In February 2022, the price of a metric ton of lithium carbonate rose from a maximum of $9,600 a year ago to $69,000, and the price of this material is driving up the cost of lithium batteries.
In this regard, foreign expert Harry Valentine wrote that aluminum air battery energy storage technology has a high energy storage capacity and can be installed in a standard 20-foot container, which can become a new choice for ship power.
Lead-acid batteries consisting of lead, lead oxide and sulfuric acid have long been the mainstream rechargeable electrochemical battery technology and are widely used in the automotive industry. In recent years, the expansion of solar and wind power has created a demand for large-scale energy storage technologies. Some progress has been made in electrochemical energy storage technology for fixed grid scale applications.
Some large-scale electrochemical, grid-scale battery technologies can already operate inside containers. This is the case with aluminum-air battery technology from Israel, which stores 4,800 kWh in a standard 20-foot container and provides a stable 240 kW (320 hp) output. At the same weight and volume, aluminum-air batteries can store more energy than vanadium flow, liquid metal, or zinc-bromo-gel technology; it is superior to lithium-ion technology in terms of cost and storage capacity.
The structure of a DC battery consists of anode and cathode, with the anode typically accounting for 70% of the battery weight and the cathode accounting for about 5% of the total weight. Aluminum-air batteries are made of anodes made of pure lightweight aluminum combined with air cathodes. The combination of light weight and chemical composition allows it to provide three times more energy density than more expensive lithium-ion batteries.
Aluminum-air batteries generate aluminum hydroxide, i.e. Al(OH)3 or H3AlO3, in use. Aluminum-air batteries cannot be recharged, but can be fully recycled. When the aluminum-air battery is depleted, there are multiple chemical methods to extract pure aluminum from aluminum hydroxide, which allows the aluminum-air battery to achieve continuous recovery.
The cost of aluminum-air batteries and their recyclable properties make them competitive compared to lithium batteries. Packed containerized aluminum-air batteries can operate with a stable output over a longer period of time. In offshore operations, battery containers need to be used, installed and replaced quickly and easily, which makes it possible for tugboats and barges serving in inland rivers and coasts to use aluminum-air batteries.
A battery-powered tugboat that is 90 meters long, 26 meters wide and has a draft of 3 meters can carry 120 container batteries, provide 576,000 kWh of electricity, and can propel a ship that requires 3,000 kilowatts (4,000 horsepower) to sail at a speed of 10 knots for 180 hours, Valentine said. These batteries provide up to 190 hours of service before they are depleted and replaced. In the waterway service, a standard Mississippi barge (60 meters long, 10.6 meters wide, and 2.4 meters draft) can carry 32 container batteries and carry 153,600 kWh of electricity.
The advantages of aluminum-air batteries also include that chemicals generated during operation prevent heat build-up, indirectly preventing possible explosions and fires in lithium batteries. In recent years, the shipping industry has had a number of ship fires directly or indirectly caused by lithium batteries.
Valentine said that compared to lithium-ion technology, aluminum-air battery technology provides a higher energy storage density at a lower cost, and the entire battery and its chemicals can be recovered and remanufactured after the energy is exhausted. This battery is best suited for applications that can be easily removed, reinstalled and less complex, such as containerized power solutions for ships.
