Several significant orders and deliveries for hybrid RTGs have been reported in recent months
Hybrid RTGs are a good compromise when the operator wants to lower the terminal’s carbon footprint, but cannot rely on the grid to support all-electric RTGs, or afford the new infrastructure (grid connections, sub-stations, possible roadway changes) in the CY.
In hybrid RTGs, the PLC has to manage the hybrid controls as well as the generator, and special software is needed to ensure the optimum level of charge for the batteries. However, this is not a big cost factor, taking into account the safety and optimisation features that are commonly fitted to modern RTGs.
Essentially, the controls return energy recovered from lowering as power, instead of dissipating it through braking resistors that are installed in conventional diesel genset RTGs. Typically, the diesel motor can be downsized from 450-750 kW to 100-150 kW when combined with battery storage, although fuel-savings vary from case to case.
ICTSI’s flagship MICT container terminal in Manila has received the first four of 16 hybrid drive Paceco Transtainer RTGs from Mitsui. The RTGs are equipped with the latest Mitsui Technoservice hybrid drive, incorporating a 200 kVA Li-ion battery pack charged from a diesel engine that is smaller than a conventional genset engine in an RTG application, although Mitsui has not provided any more details on this point.
The Mitsui hybrid RTG drive was first used outside Japan in 2013, in a retrofit application at Hutchison’s Laem Chabang terminal in Thailand. Based on the test results (ca. 8 litres/hour or 50% fuel-saving), a further five RTGs were retrofitted in 2014. The following year, Mitsui received an order for five new hybrid drive RTGs for installation at the NPCT1 terminal in Tanjung Priok, Jakarta.
According to MICT, its new hybrid RTGs will reduce carbon emissions and noise levels by 40%, and provide up to 60% better fuel economy. The other 12 hybrid RTGs are all due to arrive from Japan during H1 2019.
Kalmar for BA
Towards the end of this year, Kalmar will supply Buenos Aires operator Exolgan with 40t SWL, 6+1/1-over-5 hybrid RTGs, along with an associated spare parts package. Kalmar says these “second generation” hybrid RTGs combine the latest Li-ion battery technology with a fuelefficient diesel power unit. The power unit is used to charge the Li-ion batteries, which power all the lifting, traverse and driving operations.
Kalmar’s VP, marketing, Maija Eklöf, says that in like-for-like operations, Exolgan can expect to make 50% fuel-savings compared to a comparable genset RTG. Speeds and performance are also comparable, but the diesel engine is “typically reduced from 400 kW to 100 kW, as the genset is used only for recharging the batteries as required.” The control software optimises the charge level to obtain the longest possible battery life.
Other machine features include Kalmar SmartRail automated gantry steering with Container Position Indication (CPI). This automatically controls gantry steering, and feeds container coordinates to the TOS. Kalmar SmartProfile spreader anti-collision is also fitted.
There is no doubt that Konecranes is going down the Li-ion battery road as far as hybrid drives for RTGs (and straddle carriers) are concerned. Speaking at a special ports conference organised by the company in Rotterdam in October, Prof Dr Egbert Figgemeier of RWTH Aachen University in Germany described Li-ion batteries as “powerful enablers of disruptive technology”.
Prices have gone down much faster than anyone thought a few years ago, he said, and the current price is around €209/kWh at pack level, in relation to Konecranes Gottwald’s latest all-electric AGVs. To ensure maximum return, the longest possible life obtained by keeping the charge level between 40% and 60%, depending on the application.
Dr Armin Wieschemann, R&D manager, Konecranes Port Cranes, also focused on AGVs. In 2017, the price comparison was €100/kWh for lead-acid batteries and €1,500/kWh for Li-ion batteries, but that picture had been transformed. Furthermore, while lead-acid provided 54% efficiency (a big improvement on diesel-electric), Li-ion provided 71% efficiency.
These figures cannot be directly translated into an RTG since, as the speakers explained, there is a spectrum of Li-ion batteries according to chemical composition as well as size, with applications ranging from cars, through buses and small FLTs, to heavy lifting equipment, for which a key factor is the ability to absorb a high input power spike.
Nevertheless, the message is clear. HHLA has commissioned the first two Konecranes Noell new-generation hybrid drive straddle carriers at its Tollerort Container Terminal in Hamburg ((see p2 of this issue and WorldCargo News, September 2018, p39-40).
In the past two months, Konecranes has reported orders for eight hybrid RTGs from the Port of Houston, and three hybrid RTGs from South Carolina Ports Authority for deployment in Charleston. All the units ordered are 50t SWL, 6+1/1-over-5 machines, and they will be delivered in Q1 2020 to Houston’s Barbours Cut terminal and Charleston’s Wando Welch facility.
They will be the first Konecranes hybrid RTGs on the market and, Konecranes notes, the hybrid package is retrofittable. This could be very significant going forward, given Konecranes’ strong presence in the USEC/Gulf coast markets. Houston alone operates 90 Konecranes diesel genset RTGs.
The battery management system monitors the charge level and the general health of the batteries, and Konecranes can monitor the status of this system via its Truconnect remote connection. In line with USA EPA requirements, the diesel engines comply with Tier 4f and they are there only to charge the batteries.
Other common features are Konecranes’ Active Load Control system, Auto-Steering, Autopositioning, Stack Collision Prevention, Truck Lift Prevention and Auto-TOS Reporting.
Svend Videbaek port cranes marketing specialist at Konecranes, stressed the “uncompromised performance” of the hybrid drive with regards to hoisting and trolley speeds. In the machines to be delivered to Houston, for example, power output of the equivalent diesel genset would be around 500 kVA.
Konecranes has always been sceptical when it comes to fuelconsumption comparisons, because a distinction has to be made between fuel used per running hour and fuel used per move. If, say, an RTG makes 10 moves per hour, its hourly fuel consumption is meaningless if compared to the hourly fuel consumption of an RTG that made 15 moves. If the traffic level is the same, one has to ask why one machine is doing 10 moves and the other 15.
Videbaek makes an additional point in relation to hybrid drive. “When talking about fuel consumption between diesel and hybrid machines, one must discuss the level of technology in the diesel engine control,” he said. “If hybrid is compared to simple single or two-step rpm diesel generators [i.e. constant speed generators], the savings are remarkable when moving from diesel to hybrid technology.
“However, if the comparison is made against Konecranes advanced Fuel Saver technology with variable speed engines, the saving is a couple of litres per hour.
“In addition, though, when comparing the technologies, we should also remember that with hybrid drive, emissions are reduced, noise is reduced, and reliability improves because the machines are always powered. On top of that, the modular design means that new features and new technologies can be easily integrated as they become available.”