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we need solar energy in our daily use. if cost affortable we can save globle threat of envormental disturbances, there by saving earth and mankind

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capture heat from the sun to create a heat exchanging hot water heater. If 75% of the USA used heat exchanging technology to heat water, when they could, how much energy and money would we save? How affordable is this technology? It is black aluminum or copper tubing with water connected to an insulated tank; the tank has a coiled tubing running through it with cold water in and hot water leaving as it is heated in the tubing coil. I have heard these things get so hot that anti-freeze coolant is needed to keep the water from boiling. How do you measure 'affordable'? What means are there to provide incentives? I think it would be inexpensive to install this device on most sites but I think people are too busy to bother to investigate. Incentives or penalties are probably the most effective way to get people to get things done (or lose a local election ). For your living space- store heat overnight in a room or rooms in your building that have many windows, made of black bricks that can retain heat, and has windows or doors that allow the heat into the other parts of the building during the night or cold times. These rooms can hopefully retain heat during the day and give off heat during the night. Maybe some heat exchanging tubes can supply heat by being built into your flooring and turned on and off with a simple valve that allows the hot water through the circuit. Now you need to store the suns energy for light and electricity to run motors and stuff? That would be convenient eh? Perhaps you can use wind or wave power for the other uses like running my computers and my hair clippers. I think you would save much power by using passive heating. Can I cook food using passive heating? That is what I would like to be able to do- and do it with rudimentary technology.

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If every roof in Florida had solar panels and our meters could run backwards to the grid that might provide the incentive to mainstream solar energy production.

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Solar thermal already reaches efficiencies of up to 40%. Power storage is essentially a solved issue, and the technology has been put into production world wide. http://news.cnet.com/8301 -10784_3-9775824-7.html http://news.zdnet.com/210 0-9595_22-6166113.html http://news.cnet.com/Full -steam-ahead-for-Nevada-s olar-project/2100-11392_3 -6166113.html

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Solar energy is already practical and economical today. Here is why. Often from an econmic perspective people measure the cost of wdigets from a production perspective. They leave out some costs that to them seem indirect to the prcoess. For example, we routinely hear about nuclear electricity being the cheapest to produce. But the cost does not include the 15 years environmental impact studies and attendant battles nor does it include the cost of decommissioning the plant after use. What would be the price solar electricity if large swatches of the American Southwest were layed out with even the current technology of solar. What if the UN would ring the world with a solar electircity belt comlelte with "inefficient" solar panels and highly efficient solar tehermal plants. I think the cost would be offset by the retirement of the current polutting technologies that currently damage our world and would reduce the cost of reversing the damage. In other words the true cost of the process should also include the effect of the result. When we include the overall costs (such as pollution from coal and nuclear) solar looks mighty cheap and we haven't even discussed the reduction of armament production since we would not have to fight each other for that last drop of oil.

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Solar thermal electric technology can store heated fluid and generate electricity 24 hours per day. According to a paper by Nobel Laureate Carlo Rubbia (delivered at the 2006 SolarPACES conference in Seville, Spain), a mere 15 000 square kilometres of land in the sunbelt will produce an AVERAGE power of 1000 GWe -- which is about (or more than) what the US uses now. I believe Rubbia refers here to Linear Fresnel Concentrators -- which has not been as widely used yet as parabolic trough concentrators, but will see some 400 to 800 MWe in California soon. For parabolic troughs and central receivers the land used will be 40-90% more, depending on what variant is used & how closely the mirrors are spaced. Yet the land needed to supply the US or the world with secure clean electricity in abundance is tiny. And NREL projects its cost to drop from the present ~ $120/MWh to below $50/MWh within a decade -- which apparently is below the cost of new coal (not to mention clean coal). The cost per MWh of solar thermal electric is far below the best Photovoltaic, has been for decades, and will probably remain so. Is it wise to give so little attention, and so little priority to improving and effectively promoting this and other clean energy technologies, to minimize CO2, mercury . . emissions that threaten our climate, our health and our future? I fear that our generation will be judged harshly for not doing so. Instead money is spent on oil wars that serve no purpose other than impoverishing Iraqis (and the US) and strengthening Islamist radicals & regimes.

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Dear Sirs, Just take a look at this: http://www.nrel.gov/analy sis/forum/pdfs/2003/summa ry_03.pdf http://commonhorizon.blog spot.com Thanks, Gonzalo

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I believe new emerging solar cell technology like dye solar cell and polymer solar cell will make solar energy cost effective in near future. However, conventional fuels may not be completely substituted by solar/wind/geothermal technology, what we can expect will be a hybrid of renewable with fossil fuels.

"...research should not be limited to photovoltaics; other methods of utilizing solar energy should be explored." 

The current cost of photovoltaics is too high for their large scale implementation in the third world. Moreover, the technologies and skills required to manufacture components for photovoltaics are also rare in these regions. The first step should be establishment of the infrastructure required to make mass production of photovoltaics possible. This will be best done through global outreach programs and multilateral funding. Yes, research should not be limited to photovoltaics; other methods of utilizing solar energy should be explored. One such method is to heat water to steam and then to store it in pressurized caverns underground, and then using it to turn the turbines. Another method can be the concentrated solar technique. These methods will work optimally with efficient heat exchanging systems, so research should be focused on them. If all of these solar opportunities are explored and implemented to complement one another, the overal long term cost of solar power may be brought with in the range of the third world's kitty.

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I think a discussion of solar energy should include the solar thermal generation technologies that are currently more cost-effective at large scale than photovoltaics.

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Cheap energy will make automated trashcans possible!

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Solar Energy? For me I should say YES! But how? I want to learn about Solar Energy and Wind Power. The Philippines is a tropical country so it is ideal here. But this is expensive here and very little information about Solar and Wind Power! Thanks!

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It was great to know that efficiency of some of experimental solar cell have reached 40%. 87,100 TW is the amount of sunlight that falls on the Earth's surface, 370 TW is all the energy in the wind, and 15 TW was the global rate of energy consumption in 2004 (source :- wikipedia) . Difference between energy from wind and sun is straight forward. I hope one day will come when every house will have solar roof. Even plane, train, etc. could be running on solar power. But what remains Question to me is Cost-Effectiveness and efficiency of solar cell in coming period of time. If any one wants to share information about solar power/energy/production do let me know. As a student, I am very much interested in knowing more about solar. mihir.shingala@yahoo.co.i n

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At first I would like to say that, sir this the best source energy (IN THE SCIENCE AND TECHONOLOGY POINT OF VIEW) and specially for the middle class family. This project is go reapetedly in the rural area and I lastly say that govt should finance this project in the rural area

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I used solar panels on my VA/FHA Four-plexes back in the mid 80's to heat water. The project was built to Gov. spec, however, I could not get the solar included in my appraisals at the time. I want to repeat that program now and want to go solar as much as possible. Is there VA/FHA approved solar for housing now and if so what is my best strategy to get necessary Gov. approvals and credit ? A well engineered project like this could gain a lot of positive exposure for the solar industry. Maybe one of your Solar Teconics would like to expose leading edge solar panels in a joint venture. We are also trying to go solar in another way i.e. Hydroponic (water) farming of organic vegetables both for consumption and, in the case of sugar beets, conversion to ethanol as a renewable energy source. In Texas we can do this perpetually in very large green houses by growing sugar beets which have an 85% conversion ratio.

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I think we should review and revive development of amorphous silicon solar cells. They, according to me, still will be a cost effective alternative. I was involved in the development of a-Si cells for some time. Could produce 3 sq ft area modules - double junction- in a single chamber. Stability was good. Degradation compared well, too. Foe sustainable development, Solar (SPV) is an indispensable imperative.

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For those of us old enough to remember: before the transistor and silicon valley there was the vacuumtube. Theyve got a bad reputation for their burnouts but we still use them daily in our microwave ovens: the magnetron operates at 65 % efficiency whereas a transistor would not reach more then half that for same purpose. In order to economize consumer solar electr. generation should the solar industry go retro? Thermionic electric converters (TEC) harness the whole solar spectrum with higher theoretical efficiencies of up to 70 %. Just the approach taken by Vanderbilt and Tufts univ. of engineering. (see also: advanceddiamond.com). With a 50 % lab efficiency and good radiation resistance, the goal here is 10 $ CENTS/WATT material, to be made possible by advances in IC mass-manufacturing and CVD nano-crystalline amorphous diamond coatings, either in the form of roof panels, or as cellular vacuumtubes, in conjunction with cheap CSP-devices hooked up to open source sun-tracker software. At that price who wouldnt go solar? But regardless the outcome of this, until silicon valley produces the perfect multijunction solar cell, matching the solar spectrum from a single alloy, TECs will play a future role. Perhaps our blue chip giants, with their economies of scale, could reverse-engineer TECs, make solar go more mainstream and restore some of their old glory. (Oh and while they do that, could they please phase out the incandescent lamp for (O)LEDs? It would save 20 % of worldwide electricity use-an annual production of about 268 coal-fired powerplants. Edison would no doubt be quiet happy to see the positive effects of (t)his).

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I think continuous thin film production is the best approach to drive down the cost of photovoltaics, which could be mounted on roofs with local battery or flywheel storage. The latter is also useful for wind and other intermittent sources. Solar thermal plants might be worthwhile in the Southwest, and potentially can operate as baseload plants by storing heated liquid in large tanks during the day for power generation at night.

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My photovoltaic solar stack would use a lens to concentrate sunlight into a beam that would be injected into an illumination tube to stimulate the gas to generate light that would shine on solar cells that are arrange in a hexagon. A solar stack assembly could be made up of thousand or millions of stacks. They wouldn't be as efficient as a flat display on the surface. But since most of the stack is below the surface and even at 1/3 efficiency, more electricity could be generated, the stack would be better than a surface display. My latest solar stack would be the solar steam stack. It would use a lens to concentrate sunlight into a heat beam that would strike water tubing to create steam. The steam would run a turbogenerator to generate electricity. There could be thousands or millions of stacks each producing steam to run generators. If each generator produced a kilowatt of energy, multiply them by the number of stacks used. Storage of excess energy could be in stacked flywheel units. They would be sealed and the motor/generators between the flywheels would be liquid or forced air cooled to prevent vacuum leakage. There could be two motor generators sandwiched between the flywheels that would be made from either rock quartz or one of my ultra-stressed crystalline molecular solid materials that would have magnetic bands around their circumference that would face magnetic bands in the chambers to produce a linear induction effect. My goal is for the flywheels to store at least 100 watt-hours of energy kinetically safely. As one flywheel is being respun up to speed, the other might be producing energy with the second motor/generator. In space, we should use induction coils to use the charged particles from the sun's solar wind to produce electricity. The electricity could be beamed down to earth either as microwaves or a small injection reactor might be used to produce a carrier beam that would ionize the air and allow the transmission beam to reach a surface station without loss. Solar steam might be more economical and practical than solar voltaic. Even gas cycles that would produce steam on the surface and condense below the ground to run turbogenerators might be part of the answer. I counting on the stacks to possibly be what we need for large-scale solar electrical production.

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It is not just the cost, it is about how many people are willing to switch to this kind of energy without thinking of the space that can occupy or it aesthetic. The short-term cost is much, but in long-term it pays for itself.

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I have been involved with solar energy engineering for much of my career. For most of that time, the solar energy research establishment in the US has seemed like a dead hand on this R and D enterprise for decades. The tendency has been for the establishment to promote the same old well-favored or well-connected technologies like PV and disparage cost-effective technologies like DHW and SHCOB. This poor public-sector leadership has tended to mislead private industry and investors into making poor choices. Part of the problem has been the natural inclination of well-funded science-oriented researchers to pursue merely novel if not necessarily useful paths just because this approach generates quick and plentiful reputation-enhancing publications. In addition, well-meaning engineers the national labs have too much involvement and influence with private industry, which discourages industry from working with independent researchers who might have some innovative and cost-effective ideas. There probably is a useful role that federal involvement could play, but the top down approach does not seem to work. A good first step would be for the national labs and especially NREL to stop competing with independent researchers and stop trying to pick winners in the solar derby. Many of those contributing to this page correctly point out that solar heat -- whether DWH, SHOB, or CSP - is more efficient and cost effective than PV. The DOE is enamored by high-tech PV and has diverted too much effort into that inherently limited field. This is an example of well-connected science-oriented researchers forcing the research effort into non-productive areas. DOE and NREL should step out of the limelight for a while and let some freedom of thought and cost-effective ideas flourish.

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Have solar energy scientists considered ways to duplicate the process of photosynthesis? Could we use genetic engineering to speed up the natural photosynthesis processes to acquire a new source of glucose and then make a better biofuel?

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The obvious place to put solar panels is on building roofs. If panels could be cheaply produced at about the same size and sturdiness as roofing tiles, they should be made compulsory for new construction and for re-roofing (except where some clear reason not to do so exists) over the next fifteen years, after which time building owners should be required to replace roofs with solar tiles.

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The cost of solar energy is dropping. But it is not dropping enough. So that the solar energy could be used commercially and espacially the residential use of this energy is still a dream. The cost shold be dropped down to its real production cost and this is only possible if the solar energy component producers narrow their profit margins. The solar energy is powerful enough that one can install it at his home and obtain energy for nearly all home use. Together with the wind energy, This thing can change the world

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I think that making solar more affordable is a huge priority. However, your article does NOT mention the technology with the most potential to do that. The sun's energy comes to us as heat for the most part. It also comes to us as light. Capturing solar energy to use for heating fulfills a HUGE need for energy in the world. We need to heat homes, buildings and water, as well as many industrial processes. Harnessing the sun's energy for heat is much more cost effective than using it to generate electricity. By mass producing solar thermal collection equipment, the costs will drop significantly. If a single chinese company (of several thousand companies) can install several million solar water heaters in a single year, the mass production capability is here to make this economically feasibility. PV is an excellent technology, but we should not close our eyes to the larger need of heating, as you have indicated in your article. Best regards, Don Halme, P.Eng Solar and geothermal program engineer.

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While making solar cells cheaper and more efficient is great we should also be seriously looking into solar power satellites. These will allow areas that receive low amounts of sunlight the same amount of power as those who receive full sunlight most of the year. The power is collected in space where the suns rays are not 'diluted' by the atmosphere and can be safely beamed down to a receiving station in the form of microwaves.

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Wait! Solar energy isn't economical? Then why do so many countries already use solar hot water heaters? Why do so many countries already use solar electric? Why do so many countries use more efficient building designs to conserve energy? Why do so many other countries have energy conservation policies? Are all those people in other countries just being stupid? Are they spending money foolishly? Maybe they are. But, maybe the U.S. is the place that is full of stupid people? The only challenge I see is in the mindset of the people of our nation. There are many ways that we could conserve. There are many efficient, economical ways we could use solar today. But, the people of the U.S. don't want that. They want to continue to have their cake and eat it too. And, as long as the fiscal/energy policy of our country is what it is, there is likely no way to change that mindset. Focus on the problem, not a symptom of the problem. There are no technical solutions to people problems. If you don't believe me, try it sometime. It just makes the people problems worse.

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Should be Renewable Energy! Why is solar energy singled out as being the best option? Wind energy, wave energy, tidal streams, ocean thermal and biomass are all renewable energies in various states of competitiveness. While wind energy is already competitive in a lot of sites (our lab calculated generation cost with existing technology at one site in Egypt to be around 2 USc/kWh!), wave energy is just beginning to get close. Biomass can economically be used for local combined heat and power plants, and is much better used in those than as feedstock for ethanol plants. Maybe I'm just irked because I work in wind energy...

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Here in SA, with an unstable primary energy supplier, the end-to-end costs of coal-fired power stations compared to that of of solar power are difficult to compare apple-to-apple. Coal supply risks like supply costs, wet coal, supplies running out and 450 ppm atmospheric CO2 by 2050 are costs, in my book. Are the medical costs of atmospheric pollutants added to the cost of coal-fired power plants? Not to my knowledge. Amortised over 20 years, solar power is on a par with coal. Factor in carbon fine