Abstract:
A desalination greenhouse of the invention provides both winter and summer crop growing operations and to produce a source of potable water given an input of only brackish or sea water. A consistency of temperature is produced by insulation and compensating absorption of heat in summer, with the release of heat in winter to keep crops more isothermal, but without obstructing natural light transmission to the crops. A very thin layer of brackish or salt water is evaporated from an inner shell and condensed onto an outer shell. Supplemental heat exchange can be applied to cool water used for crop irrigation.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention relates to improvements in water efficient greenhouses for efficient growth of agricultural produces and more particularly to a renewable energy desalination greenhouse which can utilize seawater or brackish water to perform a desalination process which, using renewable energy, grows crops in a shorter time period while using only a small fraction of the water which would otherwise be utilized in open field production. The present invention is also shown to be amenable to automated and continuous agricultural production. 
       BACKGROUND OF THE INVENTION  
       [0002]    In arid areas of the world a conventional greenhouse has a number of disadvantages. Increased sun light can cause a greenhouse to overheat. The answer to overheating has been to open the greenhouse to a cross breeze and increase evaporation for cooling. However, in desert areas this simply translates into a prohibitively greater water usage than would be experienced with the greenhouse in cooler climates. A conventional greenhouse project in the desert would normally require a commitment of several multiples of the amount of water than would be necessary in a cooler climate. Conventional greenhouses contemplate fresh water to be applied to plants in an amount to not only provide a nourishment medium for the plants, but also to humidify the internal space within the greenhouse. However, the internal space within the greenhouse must not over heat, and the main mechanism to prevent overheating is to create a cross draft of outside air to cool. However, this cooling evaporates and dehumidifies the interior growing space of the greenhouse. 
         [0003]    The desert environment is well known to have very little fresh water available, or perhaps only sea water, brine from groundwater desalination plants or brackish water available. Such desert environment is also known to have high solar availability, but suffers from excess temperatures associated with the intense solar exposure. The shortcomings of the conventional or more advanced solar still design, where water in an enclosure with a sun facing inclined transparent cover condenses desalinated water on the inside of the cover for collection. Its heat input may be increased by mirrors in order to increase yield of desalinated water per square meter of cover per day, however the original simple solar still and its many variations suffer from the following shortcomings: (1) when the solar still is dedicated for desalination only the cost of the structure becomes very expensive and so does the desalination process and output; (2) as the moisture in the tightly closed cavity of the still increases upon solar heating the evaporation is reduced and the still becomes less efficient; (3) Some of the desalinated water that condenses on the lower side of the transparent cover is preferentially evaporated relative to the salty water in the basin because of its lower density and therefore less salty water is evaporated; (4) there is a problem of obtaining an efficient condenser for the solar still and reliance on the air temperature outside the still to condense the water is not efficient, and the transparent cover becomes hot itself and the temperature drop between the evaporating moisture and the cover is not significant enough to allow substantial condensation; and (5) the above factors result in a still that is expensive with a low output of 2-5 liters per square meter per day. It is therefore desirable to invent a solar desalination device that is less expensive and is more productive per unit of space per day. 
       SUMMARY OF THE INVENTION  
       [0004]    The desalination greenhouse is a solar still that doubles as a greenhouse. The desalinated water produced could be used for any purpose such as drinking, boiler water and chemical industry due to its high purity or for agriculture and any combination of the above as it is inexpensively produced. The structure is essentially a greenhouse with an additional inexpensive extra cover and with a side benefit of desalination. The capital cost is therefore appropriated primarily for the greenhouse crop product, and the capital cost of desalination is significantly reduced. The desalination greenhouse of the invention also provides a number of flexible operation controls to produce crops rapidly in a desert environment using brackish water. Both winter and summer operations can be optimized and the desalination greenhouse helps to compensate for changing exterior process operating conditions. Even more surprisingly the desalination greenhouse can produce a source of potable water given an input of only brackish or sea water. 
         [0005]    The desalination greenhouse can be optimized for superior crop production and minimization of diseases. It minimizes heating and cooling requirements due to its superior insulation and absorption of heat in summer and its release in winter without obstructing natural light transmission. It uses renewable energy to desalinate water through condensation of sun and wind heated air that is forced through the cavity between the two structures to evaporate a very thin layer of water, and then to a black cover heated zone, to evaporative cooler wet pads. Condensation occurs on the inner surfaces of the outer and inner sections of the desalination greenhouse. Condensation of the inner greenhouse humid air may be achieved through a heat exchanger carrying the cooled water piped from the through of the evaporative cooling pads. The roof of the inner section of the desalination greenhouse is wetted evenly with sea or brackish water for evaporation which also cools the structure of the inner section of the desalination greenhouse. 1.0 to 10.0 mm v to u shaped grooves in the hard cover roof material of the inner section of the desalination greenhouse, preferably made of polycarbonate, guide the water downward and spread it evenly over the surface, providing the right depth for effective evaporation and cooling of the inner greenhouse. The inner greenhouse frame structure elements may be extended to support the outer greenhouse poly cover. The double shell greenhouse as described provides an efficient and cost effective means of heat utilization to desalinate sea or brackish water for irrigation and other uses, reduce heat input into the inner greenhouse, and minimize the crop requirement by over 95% by cutting the production cycle substantially and recovering the evapo-transpiration water. 
         [0006]    The space over the water being desalinated is never saturated due to continuous air movement. The thickness of the salty water being evaporated is maintained very thin, within one centimeter, in order to chill the water to lower temperatures through evaporation and removal of moisture by the air. The even distribution of the salt water and its thin layer covering the roof and sides of the production greenhouse, made possible by the channel design (grooves) provides the production greenhouse with a cold surface that makes the environment more conducive to optimal plant growth and enhances condensation on the ceiling and sides of the production greenhouse. The outer shell greenhouse is a canopy to trap the moisture evaporating from the roof of the production greenhouse and enhances condensation on the ceiling and inside wall of the outer shell greenhouse. 
         [0007]    An 1008 square meter floor greenhouse, for example, (36×28 and 4 meter high at the gutter and 8 meter high at the center) with one meter space between the inner and outer shell, has a total surface are of roof and sides of 2800 square meters allowing for doors and other vents. This area shall produce about 10 liters per square meter per day, or 28,000 liters per day. A seawater desalination greenhouse of a single shell (1), which relied on cold deep seawater as a condenser, produced between 3 and 6 liters per square meter per day depending on whether the environment is tropical or oasis. When the crop produced in the present desalination greenhouse invention is barley for animal forage production, the cycle per crop averages ten days from seed to harvest (2). The desalination greenhouse will produce 1500 tons of forage annually and consumes 4500 cubic meters of desalinated water per year for irrigation. 
         [0008]    The desalination greenhouse of the current invention produces over 10,000 cubic meters of desalinated water, enough for forage irrigation and drinking water for 1000 people, each using 15 liters per day. The desalination greenhouse of the current invention could contribute to solving problems of many regions of the world that require desalinated water for human consumption, industry and irrigation of crops. The high value of the desalinated water makes it valuable for boiler and chemical process water which is expensive to produce and requires substantial energy due to its high level of purity. 
         [0009]    The air cycle steps of the desalination greenhouse may be represented as follows: Ambient air&gt;disinfection&gt;filter&gt;blower&gt;distribution&gt;roof humidification&gt;heating&gt;pad humidification&gt;condensation&gt;ambient air. The water cycle steps in the desalination greenhouse may be represented and summarized as follows: a) Salty water. Salty water spread over roof of production greenhouse&gt;evaporation and cooling on roof&gt;evaporation and cooling on evaporation pads or water shower&gt;heat exchanger condenser&gt;Collection and recycle with bleed and blend with fresh salty water; b) Desalinated water. Condensed water on inside and walls of outer shell+Condensed water on inside and walls of production greenhouse+condensed water on heat exchanger carrying cold water from evaporation pads 
         [0010]    All condensate is collected in their own gutter like channels separate from salty water channels. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
           [0012]      FIG. 1  is a perspective skeletal view of the desalination greenhouse of the present invention showing a nesting of the structures to create a separation space between an inner section and an outer section; 
           [0013]      FIG. 2  is diagram of the structures within the desalination greenhouse which inlet air experiences during the expected operation; 
           [0014]      FIG. 3  is a section taken along line  3 - 3  of  FIG. 1  to illustrate the conversion of brackish water to potable water by condensation onto the inside surfaces of an outer section of the desalination greenhouse; 
           [0015]      FIG. 4  is perspective of a panel having channels (grooves) in the plate surface which have a triangular cross-sectional shape to produce triangular channels, the plate used for roof and outer sides of the inner and outer shells of the desalination greenhouse; 
           [0016]      FIG. 5  is cross sectional view of a plate which may or may not be the same overall size of the plate of  FIG. 4 , and illustrating a cross sectional profile having abbreviated height projections which define wide shallow channels; 
           [0017]      FIG. 6  is cross sectional view of a plate which may or may not be the same overall size of the plate of  FIG. 3 , and illustrating a cross sectional profile having height projections which have a separation of about the same distance as their height; 
           [0018]      FIG. 7  is a schematic of the components of a vortex system which is utilizable for cooling at one end and heating at the other in conjunction with the desalination greenhouse; 
           [0019]      FIG. 8  is an expanded sectional view of the portion of the desalination greenhouse and illustrating separated vertical walls, and a fresh water reservoir feeding a system which includes heat exchange, storage, irrigation system storage and metered fertilizer; and 
           [0020]      FIG. 9  is a perspective skeletal view of a stackable production bin which may be preferably used on a conveyor. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    Referring to  FIG. 1  a perspective skeletal view of one type of embodiment of a desalination greenhouse  21  which is shown as a long rectangular building, but need not be of the shape shown. The desalination greenhouse  21  is shown in a transparent view and includes an outer shell  23  for containment of water vapor, desalination, and light transmission; and inner shell  25  which is in effect an inner greenhouse, and is for crop production, evaporative cooling and condensation of moisture. 
         [0022]    The outer shell  23  shown is of simple construction and includes a series of vertical walls  31  which include side walls and end walls and topped by a roof  33  which includes a pair of sloped roof walls. Likewise, inner shell  25  shown is of simple construction and includes a series of vertical walls  37  which include side walls and end walls and topped by a roof  39  which includes a pair of sloped roof walls. Roofs  33 ,  39  of both greenhouses are preferably similar to each other (although shown in  FIG. 1  as being parallel), they need not be. Both the roofs  33 ,  39  have roof walls shaped with a slant angle more than 15 and less than 60 degrees to facilitate condensate gravitationally sliding downward. Outer shell  23  has an inner chamber  41  while inner shell  25  has an inner chamber  43 . Inner chamber  41  contains the inner shell  25  and is smaller, with the annular space between the outer shell and inner shell being referred to as a cavity and including a roof cavity  45  between the roofs  33  and  39  and a side cavity  47  between the vertical walls  31  and vertical walls  37 . 
         [0023]    Any number and type of protruding supports  51  may be anchored to the structural body of either of the outer shell  23  or inner shell  25  and for the purpose of anchoring the desalination greenhouse  21 , securing the outer shell  23  or inner shell  25  to each other, or for anchoring the outer shell  23  to the ground, with  FIG. 1  being a skeletal view to show the nested relationship of the outer shell  23  and inner shell  25 . Differing construction materials and methods of support, such as positive air pressure and the like, can be used to construct the desalination greenhouse  21 . Supports  51  may include any frame member, as well as any member from which external or internal support may be facilitated by any other structure or object. Also, the desalination greenhouse  21  has been recited in terms of an outer shell  23  and an inner shell  25  such that roof and side cavities  45  and  47  can be available to promote condensation in the outer shell. It is understood that, especially for desalination greenhouse  21  which are much longer than they are wide, that the ends can be similarly situated to have a side cavities along with some portal access such as a door bridge to extend between them, but that in a long desalination greenhouse  21  most of the action will occur between side cavities  47  of the major long sides of the desalination greenhouse  21 , as well as the roof cavities  45 . 
         [0024]      FIG. 1  illustrates a crude schematic possible location for a pair of air inlet air moving devices such as fans  53  shown, but not necessarily forced to be located nearer the roof  33 , which force outside air into the roof and side cavities  45  and  47 . A pair of exhaust or outlet air moving devices, such as fans  55  are shown, but not necessarily forced to be located, in the middle of an end vertical wall structure  57 , and connect inner shell  25  inner chamber  43  to the outside atmosphere. Vertical wall structure  57  may include a door  59 . The further details of an entry door  59  will be omitted, but suffice it to say that door  59  may be located in a connective portal which engages both the outer shell  23  and inner shell  25  to disrupt any breach or interruption of the roof and side cavities  45  and  47 . In this way, a single door  59  can be operated to give access to the inner chamber  41 . 
         [0025]    Conversely, a separate door may be provided for each of the outer shell  23  and inner shell  25 , with the space between the two doors remaining an active part of the roof and side cavities  45  and  47 . This may not be as preferred as the opening of either of two such separate doors would disrupt the action and flow going on in the roof and side cavities  45  and  47 . When access to the inner chamber  41  is had over a long time, such as the introduction or removal of soil and plant materials, the roof and side cavities  45  and  47  would be significantly disrupted. In yet a further alternative, the end wall  57  may be designed not to contain a side cavity  45  and to be built as a wall and support structure common to both the outer shell  23  and inner shell  25 . In this case, the user is giving up the desalination action at the end wall  57 . However, as can be seen in  FIG. 1 , and in the end wall  57  and roof portion of end wall  57  supports four fans  53 , 57  and a door  59  which combine to occupy a significant percentage of the end wall  57 . It may thus be desirable for simplicity of construction for doors  59  and fans  53 ,  57  to be located in an isolated cluster which will enable the use of a single wall to thus eliminate the need for double sealing, and accommodating other insulatory structures to enable the action to be described in the roof and side cavities  45  and  47  around such access accommodating and insulatory structures. 
         [0026]    With the basics of an overall structure of an example desalination greenhouse  21  having been seen in  FIG. 1 , and without the need to make duplicative burdensome specifically located structures to illustrate the operation of the desalination greenhouse  21 , a diagrammatic representation of the overall flow is shown in  FIG. 2 . Referring to  FIG. 2 , a block diagram illustrates the general flow of air through the desalination greenhouse  21 . From the outside atmosphere  61 , air may be drawn in through forced air fans  53 . Where the desalination greenhouse  21  is much larger than the simple design of  FIG. 1 , the inside of air fans  53  may be fitted with a distribution duct to insure that the incoming forced air from the atmosphere is spread as evenly as possible through the roof cavity  45 , even to the most distant portion of the desalination greenhouse  21 . It is understood that even though the general structure of the desalination greenhouse  21  is oblong, that if a desalination greenhouse  21  was wider than long, there may be several forced air fans  53  operating with generally parallel hot air distribution lines (not shown). In the case of a single, extraordinary long desalination greenhouse  21 , a large forced air fan  53  might be used with a significant sized ambient air distribution pipe or duct (not shown). 
         [0027]    The forced air fans  53  introduce ambient air into the roof and side cavities  45  and  47  throughout the desalination greenhouse  21 . The hot air will be utilized to evaporate and possibly cool any saline or brackish water which may be introduced onto the surface of the outside of the inner shell  25 . The air circulating in the roof and side cavities  45  and  47  whose humidification may be increased after contact with moisture from the outside of the inner shell  25  may deposit some fresh water droplets via condensation on the inside of the outer shell  23 . The air circulating in the roof and side cavities  45  and  47  whose humidification may be increased after contact with moisture from the outside of the inner shell  25  may then proceed into the inside of the inner shell  25  through an optional cooling pad  63 . Cooling pad  63  may be a matrixed structure which entrains some liquid to facilitate an increased contact between air circulating in the roof and side cavities  45  and  47  and liquid water which may be present in the cooling pad  63  through a variety of mechanisms. 
         [0028]    The cooling pad  63  can be a passive fibrous flow device to enable a passing gas to make a greater degree of contact with a wetted area. Cooling pad  63  can include a recycle branch to collect and recirculate liquid which typically passes through it from top to bottom. Cooling pad  63  may also be connected to external heating sources or cooling sources (not shown in  FIG. 2 ) which provide thermal transfer through a conduit such as a heating coil or cooling coil. Cooling pad  63  also, regardless of whether or not connected to external heating or cooling sources, can act as a stabilizing passive heating or cooling mass to protect plants within the inner shell  25  from momentary changes such as between full sun and cloud cover, as well as between day and night. Physically, the cooling pad  63  may likely be located within the inner shell  25  and likely beginning at the boundary between the inner shell  25  and the roof and side cavities  45  and  47  and continuing into the inner shell  25  for a sufficient distance (typically horizontal distance) to provide adequate contact between the air flow entering the inner shell  25  and any wetted surfaces within the cooling pad  63 . 
         [0029]    Air which emerges from the cooling pad  63  enters the inner shell  25  which it is available to humidify and provide gentle and stable appropriate temperature air for any growing plant matter located within the inner shell  25 . The air from the cooling pad  63  may be arranged for maximum circulation within the inner shell  25 , including other circulating fans, such as ceiling fans and blowers, located within the inner shell  25 . From inner shell  25 , the air passes to and through exhaust fan  55  and back to the atmosphere  61 . It may be preferable for inlet fan  53  to operate at a higher pressure rate than exhaust fan  55  so that the air within the outer shell  23  and inner shell  25  may be somewhat slightly pressurized. 
         [0030]    Referring to  FIG. 3 , a schematic view taken along line  3 - 3  of  FIG. 1  shows some operational details of desalination greenhouse  21 . The previously seen inlet fan  53  is seen as blowing air into a conduit or duct  65  which continues to extend along a significant length of the rectangular elongate shape of the desalination greenhouse  21 . Duct  65  may be a wide plastic pipe and may be configured to be heated by the sun. The relationship of the roof  33  and roof  39  separated by the roof cavity, and the relationship of the vertical walls  31  and vertical walls  37 , separated by the wall cavity  47  is better illustrated. Above a top portion of the roof  39 , a brine distribution header pipe  71  is seen as having ability to distribute, drip, spray or otherwise convey in any manner, brine  73  in an even as distribution as possible to coat and move slowly across the roof  39  and thence walls  37  of the inner shell  25 . As will be shown, the materials of construction of both the inner shell  25  and outer shell  23  are so as to promote an enhanced holding time for brine  73  so that it will have an opportunity to evaporate from the exterior of the inner shell  25  and condense on the inside of the outer shell  23 . 
         [0031]    Not shown in  FIG. 1  were details of construction of the desalination greenhouse  21  as the details of other structures would have been obscured. The materials of construction for the inner and outer shells  25  and  23  of the desalination greenhouse  21  may include a plurality of uprights  77  and cross bars  79  to support panels (not yet shown) which may be replaced if damaged or broken. Uprights  77  and cross bars  79  may be made from galvanized steel, aluminum or other suitable material. In the perspective of  FIG. 3 , some of the uprights  77  are shown as segments between the cross bars  70  which are shown as expansions located along the uprights  77 . It is also noted that the walls  31  and  39  need not be vertical, but may be sloped or curved. Any sloping and curving of the walls  31  and  39  may be configured to combine with the shape of the roofs  31  and  39  to produce an advantageous gravity and slope controlled flow. 
         [0032]    Explained, the exterior of inner shell  25  will have an even flow of brackish water or brine  73  over its exterior surface. Any energy input into the inner shell  25  will cause water to be vaporized. Vaporized water may condense on the inside of the outer shell  23  and run down the inside of the roof  33  and down the inside of wall  31 . At the base of the walls  37  and  31 , the clean condensed water from the inside of wall  31  would otherwise mix with the brackish water, or brine  73  flowing down from the outside of wall  37 . The prevention of mixing of these two streams by segregating and conserving the pure condensed water provides a source of desalinated water. A barrier  81  separates the flow at the base of the walls  31  and  37  into a brackish water reservoir  83  and a fresh water reservoir  85 . Brackish water reservoir  83  may have a lower drainage tap  87  and a fresh water reservoir  85  may have a drainage tap  89 . Taps  87  and  89  will assist in harvesting and or recycling the brackish water  73  or the condensed water as needed. 
         [0033]    Referring to  FIG. 4 , a panel  91  is shown which has a series of channels or grooves  93  seen in parallel across the upper surface of the panel  91 . When the panel  91  is arranged so that the grooves  93  extend horizontally, the grooves act to entrain some of the brackish water  73  and hold onto it while giving it an opportunity to evaporate. At minimum, the grooves  93  increase the effective vertical height of the walls  37  and optionally the flow path length along the roof  39 . At best, the grooves  93  could be angled unevenly to form little “shelves” each of which could provide a significant residence time for brackish water  73  on its way to brackish water reservoir  83 . In some cases the grooves  93  could even have a negative load flanking to form a horizontal drainage channel with or without interruptions in a horizontal to even further increase the mean flow path. In other words, if every other groove were “nicked” at its end, and if the upper angle were less than horizontal, brackish water  73  could be caused to follow a serpentine path down the panel  91 . Other variations are possible. 
         [0034]    The panel  91  may be made of conventional greenhouse building material products such as plastic, polycarbonate, or any other material which is at least partially clear. The grooves  93  may be formed by molding or by matching or by other technique. An outer covering may be of lighter materials such as polyethylene for economics and for easy removal when cleaning of the roof  33  is needed. Air and water within the desalination greenhouse  21  may be uv-disinfected at any, and at many points in the system for to enable the use of an organic crop label for plants grown. Referring to  FIG. 5 , and as a further variation on panel  91  of  FIG. 4 , an end view of a panel  101  is shown as having a series of spaced apart and low profile protrusions  103 . Likewise, Referring to  FIG. 6 , and as a further variation on panel  91  of  FIG. 4 , an end view of a panel  111  is shown as having a series of spaced apart and high profile protrusions  133  to form a series of rectangular channels approximately as wide as the protrusions are tall. 
         [0035]    The use of a vortex system could be employed with the desalination greenhouse  21 . Referring to  FIG. 7 , a schematic block diagram of such a system is shown. A vortex system  151  includes equipment to make a process flow of air. A vortex diverter system  151  is used for heating on one end and cooling on the other and which may be controlled to increase or decrease as required. A compressor  153  pressurizes air into an air storage tank  155  at about 100 PSI. The pressurized air exits from the tank  155  and passes through an air filter  157  and a moisture trap  159  before it inters a vortex device  161 . The vortex device  161  splits the air into cold stream exiting from one end of the vortex device  161  and hot exiting from the other end of the vortex device  161 . The hot air output of the vortex device  161  may be introduced into the duct  65  either upstream or downstream of the inlet fans  53  where it will ultimately enter the roof and side cavities  45  and  47 . The cold air output of the vortex device  161  may be passed through a coil or other heat exchange structure inside a water pipe (not shown) carrying the cold water to the inner shell  25  of the desalination heat exchanger  21 . In the summer when more cold air from the output of the vortex device  161  is needed to condense more water, the cold portion of the air is increased which will decrease the warm output of the vortex device  161 . In winter the arrangement is reversed as more hot air from the vortex device  161  is needed for introduction of heated air duct  65  either upstream or downstream of the inlet fans  53 . Mechanical controls on each end of the vortex device  161  outlets facilitate adjustment of heat and cold flow. In instances when the air filter  155 , and heat and residence time in the vortex system  151  do not disinfect enough, the air passing into black, heat absorbing conduit or duct  65  can provide some additional sterilization. 
         [0036]    In general, the use of a vortex system could be employed with the desalination greenhouse  21 . The cool air under positive pressure from the air blower  153  will eventually enters inner shell  25  through evaporation or cooling pads  63 . Cooling pads  63  may be switched off by either being taken out of the path of flow or simply allowed to run dry, to remove its ability to cool inner shell  25  of desalination greenhouse  21  using cooled air from roof and side cavities  45  and  47 . Conversely, cooling pads  63  may be switched on or into or out of the path of flow and with the brine distribution header pipe  71  used wetting roof  39  and side walls  37  of inner shell  25  of desalination greenhouse  21  with roof and side cavities  45  and  47  switched off or isolated from flow, in humid climates so that heating the air reduces its relative humidity and makes it effective in cooling inner section  24  of desalination greenhouse  21 . Cool air then passes from roof and side cavities  45  and  47  into inner shell  25  of desalination greenhouse  21  to cool the growing crop, to enable the growing crop to transpire, supply oxygen and remove carbon dioxide and other gases. Air becomes warmer and more humid as it passed from one end of to the other of inner shell  25  of desalination greenhouse  21  due to the incident light and heat and transpiration of the crop in inner shell  25  of desalination greenhouse  21 . Air may exit inner shell  25  of desalination greenhouse  21  through a heat exchanger (not shown in  FIG. 7 ) through which cold water is circulated. The air loses its moisture to heat exchange and exits to ambient environment or fed to the inlet of the inlet fan  53  feeding roof and side cavities  45  and  47 . An advantage of circulating air is to reduce dust and germ, insects, seed and other undesirable foreign matter into desalination greenhouse  12 . Ultra-violet disinfectant  80  helps classify a crop as organic as no chemical disinfectants or herbicides are used. 
         [0037]    Referring to  FIG. 8 , a portion of a possible flow scheme utilizable in conjunction with the desalination greenhouse  21  is shown. A section including the inner shell  25 , outer shell  23  and barrier  81  is shown with a connection to drainage tap  89 . Drainage trap  89  can be connected into a heat exchanger  171  which can be used dehumidify the humid warm air exiting inner shell  25  before being discharged to atmosphere. An air inlet  175  is shown and which may optionally be connected either upstream or downstream of the exit fan  55  seen in  FIG. 1 . An air outlet  177  would typically be vented directly to atmosphere  61 . A number of shutoff and bypass valves, storage tanks and piping (not shown) may be used to shutoff, bypass water flow to any of the devices when not in use and store water. 
         [0038]    Heat exchanger  171  exit condensate is preferably collected through exit line  179  and is piped to an insulated underground cold water storage tank  181 . A portion of the desalinated water is transferred by pipe  183  to an insulated underground irrigation tank  185  tank used as an irrigation reservoir. Well balanced fertilizers that include macro and micro nutrients required by the crops may be contained in a fertilizer tank  187  are dosed into the irrigation tank and are topped as the crop uses the fertilizers through a dosing line  189 . One possible method of hydrating the plants may involve cold irrigation water is fed to the crop through piping that connects to soaker hoses laid in parallel under the crop. Excess irrigation water may be drained to the irrigation system tank  185  which is topped with fertilizers and desalinated water as needed. 
         [0039]    Referring to  FIG. 9 , a stack of two growing trays, including growing tray  201  and growing tray  203  are shown in stacked relationship to emphasize the efficiency which can be achieved in conjunction with the desalination greenhouse  21 . The growing trays  201 ,  203  contain the sprouted seeds to grow the crop. The growing trays have edges  205  which may overlap so as to contain irrigation water within the trays  201 , 203 . Trays  201 ,  203  may each have a drainage hole  207  and several openings  209  to admit light to promote growth even though the trays  201 , 203  may be in stacked position. One set of dimensions that may work well for a given growing tray  201  may include a width of about 100 centimeters, a depth of about 120 centimeters, and a depth of about 40 centimeters. 
         [0040]    The growing trays  201 ,  203  may also extend along the same direction as a soaker hose  211 . Soaker hoses  211  may extend along the length of the desalination greenhouse  21  and may be fed with cold water from fertilizer added irrigation system  185  seen in  FIG. 8 . Several soakers hoses  211  may connect to a header for pressure equalization. Soaker hoses  211  may also deliver a desalinated water rich in nutrients in the form sprayed fog. Irrigation frequency is scheduled to provide the crop with adequate irrigation water, without excess, during, for example, a 10-14 day growth cycle, for forage production. Using the growing trays  201 ,  203  shown and soaker hose  211  shown, the root mat for plants grown will be removed with the crop during harvest. 
         [0041]    In terms of overall process operations, the water for feeding crops is typically the desalinated water which originates at the inside surface of the outer shell  23  of the desalination greenhouse  21  resulting from evaporating of sprayed brackish water  73  using relatively hot air within roof and side cavities  45  and  47  and producing, condensation of inside of roof  33  and sides  31  of desalination greenhouse  21  resulting from evaporation of sprayed brackish water  73  onto the roof  39  and walls  37  of the inner shell  23  of the desalination greenhouse  21  and possibly from cooling pads  63  when operating and evapo-transpiration of the crop. Condensate from vertical walls  31  of the outer shell  23  are collected in a fresh water reservoir  85  which is preferably separated from a brackish water reservoir  83  such as by a barrier  81  as was shown in  FIG. 8 . Desalinated water may be collected in an insulated underground storage tank  181  and utilized both for crop watering and as a source of fresh water. 
         [0042]    In terms of process, and in further detail as to operation, air forced by inlet fans  53  are distributed evenly throughout the roof and side cavities  45  and  47 . When this air is heated, it evaporates sea or brackish water  73  on the exterior surface of the inner shell  25 . Downward flow of brackish water  73  is delayed by grooves  93 ,  103  or  113  of panel  91 ,  101 ,  111  which make up the roof  39  and side outer surfaces of vertical walls  37 , except for doors  59  and vents associated with the inlet and exit fans  53  and  55 . Transparent roof  33  of outer shell  23  of the desalination greenhouse  21  preferably passes maximum light and heat to roof and side cavities  45  and  47 . Roof  39  and vertical sides  37  of inner shell  25  of desalination greenhouse  21  is wetted with a thin sheet of brackish water  73 , of about two centimeters or less thick, fed from a source of sea or brackish water  73  from brine distribution header pipe  71  by a low pressure pump and spread evenly as guided by grooves  93 ,  103  or  113  of panel  91 ,  101 ,  111 . Cool air from to roof and side cavities  45  and  47  produced by hot air giving up its heat to vaporize water, especially where brackish water  73  is heated in a black lining sun exposed section of the outer section of the desalination greenhouse  21 . As inlet air is heated its relative humidity drops. It then passes through the cooling pads  63  where it may pick up more moisture and cools the inner shell  25  of desalination greenhouse  21 . Brackish water  73  on the roof  39  of inner shell of desalination greenhouse  21  is cooled through evaporation and transmits this cooling effect through panel  91 ,  101 ,  113  to the inner shell  23  of desalination greenhouse  21  to aid in the cooling of the crop environment and condensation of moisture on the inside of the outer section  23  of the desalination greenhouse  21 . Cool air is blown into inner chamber  43  through the cooling pads  61 . 
         [0043]    When roof  39  of the inner shell  25  is not wetted, as in winter when crop water requirement and cooling are not required, hot air passes through water soaked cooling pads  61  to pick up moisture to produce cool air within inner chamber  43  and to produce cold water where a coil is provided in the cooling pad  61 . Cool air will then exit evaporative cooling pads  61  into the inner chamber  43  of the inner section  25  of the desalination greenhouse  21  to cool growing crops and then exit through exhaust fans  55  which operate at lower pressure than forced air fans  53  to maintain positive pressure in both the inner chamber  43  and the roof and side cavities  45  and  47 . In the alternative, exhaust fans  55  can be minimized or eliminated with certain designs, particularly a passive exit where overall pressure and air flow in the desalination greenhouse  21  is maintained high. 
         [0044]    The forage crop production system in the desalination greenhouse  21  is and can be a 24/7 production system. A quantity of the seeds, depending on the size of the growing tray  201 , may be soaked in disinfected water for 24 hours, then drained and covered to germinate in a pail or other container. The seeds may be irrigated with mist nutrient twice a day. Within 3-4 days the germinated seed may be spread in a growing box such as growing tray  201  and placed on a conveyer belt or rollers. The growing trays  201  may be stacked 4-6 high to utilize the inner chamber  43  of the desalination greenhouse  21  effectively. The growing trays  201  may have openings  207  on the sides for light, ventilation and irrigation. The growing trays  201  may be irrigated with a mist of nutrient rich desalinated water. A conveyor built/roller (not shown) can be operated daily to move ⅛ to 1/10 the distance per day so that a crop has an automated harvest indication each day after it has been on this type of moving belt for 8 to 10 days. 
         [0045]    The crop, including the roots, may be tipped from the growing tray  201  and into a tub grinder which may cut or otherwise process the crop and feeds it into a wagon or conveyance to be transported fresh to its needed consumption point, such as to a grazing animals for feeding. A typical desalination greenhouse if 1000 square meters area, producing 4 tons of barley forage per day. It will use 50 cubic meters of sea or brackish water per day compared to 10,000 cubic meters per day in field production of sweet water. The energy requirement is 96 KWH per day for the fans. Conventional Reverse Osmosis desalination alone will require 200-400 KWH per day. 
         [0046]    Controls of the desalination greenhouse  21 , not shown, may be used to control the equipment set forth and other equipment. Equipment controlled includes ventilation, evaporative cooling, spraying and use of both fresh and brackish water, irrigation, vortex device  161  operation, warning systems, pumps and other functions. The advantages of desalination greenhouse  21  are to desalinate brackish water  73  for potable and agricultural use and insulation property of two preferably transparent bodies, as the bulk of the internal and external shells  25  and  23 , with air in between within roof and side cavities  45  and  47  which enables a level of control and combine to save major running expenses compared to conventional greenhouse operation. The brine distribution header pipe  71  sprinkling system within the roof and side cavities  45  and  47  creates a sheet of water on the roof  39  and vertical walls  37  of inner shell  25  of desalination greenhouse  21  further insulating it without obstructing light transmission and while cooling inner chamber  43  of desalination greenhouse  21 . The superior properties of water to absorb heat to the extent of 540+ calories per cubic centimeter (cc) when evaporating is an effective cooling mechanism in summer while the outer shell  23  of desalination greenhouse  21  insulates it from cold and snow in winter. Such arrangement exemplified in the desalination greenhouse  21  saves energy and is environmentally friendly. 
         [0047]    Another advantage of desalination greenhouse  21  is the use of the crop growing structure of inner shell  25  of desalination greenhouse  21  as a support structure for the cover of inner shell  25  of desalination greenhouse  21 . Cooling of crop roots using soaker hoses  211  is another advantage of desalination greenhouse  21  for the crop shoots to be enabled to tolerate higher temperatures in their potentially high temperature growing environment. An additional advantage of desalination greenhouse  21  is the ability for sterilization of the air through heat and ultraviolet treatment which enables desalination greenhouse  21  to grow organic crops and reduce insecticide use. A further advantage of desalination greenhouse  21  is use of natural lighting while providing a general thermal insulated inner section  25  of desalination greenhouse  21 . 
         [0048]    Another advantage of desalination greenhouse  21  is the heating of air for use for effective evaporative cooling where it would otherwise be ineffective in humid areas. A further advantage of the desalination greenhouse  21  is the flexibility and efficiency of using many features independently, especially heating and cooling which contributes to an overall cost reduction. A further advantage of the desalination greenhouse  21  is the use of renewable energy for some or all of its operations. The aforementioned advantages makes the desalination greenhouse  21  simple to operate and competitive especially in developing countries where fuel is expensive and potable water may not be available. 
         [0049]    While the present invention has been described in terms of a desalination greenhouse  21  and components which can be used with control to affect (1) fresh water production, (2) quick crop growing times, (3) combination summer and winter operating configurations, the construction and process operation of a desalination greenhouse within the teaching above can be used to make a wide variety of alternate variations thereof. 
         [0050]    Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted herein are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.