Abstract:
Systems, apparatuses and methods for circulating and agitating algae ponds or reservoirs are described. Inflatable or floatable masses resident in the algae ponds are cyclically or rhythmically moved thereby causing propagating waves to advance along ponds. Waves encourage increased equilibrium of oxygen and carbon dioxide between ambient air and growth medium and thereby improved growth of algae and increased production of biomass. With relatively little energy input, large quantities of algae or biomass may be grown in relatively large ponds and on an economically viable commercial scale.

Description:
FIELD 
       [0001]    The present invention is related to functions related to circulation of algae or biomass in cultivation ponds or reservoirs. More specifically, the invention relates to propagating waves efficiently across relatively large ponds and reservoirs to promote oxygen delivery to and growth of biomass. 
       BACKGROUND 
       [0002]    A massive quantity of carbon is available in the atmosphere in the form of carbon dioxide. Within the past 150 years, the concentration of carbon dioxide in the atmosphere has increased substantially. Whatever the cause, atmospheric carbon dioxide could be an economical, industrially viable and successful source of fuel, food, building materials and the like if combined with other constituents. One way of processing atmospheric carbon dioxide is to capture it through photosynthesis. Algae is one medium through which photosynthesis can be put to use. 
         [0003]    Algae has many advantages over other plants. Plants as used herein include organisms capable of performing or facilitating photosynthesis. Advantages of algae include fast growth, high sequestration of solar energy, ease of processing and good nutrition. Over the last two decades, algae has become a popular focus of research for engineers and scientists. Various aspects of algae have been studied. For instance, algae can be used as a food substitute, a medium for carbon sequestration, an agent for generating oils and converting the oils into biodiesels for use as an energy source. 
         [0004]    Therefore, it is important for scholars, researchers and producers to quickly cultivate massive quantities of algae to serve as a raw material for further processing. Algae cultivation is often the bottleneck for producing products on a viable or economic scale. Algae cultivation requires sufficient light, carbon dioxide and nutrients. Sunlight and carbon dioxide are in abundance. However, efficient and effective delivery of light, carbon dioxide and nutrients to a substantial quantity of growing algae cells is tricky. 
         [0005]    One popular and relatively inexpensive location for cultivating algae is in ponds or reservoirs. Ponds and reservoirs can be of any size; large ponds could be a source of large quantities of algae. However, to effectively use light energy in a pond cultivation process, light must reach the cells of the algae. Cultivation ponds suffer from several drawbacks. As algae grows at the surface of cultivation ponds, newly formed algae creates a barrier to and throws a shadow on other algae found slightly lower in the medium. Carbon dioxide is captured by the top layers of the algae and a decreasing concentration of carbon dioxide is available for algae growing deeper in the medium. 
         [0006]    Over the years, many systems and devices have been proposed to overcome these and other limitations associated with algae ponds. For example, transparent tubes and open-air circulation troughs have been proposed to more efficiently expose algae to light. Other solutions have suggested the use of jets, paddle wheels, etc. to circulate the growth medium (e.g., water) or to circulate the algae in container (e.g., ponds, troughs, tubes). However, nearly all of these inventions are prohibitively expensive or are incapable of producing relatively large quantities of algae. One problem with these systems is that jets and other components are too vigorous for most forms of algae because algae is relatively fragile. Algae does not contain or require substantial amounts of cellulosic fibers that are necessary to support non-aqueous plants such as trees and land-based crops. Another problem associated with efficient circulation is that mechanical energy input into the system is quickly damped and circulation is thwarted. Pond photosynthesis reactors have been used at various stages in algae cultivation. Photosynthesis occurs near the surface of the reactors. Growth is initially fast, but growth rapidly declines over time. One reason is that sunlight fails to reach more than about one-half inch of the algae in the water in stagnate or circulated algae ponds. Further, algae tends to sink as it grows. 
         [0007]    Canal style photosynthesis reactors have been proposed as an improvement over ponds. In a canal type photosynthesis reactor, the cultivation liquid is flowing, and a turbulent current produced between the fluid and the channel walls can provide effective mixing or agitation of the cultivation liquid (medium) and suspended algae cells. Thus, a cell growth curve of a general channel type photosynthesis reactor shows much better results for canal type photosynthesis reactors as compared to pools or ponds. However, both pond and canal style reactors suffer some disadvantages such as a propensity for contamination by other organisms, dust and other pollutants. 
         [0008]    These and other disadvantages can be overcome with the teachings provided herein. 
       SUMMARY 
       [0009]    Embodiments and techniques described herein include improved systems, apparatuses and methods for circulating and agitating algae ponds or reservoirs are described. Agitators create propagating waves which advance along some or all of the length of each pond. Propagating waves encourage increased equilibrium of oxygen and carbon dioxide between ambient air and growth medium and thereby improved growth of algae and increased production of biomass. Propagating waves circulate or cycle algae vertically through the water column thereby promoting healthy, sustainable algae growth. With relatively little energy input, large quantities of algae or biomass may be grown in relatively large ponds and on an economically viable commercial scale. 
         [0010]    In certain implementations, relatively long and relatively narrow ponds are constructed and lined. Water and algae are introduced therein. An agitator includes a floatable or inflatable agitation element disposed in or adjacent to the water such as at or in a narrow end of each of the ponds. Each agitator may be operated independently of one another or may operate in tandem or synchronization with other agitators. The agitation elements are cyclically or rhythmically actuated or moved thereby creating propagating waves. 
         [0011]    One or more compressors, ducts, dampers, bladders, vents and other elements are used to inflate the agitation elements. The various components of the system, including the agitation elements, and ponds may be sized according to various factors. 
         [0012]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, and this is not intended to be used to limit the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    While the appended claims set forth the features of the present invention with particularity, the invention, together with its objects and advantages, will be more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings. Throughout, like numerals refer to like parts with the first digit of each numeral generally referring to the figure which first illustrates the particular part. 
           [0014]      FIG. 1  shows a perspective view of a single algae cultivation pond (herein “pond”) according to one implementation of the invention. 
           [0015]      FIG. 2  shows a profile cross-sectional view of an algae cultivation pond and exemplary agitation mechanism according to one implementation of the invention. 
           [0016]      FIG. 3  shows an overhead view of an algae cultivation pond and exemplary agitation mechanism according to an alternative implementation of the invention. 
           [0017]      FIG. 4  shows an overhead view of an array of algae cultivation ponds and system of agitation mechanisms for production of algae on an industrial scale according to one implementation of the invention. 
           [0018]      FIG. 5  shows a flowchart of one implementation of a method for causing agitation (e.g., propagating wave) in an algae cultivation pond. 
           [0019]      FIG. 6  shows a flowchart of one implementation of a method for cultivating algae according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    In the following description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these specific details. In other instances, structures, devices, systems and methods are shown only in block diagram form in order to avoid obscuring the invention. 
         [0021]    Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments. 
         [0022]    Broadly, embodiments and techniques of the present invention disclose or relate to systems and methods for circulating or agitating the medium, liquid, fluid or water in an algae cultivation pond. While there are various mechanisms to circulate or agitate the medium (e.g., impellers, propellers, water jets) a preferred mechanism is to periodically generate a propagating surface wave. In a preferred implementation, a propagating wave travels the length of the pond. It was found that a propagating wave adequately circulates the medium in the pond and does not appreciably disturb or inhibit growth of the algae. In fact, circulation of the medium by propagating waves was found to be preferable to other means of circulation. 
         [0023]      FIG. 1  shows a perspective view of a single algae cultivation pond  100  (herein “pond”) according to one implementation of the invention. With reference to  FIG. 1 , a pond  100  is at least partially filled with a cultivation medium (e.g., water, water-based solution of algae feeding nutrients)  102 . The medium  102  is prevented from escaping the pond  100  by a liner  104  spread over the bottom and sides of the pond  100 . The liner  104  also facilitates harvesting of the algae (not shown) as described in more detail below. 
         [0024]    At or near a proximal side or edge  106  of the pond  100 , an agitator  108  is installed or placed in the pond  100 . The agitator may be maintained in place such as with permanent, temporary, moveable or removable anchors  110 . The anchors  110  are optional. In one implementation, the agitator  108  is made of an inexpensive, flexible polyvinyl or plastic material. In this implementation, the agitator  108  is an inflatable bladder. 
         [0025]    Intermittently, the agitator  108  is caused to generate a traveling or propagating wave  112  that travels the length or width  114  of the pond  100  to a distal side or edge  116  of the pond  100 . In one implementation, the propagating wave  112  is created as follows. The agitator  108  is partially or fully submerged in the pond  100 , and the agitator  108  is rapidly filled or pulsed with air through a hose or air duct  118 . A fast-acting damper (not shown in  FIG. 1 ) may provide air to the air duct  118 . In one exemplary implementation, the damper is charged or pressurized to 25-30 inches water column (62-75 mBar). In response to the pulse of air, the agitator  108  rapidly floats to the surface of the pond  100  and emerges there. The movement of the agitator  108  through the vertical distance  120  creates a propagating wave  112 . The agitator  108  is allowed to deflate and re-submerge into pond  100  to await another inflation cycle. In a preferred implementation, several inflations are performed per minute. Accordingly, several propagating waves  112  may be incident in the pond  100  at any given time depending on the dimensions of the pond  100  and other conditions. 
         [0026]    In an example of such implementation, a 12-inch (30 cm) diameter bladder or agitator  108  at rest is deflated such that about 24 inches (61 cm) of its diameter is deflated or collapsed. The result is about a 12-inch (30 cm) diameter partially or fully submerged agitator  108 , or about a six-inch (15 cm) diameter partially or fully submerged agitator  108 . When pulsed with air, the bladder or agitator  108  is again inflated and displaces about 0.75 cubic feet (ft 3 ) of water for each running foot of agitator corresponding to about 0.07 cubic meters of water for each meter of agitator. After causing a pulse or relatively rapid inflation, another fast acting damper (not shown) is used to deflate the agitator  108 . In addition to (or in place of) a deflating damper, deflation vents or vent holes may installed in the agitator  108  or inflatable portion of the agitator  108 . In one implementation, one or more deflation vents are located along a bottom edge of the agitator  108  so as to encourage draining of any water that enters the agitator  108 . Even with some water entering the agitator  108 , inflation and deflation of the agitator  108  causes substantial and sufficient agitation so as to create a propagating wave that travels all or substantially all of the length or width  114  of the pond  100 . 
         [0027]    Alternatively, other movements and other means may be used to cause a propagating wave  112 . For example, the agitator  108  may remain inflated and may be rapidly moved downward or pulsed rapidly in a horizontal or other direction(s) (not shown) to cause the propagating wave  112 . In yet another alternative example, instead of using air to inflate the agitator  108 , a series of cables or cords are used to provide a pulsing motion to the buoyant agitator  108 . In yet another alternative, the agitator  108  is made of two or more materials such as one or more foam portions and one or more hollow or inflatable portions. An air pump would then only need to fill or partially fill a smaller volume to cause the agitator  108  to float to the surface of the pond  100 . In any event, the agitator  108  may be made of other materials (e.g., wood, straw, composite, dried and treated algae, metal, foam polymer). 
         [0028]    With reference to  FIG. 1 , algae cultivation preferably includes a nutrient line  122  at or near the distal edge  116  of the pond  100 . The nutrient line  122  preferably runs along substantially all or a substantial part of the length or side  124  of the pond  100 . In a preferred implementation, the length  124  of the pond  100  is substantially larger than the width  114  of the pond  100 . Nutrients (not shown) are released into the medium  102  over the course of time. Nutrients may be intermittently supplied, or may be continuously fed to the medium  102 . Nutrients or a nutrient-enriched flow is provided to the nutrient line  122  through a nutrient supply  126 . The nutrient line  122  may require an intake line (not shown) that draws medium  102  from the pond  100  and recycles it to the pond  100 . A nutrient line  122  alternatively may deliver a variety of materials not traditionally considered as “nutrients” or fertilizers for algae including carbon dioxide or other off gases from power plants, or other gaseous or liquid based materials from production or processing facilities. By delivering materials to algae ponds, materials can be sequestered or captured by algae or other organism cultivated in ponds. While a single nutrient line  122  is shown, multiple nutrient lines may be provided. One or more nutrient lines may be arranged in or around the pond  100  in a variety of ways conforming to the needs of the algae, environment and pond  100 . 
         [0029]      FIG. 2  shows a profile or lateral cross-sectional view of an algae cultivation pond  100  and exemplary agitation mechanism according to one implementation of the invention. The elements shown in this view are not drawn to scale but are shown for illustration purposes only. (The same applies to the other figures.) The width  114  and pond  100  are cut to show that the width  114  and pond  100  are not limited in size relative to the length (not shown) of the pond  100  or consistent with other typical algae ponds. With reference to  FIG. 2 , an agitator  108  is located at the proximal edge  106  of the pond  100  such as by one or more anchors  110 . The proximal depth  202  of the pond  100  (or, more accurately, the depth of the medium  102  near the proximal end  106 ) as measured at or near the proximal edge  106  is preferably larger or deeper than a distal depth  204 . However, the proximal depth  202  and the distal depth  204  may be the same or about the same. As a specific example, a proximal depth  202  could be about 20 inches (51 cm) and a distal depth  204  could be about 12 inches (30 cm). In this example, for a round-shaped agitator  108 , a diameter  208  of the agitator  108  could be about 12 inches (30 cm). 
         [0030]    Propagating waves  112  originate at and travel from the proximal edge  106  to or toward the distal edge  116 . In one example, propagating waves are generated by a generally rapid and generally vertical movement of the agitator  108  shown by a distance  120  in  FIG. 2 . As viewed along the width  114  of the pond  100 , the bottom of the pond  100  is preferably substantially smooth to encourage recycle  206  of flow of medium  102  and nutrients (not shown) from the area near the nutrient line  122 . In one implementation, leveling machinery is used to create a substantially smooth pond bottom that has little or no slope. In another implementation, a slight slope is provided to each pond with a proximal depth  202  being greater than a distal depth  204 . Nutrients may be carried from the distal end  116  toward the proximal  106  in a counter-current fashion in the pond  100  as shown by the arrows in  FIG. 2 . Thus, nutrients may travel by diffusion and circulation of the medium  102 . 
         [0031]    The propagating waves  112  are useful for more than dispersing nutrients. First, the propagating waves  112  agitate the surface of the medium  102 . Such agitation encourages exchange of oxygen, nitrogen and carbon dioxide with the ambient air. Carbon dioxide is generally absorbed by the algae and oxygen is released into the medium  102  and ultimately the ambient air. Second, the propagating waves  112  agitate the medium  102 . As algae captures light at the surface of the pond  100 , the algae grows. The agitation of the medium circulates growing algae to other depths of the medium  102  thereby allowing the algae to grow to a greater depth than would normally grow without agitation, which, in turn, causes increased growth of biomass over a same amount of time as compared to a stagnant pond or one that is agitated with impellers or propellers. Third, the propagating waves  112  promote dispersion of nutrients along the width  114  of the pond  100 . Without propagating waves  112 , nutrients generally have to be introduced at a substantially greater number of locations in each pond  100  or in a more cumbersome fashion. A first pond  100  is separated from neighboring ponds  212  by berms  210 . The width of each berm  210  may be selected based on convenience when harvesting algae from a series of neighboring ponds  100  and  212 , or the width of each berm  210  may be uniform. 
         [0032]    Alternatives 
         [0033]      FIG. 3  shows an overhead view of an algae cultivation pond and exemplary agitation mechanism according to an alternative implementation  300  of the invention. With reference to  FIG. 3 , an agitator  108  is placed at an arbitrary distance along the width  114  of the pond; in  FIG. 3 , the agitator  108  is shown located somewhat toward the proximal edge  106  of the pond. The agitator  108  is placed at an arbitrary angle  302  as measured between a line parallel with the proximal side  106  of the pond and the agitator  108 . A first end  304  of the agitator  108  is located a first distance  306  from the proximal edge  106  of the pond. A second end  308  of the agitator  108  is located a second distance  310  from the proximal edge  106  of the pond. In this example, propagating waves  112  are directed to both the proximal edge  106  and the distal edge  116  of the pond. The alternative arrangement may reduce the amount of equipment needed to supply propagating waves  112  to the pond, or may reduce the number of ponds (not the surface area of cultivation or volume of media  102 ) needed to cultivate a desired amount of algae. This alternative arrangement may allow the ponds to be of other than rectangular shape, or may allow for increased propagation of waves or some other benefit. The alternative arrangement may provide needed flexibility based on construction, harvesting or other considerations or restrictions. 
         [0034]    In an alternative implementation, the agitator  108  may occupy substantially all of the length  124  of the pond  100  as shown in  FIGS. 1 ,  3 . In another implementation, the agitator  108  merely occupies a portion of the length  124  of the pond. In yet other implementation, the agitator  108  is broken into several portions or units (not shown in  FIGS. 1 ,  3 ). Each agitator unit may operate independently of other agitator unit(s), or may act in concert or coordination with other agitator unit(s). For example, each unit may operate in sequence to cause a rolling wave or wave that travels in a direction that is not substantially parallel to the width  114  or length  124  of the pond  100 . Alternatively, the units may operate in sequence starting at a middle portion of the length  124  of the pond  100  and ending at the edges of the pond—a V-shaped wave may be created and propagated. 
         [0035]    In yet another alternative implementation, waves of different magnitudes may be generated over time. For example, propagating waves  112  may be created in a pattern or rhythm such as two waves of relatively small magnitude followed by two waves of relatively large magnitude. In this example, perhaps the waves of relatively small magnitude fail to reach the distal edge  116  of the pond  100 , but the waves of relatively large magnitude do so. In yet another variation of propagating waves  112 , as the algae biomass increases over time, the magnitude of propagating waves  112  is increased as needed or as measured (e.g., in real time) to ensure that the propagating waves  112  reach the distal end  116  of the pond  100  or detectably reach a point of measurement along the length  114  of the pond  100 . In such a scenario, a propagating wave magnitude sensor (not shown) relays feedback to the control system of the actuator of the agitator  108  so that a proper or desired magnitude of propagating wave  112  is delivered at any given time. Propagating waves  112  may be varied in frequency depending on a variety of factors including, but not limited to, time of day, day versus night, width of the pond, density of algae, strain or type of algae, depth of water in the pond, age of the inflatable agitator. 
         [0036]    In the implementation shown in  FIG. 3 , a bridging section  312  may connect agitators  108  in neighboring ponds. That is, compressed air may be passed into the agitators  108  of neighboring ponds at substantially the same time, or that agitators  108  of neighboring ponds may be actuated at substantially the same time or through the same actuation or mechanism. 
         [0037]    Scaling Up 
         [0038]      FIG. 4  shows an overhead view  400  of an algae cultivation system including a set of algae cultivation ponds and a system of agitation mechanism(s) for production of algae on an industrial scale according to one implementation of the invention. With reference to  FIG. 4 , a first array  402  and a second array  404  of cultivation ponds  100  are evident. As one example of the arrangement of ponds, each of the ponds may be about 40 feet (12 meters) in width  114 . 
         [0039]    Given that each pond  100  is about 1 mile long (1.6 km), about 120 ponds may be placed side by side in a square mile with about 4 feet (1 meter) of berm  210  between neighboring ponds  100 . During algae cultivation, propagating waves  112  are capable of traveling from one edge of these mile-long ponds to the other. Other arrangements are possible. For example, ponds  100  may be about ¼ mile (0.4 km) long. One disadvantage of such an arrangement would be the requirement for four times the number of agitators  108  and increased amount equipment needed to actuate the agitators  108 . 
         [0040]    An industrial scale compressor  406  provides air through ducts  408  to agitators  108 . Control equipment such as valves, computers, actuators and the like are not shown in  FIG. 4 . However, it is to be understood that such are used to operate the agitators  108  and other components of the system. For example, dampers (not shown) provide pulses of air to agitators  108 . 
         [0041]    In a first array or set of ponds  402 , the agitators  108  are operated in synchronization with each other. This is evident by the propagating waves  112  shown at about the same position in each of the ponds  100  at a given instant of time. In this implementation, air is introduced into each inflatable portion of the agitators  108  at about the same time. This may be accomplished by connecting neighboring agitators  108  with each other so that only one or just a few ducts  408  are needed to actuate agitators in the ponds  100  in the first array  402 . 
         [0042]    In another implementation, in the second array  404  of ponds, the agitators  108  are operated (one or more at a time) in series according to a control scheme. For example, each of the agitators  108  receives a pulse of air from the compressor  406  in turn. This is evident by the propagating waves  412  shown at different positions in each of the ponds  100  at the given instant of time. This scheme would require a damper for each agitator or group of agitators  108  receiving a pulse of air. The scheme in the second array  404  provides a more balanced load on the compressor  406  and related equipment. 
         [0043]    The air compressor  406 , ducts  408  and various equipment could be sized depending on a variety of factors including (but not limited to): the number of propagating waves desired each hour for each pond, the desired size of propagating wave in each pond, the length or width of each pond or the array of ponds, the number of agitators operating in tandem or synchronization, the ambient temperature, the amount of algae biomass in each pond, and the energy source used to compress the air. In one implementation, an air compressor  406  is sized to supply enough compressed air for operating agitators  108  in both the first array  402  and second array  404 . 
         [0044]    In one implementation, an algae cultivation and harvesting system comprises a central facility for growth media preparation, one or more feed canals a set of pulse agitated cultivation ponds  402  and one or more harvest canals. 
         [0045]    The growth media for the algae may be enriched with carbon dioxide. There are many sources of carbon dioxide. A predominant source of the carbon dioxide may be a gaseous exhaust of an industrial scale fermentation, industrial combustion gaseous exhaust, or may be taken from a source of geologically-derived carbon dioxide, or any combination of such sources such as a combination of gaseous exhaust of an industrial scale fermentation, geological carbon dioxide, and gaseous exhaust from an industrial combustion. 
         [0046]    The algae cultivation system shown in  FIG. 4  preferably includes pulsed agitation predominantly across the respective short dimension of each pond  100 . During cultivation, it may become necessary to include a source of makeup water. This makeup water may be derived from various sources including from: oil and gas production water, saline aquifers, inland saline lakes, sea water, surface fresh water, and fresh water aquifers. 
         [0047]    The algae cultivation system such as the one shown in  FIG. 4  may produce a wet algal cake or a dry algal powder. The algae cultivation system or facility may an algal product into two or more commodities. Alternatively, the cultivation facility may use fermentation to separate starch and sugar from protein, oils, or from the protein and oils. The ponds  100  of the algae cultivation system may be covered, lined, or covered and lined. The pulse agitation sub-system  406 ,  408  (and other parts not shown in  FIG. 4 ) may include a source of compressed air, ducts to distribute the compressed air, and control dampers. The in-pond agitators may take the form of ballasted floating bladders. 
         [0048]      FIG. 5  shows a flowchart  500  of one implementation of a method for causing agitation (e.g., propagating wave) in an algae cultivation pond. With reference to  FIG. 5  and as explained at least in reference to  FIG. 4 , a compressor may compress air or other gas  502 . When desired, a damper is actuated  504  and an inflatable portion or portions of an agitator are inflated  506 . The action of pulsing or relatively rapidly inflating the agitator  506  causes a propagating wave in the growth medium of an algae pond. The propagating wave travels in the algae pond. Before a next pulsing, the agitator is deflated  508 . Deflation allows the agitator to sink back into the pond or otherwise configure itself to a starting or ready position. It is through intermittent or cyclical application of pulses of compressed air or gas that propagating waves are introduced into a pond and thereby improves or encourages growth of algae. 
         [0049]      FIG. 6  shows a flowchart of one implementation of a method for cultivating algae according to the invention. With reference to  FIG. 6 , algae may be cultivated by supplying growth medium to a recess  602 . The recess may or may not be lined or enclosed. Generally, a recess is a pool, pond, furrow, channel, tube or canal formed specifically for the purpose of cultivating algae. Nutrients and other materials may be supplied to the growth medium  604 , either before, during or after algae is supplied to the growth medium and recess  606 . These first steps  602 ,  604  and  606 ) may be performed in any order, all at once, intermittently, or continuously. At some point in time, propagating waves are generated in the growth medium  608 . The propagating waves may be generated frequently or infrequently, but at least frequently enough to provide improved growing conditions over those associated with a non-agitated growth medium. 
         [0050]    When it is time for algae harvesting, the growth medium in the recess is drained  610 , and the algae is dried or allowed to dry  612 . In preparation for another batch of algae, the dried or partially dried algae is removed from the recess  614 . The process or method for cultivating algae may then be repeated. 
         [0051]    Glossary 
         [0052]    Unless stated otherwise, or found in conflict, the following language provides at least one meaning of the terms used herein to describe and explain the invention. 
         [0053]    Algae medium refers to the liquid, fluid, water and the like refer to the liquid medium resident in ponds for algae or biomass cultivation. An example of an algae medium is found in  FIG. 1  as  102 . 
         [0054]    An algae cultivation pond or reservoir has been referred herein to an open recess in which a liquid medium for algae or biomass cultivation is disposed. However, the concepts described apply equally well to all sizes, shapes and arrangements of equipment and materials. For example, propagating waves may be applied from a nano-scale up to and including ponds and reservoirs that are miles in length. 
         [0055]    Although the present invention has been described with reference to specific exemplary embodiments, it will be evident that the various modification and changes can be made to these embodiments without departing from the broader spirit of the invention. In an area of technology such as this, where growth is fast and further advancements are not easily foreseen, the disclosed embodiments may be readily modifiable in arrangement and detail as facilitated by enabling technological advancements without departing from the principals of the present disclosure.