Active regeneration cuts engine emissions

American Airlines has modified its airside vehicles in use at Heathrow Airport to meet new stringent emissions guidelines.

Within the approval process for the building of Terminal 5 at London Heathrow (LHR) Airport, the airport operator (BAA) had to demonstrate an action plan on reducing exhaust emissions.

Airport vehicles are one of the largest contributors to airport emissions and as a result, the licensing of vehicles now greatly depends on their age and "environmental friendliness".

For example, equipment entering service for the first time must be newer than 5 years old and those in operation cannot be older than 15 years.

One airline that is committed to its environmental impact is American Airlines, which operates out of Terminal 3 at Heathrow.

Kevin Robins, Manager of Transportation and Automotive for American at London Heathrow explains: "The equipment used deploys some big engines that emit large volumes of exhaust gas and we have a responsibility to do all we can to ensure their cleanliness and reduce the overall effect on the environment".

American operates nearly 200 vehicles including 70 tonne push back tugs, baggauge loaders and a variety of other ground support equipment, most of which have been in operation for many years.

"We embarked on a programme to demonstrate that the existing equipment could be as clean, or cleaner than new equipment".

In 2000, several airlines started to work with environmental company, Envirosafe which provide exhaust emissions solutions for industrial vehicles, with a view to prolong the life of the vehicles.

Jim Maloney, General Manager of Envirosafe explains: "Temperature was the biggest problem with ground handling equipment".

"There was no truly effective solution that ticked all the boxes to help reduce CO, HC and soot from the large diesel engines used at airports".

"They were typically old vehicles operating for short periods at low speed".

Kevin Robins was so convinced that there was a solution: "The fleet that operates airside has a 25km/h speed limit with low duty cycles".

"The fleet is aged, but it is well maintained, does exactly what it is supposed to do and could continue in operation for many years to come".

"The difficulty is that the engines are not up to the current standards and the duty cycles make it difficult to find environmental solutions to reduce harmful diesel engine emissions since temperatures do not get high enough to allow catalysts or filters to work".

There was room to improve the technology which led Envirosafe to specifically develop Acti-trap.

The development of Acti-trap was led by low temperatures and the use of ultra-low-sulphur fuel/gas oil.

The product works as a catalyst and filter combination and its intelligent electronic control system (ECS) and "active ingredient" ensures temperatures are high enough for the chemical reaction to take place, even during low duty or speed.

BAA at Heathrow was so convinced by the results of the system that it granted American Airlines not just a 5 year extension on the push back tugs and other equipment, but a complete re-life of 15 years.

Maloney adds: "Existing fleets can be re-licensed for a further 15 years at LHR removing huge potential capital costs and related issues".

Acti-trap was in development for several years with help from Envirosafe's parent company, explosion protection specialist Pyroban Group and the leading independent diesel engine test company.

With extensive trials at Heathrow, Gatwick and at the Rotterdam docks, the product stands alone in its field.

Robins explains: "We didn't just fit Acti-trap, we took the decision to give the equipment a complete relife".

"We replaced the original engines with new Euro II units, fitted with Acti-trap technology, changing the hydraulics, pneumatics, braking system and tyres".

Maloney adds: "We were able to prove categorically that the emissions on the American fleet were cleaner than some of the new engines going into operation".

"Independent tests completed by the leading engine test company showed just how significant the results were".

"There was no argument; Acti-trap provided the solution".

Robins continues: "We have a duty of care, to our employees and others, and we recognised this great opportunity to make a real difference by capitalising on a good technical solution in ameliorating the harmful effects of a large fleet of diesel powered vehicles".

"We have fulfilled American's corporate policy at LHR in being environmentally responsible and hope that equipment operators across the world embrace this technology for the good of everyone".

Acti-trap takes catalysts and wall-flow filter technology and combines it with a sophisticated control system to create an active regeneration system.

A catalytic coating reduces HC and CO by up to 99% and a wall-flow filter reduces the PM, visible soot, by up to 95%.

By monitoring key information from the vehicle exhaust, Acti-trap's patented technology is able to create controlled regeneration opportunities to "burn-off" the trapped soot particulate.

Acti-trap is suitable for naturally aspirated engines up to 6 litre in sise operating ultra-low-sulphur diesel.

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