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Solar lighting/power idea - viable?

  1. Dec 9, 2009 #1
    Hello. I've been kicking an idea around for a while, and can't decide if it is worth pursuing. The main idea was to simply provide indoor lighting both day and night. The more evolved idea is to combine several current technologies to provide indoor lighting, power, heat, refrigeration and pure water.
    The basic premise is to have a reflective dish focused up into a small reflective dish that focus back down to a magnifying lens near the base of the first dish. The lens would focus onto a glass coil perpendicularly, so the top coil takes the main heat. The light that passes through the coil would travel fiber optic cables to provide indoor lighting. The coil would be water cooled (or conversely, the lens would focus sunlight onto the coil to vaporize the water) with water flowing upwards through the coil from a source. The steam would be used to power a small turbine for generating power, and then the water would be recaptured in a serparate tank. The excess air pressure could be harnessed to compress a tank. The compressed air could be used to cool a refrigeration box that has metal bands wrapping around the inside, small nozzles hit the bands with compressed air to provide refrigeration. Edge of large dish would have solar cells for trickle charging a battery. The dish would close up at night, and rings of leds around the magnifying lens would light up in an on-demand basis powered by the battery.
    Is this a feasible idea? I'm not looking for big efficiency in anything but the lighting, as the rest was something I came up with later. It just seems to me the main drawback on fiber optic lighting is strength of emitted light, but I haven't seen any systems that use magnifying lens etc to concentrate the light beam itself as it is collected. Is there a way to try to make the collected light more coherent? I know I'm tossing out several ideas simultaneously, but I thought all might be interesting for discussion.
  2. jcsd
  3. Dec 9, 2009 #2
    Individually those ideas have some merit. Together, it's doubtful.

    Fiber optic solar lighting shows great promise. Although only a small handful of companies are doing it and the price is high it has so many benefits it should become cheap and commonplace within ten years.

    Solar steam cycles are great for large scale power generation but not suitable for home generation. Without a lot of control systems you have something that needs constant operator support. Even with a solid control system, you still need to deal with problems associated with licensing a small boiler (also known as a steam bomb.). There are also no off the shelf turbines that are suitable for home generation, especially none that are cheap and require no maintenance for 10+ years.

    Solar cells on a dish are a little counterproductive because they make the dish bigger and would be almost as happy just mounted on the roof.

    LEDs to supplement the solar lighting at night is a good idea, but it would be better to put them at the point of use than at the dish, otherwise you will have losses through your light pipe.

    Look up hybrid solar lighting. You will find the lighting aspect of your idea is already well underway. It is quite possible to focus sunlight down a fiber optic cable, you just have to filter out the UV and IR first.
  4. Dec 11, 2009 #3
    Thanks for the feedback. So, there is nothing preventing the viability of this idea. It just needs the ingenuity to fabricate the different parts which are not currently commercially available at the desired price/scale. Perfect! =) Thank you
  5. Dec 19, 2009 #4
    You system is pretty complicated if you are talking about a single home installation. This would likely cost many millions of dollars, have poor efficiency, and only be able to produce a decent amount of light on bright, sunny days. If you are talking about a large scale project in an area with a lot of solar resources (a MW level system in southern CA, for example), then you might have something. In general, however, if you are using a steam turbine on a small scale you are looking at high cost and low efficiency. Plus, you are talking about a very complicated system with lots of supporting systems that add cost and inefficiency. Plus, you need a way of tracking the sun with this type of focusing system.
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