Patent Publication Number: US-2012038210-A1

Title: Apparatus and method for electric floating storage and offloading

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/372,761 filed on Aug. 11, 2010. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to electrical power systems. More particularly, it relates to a system for supplying power to an electrical grid system from a floating vessel having storage means for electrical energy. 
     2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98 
     Some renewable electric power generation facilities produce electric power intermittently or in small quantities because renewable electricity can only be generated when the source energy is available in the environment. In contrast, electricity must be dispatched to the market when needed and in the amounts required. When renewable electric power generation capacity is relatively small, as it is now, conventional dispatchable sources of electricity, such as distributed gas fired power plants, are taken online/offline to accommodate the availability of renewable energy sources, but this is not an economic long-term solution due to start-up and shut-down cost of the stand-by generating units. Increasing amounts of energy storage will be required as more renewable electrics are connected to the grid. Energy storage capacity bridges the disconnect between the supply and demand for renewable electricity and adds value to renewable electric installations much as oil storage adds value to remote oil reserves. 
     Although the growth of renewable electrics highlights the need for energy storage on the grid, Energy Storage Systems (ESS) are already being added to the grid for other reasons. For example: 
     1. Load-shifting. ESS can be used to accumulate lower-cost, off-peak electric energy for later sale at higher rates. This presents financial opportunity and also has the real benefit of allowing deferral of investment in transmission, distribution, and generation facilities. 
     2. Ancillary grid services. ESS can provide critical ancillary services such as frequency regulation and voltage support that improve grid stability and reliability. 
     BRIEF SUMMARY OF THE INVENTION 
     One illustrative embodiment of the invention comprises an Electric Floating Storage and Offloading system that: (1) may be moored at a location convenient for connection to the power grid; (2) supports an array of grid-scale batteries; and, (3) provides means for delivering stored electrical energy to the power grid or to an end user. In another embodiment, an accompanying crane barge lifts energy storage modules (e.g., grid-scale batteries) from a transport vessel (e.g., a barge) onto a shore foundation so that the facility transport barge can be released. 
     Another embodiment of the invention provides an energy transport system for supplying an electrical grid with power previously produced at another location (e.g., a renewable energy source). An exemplary embodiment comprises: an offshore source of electrical energy (e.g. wind, wave, tidal, ocean thermal, etc.); an energy storage device on a vessel [e.g., grid-scale batteries]; and, a shore-side (or river-side) electrical connection to a grid (to which the energy storage device may be transported by and connected). In another embodiment, stranded offshore gas reserves are used as fuel to generate electricity (at an offshore location) which may then stored in an ESS on a vessel for transport to an onshore grid connection. 
     Yet another embodiment of the invention permits electrical energy to be deployed in or near shipping lanes to replenish hybrid electric vessels (analogous to the “oilers” used to refuel naval vessels that use petroleum-based fuels). In this embodiment, one or more vessels carrying an energy storage device (or array of such devices) are stationed along a predetermined route of a hybrid electric vessel. The deployment positions may be at or near a renewable energy source thereby permitting the energy storage device to be charged. During the replenishment operation, the vessel having the ESS may be brought alongside the hybrid electric vessel and an electrical connection may be made which enables a transfer of electrical energy from the storage vessel to the hybrid electric vessel. As is now done with oilers, this may be accomplished while both vessels are underway. 
       FIG. 1  illustrates the general concept of a coastal electric floating, storage and offloading vessel (“e-FSO”). 
     Several types of battery technologies are evolving in the US/EU in response to large R&amp;D programs in the automotive, utility, and defense industries. Grid-scale batteries have been put into service at locations in the US and abroad. These facilities have been constructed on location using truckable modules and components. A publication indicated that budget, schedule, and/or relocation was an issue on at least one of these projects. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1A  is a plan view of an e-FSO according to one embodiment of the invention shown in a coastal deployment. 
         FIG. 1B  is a side view, partially in cross-section of an e-FSO in a coastal deployment connected via a floating umbilical system to the shore-side power grid. 
         FIG. 1C  is a side view, partially in cross-section of an e-FSO in a coastal deployment connected via a buried umbilical to the shore-side power grid. 
         FIG. 2  is a plan view of a sequential deployment of an e-FSO according to the invention in an inland locale. 
         FIG. 3  is a plan view of two e-FSO&#39;s according to the invention deployed along an ocean shipping lane. 
         FIG. 4  is a perspective view of an e-FSO according to an embodiment of the invention which comprises a mechanical-type energy storage device. 
         FIG. 5  is a schematic representation of an e-FSO according to the invention connected to an on-shore electrical substation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Many population centers, and therefore centers of electric power demand, are located in coastal areas or along navigable rivers. The type of vessel that supports the ESS may depend on the specifics of the application and the given marine environment. For example, if electricity were to be stored near a coastal load center like Monaco or New York City, the batteries may be integrated into a ship-shape, semisubmersible, or barge that offered reasonable motions in that marine environment. If energy storage were to be provided to a city on a river, e.g., St. Louis, Mo., the battery array may be integrated into a barge that may be transported on an oceangoing vessel, offloaded, and towed to final location on the river ( FIG. 2 ). 
     An e-FSO may also be located along shipping lanes and store energy for periodic discharge into hybrid electric ships ( FIG. 4 ). The military may nucleate early infrastructure which may then subsequently become available and expanded for later commercial users. 
     Various types of energy storage devices may evolve to be supported on a marine vessel. A mechanical battery, which is a special type of e-FSO, may be possible when: (1) the marine climate is mild and (2) deepwater is relatively near the coast and grid-connection points. As shown in  FIG. 5 , potential energy may be stored underwater by using an electric motor to raise large, engineered, submerged weights. Electric power may later be delivered on demand, by lowering these same weights and converting the kinetic energy of the turning winch drums into electricity using a generator or alternator. 
     An e-FSO according to the present invention offers the following advantages: 
     Minimal Real Estate.  
     Large ESS&#39;s may be located near major cities and load centers without requiring expensive coastal real estate. 
     Safe Operation.  
     Advanced technology batteries may be located at safe distances from populated areas. This may be an advantage as certain grid-scale batteries operate at high temperatures and/or contain hazardous materials. 
     Flexible Growth.  
     Additional units may be installed over time as energy storage requirements increase. 
     Adaptable to Battery Technology Improvements.  
     The battery array on a given vessel may be changed out as battery technology improves over time. 
     Mobility and Residual Value.  
     Energy storage units may be relocated as generation and load centers change over time. In some cases, an e-FSO according to the present invention may allow deferral of power generation facilities by enabling storage of off-peak energy for later discharge during daily peak demand. 
     Reduced Construction Costs.  
     Large battery arrays may be cost-effectively integrated into the vessel at a manufacturer, shipyard, or fabrication yard and economically transported to the installation site. On-site construction work may be minimized. 
     Transition to Renewable Energy Sources.  
     Energy storage units may be justified initially by enabling the purchase of energy at low off-peak rates for resale that same day at higher peak rates. As renewable electrics are added in a region, expandable energy storage infrastructure would already be in place to aggregate renewable energy and create more valuable dispatchable energy. 
     Adjacent Technology.  
     As will be appreciated by those skilled in the art, much of the technology used in FPSO vessels used in petroleum production may be adaptable to the practice of the present invention. 
     Referring now to  FIG. 1A , an e-FSO  110  floating in body of water  106  and comprising grid-scale battery  110  is moored at shore connection facility  104  and connected to power grid  100  via floating umbilical  112  and transmission facility  102 . 
       FIG. 1B  shows e-FSO  105  comprising grid-scale battery  110  in electrical connection with on-shore transmission facility  116  via floating electrical umbilical  112 . 
       FIG. 1C  shows e-FSO  105  comprising grid-scale battery  110  in electrical connection with an on-shore electrical conduit  116 ′ via electrical umbilical  114  which is buried in the seabed for at least a portion of its length. 
       FIG. 2  illustrates how a charged, grid-scale battery  110  may be transported by an oceangoing vessel  124  (which may be towed by tug  122 ′) to near the mouth of navigable river  120 . While still in body of water  106 ′, battery  110  may be transferred from vessel  124  to river barge  126  which may be pushed up-river by tug  122  to a mooring  128  for connection to electrical transmission facility  102 ′. 
       FIG. 3  shows how e-FSO&#39;s  105  according to an embodiment of the invention and comprising grid-scale batteries  110  may be deployed along a shipping lane  300  to replenish ship  302  which comprises a propulsion system that is at least in part powered by electrical energy. In certain embodiments, ship  302  may be replenished while underway with e-FSO  105  alongside it. 
     In the illustrated embodiment, battery  110  on e-FSO  105  is charged by renewable energy source  312  while battery  110 ′ on e-FSO  105 ′ is charged by renewable energy source  310  which may be the same or a different type of energy source as  312 . 
     Also shown in  FIG. 3  is floating power production source  314  which may be an offshore platform having generators powered by stranded natural gas produced offshore at or near platform  314 . The electrical power generated on platform  314  may be used to charge grid-scale battery  110 ″ on e-FSO  105 ″. After charging, e-FSO  105 ″ may rendezvous with ship  302  for replenishment of its on-board electrical storage means. 
       FIG. 4  illustrates a mechanical battery  410  mounted on semi-submersible vessel  400  which comprises submerged hull  405 . Winches  420  support submerged weights  440  on cables  430 . Power generation modules  450  which may include solar power panels  460  supply the electrical power to winches  420  to raise weights  440 . When power modules  450  are not producing power, weights  440  may be lowered, turning the drums of winches  420  which are mechanically connected to generators or alternators which produce electric power for immediate consumption. 
       FIG. 5  is a schematic view of an e-FSO according to an embodiment of the invention. e-FSO  105  comprises grid-scale battery  110 , power conversion system  510  (which may comprise an inverter for converting the direct current supplied by battery  110  to alternating current) and transformer  520 . Power may be supplied via electrical connection  530  to on-shore transformer  540  which, under the direction and control of power control system  550 , may feed electrical power to an on-shore electrical power grid. 
     Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.