[ad_1]
Harry Valentine
2019-07-06 18:12:01
Until recently, the short lifespan of electrochemical batteries and their high replacement cost deterred water transport companies from investing in the electric propulsion of boats. New developments in network – scale vanadium oxide discharge batteries and in the technology of molten metal batteries now provide the industry with batteries capable of delivering 15 to 20 years of service.
The ongoing development of battery storage technology is aimed at increasing storage density and service life. For stationary applications, large grid cells combine a large physical size, low storage density and a significantly extended useful life. Size, weight, low storage density and low vibration and shake tolerance make these batteries unsuitable for rail and road applications. However, maritime vessels operating at low speed along inland waterways and providing short-haul excursion and tourism services have relatively low power and can be partially recharged during short stopovers.
A navigation vessel that sails at a speed of 12 miles at the hour along a narrow channel needs 3,375 times the propulsion energy of an identical ship sailing at eight miles at the hour. There are countries where hydroelectric power and nuclear energy sell a fraction of the price per kilowatt hour as diesel fuel for propulsion engines. During slack periods at night when the demand for electricity in the market is minimal, it becomes possible to recharge an energy storage technology at the network scale at prices well below the market prices. market, including batteries on board ships engaged in a short sea day operation.
Competitive long-term batteries
Cell-CubeTM is the manufacturer of the vanadium oxide flux redox long-life battery that recharges the electrolyte and offers a 20,000-cycle deep cycle recharge-discharge capability. Each unit is built to the same dimensions as 40-foot shipping containers and offers an output power of 200 kW to 500 kW over a period of three to eight hours. The competitor AmbriTM offers an equivalent-life liquid metal battery constructed with dimensions comparable to those of 20-foot containers (20 feet long by 10 feet wide by 8 feet high) with an output capacity of 500 kW. Both technologies avoid the cycle-by-cycle loss that affects some electrochemical storage battery technologies.
The vanadium oxide flow battery can operate at ambient air temperatures between -20 ° C and 50 ° C with an output of 400 volts and a specific energy density of 39, about 14 Wh / kg. Since the barges were carrying sections of freight trains loaded on rivers, a tug could be built to support the full weight of the vanadium oxide batteries as well as the weight of the Molten metal batteries operating at over 300 ° C. Liquid Metal Adaptation Battery technology for the operation of waterways would require innovations in insulation, such as the use of watercraft sections. Zirconium oxide to attach the battery to the ship's structure.
Advantage of the scale
A tug and a battery ship use much more transportation technology than road or rail vehicles. Larger scale and comparatively low travel speeds allow for viable use of long-life, large-scale battery technologies that would otherwise be unworkable for road and even rail transport. A marine vessel that navigates the inland waterways will withstand longer than road and rail utility vehicles, thereby enhancing the viability of investing in battery technology at the grid scale to store energy. propellant. Operators of inland waterway vessels have competing battery technologies to choose from for their unique applications.
Batteries and vehicle technology
Battery-powered road vehicles consume extra energy and support the energy storage system to mount at altitude, requiring light batteries with a very high specific energy density greater than 50 Wh / kg. Commercial road vehicles such as school buses only operate during AM and PM hours for three to four hours a day. Public transport vehicles using batteries can be partially refilled regularly throughout the day of service in terminals and stations. In terms of energy consumed per unit weight of the vehicle, road and rail vehicles are less efficient than shipping.
Commercial electric waterborne transport vehicles do not have to bear the weight of energy storage technology. During transit to another altitude at the navigation locks, it is possible to partially recharge the batteries. Because of their physical size and carrying capacity, vehicles powered by battery-powered waterways can use long-life network batteries with a comparatively low specific energy density of 10-20 Wh / Kg. At the present time, none of the battery technologies applied to road and rail propulsion can offer the long service life of grid-scale batteries that can be adapted to the propulsion of waterways .
Research on changing batteries
The research on flow batteries undertaken by the materials engineering group of the National University of Singapore (NUS) has focused on increasing the storage density of water. energy from redox flow batteries, including higher storage density from vanadium-based flow batteries that can apparently contain up to twice as much energy. at temperatures up to 80 degrees C. Flow batteries include large tanks of aqueous electrolytic solution of materials such as vanadium oxide and even salt solutions. The pumps dispense the aqueous solution through cell stacks to deliver electrical energy.
NUS research on Redox Flow lithium batteries has focused on offering vanadium flow batteries up to five times the storage density, which, when applied to navigation, should allow a navigation distance five times higher. A Flow battery concept still under research and development at NUS uses two tanks, a titanium oxide tank and a second lithium-iron-phosphate tank that can hold up to 10 times the storage density of vanadium batteries. with redox flow. If the search succeeds, the technology could find a propulsive maritime application.
Tugboat on the waterway
Depending on their geographical location, 10 m (35 ft) wide barges navigate the waterways with a 2.7 m (6 ft) draft. The tug that pushes the barge sails navigates in the hydraulic shadow of the vessel that precedes it, allowing it to navigate in an almost identical cross section and allowing the weight of the grid weighing batteries to expand on a large scale. floor area. A 180-foot tug could carry 12 grid-scale batteries built by Cell-Cube to the same dimensions as a 40-foot container and placed three times along the length.
Each vanadium oxide flow battery can deliver 200 kW at 500 kW for three to eight hours, or 2,400 kW (300 hp) at 6,000 kW (8,000 hp) with a deep cycle discharge / discharge capability. more than 20,000 cycles. Stopping the navigation locks in transit allows the batteries to be partially recharged when the tug / barge combination changes altitude. To speed up tugboats and barge trains leaving navigation locks, it is possible to install a trolley cable a short distance along the shore of the channel to allow the tug to draw energy directly from the network , the batteries mixing as the badembly reaches its cruising speed.
River boats
While ocean-going mega-ships attract a significant number of customers, a percentage of the tour market chooses to take vacations aboard small ships that navigate the waterways. These ships usually only sail during the day and remain in the river ports during the night when it becomes possible to recharge batteries at the network scale at peak rates. River cruise ships on batteries could attract the segment of the eco-tourism market. These ships also stop at points of interest to allow guests to visit local attractions while the batteries are partially recharged.
The sheer weight of low-altitude network batteries in the boat provides increased stability during daytime hours when the majority of pbadengers can occupy the highest elevations of the boat. With the low speed of navigation, customers could benefit more from the landscape along the shoreline. The combination of low speed navigation, night calls and a few day calls, including navigation locks, allows the vessel to serve customers while charging the batteries regularly and partially.
Short sea ocean service
Ongoing research at NUS offers the possibility of electrically propelled vessels navigating on short ferry services, such as Dublin – Liverpool and Belfast – Liverpool on the Irish Sea, Helsinki – Tallinn in the Gulf from Finland, Helsinki – Stockholm and the Baltic Sea. , Foo Chow / Amoy – Taiwan in front of the Taiwan Strait, Jeddah – Port Sudan in front of the Red Sea, Buenos Aires – Montevideo in front of the Rio de la Plata, Wellington – Picton in front of the Cook Strait, Victoria – Tasmania in front of the Bbad Strait and several ferry services like Nice – Corsica, Athens – Crete, Rome – Sardinia and Barcelona / Valencia – Balearic Islands.
conclusions
While the manufacturers of long-lasting networked electric accumulators focus exclusively on fixed installations, the same battery technology can have a mobile application providing propulsive energy to a small variety of seagoing vessels sailing on the waterways. While flux redox batteries and molten metal batteries would not be practical for road and rail propulsion, these technologies could find application in marine propulsion.
Web pages
Ambri Battery – www.ambri.com
Cell-Cube – www.cellcubeenergystorage.com
NUS (Singapore) – http://technology.nus.edu.sg/technologies/15141n-11179n_advanced-redox-flow-batteries
The opinions expressed in this document are those of the author and do not necessarily reflect those of The Maritime Executive.
Source link
