Keeping track of global cargo

There are around 17 million shipping containers in use today – and everyone looks the same. Logistics professionals rely on battery-powered smart technology to locate them as they travel the world’s oceans.

Anyone who has ever played the video game Tetris has some idea of what it was like to work as a docker before the mid-1950s. Loading and unloading cargo was a challenge to find the most efficient way to pack together boxes of assorted sizes. In 1956, Malcolm McLean, a transport entrepreneur, realized that it would be an advantage if containers were of a uniform shape and size, and developed what is known today as the “intermodal shipping container”.

These are the steel boxes that you might have seen stacked in shipping yards or packed onto a container ship. Their common size makes them easier to store in either situation, as well as fitting onto a semi-trailer or train to be transported by land.

The effect on the shipping industry was transformative. In 1965, according to the World Trade Organization, a single dock worker could move 1.7 tons of cargo per hour. By 1970, that had increased to 30 tons. Container ships got much, much bigger and so did ports – and all the while, the shipping trade boomed. There were other bonuses: they were more secure, for a start, limiting theft and damage; and many of them found a novel second life in trendy architecture projects in cities worldwide.

There are 17 million shipping containers in use today, and the world’s largest container ship, the MSC Oscar, can carry more than 19,000 at once. The average container ship travels more than 500,000 km per year.

These metal boxes have long been praised as one of the 20th century’s greatest innovations, and in recent years – thanks to the Internet of Things – they have become smart. By means of sensors, owners of the boxes can track where they are and what is happening to them.

Simply knowing where each container is helps shipping firms to optimize the supply chain. A company might have a theoretical timescale for how long it takes a product to go from, say, Hong Kong to the Netherlands, but tracking that information in practice might show that it takes longer.

Having a sensor in a container also helps to prevent it getting lost. One downside of having tens of thousands of identical boxes traveling around the world is that, occasionally, they get put in the wrong place. Tracking devices help reduce the delays caused when this happens.

However, sensors can give more information than just where the container is. Depending on the customer’s needs, they can track temperature, vibration, light and various other conditions. This data can be useful for several reasons: temperature is important if the contents of a container could be damaged by excess heat or cold. In some situations, it might be possible to fix the conditions before any damage is done; in others, it might be a case of providing evidence for an insurance claim.

Activity picked up by vibration or light sensors, meanwhile, could be a sign that the container has been opened, which might indicate a theft or attempted theft. Again, it won’t always be possible to act in time to remedy such a situation, but multiple signs of containers being opened in a particular location could build a case for an investigation.

Overall, we know much more now about what is happening to shipping containers during their journey, but these sensors are only able to provide information because of the batteries that power them.

The batteries Saft supplies for these sensors are mostly primary (non-rechargeable) lithium batteries. Some container sensors, such as those used on German freight trains, do have rechargeable batteries because power is easily accessible. On ships that isn’t the case, so long-life primary batteries are used instead.

It’s vital that these batteries can work in all conditions; it can get very hot inside a steel shipping container, and the battery needs to power the sensor regardless. The same applies when the temperature plummets, as it does on some of the seas that cargo ships traverse. Since the containers are designed to be used all over the world, the battery must be able to function in the full range of conditions.

Usually, the sensor relays its signals using the cellular network. However, in the middle of the ocean the cellular network is out of range so if the sensor needs to transmit then the only option is to send a signal to a satellite. Doing so requires a lot of power and having the right battery for the job is imperative.

Global trade continues to expand, and thanks to its new smart capabilities, the shipping container is likely to play as important a role in this century as it did in the last.

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