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Optimized for container handling industry, MHC and LT products
Konecranes offers container cranes that produce zero local carbon emissions because they run on electricity from the local grid. Recently, the company made an electric leap forward by introducing battery-driven operation for its Rubber-Tired Gantry (RTG) crane, a big, mobile container handling machine. This was a world-first. It also introduced a battery-driven straddle carrier system. An 18-ton, battery-driven forklift truck (the E-VER) is also available, as well as all-electric Generation 6 mobile harbor cranes.
This article briefly outlines the history of battery technology in Konecranes, why the company uses Li-ion batteries, and how those batteries are used in practice. Also discussed is battery replacement and recycling as well as how battery technology is likely to evolve in the future.
From diesel to electric: the great leap forward
The global economy depends on the continuous movement of goods, much of which are shipped in standardized containers. Seaport container terminals have traditionally used diesel power for container handling equipment that is “mobile”, that is, maneuvered on rubber tires. Rubber-Tired Gantry (RTG) cranes are the prime example. Diesel engines have offered power, performance, durability and reliability – but at a price.
Unfortunately, container handling equipment is the main source of energy consumption and carbon dioxide emissions in ports. Meanwhile, climate research has been revealing an ever more urgent need to cut CO2 emissions to limit global warming. Environmental regulations are becoming stricter around the world, and diesel engines are much more efficient than in the past. But it isn’t enough. Port equipment has to go electric, and battery-driven operation gives great flexibility: there is no need to connect to container yard electricity infrastructure (cable reel systems, busbar systems).
The first Konecranes product to get a battery was the Konecranes Gottwald Automated Guided Vehicle (AGV). These vehicles are used in automated container terminals to move containers between the Ship-to-Shore (STS) cranes and the container yard. There are also Lift-AGVs, which can place and pick up containers to and from the container yard. Apart from this, the main job of AGVs is to carry containers from A to B, similar to an electric truck. Since the average power requirement is less than that of equipment that also stacks containers, the AGV was an ideal first candidate for electrification.
The hybrid straddle carrier and hybrid RTG were the next steps. In these machines, a smaller diesel genset is used in combination with batteries. This was an important development: hybrid straddle carriers and RTGs are becoming popular thanks to much reduced diesel fuel consumption and tailpipe emissions. Ultimately, the goal is the elimination of tailpipe emissions.
The lithium-ion (Li-ion) battery is the innovation that makes this possible.
Li-ion, king of the battery jungle
Lead-acid is still a common type of battery used in industrial applications. But lead-acid batteries come with certain known problems, including a short lifetime, slow charging and low energy efficiency. They are heavy and need regular maintenance. Charging requires special ventilation due to heating and hydrogen emissions. Accidents that damage a lead-acid battery can cause dangerous chemical leaks. For all of these reasons, Konecranes sees a future for Li-ion batteries in applications that still use lead-acid batteries today.
Most people know Li-ion batteries from mobile devices and electric cars. Now Li-ion is becoming more prevalent in industrial settings because of their many advantages over lead-acid. Charging time is much shorter and overall battery life is much longer. Fast charging, zero maintenance and their light weight make them ideal for equipment in frequent use. They can be charged conveniently at locations with an electrical connection as they don’t give off emissions and don’t require special ventilation.
The Konecranes E-VER forklift truck lifts 10-18 tons in fully electric operation. Charging takes around 45 minutes.
Li-ion batteries used in an RTG or forklift truck are not as simple as the Li-ion batteries used in laptop computers or smartphones. Large machines need a much higher voltage and current to operate. Konecranes uses a modular system consisting of battery blocks with parallel connections between the blocks for scaling the available power and energy. An advantage of the technology is that power is drawn only when needed for operation.
For example, if an RTG is sitting idle, it uses only a little power for its lights, sensors and the operator’s cabin. If it’s driving over a container stack in the container yard, its motor requires more power. If it’s lifting a fully-laden container, which can weigh up to 50 tons, it will draw on the maximum power output to move the trolley and hoist and keep the load steady.
“The batteries that power the latest Konecranes products combine performance with efficiency, safety and maintenance-free operation,” says Jan Schmidt-Ewig, Manager, Product Management, Port Solutions. “But keep in mind that batteries also change the way the terminal operates, because every battery needs to be charged.”
Taking charge of the situation
Charging is fundamental to the operation of battery-powered equipment, with a great influence on battery performance and lifespan. Batteries must be charged regularly as part of the work cycle. Different products have different energy requirements, and charging takes time – it’s not as quick as refilling a fuel tank. Therefore, a charging strategy is essential.
The charging strategy is developed when planning the infrastructure needed to power a fleet of battery-powered port equipment. Mobile machines like AGVs, straddle carriers and lift trucks can use automated charging stations (ACSs) at key locations on the ground around the terminal. RTGs can utilize similar stations placed in the container yard – even in a container stack for maximum convenience. Konecranes has a solution for this:
Charging takes time, so the charging strategy needs to keep the machines running without affecting production schedules. In RTG and straddle carrier operations, about 50% of regenerative energy from braking and lowering motions can be charged back to the batteries. But that’s not enough, even if the equipment is in continuous use. A mix of fast charging and slow charging can be designed to best suit the equipment type and its work cycles. Slow charging will usually be done when the equipment is off-shift and shut down.
Every battery-driven Konecranes product has a Battery Management System (BMS) that monitors and controls battery function to maximize performance. It manages the temperature of the battery, synchronizes the battery blocks, and alerts the operator when charging is needed. It also indicates when the battery should be replaced.
What to do with old batteries
It’s hard to estimate the exact lifetime of a battery, because that is a function of how the product is used. However, a good charging strategy acknowledges that batteries will eventually be unable to hold enough charge to power lifting equipment. The strategy uses industry averages to plan ahead, so that the terminal is ready when it happens.
Exhausted Li-ion batteries can be used for other things that don’t need as much power. At a container terminal, they can offer power reserves: while the lifting equipment uses newer batteries, the old batteries can store energy from the grid and reduce power demand during peak times. They can also be taken off-site and installed in wind or solar plants for backup power if natural sources don’t provide enough supply. Old batteries can also be rebuilt or retrofitted for reuse, and much of the battery unit can be recycled.
Konecranes partners with respected battery suppliers who take care of battery replacement according to Konecranes’ strict environmental requirements and local legislation. Disposing of old batteries is free of charge to Konecranes customers.
“Typically, Konecranes equipment lasts for decades, so today’s batteries will need to be changed over the lifecycles of our ports products,” says Hannu Oja, Vice President of Technology, Port Solutions. “We’ve recently introduced Battery-as-a-Service (BaaS). With BaaS, customers can buy port equipment but rent the batteries. This helps them handle battery issues as seamlessly as possible.”
The future of batteries
Battery technology is improving quickly. With each new generation of batteries, the time a full charge lasts increases. The number of times a battery can be charged (charge cycles) across the battery’s lifetime is also growing quickly. It’s difficult to say, but one day there might even be a battery with a lifetime as long as a Konecranes forklift truck or RTG.
Currently, most battery charging in port environments requires a physical connection to the grid. Efforts are being made to develop cable-free charging at scale. This would make charging safer and more flexible in the busy port environment.
The three most promising solutions are conductive wireless charging through a pantograph (the device usually seen on top of an electric train), inductive magnetic charging (like an electric toothbrush), and the “electric track”, an operational area that charges mobile equipment on wheels while it’s moving.
“Konecranes port products use Li-ion batteries because they eliminate tailpipe carbon emissions using the safest and most efficient battery technology available today,” says Joona Merimaa, Chief Electrical Engineer, RTG Cranes, Port Solutions. “In future, batteries will be more sustainable, resolving environmental challenges in production and recycling, reducing reliance on precious resources and making the reuse and disposal of materials easier.”
Take a closer look at Konecranes battery-driven port equipment:
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Charging takes time, so the charging strategy needs to keep the machines running without affecting production schedules. In RTG and straddle carrier operations, about 50% of regenerative energy from braking and lowering motions can be charged back to the batteries. But that’s not enough, even if the equipment is in continuous use. A mix of fast charging and slow charging can be designed to best suit the equipment type and its work cycles. Slow charging will usually be done when the equipment is off-shift and shut down.