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Retrofitting greenhouses to make them more viable for desert agricultural production

From his talk I derived that the flexible PV material, that is soon to come out on the market, could be implemented in greenhouse designs possibly with great effect. I am proposing replacing standard glass used for the flexible PV material in a traditional hoop style/ semicircle. The ability to collect the energy from the sun could be used to power LED lighting systems that would provide the spectrum of light necessary to each specific crop. Drawing upon his ambient temperature idea I would like to also postulate that using a system of pipes run underneath the greenhouses would be capable of creating ambient temperatures suitable to crops. In colder deserts would it be possible to tap geo-thermal energy and use the same pipes that cools the greenhouses to also heat them? I viewed an interesting TED talk that discussed greenhouses that captured ocean mists for cooling and water with great effect and believe that their design could be implemented with the PV and ambient temperature designs. Thoughts and comments are greatly appreciate and most important thank you for your time.

  • Jul 12 2012: There are presently production greenhouses that recycle their water so once you obtained enough water for your crops the excess can be recycled and you just need make up water. PV could be used to power cooling pads and fans also a production technique to cool greenhouses. As for the heating with pipes there are greenhouses in production that are using waste power plant heat using underground pipes from the cooling tower. Heating cost in PA is cost of power to run pumps. With a PV system and a heat sink you could operate a greenhouse for very little. I think we could build greenhouse ranges near any or all power plants and make incredible use of the waste heat, provide jobs, food and flowers.
    • Jul 20 2012: Do you happen to have any links or other info on these technologies? Very interesting and I would love to read more about them. Thanks for the input on the discussion.
  • Jul 10 2012: The Anupam Mishra talk is absolutely wonderful and fascinating. He brings up a point about mixing art and architecture which I really believe is missing today. As for the actual conversation it is amazing the efficiency of these water collection systems in the Golden Desert. The water tower collection idea is very interesting as well. It seems that it would be easy to implement. Thanks for all the great links Kurt.
  • Jul 7 2012: I just watched this Ted talk, https://www.ted.com/talks/anupam_mishra_the_ancient_ingenuity_of_water_harvesting.html, again related to water. It is a good reminder that we don't always have to look to new technology for answers, there are many solutions we humans created a long time ago that are better, simpler and more efficient than the ones we have today.
  • Jul 6 2012: In answer to Lindy Taylors question, there is water everywhere, the problem can be collecting it. There was this http://peswiki.com/index.php/Directory:Max_Whisson%27s_Gust_Water_Trap_Apparatus great invention in Australia a number of years ago. It was demonstrated to be working and could even produce water in the desert. I contacted the inventor a few years back and he was struggling to get funding for manufacture, now it appears that the idea has completely disappeared.
    Jacob, this should give you another potential source of water other than the sea, this invention is not the only possibility, there are other ways to condense atmospheric water. If all of the water used for cooling/heating etc is reused the ongoing need for water should only be for the plants. The Earthship folks also have some great water harvesting / saving ideas, check out their website http://earthship.com/.
  • Jun 29 2012: I want to thank everyone for the great feedback. The first comment I would like to address is the water issue. If the greenhouses were close to ocean shores I believe that a system discussed in this talk would work for a water collection system though maybe only partially.http://www.ted.com/talks/michael_pawlyn_using_nature_s_genius_in_architecture.html . From this talk it seems possible from their discoveries that terraforming deserts could be a not so distant future. If ocean mists are not available then tapping an aquifer would be necessary and responsible irrigation could ensure the protection of the aquifer.
    As for the lighting issue, I currently attend Purdue University and have witnessed first hand their implementation of LED lighting in agricultural production http://www.agriculture.purdue.edu/agcomm/agnews/public/story.asp?newsid=3033. The idea behind using the flexible PV for covering greenhouses is to cut down on heat transfer into the greenhouses. http://news.cnet.com/8301-17938_105-20078431-1/mit-demos-flexible-solar-panels-printed-on-paper/ . By reducing this heat transfer you would be creating a more ambient temperature while installing the proper infrastructure to control the greenhouse climate.
    I really liked the idea of using both warm and cool greenhouses for climate control. What about implementing a control system that could use backdrafts, negative and positive pressures and convection in the pursuit of a stable greenhouse climate? Also I'd like to hear more on using a reservoir or piping for climate control. Robert, I looked into the Biosphere project and it is extremely interesting. They are doing studies a little bit more grandiose in scope than this discussion but I can see the relation quite clearly. I would recommend anyone not familiar with the Arizona Biosphere project look into it. Thanks for the input, keep it coming.
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    Jun 25 2012: Isn't 80% shade cloth already available at a fraction of the cost?
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    Jun 25 2012: Jacob, The biosphere projects in Arizona conducted these experiments in the late 1970's. Perhaps an upgrade of thise results are what you are looking for.

    All the best. Bob.
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    Jun 24 2012: I never really understood why people think the desert is a great place to grow crops. How would you deal with the water issue? Which desert?
  • Jul 20 2012: Jacob,
    The greenhouse I was referring to was Green Circle Growers in Oberlin, OH. They have built a 5 acre range that recycles all their water. They also use robots in their African Violet range. The greenhouse heated by cooling tower water is adjacent to the Homer City Power Plant in Homer City, PA. I don't know the present owner but they have 11 acres, heat with cooling tower water at 95 degrees and give the water back at 90 degrees. I think they paid $10K for the power to run the pumps. The biggest problem at Homer City was the ground heat caused the plants to stretch.
  • Jun 27 2012: Jacob, an expansion on your idea would be to use a desert w/ a moderate temperature to have both warm and cold climate crops - take the heat from one greenhouse (cold climate) and pump it into the warm climate greenhouse.

    Also, since deserts don't have much water in their environments, they endure vast temperature swings between day and night. It'd be a good idea to use the ground (directly) or an underground water reservoir to act as a thermal reservoir to buffer the greenhouse temperatures.

    As for LEDs that are tuned to each crop's light spectrum, I don't think that's a great idea. PVs only convert ~50% of the light they receive into electrical energy - and that's for the expensive multi-junction panels. LEDs aren't 100% efficient either, so you're talking about a lot of energy lost before the plants ever have a chance to absorb anything. It'd be more practical to just let nature do what nature does and let the light go directly to the plants.
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    Jun 24 2012: There's a company in the USA that makes parking lot 'trees' which are solar collectors that not only provide shade and comfort for the employees to and from their cars, but provides enough energy to supply the whole building with its electrical needs and sell the unused energy production back to the electric company. Payback on the investment is reportedly 3-5 years. This idea though of yours though, is a whole another step from mearly cost effective energy production. Where did you see the greenhouses with the ocean mists?
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    Jun 24 2012: This is one of the best ideas I have read about.
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      Jun 25 2012: Read about the biosphere in Arizona.

      All the best. Bob.
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    Jun 23 2012: Now that is cool (no pun intended!). Keep goin'!