Technical Summary

 

A Technical Summary of AEEA’s Orca Wave Energy System

(Patent 8193651)

System Overview

The benefits of the system developed and patented by AEEA are: (1) exploitation of the greater wave energy density in the more remote off-shore locations; (2) usage of existing industrial fuel storage and distribution infrastructure; (3) provision for a gradual transition to more environmentally friendly vehicle fuels; (4) avoidance of environmental destruction and visual impairment, with minimal impact on commercial fishing and recreation uses; (5) fostering the development of a new maritime and energy industry; (6) avoidance of the high capital investment in mooring and anchoring, seabed electrical cable installation and seabed restoration; (7) development of flexibility by deployment of fleets of these vessels to supply widely separated market locations using coastal and national waterways; and (8) provision for the addition of fleets without depletion of primary feed stocks, as in nuclear energy systems [2] Fig (1 In summary, the system converts wave energy from the nearly unlimited world-wide resources of the open ocean (as illustrated in Fig. 1) to gasoline, diesel fuel, or jet fuel, while at sea. The production process also releases oxygen into the atmosphere and also reduces carbon dioxide (CO2 ) in the atmosphere. The reduction of carbon dioxide also generates revenue from the sale of carbon credits. Further, the system uses most of the existing common facilities and personnel trained to perform energy conversion, storage, transportation, and distribution within existing energy suppliers.


Fig. 1 The Global Wave Energy Resource , Annual Average Wave Power Density, Kw/M [10]

Background of the Prior Art

The use of floats to capture the largely untapped energy available from ocean waves has been known for many years. The more successful applications and the ones most related to the AEEA concept utilized wave energy conversion in conjunction with hydraulic systems, servomechanisms and turbo-electrical generators to adapt to a wider range of sea conditions including wave amplitudes and spectral wavelengths. Examples include Hagen, [4] Cockrell [5] and Talya [8] and McCormick; [9]. Systems in advanced development and, perhaps best known, include the Power Buoy ,of the Ocean Power Technology organization, and the Pelamis, of Pelamis Wave Power. All of these and other known systems have certain common characteristics which limit their adaptability to the

previously described guidelines. Due to their coastal locations, requirements exist for permanent moorages and the need for costly and environmentally abusive marine sea-bed cable deployments, and interfaces with the coastal electrical power grids. Start-up costs are considerably increased by the high price of prime coastal access space and the overlapping permitting procedures from federal, state, municipal and tribal regulatory agencies.

Concept of Operation

Fleets of ocean going vessels are coupled together in longitudinal rows, and transversal columns (Fig.8a) which operate in unison to convert wave motion to electricity. Subsequent processes sequentially perform a caustic air scrubbing function from the atmosphere to obtain carbon dioxide in a form suitable for processing with hydrogen to first, obtain a basic feedstock of methanol. Then, the methanol is subjected to catalytic dehydration to obtain gasoline as the current priority product. The hydrogen and carbon dioxide are produced by using a unique, 3-cell electrolysis of makeup and recycled water from shore-based sources and a sodium carbonate solution. Other hydrocarbon products may be obtained by suitable adjustment to the dehydration process. If and when future electrical storage methods are economical, they may be stored directly in an electrical form. Means are provided to optimize the wave energy conversion process to accommodate changes in wave direction, wavelength, amplitude and phase. Designated vessels are self-powered for off shore or inland waterway navigation. Fully articulating stern thrusters are used for dynamic position keeping as an alternative to anchoring, and for propulsion in the delivery of the product to ports of call.

This system is well suited to organizations that have a worldwide scope of operations.   Fig. 1 illustrates the worldwide abundance of suitable wave energy densities. Current deployment is based on average power densities of 40 kw/m of wave crests. Other figures may be economically feasible dependent upon market conditions.



















Fig. 2 Interrelated systems of energy collection, processing and product delivery

The “system of systems” required of the fleet are identified with their functional interactions in Fig. 2 which include: production, control and storage of electrical energy through hydrocarbon feedstock synthesis, integrated propulsion/dynamic positioning, semi-automatic fleet attachment, cargo storage, inter-barge and barge-shore cargo transfer. Provisions for safety standards, crew work stations, and living accommodations also are included.

A Typical Regional Fleet Organization and Operation

A fleet of 64 barges in a 4 x 16 array has been chosen for our on-going configuration studies which is a self- contained unit and depicted in Figure 3. The number of these fleets deployed in a geographical area depends upon market factors. The 64 barge fleet is shown in the schematic below:







Fig. 3 Typical Regional Fleet Configuration, Type 1, 2,3, and 4 Barges

At the opposite corners of a fleet would be the type 1 delivery barges (blue).  Next to the type 1 barge would be a type 3 holding barge (green).  The other two barges at each end of the fleet would be the  type 2 production barges (purple). The fourteen rows in between the two ends would be comprised of four columns  type 4 worker barges (white). The two type 1 barges would be double hulled since they would be the only barges designated to transport the gasoline cargo. They would also have the crew quarters and the means to provide supervision and control of operations. In addition to generating electricity, these barges would be used for dynamic positioning, and to ferry the gasoline product to shore. Methanol is produced on the type 2 barges and transferred to the type 3 barges which perform the methanol to gasoline (MTG) synthesis and short term storage.  Long term storage and transportation to port by the type 1 barges. In addition to the safety precaution provided by the double hull construction this double-hull design of the type 1 barges provides storage for make-up water on the return trip to the fleet from the shore delivery.

The type 1 barges have semi-automatic systems of attachment with the type 3 and type 4 barges with which it connects at the corners of the fleet. These barges are propelled with two electrically powered, stern mounted outboard engines having full articulation capability which is powered and controlled from the barge power and data busses. Each type 1 barge has a four-person crew who work with the two mechanics assigned to each end of the fleet.

The Type 2 production barges are single hulled, and are located at each end of the fleet. They produce electrical energy, as do all barges of the fleet, and are connected to the fleet power bus. Status monitoring and control is established through the fleet data bus by the Control Modules on the Type 1 barges. The Type 2 barges have similar propulsion and dynamic positioning as the Type 1 barges. Its purpose within the fleet is to perform all functions necessary to produce the methanol feedstock which includes obtaining CO2 from atmospheric sequestration and re-cycling NaOH from the 3 cell electrolysis. The methanol is transferred to the Type 3 barges on a coordinated aggregation basis. The type 3 and type 4 barges, produce, transfer, and use electrical energy through their attachment system connection with the fleet power and data busses.  For a more complete description of our Orca Wave Energy System’s Concept of Operations visit that section on this site.

Vessel Attachment System

A basic feature of the fleet architecture is the ability to attach adjacent vessels together that permits semi- automatic coupling/decoupling actions that: 1) permit vessel heave, pitch and roll, but restrict yawing and longitudinal movements shown in Fig7b; 2) consist of robust construction that will enable survivability against storms; 3) be designed to eliminate line handling and other labor intensive actions; 4) and provide for liquid cargo and water transfer between vessels; 5) provide for electrical power to be transferred between vessels; and 6) data accumulation, operational control signals and crew communication. Fig. 4 illustrates the principal subsystems and their components. Each vessel will be provided with latching sockets located on the stern and starboard sides and attachment probes on the bow and port sides as shown in the figure. The rigid couplings will be located near the bottom corners of the hull of each vessel. The upper couplings will be comprised of an articulated assembly of hydraulic cylinders, which derive the energy from the differential motion between the vessels and will actuate hydraulic motors and electrical generators. The Attachment System also provides liquid transfer between designated vessels as well as electrical coupling to the Electrical and Data busses.

The relative motion between the attachment points of the upper members will require freedom of motion in the three rotational axes: pitch, roll and heave plus the linear extension and retraction of the hydraulic piston as the vessels rotate about the rigid attachments. When coupling or decoupling the vessels, each attachment mechanism will be controlled by a closed loop sensor/servomechanism system capable of detecting the free space .location of mating components and positioning the probe for semi-automatic engagement during conditions of up to moderate sea states.


Fig. 4 Principal Components and Locations of Standard Vessel Attachment System



Fig. 5 Examples of Candidate Modular Components of the Fleet Modularity as a Design Principle


Ways and means have been adopted to apply a modular design approach to the major components of the fleets of barges to achieve cost savings through mass production. Other advantages include the ability to reconfigure the system to meet market changes . It is recognized that opportunities may arise to serve worldwide geographical markets not economically accessible using existing resources within an organization, nor within a limited reaction time to meet competitive deadlines. For these reasons most of the major systems would be designed to be installed in standard ISO containers as illustrated in Figure 5. These containers could be installed in “standard barges” to enable the use of existing port infrastructure for assembly. The systems could be supplied by competitive subcontracting suppliers from diverse geographical locations and delivered to the assembly ports by multi-mode ISO transportation facilities.

It is recognized that existing suppliers of the barges required for the fleets would have to be structurally reinforced to meet the projected stresses anticipated in extreme weather. However, after a modification design had been determined, all of the types of the basic ballast pre-adjustments of the barges inertial moments may be required to bring them into the adaptive range barges described in Figure 3 could be interchangeable. The ocean going deck barge design typified by the McDonough Marine Service is illustrative of the type under consideration.

The modularity design principle also would apply to the use of outboard mounted engines envisioned for the Type 1 and 2 barges and illustrated in the figure. This class of engines enables significant flexibility in the designation of these barges needing dynamic positioning and propulsion. The objective would be to eliminate or minimize through hull penetration for specialized thrusters , propulsive shafts, rudder mounting, control and fuel lines, etc. Having Two stern mounted engines, are typified by the Harbormaster Marine, Inc. and Thrustmaster of Texas . On board product would provide fuel or electrical power for propulsion, and the two engines would provide lateral control and space for the bow and stern attachment components to be efficiently located.

The flexibility of operation by applying a modular design lends itself to novel applications. An example, which typifies this principle is given: If moving a regional fleet to another location is required, most of the principal systems could be temporarily stored in ISO containers and after being transported in compatible carriers re- assembled at the destination.

It appears reasonable to envision “flotillas” or “segments” of a fleet that could be dispatched under their own resources to more remote locations to a new service location. This operation would require a sufficient number of Type 1 and Type 2 barges be assigned to supply propulsion and navigation to the fleet . Stretching the concept a bit further, the unpowered Type 5 barges could be temporarily converted to Type 2 barges by the attachment of outboard propulsion units. The electric outboard motors could be supplied by the fleet power bus and controls through the data bus, while all barges contributed to replenishing energy consumed during the transportation phase of relocation.

Critical Technologies

A multi-discipline technical approach is required to meet the program objectives. These would include a chemical processing technology suitable for the off-shore mobile application, electrical network design, distributed data processing, innovative mechanical and servo mechanisms, and marine structural design:

  1. A.On-board Production of Gasoline – A method of economically producing gasoline aboard the fleet vessels is shown in Figure 6. In the method adopted by AEEA, carbon dioxide is recovered directly from the atmosphere using a caustic air scrubber employing a sodium hydroxide solution. This solution is ready for the electrolysis of the resulting sodium carbonate solution in a 3 compartment electrolytic cell. Hydrogen is collected at the cathode, carbon dioxide collected at the center compartment, and oxygen at the anode and vented to the air. The hydrogen and carbon dioxide are collected and compressed to between 50 and 100 atm and heated to a temperature of 350 deg. C. over a copper catalyst to produce methanol. The methanol, an oxygenated hydrocarbon, becomes the feedstock for the production of gasoline. Dehydration of the methanol, using a ZSM 5 zeolyte catalyst at 350 deg. C. at 100 atm produces a gasoline distillate, the current product of emphasis. Other hydrocarbon products may be produced by varying the pressures and temperatures of the dehydration process. The caustic solution, NaOH, is recycled along with the water for reuse in the process. When the carbon dioxide is taken from the air, a chemical conversion efficiency of 57 per cent is achieved. This method is based on the pioneering work of. Meyer Steinberg [3].
















Fig. 6 Economic Production of Gasoline at Sea


b) Wave Energy Conversion - Wave energy conversion is performed by utilizing the shape, dimensions, orientation and differential motion between the fleet vessels in a manner to obtain maximum wave energy transference. The principal operations and assemblies comprising this operation within the Wave Energy Conversion System are the considerations of the hull dimensions of the fleet , establishment of orthogonal processing of the roll and pitch channels, hydraulic to electrical energy conversion and means off controlling the differential motion of the vessels to obtain fleet resonance to impending waves.

Fig. 7 illustrates the principle of a vessel in resonance, by showing its reaction to an ideal, or sinusoidal ocean wave. It indicates that the height, or amplitude, of a wave is measured from the crest to the trough, which corresponds to an ocean wave length of λ/2.In this example a vessel impacted by the wave would be at a maximum roll or pitch angle or its natural state for wave λ. In a typical wave environment, however, ocean waves contain a random spectrum of wavelengths of varying amplitudes, phases and directions of arrival (Fig. 8) at the vessel, but this principle of resonance applies to any component of a complex wave. These ocean waves, in turn, are composed of wind waves and swell waves, each class arriving from independent directions.











Fig. 7 A Vessel in a Natural Resonant State

Wind and swell waves off of the Washington and Oregon coasts, are typified by aggregate average power densities of about 40 kW/m of wave front and wind and swell waves having λ/2 wavelengths from 60 to 120 meters. To accommodate the range of natural resonances occurring for vessels responding to wave fronts impending on their roll and pitch axes, minimum and maximum dimensions of the vessels were chosen. This was accomplished in the wave energy conversion (WEC) design by the application of two principles: These are:

(1) Orthogonal wave conversion, is defined as having independent conversion channels for the roll (transverse) or pitch (longitudinal) axes (Fig.7). As the vessels are normally attached in rows and columns, the hydraulic pumps driving electric generators that are incorporated in the Attachment Systems, shown in Fig. 4 can process the orthogonal components of waves encountered from any direction and then optimally combined. The vessel fleets, being free floating and under dynamic position control, can adjust to the most favorable wave front direction.

(2) Adaptive Resonance: To achieve the efficiency of the natural resonance state described by Fig 7, each wavelength component of the spectra of an impending wave front should be matched by a corresponding increment of width or length of a vessel exposed to an incoming wavefront. Previous studies have suggested providing rafts of floats with incrementally increasing dimensions tuned to the segments of the spectrum of the complex wave structure [4],[5.] In the approach used in the present concept equivalent resonant conditions are achieved by using identical hull, and attachment and station keeping systems and most of the other on-board systems of the fleet of standard vessels. This approach achieves cost reduction through limiting the number of different vessel designs, utilizing common manufacturing tooling, and which can retain the sea worthiness of ocean certified maritime barges. This is attained by applying the principals of network design and implemented in the Operational Control Module, Fig. 9.

  1. (3)Equivalent Resonant Barge Dimension Synthesis – The equivalence of establishing resonance to a particular Fourier component of an ocean wave, but retaining fixed dimensions of the floating platform described by Figure 7 is in establishing a “stiffness” control of the rotational motion about the axes between adjacent barges aligned in the path of the wave front. This is established on a scale of 0 stiffness (no restraint of rotation between a pair of barges aligned in the wave oncoming direction) and W =1 (maximum restraint between the pair of barges). For example, a stiffness weight W = 0 restraint between two such adjacent barges, each of width λ/2 are resonant to a wave component of λ. When the weight is changed to W= 1, the combination of the two barges is resonant to a Fourier wave component of wavelength 2λ. Thus, a segment (collection) of n barges of widths λ/2 would be resonant to any chosen wavelength component within an impinging ocean wave of length of from λ to nλ,with weights assigned to each barge. A full explanation of how the principles illustrated by this simplified example are developed and expanded to address a full complement of a fleet of barges are included in the AEEA patent publication [11]which is available on the Internet

































(4)  Resonance by means of control of the coupling stiffness - The means of achieving resonance of a segment of vessels of a fleet allowed the freedom to rotate about their roll and pitch axes as shown in Fig. 8 is performed by the Hydraulic to Electrical Energy Conversion System ,Fig. 9. The wave action creates a differential motion between the adjacent vessels which is coupled to arrays of hydraulic pumps in the Attachment System.. The hydraulic components, in turn, drive regulated electrical generators feeding the fleet Power Bus. The pump arrays are assigned to the independent roll and pitches axes identified in Figure 9a. Back pressure on the roll and pitch cylinder arrays of the WEC may be controlled to create the variable stiffness in the mechanical coupling between the vessels. Servo loops which consist of a flow control valve, a hydraulic by pass return, the pump cylinder valve return and a stiffness control vector input to the flow control valve are show on in Fig. 9b. This loop manages output to a system accumulator, hydraulic motor and generator thus varying the apparent mass of a vessel to each wave passage.

The outputs of the pitch and roll flow sensors sense the energy extracted from each wave passage and the values are transmitted via the Data Bus to the fleet Control Module which calculates the proper control vector to be transmitted via the Data Bus to the actuators of the flow control valve.



Fig. 9a Hydraulic to Electrical Energy Conversion System


Fig. 9b Inter-barge Stiffness Control

(5) Implementation of WEC Control Within the Vessel Control Module: Fig 10 illustrates the application of the Adaptive Resonance principle in an implementation within the Vessel Control Module (Fig. 2) to any or all selected segment of vessels within a fleet . Using the wave transit time of the least dimension of a standard vessel, ti. the width, to define the shortest wavelength to be processed, impending waves are characterized, ie, sampled at ti intervals and transmitted to all vessels via the fleet Data Bus. Thus, the transfer functions of the vessels themselves, when coupled together become elements of transverse FIR filters.


Fig. 10 Wave Energy Conversion Display and Control Within a Vessel Control Module

These filters are utilized to implement either a manual or automatic control of fleet resonance. A display of wave characteristics existing in the fleet is available from any Vessel Control Module station in the fleet (Fig .2). Stiffness weights, W1...Wn, , may be employed to activate resonance of selected segments of the fleet on the basis of observations at the Monitor and Control facility using pre-stored filter resonant characterizations. The stiffness functions are applied as controls to the servo system illustrated in Fig.9b. If the adaptive resonance mode is chosen, this operation is automatic. Each FIR is utilized as an adaptive filter with an algorithm, the Least Mean Square (LMS,) developed by Widrow and Hoff [6]. In this application the current wave front is characterized to obtain samples A1 ...An and which are compared (subtracted) with values of the outputs of the vessel generators to develop an incremental error coefficient between the processed segment output and the unfiltered, but characterized, wave measurements. This error signal is continually minimized through successive iterations to maintain optimum conditions which exist at segment resonance. Ballast pre-adjustments of the barges inertial moments may be required to bring them into the adaptive range. The results of a computer simulation of the convergence time to achieve resonance of a 6 vessel fleet segment is shown in Fig. 11.




Fig. 11 Least Mean Square Convergence Time to Obtain Resonance for a 6 vessel Segment– Four Principal Wave Components

C) Distributed Data Processing

To perform all the control and monitoring functions of the system operation requires a high speed data network connecting the vessels of the fleet. These functions include: semi-automatic barge attachment, dynamic positioning, product processing, wave energy conversion, and inter-barge cargo aggregation, transfer and delivery. The approach used would be similar to that employed in military and commercial systems that use high speed data busses that link the network of remote data processing modules. In general, each major system would be assigned a group of dedicated standard data processing modules with the application software developed and imbedded to perform the function it is tasked. The interaction with the supervising Control Module is principally limited to directing task assignments and monitoring of the federated systems. However, centralized collection of data from the barges to perform processing operations that needs the remote data to perform functions common for the entire fleet cn be and is performed in the present concept. An example of this exception is in the ocean wave sampling, processing and transmission of stiffness instructions to the fleet stiffness servos described in Fig. 9b.

The objective of this general approach is to achieve robustness to system failure by avoiding overly centralized processing .Centralized process and control is inherently sensitive to catastrophic failure. The use of semi- independent modules assigned to the various major systems increases the overall “system availability”. The use of these “standard data processing modules” permits the fault detection and location to a particular module. Then reserve modules can automatically be brought on line and substituted for the failed processor. Routine maintenance can then substitute new modules for the failed ones without substantial loss of service. This philosophy has been adopted in applications where continuous service is required as in the latest military aircraft.

Preliminary System Performance Estimate

The present estimate of production for a regional fleet of vessels is about 5,000,000 gallons per year, and occupying 20 acres of sea surface. In electrical terms this is about 332 million kwh/year/fleet. No significant contaminates are produced in the chemical processes described, such as sulfur, nitrates requiring additional processing beyond that described in the present concept. A comparison may be made with that of a nuclear utility plant. A nuclear utility facility may typically provide on the order of a GW of electrical power. An ocean energy facility of the type described in this report would comprise 25 fleets and occupy about 500 acres, an insignificant expanse in the Outer Banks and would not have the have problems of waste disposal, potential for catastrophic failure and extensive certification procedures.

Conclusions

It is noted that the emphasis of the current AEEA activities is on gasoline production for various reasons. It has been recognized that the extraordinary increase in the market value of gasoline in the last several decades dwarfs the value of other potential product areas such as jet fuel, methanol, dimethyl ether (DME), synthetic diesel and other hydrocarbon products. It would appear that concentrating on gasoline provides an immediate market without compromising participation in future fuel and industrial chemical exploitation. If there is a transformation in future decades from the present dominance of gasoline as the mobile fuel of choice, to other fuels such as neat methanol, M85 methanol, gasoline, dimethyl ether (DME), hybrid and pure electrical propulsion, hydrogen-based fuel cells, direct methanol fuel cells (DMFC) and others, the basic industrial components would be in place with the present system concept. In other words, this could happen on a seamless basis with no appreciable premature obsolescence of the existent energy infrastructure.

It also is significant that the major emphases on the development of the most popular renewable energy endeavors such as wind, solar, geothermal and even ocean wave energy conversion sytems are directed to interface with the national utility grids, not for the transportation market. To serve the present major transportation applications additional conversion is required to convert these energy sources into a liquid form. The major interest of the AEEA group is in providing competitively priced liquid fuel (gasoline) as a primary product.The other applications will be serviced as the market requires with minor equipment investment. In this regard, the adaptation of the present AEEA configuration is easily modified for static applications for gas turbine generated electrical energy for the utility grids and industrial plants using methanol and DME. GE has shown that performance and emissions are comparable to that of natural gas and produces no SOx emissions.

References
[1] M.E. McCormick, Ocean Wave Energy Conversion, Dover Publications, p.5.

2] D. Abbott, “Hydrogen Without Tears: Addressing the Global Energy Crisis via a Solar to Hydrogen Pathway”, Proceedings of the IEEE, December, 2009, Vol. 97/No. 12

[3] United States Patent 3,959,094 Steinberg, Meyer, Electrolytic Synthesis of Methanol from CO2, May 25, 1976. [4] United States Patent 4,077,213, Hagen, Glen E. , Wave Driven Generator, March 7, 1978

[5] United States Patent 4,098,084, Apparatus for Extracting Energy from Wave Movement, Cockerell, Christopher, July 4, 1978.

[6] Widrow, Bernard B., et al, “ Adaptive Noise Canceling: Principles and Applications”, Proceedings of the IEEE, vol. 63, No. 12, December 1975, pp. 1692-1716.

[7] Olah, George A.; Goeppert, Alain; Prakash, G.K ,Surya, Beyond Oil and Gas 168-208, Wiley-VCH

[8] United States Patent 7,322,189 Talya, S., Bose, Sumit, “Wide Bandwidth Farms for Capturing Wave Energy, January 29, 2008.

[9] United States Patent 20090084296, McCormick April 2, 2009. [10] United States Patent Publication No. US-2010-0320759-A1



 

Fig. 8a