Our future is green baggage

Baggage conveyor

Baggage systems consume a lot of power and increasingly airports are demanding energy efficiency and sustainability from their system supplier says Heidi Klit.

Baggage conveyorAir transportation is generally associated with high energy consumption and greenhouse gas emissions. In the public eye it is aircraft that are the most obvious consumers and polluters, but airports themselves are also responsible for considerable energy use and CO2 emissions. According to CASCADE, a European research project funded by the EU, the typical electricity consumption of a large airport is 100-300GWh per year.

With passenger numbers continually on the rise and energy being a major operating expense – in addition to the need to be, and to be seen to be, green – when airports are looking for a new baggage handling system, the combination of low power and speed is an irresistible attraction. Such low power consumption is particularly important for airports because the personnel costs of baggage handling are borne by the ground handlers, meaning that power is a large proportion of the total operational cost.

While heating, ventilation, air conditioning, lighting and passenger conveyance systems are obvious factors that influence overall energy consumption in airport terminals, the baggage handling system also accounts for a substantial proportion of total energy costs. It is therefore imperative that the motors that drive the system, as well as other aspects of the sortation technology, must be designed for the greatest energy efficiency.

Reducing the amount of energy consumed by baggage handling systems has long been a major focus for many BHS engineers, system designers and software specialists. With power-saving features having been a major part of product strategy for at least the past decade, BHS suppliers have developed techniques and technologies that have revolutionised baggage handling and created new standards in power efficiency.

Innovating energy efficiency

A lot of smart thinking lies behind these airport baggage handling system solutions. It is clear that the greatest benefit results from a combination of low-power hardware and an intelligent control system. This delivers the greatest energy efficiency and lowest operating costs, as well as enhanced integration with existing systems.

A good example of an intelligent control system in use can be seen in Crisplant’s CrisBag® system, which has a ‘look-ahead’ feature that can tell when a tote is approaching. When the transport belt on an element is stationary but the system knows that a tote is on the way, the belt only starts running in time for it to be up to speed when the tote reaches it. The control system continues to monitor upstream on the line to see if another tote is approaching, and accordingly either continues running or stops as soon as the tote has left the element. The situation is quite different with a conventional conveyor, which usually has to be run for one and a half lengths of the system to make sure that it is empty before it can be powered down.

This technology is a major and proven development in baggage handling, optimising energy efficiency and lowering operating costs. For more than a decade it has represented a benchmark for sustainable development by reducing energy consumption and carbon dioxide emissions at many airports around the world, supporting their desire to be – and to be seen to be – green.

Minimising energy consumption

As mentioned, in addition to an intelligent control system, the other essential ingredient of an energy efficient baggage handling system is low-power hardware.

Linear motors generate their propulsive force from electromagnetic energy, without any mechanical friction between moving parts, as in a regular DC electric motor. This has a dramatic effect in reducing energy consumption and noise while increasing speed and reliability. The two most common types in general use are linear induction motors (LIMs) and linear synchronous motors (LSMs), with the difference between them lying in the way they produce their electromotive forces. Conventional tilt-tray systems typically use LIMs, which use electromagnets to create the magnetic fields that push the cart along the track. This technology has been widely adopted because it provides a fast and efficient method of propulsion that is durable and highly controllable.

LSMs, on the other hand, have the benefit of being far more efficient at converting electrical energy into thrust, and this efficiency is relatively unaffected by the speed of travel. A second advantage has to do with thermal efficiency. In an LSM, where the field on the moving element is usually provided by permanent magnets, almost no currents are induced and hence very little heating occurs. This thermal efficiency makes the LSM cheaper to run.

LIMs have been used in high-capacity sorting since 1990; LSMs have been used in drive design since around 2007. LSM technology takes electromagnetic technology to new levels of power efficiency, with the result that they use approximately 75% less energy than comparable sorters with LIM motors, even at higher operating speeds.

The figures speak for themselves. Take the example of a baggage handling system with a 300m sorter, equipped with a conveyability kit and operating at a speed of 2.0m/s with no change in level over the course of the conveyor. Assuming that the system operated for 20 hours per day, 365 days per year, carrying 1200mm pitch carts with an average load of 20kg per cart, the power consumption using conventional motors would be 219MWh of energy per year. The same system using LSM technology would use just 55MWh per year.

Airports that opt for a destination coded vehicle (DCV) system rather than a tote- or belt-based system will find their energy-saving needs equally well catered to. DCV systems can be designed to reduce energy consumption by using only the required number of transport vehicles, and switching off unused parts of the rail system as soon as possible at every opportunity. The rail system itself is completely passive, with no moving parts or active components other than the DCV itself, which makes such systems virtually maintenance free. A further advantage of there being no contact between moving parts is that the entire system operates at an ultra-low noise level, creating a safer and pleasanter working environment for airport staff.

An essential component of most baggage handling systems are regular conveyor lines, which have long been the area where it has been most difficult to keep power consumption to a minimum. The most recent and innovative designs have combatted this Achilles’ heel of baggage handling by equipping the conveyors with high-efficiency motors. The addition of permanent magnet motors with start-stop function can deliver a further 50% reduction in power consumption.

Reduced maintenance and parts

As with all mechanical parts, wear and tear will increase power consumption. That is why the industry is so keen on eliminating contact between moving parts. In addition, products that can achieve ultra-low levels of wear-and-tear also feature lower maintenance requirements, higher reliability and a reduction in the need for replacement parts. This also reduces the level of routine maintenance, the frequency of replacing parts, the cost of labour and materials, and delivers a higher level of system availability. Studies with installed systems show that 80% less maintenance work and 60% less spare parts consumption compared with conventional systems are achievable.

In baggage handling operations there is no doubt that a fast and efficient sorting system is an absolute necessity. With low-power hardware and an intelligent control system you can combine that with greater electrical and operational efficiency, and mechanical reliability, which translate directly into lower running costs.

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