As Price of Li-Ion Batteries Rises, Shipping Has Other Green Options

During early January 2021, lithium salt from Australian mines brought a market price of just under $9,600 per metric ton. A year later during January 2022, the price of lithium salt had risen to over $50,000 per metric ton with the February price at $59,000. The market situation enhances prospects to further develop competing energy storage technologies for application in grid storage and transportation propulsion sectors.

Introduction

The massive increase in the price of lithium salt over the past year will likely influence future development of electrical storage batteries. Developers of lithium based batteries will need to greatly increase energy storage density and useable life expectancy of their products while reducing the propensity for dendrite formation that has resulted in explosions and fires. The cost per watt hour per kilogram between lithium batteries and competing battery chemistries has increased significantly. There is now potential to divert more investment into refining the competing battery technologies that could find application in numerous segments of the energy market.

While the high energy storage density of lithium battery technology appeals to the transportation sector, the solar and wind energy sectors require large scale stationary battery technology capable of supplying the power grid. Several of the grid scale electrochemical battery technologies are built to be housed inside standard size shipping containers during transportation and when in service. A few grid scale batteries that fit inside shipping containers might actually fulfill propulsion requirements in some unique niches in the transportation sector.

Lithium Innovation

The popular rechargeable lithium batteries in the transportation sector include lithium iron phosphate, lithium polymer and lithium ion technologies. While small size lithium titanate batteries are commercially available, research and development has been focused on refining lithium sulfur and lithium carbon battery technologies that offer greatly increased deep cycle life expectance and increased energy storage density. 

Research has been underway over the past several years to develop a long life, solid state lithium based rechargeable batteries that would be suitable for small battery electric road vehicle, small battery electric boat, battery electric ground effect plane and battery electric airplane applications. Over the past several months, announcements have been imminent in regard to breakthroughs involving solid state battery technology from companies such as Toyota and such as Tesla. Developers of solid state lithium battery technology seek to resolve the problem of dendrite formation and subsequent explosions, as well as to extend the useable life expectancy of the battery.

Competing Battery Technologies

Alternative battery technologies would be competitive against lithium battery technology in selected unique niches in transportation applications by offering gains in capital cost per kilowatt hour and useable service life expectancy. In some applications, the additional weight of competing battery technology would either be an advantage in a transportation application or of little relevance. Ongoing research and development has resulted in the appearance of alternate batteries that use low cost materials such as iron, salt, vanadium, zinc, bromine, cadmium and antimony to provide extended useable life expectancy involving several thousand repeated deep drain cycles.

Vanadium Flow Battery: Research into advancing the liquid electrolyte chemistry has raised energy storage density from 20 watt-hours per kilogram to 40 watt-hours per kilogram with potential to exceed 60 Wh/Kg. A unit the size of a 20 ft container would weigh 24,000 pounds empty and 80,000 pounds flooded, with 55,000 pounds or 25,000 Kg of electrolyte storing up to 1,000 Kilowatt hours of power with steady delivery at 250 Kw (335 Hp) over 4 hours. A future possible storage capacity of 1,500kWh would deliver 250 Kw over 6 hours and offer a useable service life expectancy of over 10,000 deep discharge cycles. Vanadium flow batteries are a future possible onboard energy storage technology for battery electric maritime propulsion.

Liquid Metal Battery: a 10-foot length container of liquid metal battery technology involving antimony and cadmium would weigh 110,000 pounds and offer 1,000kWh of power with 250kW delivery over a period of four hours. The battery chemistry has been tested to 100,000 full depth discharge cycles with optimal performance being available over the first 20,000 cycles. The weight of a pair of liquid metal batteries installed into a six-axle locomotive chassis would provide substantial traction and be suitable for shunting operations at a maritime port. A pair of such locomotives could propel a freight train between a maritime terminal and a nearby railway marshalling yard.

Zinc Bromide Gel Battery: The zinc bromide gel battery developed in Australia offers 5,000 full depth discharge cycles and the same volumetric storage capacity as a much heavier lead acid battery. A 40-foot container could hold 770 lead acid batteries rated at 12 volts at 150 amp-hours, with up to 1,500 discharges from 100 percent to 50 percent providing 690 kilowatt hours from 90,000 pounds of weight, or 17Wh/Kg. The zinc bromine gel battery could theoretically offer 1,380 Kilowatt hours at 100 percent full depth discharge from within the space of a 40-foot container. Future research is expected to increase storage capacity by 50 percent, raising storage capacity to 2,070kWh and with future potential to sustain maritime propulsion.

Lithium Titanium Flow Battery: Scientists at National University of Singapore have undertaken research into alternate rechargeable liquid electrolyte in a flow battery that combines a tank of lithium iron phosphate (LiFePO4) with a tank of titanium dioxide (TiO2). The battery is claimed to hold some 500 watt-hours per liter or 10 times the storage capacity of earlier vanadium flow batteries. It discharges more slowly than the ESS iron salt flow battery in a 40-foot container that delivers 40kW over 10 hours, allowing125 containers to deliver 5,000kW (6,700 Hp). If NUS can develop their battery to deliver 15kW per 40-foot container, 400 containers could power a ship.

Liquefied Air Storage: A recent entrant to grid scale energy storage technology involves cooling and compressing atmospheric air to the liquid state. The combination of liquid air storage and thermal energy storage could sustain propulsion of a large ship for up to 1,000 nautical miles. Liquefied air could sustain combustion of liquefied natural gas (LNG) upstream of a turbine that drives an electrical generator, with turbine operating at maximum RPM and maximum inlet temperature over a range of inlet pressure to adjust power output. The installation of a turbocharger and exhaust heat recovery would enhance engine efficiency and power output.

Maritime Propulsion

The vanadium flow battery and zinc bromine gel battery offer possible future application in short distance maritime propulsion. A ship carrying vanadium flow batteries housed in 100 x 40 foot containers that weigh 8,000 tons would provide 100,000kWh of power. The same number of containers of zinc bromine gel batteries would weigh around 4,500 tons and provide 138,000kWh of power.

If a cruise ship weighing 150,000 tons were to be converted to battery electric propulsion, a battery weight of 15,000 to 20,000 tons would involve up to 250 x 40-foot containers of vanadium flow batteries or 400 x 40 foot containers of zinc bromine gel batteries. The Seattle – Juneau, Alaska cruise would be a suitable route for battery electric propulsion depending on future chemical development involving both battery technologies and future grid scale power generation development at Juneau, to recharge the battery cruise ships.

Port Tug Boats

While some tug vessels push barges over extended distances along inland waterways and in coastal service, other tug vessels remain at port moving large container and bulk carrier ships within dock areas as well as to and from quayside. Local port tugs operate at low speed and require massive thrust at low speed with power requirements that are suitable for the combination of large battery and ultracapacitor. While some battery electric tugs could operate in plug in mode, other tugs would need to operate in hybrid mode that combines thermal engine with battery and ultracapacitor.

The installation of ultracapacitors allows the tug to deliver almost instantaneous thrust when moving a large ship. There is scope to install gear flywheels to vertical axis thrusters that could spin to speed with blades set to neutral before activating thrust by draining energy from the flywheels. Any of several types large scale storage batteries operating together with flywheel and ultracapacitor could provide short term propulsion in a tug vessel. The rising cost of lithium salts provides opportunity to consider various low-cost battery technologies that would be suitable for port tug service.

Conclusions

The high cost of lithium salt will raise future prices of lithium battery technology and encourage end users to consider alternative electrical energy storage technologies. Future lithium batteries would need to offer greater energy storage density with greatly extended useable deep cycle life expectancy to justify the high cost, perhaps making the technology more suitable for battery electric aircraft. There is potential to adapt competitively priced grid scale battery technology for some maritime propulsion applications, with potential for competition amongst vanadium flow battery, zinc bromine gel battery and liquefied air storage technologies.