's right. And we estimate from our modelling that we'd probably get each individual device up to around about a megawatt ultimately. But they will even be larger still. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So what sort of size are you expecting for that in terms of length and mass? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Well the 100 kilowatt version, which is really our first commercial focus, may weigh between 30 and 100 tonnes in total. So it's quite a substantial device -- although, of course, you only see a small portion of it above the surface. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | How long [i.e. the length of the device] would that be underneath the water? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | It could be up to ten to 15 metres long. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | And so would you be using water as ballast -- or would it be made out of concrete, or steel, or something [equally] heavy to provide all that mass? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Yes, that's one of the secrets in fact. Most of the mass is taken up by water. So you don't have to actually tow it out [to the desired location]; you simply flood it when you get it there. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | On land it's actually quite a light-weight device, it's only when you put it into the sea that it [fills up with water and] becomes this very heavy machine? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Yes, you might argue that it's a submerged yacht with a small float sitting at the top of it. | ||
+ | * * * | ||
+ | Voiceover: | ||
+ | |||
+ | Naturally enough, IRL aren't the only company who are looking into wave energy devices. Research teams are working on a variety of different systems in countries all around the world. | ||
+ | |||
+ | The United Kingdom are investing hundred of millions of New Zealand dollars on their marine energy program, and British company Ocean Power Delivery are definitely leading the field in terms of development. | ||
+ | |||
+ | Their ' | ||
+ | |||
+ | It couldn' | ||
+ | * * * | ||
+ | Alister Gardiner: | ||
+ | |||
+ | There' | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | What are the comparative efficiencies of the devices -- do you have any sort of feel for that? | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | One can look at the Pelamis data sheets, and work out pretty quickly that their efficiency is relatively low -- perhaps just a few per cent. That has it's disadvantages in terms of the size of the device. We feel from our modelling that we can achieve a much higher efficiency than that. And so we've started with an inherent design that we think is cost efficient. | ||
+ | |||
+ | Another point, I guess, is that if a large portion of the device is below the water -- beneath the surface of the waves -- then there' | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Which is important when at least some of New Zealand' | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | Exactly, yes. New Zealand is very fortunate in its wave energy resource. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | We're fortunate in wind, too. And we've seen recently a little bit of wind coming on to the market -- there are wind farms generating a very small amount of New Zealand' | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | We think it will happen a lot quicker. | ||
+ | |||
+ | I would expect that by 2010 there will be a number of commercial (or pre-commercial) devices in the water from various suppliers. And, by 2015... maybe 2020... we'll certainly see quite substantial uptake of marine energy of various sorts. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So that's actually really quickly. | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | You've only got to look at the energy crisis in the 80s, and so on, to see the massive involvement in wind energy. Now when the fuel prices came down that more or less stopped, which is the only reason it took maybe twenty years for wind energy to get to where it is today. If that research effort had continued we would have seen wind turbines and wind farms much earlier... | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | That brings me to something else, which is whether rising energy prices are a threat to New Zealand or also something of an opportunity as well? What I'm thinking here is of Denmark. You talked about the oil crisis in the 70s, and [Denmark] responded by investing heavily in wind energy technology. And they' | ||
+ | |||
+ | Alister Gardiner: | ||
+ | |||
+ | There' | ||
+ | |||
+ | However New Zealand does need a supportive environment and an enthusiasm to capture this [opportunity]. And this is, of course, what happened in Denmark. There was a strong government support for a particular type of energy technology. | ||
+ | |||
+ | We certainly need that sort of involvement (I think) within New Zealand. Both from the energy companies -- who are obviously very keen on these technologies -- and probably government leadership [as well], and obviously the manufacturing companies that will benefit down the track. | ||
+ | * * * | ||
+ | Voiceover: | ||
+ | |||
+ | IRL have clearly come a very long way with their 'Wave Wobbler' | ||
+ | |||
+ | Theme music... | ||
+ | * * * | ||
+ | Further information on wave energy devices: | ||
+ | Read more about the HYPERLINK " | ||
+ | Read more about the Britain' | ||
+ | Read more about HYPERLINK " | ||
+ | What on earth is a Grätzel solar cell, and why is it so important? | Jan 01, 1900 00:04 | ||
+ | | ||
+ | This is a transcript of an episode of Public Address Science which was originally broadcast on HYPERLINK " | ||
+ | You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the ' | ||
+ | * * * | ||
+ | Theme music... | ||
+ | |||
+ | Voiceover: | ||
+ | |||
+ | Solar energy... in theory, it should be the answer to all our energy problems. Properly managed, more than enough solar energy falls on the roofs of New Zealand houses to provide all our domestic electricity needs. | ||
+ | |||
+ | So why don't we make use of it? | ||
+ | |||
+ | One problem is that -- fairly obviously -- the sun only shines during the day, which means that storage batteries [or similar] are required to provide energy for use at night. The other problem is that the solar cells used to generate electricity from sunlight are incredibly expensive. | ||
+ | |||
+ | That's because the raw silicon ingots used for solar cell manufacture require production technology that is astonishingly high-tech, enormously energy-intensive, | ||
+ | |||
+ | And why would you pay that sort of money when you get virtually unlimited electricity out of the power lines at a fraction of the cost and effort? | ||
+ | |||
+ | But the price of solar generated electricity is actually coming down. For each doubling of production capacity in the factories that manufacture solar cells, the price has fallen by around 20 per cent. In recent years, that's equated to a price drop of around 5 per cent per annum. | ||
+ | |||
+ | So do we all just have to wait for a few decades until we can afford those shiny solar-electricity panels on our roof? | ||
+ | |||
+ | Well, not necessarily. A new type of solar cell technology has emerged which looks set to change everything. Grätzel solar cells seem likely to slash the cost of solar generated electricity. They' | ||
+ | |||
+ | One of the research teams at the forefront of Grätzel solar cell technology is the Nanomaterials Research Centre at Massey University. I talked to Dr Wayne Campbell about what the future might hold for solar energy. | ||
+ | |||
+ | I asked him to start by explaining how conventional silicon solar cells are made. | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | The common silicon solar cell [which] you can buy is basically made from pure silicon ingots. It' | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So putting it in very simplistic terms: the energy in the photons of sunlight knocks loose electrons from the doped silicon material, which produces an electric current. In contrast, how do Grätzel cells work -- and how are they made? | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | It's a photoelectochemical cell. It works completely differently really. In a simple sense you have a dye, which absorbs light [and] excites an electron up to a higher energy part of the molecule. From there that energy transfers to a semi-conductor -- in this case it's usually Titanium dioxide -- and from there it's collected on a transparent conducting surface. It's basically photoexcitation followed by charge separation... and then you get the loop of the electron back to the dye again. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So the energy from the sunlight is first absorbed into a dye, and then there' | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | It's a very thin layer, so it's very cheap. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | And is the manufacture of Grätzel cells a simpler production process than for conventional silicon cells? | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | Yeah, basically [either] it's screen printing, or simple pyrolysis, or plasma deposition. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So I know that your research group have been collaborating with Professor Grätzel who invented these Grätzel cells in Switzerland. What aspect of the technology are you actually looking at? | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | Our main area [is] not so much developing the cell anymore -- it's just developing a better dye for these cells. The current dyes that are used are quite expensive because they' | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So you've had quite a bit of success with your research. What are the advantages of the new Grätzel cell dyes that your team has developed. | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | It's a lot cheaper to make than the Ruthenium dyes -- basically because it doesn' | ||
+ | |||
+ | It's based on a chlorophyll molecule, which is the porphyrin haem group in blood (the red molecule in blood). [So] there' | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So basing your dyes on chlorophyll, | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | The best for the Grätzel cell was with the Ruthenium dye -- and that's quoted at 10.1 per cent. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Okay, and with the new dye that you've developed? | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | The latest report from Grätzel' | ||
+ | |||
+ | The dye itself hasn't actually been optimised properly in the cell either. [Grätzel' | ||
+ | |||
+ | By modifying things like [the electrolytes] you can actually get a lot more performance out of the cell. We expect even better than 7 per cent, definitely. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So you've got good efficiency -- but not quite as good as normal silicon solar cells, which are around the 9 to 15 per cent range, but of course your Grätzel cells would end up being much cheaper, wouldn' | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | Probably it's going to be [about] one-tenth the cost -- but we don't have any exact figures really, at the moment. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Wow, that would be a significant cost reduction compared to the comparatively slow rate that the price of conventional solar cells is dropping. So even if the Grätzel cells stay at their current efficiency you're still cutting something like four-fifths off the price on a per watt basis (in comparison to silicon-based cells). | ||
+ | |||
+ | Dr Wayne Campbell: | ||
+ | |||
+ | Yeah... [the Grätzel cells will only be] a fraction of the [current] cost. | ||
+ | * * * | ||
+ | Voiceover: | ||
+ | |||
+ | Despite a somewhat lower efficiency, the much lower cost of Grätzel solar cells is certain to bring about a dramatic sea-change in the amount of solar-derived electricity in our society' | ||
+ | |||
+ | Dr Campbell expects to see Grätzel cells based on the more expensive Ruthenium dyes in shops within the next few years. Although it may take a while longer before cells with the cheaper chlorophyll-based dyes make an appearance. | ||
+ | |||
+ | Either way, the Grätzel solar cells are another important part of the jigsaw of technologies that will be needed to ensure a secure energy future. | ||
+ | |||
+ | Theme music... | ||
+ | * * * | ||
+ | Further information on Grätzel solar cells: | ||
+ | Read more about HYPERLINK " | ||
+ | Read more about HYPERLINK " | ||
+ | Read more about the HYPERLINK " | ||
+ | Read about HYPERLINK " | ||
+ | | ||
+ | | ||
+ | |||
+ | |||
+ | Will the Pulse Detonation Engine Help to Address New Zealand' | ||
+ | | ||
+ | This is a transcript of an episode of Public Address Science which was originally broadcast on HYPERLINK " | ||
+ | You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the ' | ||
+ | * * * | ||
+ | Theme music... | ||
+ | |||
+ | Background: | ||
+ | |||
+ | [Sound of a blackbird singing] | ||
+ | |||
+ | Voiceover: | ||
+ | |||
+ | For some people the song of a blackbird is the most beautiful sound in the world. Other people' | ||
+ | |||
+ | Background: | ||
+ | |||
+ | [Sound of a pulsejet flyby] | ||
+ | |||
+ | Voiceover (cont): | ||
+ | |||
+ | It's the sound of a pulsejet engine. And if you lived in London from 1944 to 1945 you might not be quite so enthusiastic about hearing it. Pulsejets powered the 10,000 Nazi V1 missiles that rained down upon England during World War II. | ||
+ | |||
+ | I've got the engineering drawings of the V1 pulsejet engine sitting in front of me. It's pretty much the simplest machine imaginable. It's literally just an empty tube with one end blocked off by a bank of one-way reed valves. | ||
+ | |||
+ | [A pulsejet] works just like a two-stroke lawnmower motor -- but without the piston. Air is drawn in through the reed valves, fuel is injected, and then the fuel is exploded. But rather than the explosion pushing on a piston, it pushes hot gas out the back of the engine at high speed... thus producing thrust. | ||
+ | |||
+ | It couldn' | ||
+ | |||
+ | So why don't they? Well, the answer is efficiency. Basically a pulsejet engine doesn' | ||
+ | |||
+ | A pulsejet engine is inefficient because the fuel is combusted in a subsonic explosion. This means that the pulsejet operates with a very low compression ratio. An efficient diesel car engine might operate with a compression ratio of 20:1, whereas the pistonless pulsejet engine can only achieve compression ratios of around 2:1. | ||
+ | |||
+ | But what if the explosion were like this...? | ||
+ | |||
+ | Background: | ||
+ | |||
+ | [Sound of a detonation explosion] | ||
+ | |||
+ | Voiceover (cont): | ||
+ | |||
+ | My ears are slightly ringing. That's the sort of supersonic detonation combustion that you can achieve if you get just the right conditions. | ||
+ | |||
+ | In this type of detonation explosion the compression ratio can reach 100:1, [which is] much higher than a normal jet engine. A pulsejet with this sort of compression ratio is called a pulse detonation engine. If such an engine could be successfully developed then it would be a breakthrough in aircraft efficiency and cost. | ||
+ | |||
+ | And that [could have] important implications for New Zealand. It would allow the air-transportation of goods and tourists (to and from) New Zealand at much lower cost, and using much less carbon dioxide-producing fuel. [In other words, reducing the energy consumption and greenhouse gas emissions for each 'air mile' | ||
+ | |||
+ | Dr John Hoke works for the United States Air Force Research Laboratory in Dayton, Ohio. He's the head researcher on their pulse detonation engine development programme. His research team have been testing their newly designed pulse detonation engine on a Rutan Long-EZ aircraft. I asked Dr Hoke how things have been going... | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | Well, we're doing basic and applied research here. We're able to detonate most practical fuels, [and] we've done high speed taxi tests with [the Rutan Long-EZ] aircraft with a pulse detonation engine attached. We've not flown that aircraft yet with a pulse detonation engine. We have every intent to do that, but at this point we're still doing research. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So you've successfully managed to achieve detonation combustion in your engine -- and therefore a much higher compression ratio than in a pulsejet. What sort of improvement in efficiency has this translated into? | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | When you detonate a fuel-air mixture, you're going to get about three to four times improvement in efficiency over what the pulsejets are getting. You also have much higher exhaust gas velocities. So where the pulsejet typically operated at about Mach 0.6 or [Mach] 0.8, the pulse detonation engine is thought to be able to run very efficiently at Mach 2 to [Mach] 4. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Okay... Mach 2 to [Mach] 4 -- in other words between two and four times the speed of sound -- that's a much faster speed than passenger aircraft operate at today. So would the pulse detonation engine actually be a suitable replacement for the ordinary turbofan jet engines on commercial aircraft? | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | The turbofan [engine] is made for lower speed. You wouldn' | ||
+ | |||
+ | Interviewer (interruption): | ||
+ | |||
+ | ... which is the combustion process you'd have in a normal jet aircraft engine... | ||
+ | |||
+ | Dr John Hoke (cont): | ||
+ | |||
+ | ... yes. And what's thought for commercial application would be to take this constant volume combustor, and stick it in the middle of one of your turbofans. And then you're talking about potentially a 5 to 27 per cent increase in efficiency of fuel economy. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So by sticking a pulse detonation engine inside a normal jet engine -- to replace the combustor -- you can get up to a 27 per cent increase in fuel efficiency. In aircraft terms, that's huge! | ||
+ | |||
+ | But what about the case where you actually want to operate a commercial airliner at, say, two or three times the speed of sound, maybe as a replacement for Concorde? Would a straight pulse detonation engine -- the sort you're working on now -- have an application in this context? | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | Potentially, | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | Okay, that's quite surprising. I've heard a pulsejet engine, and they are really loud. But you're saying a pulse detonation engine isn't actually that bad? | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | Well, you're definitely wearing hearing protection. The sound levels coming out the back of the pulse detonation engine are very directional -- so if you're standing down behind the engine you're gonna see some pretty loud noise levels, I think. At the exit of the pulse detonation engine you're talking about 190 to 210 decibels, and I believe your ears start to bleed around 160 [decibels]. But when you're travelling Mach 2 [or] Mach 3 the sound is behind you. I think you have more serious [noise] issues with the aircraft sonic boom. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So talking about a pulse detonation engine in the context of a potential high-speed application [such as] a Concorde replacement -- it's so mechanically simple compared to a conventional supersonic aircraft engine -- have you got any feel for how much that might reduce cost? | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | Our best guess is about one hundred times cheaper. It could potentially be huge. | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | A hundred times cheaper really would be huge... | ||
+ | |||
+ | So coming back to something you mentioned earlier about running your pulse detonation engine on a variety of fuels -- I was wondering if you'd tried it on bioethanol or biodiesel? | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | We've almost detonated everything, I'd say. We've done ethanol, we've done gasoline, we've done propane, we've done ethylene... hydrogen is one of my favourite fuels. | ||
+ | |||
+ | We've done aviation gasoline, [and] the jet fuels work fine. The one thing was biodiesel -- we haven' | ||
+ | |||
+ | Interviewer: | ||
+ | |||
+ | So when do you see pulse detonation engines being commercialized, | ||
+ | |||
+ | Dr John Hoke: | ||
+ | |||
+ | Theoretically the pulse detonation cycle [or] constant volume combustion cycle -- however you want to put it -- I think has a lot potential. As far as making it practical we still have yet to see how that's gonna all pan out. The thermodynamics says it should be more efficient than the constant pressure combustion [which is intrinsic to] the pulsejet and the gas turbine engine. So I'm very hopeful there. | ||
+ | |||
+ | As far as where it would first be used: it would probably be a pure pulse detonation engine, and it will be probably used for a drone or a missile-type of application -- where... it's un-manned and you're looking for a cheap engine and you're looking for fast flight. | ||
+ | |||
+ | Commercially -- and this may take off really quickly -- it depends on the engine companies and their research budgets. If the hybrid-turbine engine (using our constant volume [pulse detonation engine] combustor)... starts to pan out, that's gonna be a huge cost-saver for the airlines, and that could go very, very quickly. | ||
+ | * * * | ||
+ | Voiceover: | ||
+ | |||
+ | So Pulse Detonation Engines offer the possibility of significantly reduced fuel consumption for normal sub-sonic commercial aircraft -- and even the option of running on biofuels. | ||
+ | |||
+ | But also, perhaps, they may usher in a new generation of lower-cost and more fuel-efficient supersonic aircraft. All of which is good news for a country as dependent on air transport as New Zealand. | ||
+ | |||
+ | Theme music... | ||
+ | * * * | ||
+ | Further information on pulse detonation engines: | ||
+ | Read more about Dr John Hoke's research work into pulse detonation engines on the HYPERLINK " | ||
+ | Read more about the working principles of the United States Air Force Research Laboratory' | ||
+ | Read more about HYPERLINK " | ||
+ | Read more about Dr Hoke's test-bed aircraft: the HYPERLINK " | ||
+ | Read about HYPERLINK " | ||
+ | Read more about the HYPERLINK " | ||
+ | |||
+ | |||
+ | | ||
+ | | ||
+ | |||
+ | |||
+ | Is Body Hacking as Thoroughly Distasteful as it Sounds? | Jan 01, 1900 00:02 | ||
+ | | ||
+ | This episode of Public Address Science was originally broadcast on HYPERLINK " | ||
+ | You can listen to the programme by clicking on the 'Play the audio for this post' link at the top of this page or the ' | ||
+ | Further information on body hacking: | ||
+ | Read more about body hacking (and body modification in general) in the HYPERLINK " | ||
+ | Read more about Quinn Norton, a journalist and body hacking enthusiast, in HYPERLINK " | ||
+ | | ||
+ | | ||
+ | [[/ | ||
+ | |||
+ | Can Thorium Reactors Solve the World' | ||
+ | | ||
+ | This episode of Public Address Science was originally broadcast on HYPERLINK " | ||
+ | You can listen to the programme by clicking on the 'Play the audio for this post' link at the top of this page or the ' | ||
+ | Further information on Thorium reactors: | ||
+ | Read more about Thorium reactors in HYPERLINK " | ||
+ | Quantum Dots - Versatile, Longer Lasting Fluorescent Tags for Biology Research | ||
+ | Shortcomings in Traditional Biological Taggants | ||
+ | It is of great benefit in many types of biological research and industry to mark microscopic structures (cells, bacteria, etc) with fluorescent materials in order to track their movements and activities within an organism or other medium. Traditionally the favored materials for such applications have been organic dyes, which can be chemically engineered to adhere to a diverse variety of cellular structures. After the dye comes into contact with the proper cellular structure, technicians may use light of a certain wavelength to excite the dye into fluorescence, | ||
+ | Limited absorptive and emissive capabilities of organic dyes | ||
+ | Unfortunately, | ||
+ | Quantum Dots - superior fluorescent properties | ||
+ | Evident Technologies is the world' | ||
+ | Quantum Dots - A Superior Biological Taggant | ||
+ | Organic Dyes - fixed emissions | ||
+ | Organic dye fluorescence is controlled entirely by the molecular bonding properties of each individual dye. Incident radiation absorbed by an organic dye molecule moves electrons into excited states, whereupon they decay and release light radiation. This emission cannot be altered because it corresponds to pre-set excited states of the dye molecule that are inherent to every molecule of that type. | ||
+ | Quantum Dots from Evident - tuned to absorb or emit any visible or IR wavelength | ||
+ | Evident' | ||
+ | Quantum Dots from Evident - How They Do More | ||
+ | Evident' | ||
+ | Quantum Dot Optical and Spectral Properties | ||
+ | The underlying quantum dots within Evident' | ||
+ | have distinctive optical and spectral properties that provide unique properties and benefits for a rich variety of life science applications: | ||
+ | Fluorescence | ||
+ | Tunable emission - | ||
+ | have a peak emission wavelengths dependent upon the composition and size of the underlying quantum dots. Currently, peak emission wavelengths are available from 490-620nm in 20nm increments. Peak emission wavelengths from 350nm-480nm, | ||
+ | Narrow bandwidth (Full Width Half Max. e.g. FWHM & | ||
+ | emit light within a narrow bell-shaped (Gaussian) spectrum without any shoulders and centered at the peak wavelength. In the visible portion of the spectrum the FWHM is less than 30nm. | ||
+ | Absorption | ||
+ | Broadband absorption - In contrast to organic fluorophores that have a narrow absorption spectra, | ||
+ | have the unique property that all light that has a shorter wavelength than the emission wavelength can be absorbed with increasing strength at shorter wavelengths. | ||
+ | Stokes shift - In the visible portion of the spectrum, the peak emission wavelength is shifted from the absorption onset by 15nm. Additionally an excitation source shorter than the emission wavelength can be used. Therefore the peak emission wavelength is effectively independent of the excitation source and the effective stoke shift can be tens to hundreds of nanometers. | ||
+ | Brightness | ||
+ | |||
+ | are incredibly bright with large quantum yields, large absorption cross section over a wide bandwidth, and offer the possibility of longer integration times. | ||
+ | Lifetime characteristics/ | ||
+ | |||
+ | are based on inorganic particles that are inherently more photos stable than organic molecules and as such they can survive orders of magnitudes longer than organic fluorescent dyes under intense illumination. | ||
+ | have been shown no photodegradation after more than 2 hours of constant illumination. | ||
+ | Fluorescence lifetime | ||
+ | The fluorescent lifetime (electronic lifetime) of visibly emitting | ||
+ | have been measured to be 15-20ns independent of the emission wavelength. The fluorescence lifetime is orders of magnitude longer than typical autofluoresence lifetimes and many multiples of typical organic dye lifetimes. | ||
+ | Two photon absorption/ up-conversion | ||
+ | Quantum dots have large two photon absorption cross sections that allow for narrowband visible light to be emitted when long wavelength IR lasers are focused on the | ||
+ | . | ||
+ | Electron microscopy | ||
+ | Because | ||
+ | are composed of inorganic semiconductor nanocrystal particles, they can be also be visualized with electron microscopes. | ||
+ | Quantum Dots - A Versatile Research Tool in Life Science | ||
+ | Quantum dots offer the advantage of superior absorption/ | ||
+ | | ||
+ | | ||
+ | For More Information: | ||
+ | | ||
+ | | ||
+ | | ||
+ | Protocols" | ||
+ | | ||
+ | | ||
+ | Cheaper solar cells | ||
+ | | ||
+ | | ||
+ | Friday, 06 April 2007 | ||
+ | | ||
+ | Solar cell technology developed by the University’s Nanomaterials Research Centre will enable New Zealanders to generate electricity from sunlight at a 10th of the cost of current silicon-based photo-electric solar cells. | ||
+ | Dr Wayne Campbell and researchers in the centre have developed a range of coloured dyes for use in dye-sensitised solar cells. | ||
+ | The synthetic dyes are made from simple organic compounds closely related to those found in nature. The green dye Dr Campbell (pictured) is synthetic chlorophyll derived from the light-harvesting pigment plants use for photosynthesis. | ||
+ | Other dyes being tested in the cells are based on haemoglobin, | ||
+ | Dr Campbell says that unlike the silicon-based solar cells currently on the market, the 10x10cm green demonstration cells generate enough electricity to run a small fan in low-light conditions – making them ideal for cloudy climates. The dyes can also be incorporated into tinted windows that trap to generate electricity. | ||
+ | He says the green solar cells are more environmentally friendly than silicon-based cells as they are made from titanium dioxide – a plentiful, renewable and non-toxic white mineral obtained from New Zealand’s black sand. Titanium dioxide is already used in consumer products such as toothpaste, white paints and cosmetics. | ||
+ | | ||
+ | “The expected cost is one 10th of the price of a silicon-based solar panel, making them more attractive and accessible to home-owners.” | ||
+ | The Centre’s new director, Professor Ashton Partridge, says they now have the most efficient porphyrin dye in the world and aim to optimise and improve the cell construction and performance before developing the cells commercially. | ||
+ | “The next step is to take these dyes and incorporate them into roofing materials or wall panels. We have had many expressions of interest from New Zealand companies, | ||
+ | He says the ultimate aim of using nanotechnology to develop a better solar cell is to convert as much sunlight to electricity as possible. | ||
+ | “The energy that reaches earth from sunlight in one hour is more than that used by all human activities in one year”. | ||
+ | The solar cells are the product of more than 10 years research funded by the Foundation for Research, Science and Technology. | ||
+ | | ||
+ | | ||
+ | Photo-Voltaic (PV) - PV panels convert sunlight into electricity. | ||
+ | You've probably seen calculators that have solar cells - calculators that never need batteries, and in some cases don't even have an off button. As long as you have enough light, they seem to work forever. You may have seen larger solar panels - on emergency road signs or call boxes, on buoys, even in parking lots to power lights. Although these larger panels aren't as common as solar powered calculators, | ||
+ | You have probably also been hearing about the "solar revolution" | ||
+ | | ||
+ | Residential solar electric power systems offer an excellent alternative for people who are looking for back-up power or stand alone power systems. Solar electric systems are ideal for those who choose to live beyond the reach of conventional electric power. Solar electric power is clean, affordable and requires very little maintenance. More than 50,000 families in the U.S. have chosen solar power for their electric systems. Throughout the world, many thousands of people depend on solar electricity as their primary source of power. | ||
+ | If you choose to live more than a third of a mile from power, photovoltaic' | ||
+ | Home Made PV Cells - HYPERLINK " | ||
+ | | ||
+ | An Experts View: | ||
+ | I found my views on this subject to be extremely controversial. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | [[http:// | ||
+ | |||
+ | ]][[/ | ||
+ | |||
+ | GO Solar Company is one of the few businesses that remains in the field to this time. We have watched the resurgence of the market as solar panels become more efficient and less expensive. | ||
+ | |||
+ | Graham F. Owen | ||
+ | President | ||
+ | ph: INCLUDEPICTURE " | ||
+ | email: | ||
+ | website: | ||
+ | LED Solar Tracker | ||
+ | Duane C. Johnson < HYPERLINK " | ||
+ | | ||
+ | | ||
+ | Info: | ||
+ | The Schatz Solar Hydrogen Project | ||
+ | The Schatz solar hydrogen project was initiated in the fall of 1989 with the goal of demonstrating that solar hydrogen is a reliable and abundant energy source that is ready for use today. This full-time, automatic standalone energy system takes advantage of the solar hydrogen cycle to power the air compressor that aerates the aquarium at Humboldt State University' | ||
+ | How it works | ||
+ | This is how the system works: sunlight hits the photovoltaic panels, which convert solar energy into electricity. This electricity is used in two ways: it powers the air compressor directly, and it powers an electrolyzer. In the electrolyzer the electricity splits water into hydrogen and oxygen. The oxygen gas is vented to the atmosphere and the hydrogen gas is stored in tanks behind the lab. | ||
+ | At night or when the clouds are thick, the system automatically shifts to fuel cell operation. The fuel cell directly converts chemical energy into electricity by combining the stored hydrogen with oxygen from the air. This shortcuts the usual way of obtaining electricity from a fuel, which involves burning the fuel, using the heat to boil water, using the steam to turn a turbine, and using the turbine to turn a generator. | ||
+ | The direct conversion process of a fuel cell is quiet and efficient and its only byproduct is pure water. In this way, water and sunlight, both natural and abundant, are used in a cycle to produce power. No fossil fuels are used; no pollution is created. And because hydrogen stores solar energy, the fish in the marine lab enjoy solar air bubbles twenty-four hours a day. HYPERLINK " | ||
+ | | ||
+ | Research: | ||
+ | "The Potential Market for Photovoltaics and Other Distributed Resources in | ||
+ | Rural Electric Cooperatives," | ||
+ | Cheney (Utility Photovoltaic Group), forthcoming in Energy Journal, 2000. | ||
+ | See prepublication draft online at | ||
+ | | ||
+ | | ||
+ | |||
+ | " | ||
+ | | ||
+ | series "Solar Energy in Agriculture," | ||
+ | in Energy in World Agriculture, | ||
+ | |||
+ | Applications for Photovoltaic Power for Rural Electric Systems, by Jerry L. | ||
+ | Anderson, Rollan G. Skinner, and | ||
+ | E. Stetson. | ||
+ | the American Society of Agricultural Engineers, Summer 1991. Abstract: | ||
+ | Previous applications of solar energy for water pumping are briefly | ||
+ | reviewed. | ||
+ | for small loads (1 kW or less). | ||
+ | watt. Electric utilities serving small, remote rural loads are providing | ||
+ | PV's as a cost effective energy source. | ||
+ | cost is expected to decrease and the reliability to increase. | ||
+ | |||
+ | Solar Greenhouses Horticulture Resource List, by Lane Greer, Appropriate | ||
+ | Technology Transfer for Rural Areas (ATTRA) March 1999. See | ||
+ | | ||
+ | | ||
+ | |||
+ | Designing and Implementing a Photovoltaic Tariff for a Rural Electric | ||
+ | Cooperative, | ||
+ | American Solar Energy Society. | ||
+ | |||
+ | Rural Energy Alternatives Project, by Lloyd Hoffstatter, | ||
+ | State Energy Office. | ||
+ | American Solar Energy Society. | ||
+ | |||
+ | [[mailto: | ||
+ | |||
+ | R&C Solar/Wind Powered House | ||
+ | Contact Wayne and Barbara at HYPERLINK " | ||
+ | | ||
+ | | ||
+ | Introduction | ||
+ | This web site describes all the fun my wife and I have had building a solar-powered home on remote property. Before embarking on this adventure, we found it really helpful to read the stories of others, and to learn from their experience. So we wanted to return the favor. The goal is not to dwell on the technical stuff, but to give you a feel for planning, building, and living in this home. We hope that some readers will find that useful. Be warned, there’s some straight talk, and some of it isn't politically correct. If there’s positive feedback, we’ll improve the site as time allows. | ||
+ | The site is about 20 pages of text, includes many links, and some photos where appropriate (click on the thumbnail photos to see a larger version, and then use your browser' | ||
+ | The links at the top are for sections, some of which have multiple pages. The links at the bottom will advance you to the next page. There is a single page version if you want the whole site on one long page. | ||
+ | | ||
+ | | ||
+ | |||
+ | [[/ | ||
+ | |||
+ | Chicago School Enters New Era In Energy And Education | ||
+ | Chicago, Illinois . . . 3 March 2000 . . . The City of Chicago, Commonwealth Edison, the Chicago Public Schools, the United States Department of Energy, the International Brotherhood of Electrical Workers (Local #134), and the Illinois Department of Commerce and Community Affairs announced today that they have collaborated in providing Chicago’s Reilly Elementary School with a 10 kilowatt solar (photovoltaic or PV) electric rooftop system. The system was provided by Spire Solar Chicago, a PV module manufacturing and systems business that recently located in Chicago as a result of collaboration between Spire Corporation of Bedford, Massachusetts, | ||
+ | | ||
+ | |||
+ | [[http:// | ||
+ | |||
+ | Grid Connected PV… What's It Worth? | ||
+ | by James R. Udall HYPERLINK " | ||
+ | | ||
+ | | ||
+ | The Electric Boat Association of the Americas is an organization of individuals with an interest in electric-powered boating. Most EBAA members reside in the United States and Canada, but the membership includes a few individuals in the Caribbean, Central and South America. We even have members in Australia and Africa. We welcome new members from anywhere in the world | ||
+ | Since electrically propelled vessels do not put hydrocarbons in the air, do not put oil and other pollutants in the water and don't make loud noises, many EBAA members have a keen interest in the positive environmental aspects of electric propulsion. Other members simply like the idea of clean, silent, inexpensive boating. Low maintenance and reliability are appealing to all the members. | ||
+ | | ||
+ | | ||
+ | Solar photovoltaic cells can generate electricity from the sun's rays. The HYPERLINK " | ||
+ | Solar electric houses today are designed for three types of operation: | ||
+ | Stand alone or " HYPERLINK " | ||
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+ | Our latest development is a solar cell kit which is used for instructional purposes in universities and classrooms. We are presently highlighting the release of the HYPERLINK " | ||
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+ | Terrestrial solar cell efficiency has taken another leap forward, converting a record 32.3 percent of the sun's energy into useable power — more than doubling current efficiency ratings. | ||
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+ | Pictures and Bio's of off-gridders | ||
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+ | PVWATTS calculates electrical energy produced by a grid-connected photovoltaic (PV) system. Currently, PVWATTS can be used for locations within the United States and its territories, | ||
+ | Viva Solar Inc. is a Canadian incorporated company with head offices in Toronto and production facilities in Krasnodon, a city in Southern Russia where major developments in solar science were made. | ||
+ | The company has been manufacturing under Canadian supervision monocrystal Silicon solar photovoltaic cells and modules since 1990. The production facility has an annual capacity of 800 KWp and employs more than 70 skilled workers. | ||
+ | The important feature of this production facility lies in its versatility and flexibility allowing for rapid change of the product. Therefore this production approach is particularly attractive for small series manufacturing. | ||
+ | Numerous patents and know-how are used in Viva Solar production technology. Viva Solar PV cells and modules are known for high durability, stable power output and an elegant appearance which does not degrade with time. | ||
+ | The research and development department of the company is constantly improving the PV cells and the modules technical parameters. The minimum commercial guaranteed efficiency of Viva Solar' cells is currently 13% with majority of the cells having 14-16% efficiency. Another feature of R&D is a further development of double-sided cells and modules able to produce power from both sides thereby enhancing overall power output. | ||
+ | The company employs world class scientists, highly qualified engineers, technicians and workers with extensive experience in the solar industry of 10 to 35 years. | ||
+ | We are proud that our staff members are amongst the pioneers of world and Russian solar industry. | ||
+ | The company has export solar cells and modules for 10 years through an extended network of distributors in many countries under our own and OEM trade marks. | ||
+ | We strongly believe in the bright prospects of the solar industry . Our mission is to bring solar energy to the world marketplace and to make life sustainable for all people. | ||
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+ | Dealers: | ||
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+ | Solar electric power is an alternative energy source that is cleaner, more reliable, longer lasting and environmentally safer than nuclear and fossil fuels. Solar power systems are practical and available now. Get renewable energy equipment through the PV Bulk Buy and save money. SOLutions in Solar Electricity offers PV modules and inverters at " | ||
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+ | Take care of personal protection (fine dusk mask, safety glasses, laboratory coat, gloves). | ||
+ | Keep the work area where dyes are used clean ! | ||
+ | Clean up (well !) after preparing a solution. | ||
+ | When dye is spilled (both powder and solution) clean up immediately. | ||
+ | Keep containers of solvents and dye solutions closed. | ||
+ | Label containers clearly with the name of the dye and solvent and its concentration. | ||
+ | Wash hands after handling laser dyes/ | ||
+ | Do not eat, drink, smoke or store food or beverages in work areas where dyes are in use. | ||
+ | Personal protective equipment | ||
+ | Use a fine dusk mask. | ||
+ | Use a laboratory fume hood or glove box. | ||
+ | Use safety eye wear. | ||
+ | Use a laboratory coat. | ||
+ | Use impervious (butyl) gloves when handling dye solutions. | ||
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