Bus operator Metroline has revealed that ASDS technology, from Danish aftertreatment specialist Amminex, has been under test for the last 18 months on a seven year-old Euro 4 city bus in central London.
Ian Foster, engineering director at Metroline, confirms that the Amminex system performed more than twice as well as existing technology, reducing NOx emissions by 84% compared to the 32% reduction achieved by the standard configuration.
He also states that these results were achieved with a simple swap of the additive system.
“Using ASDS, we more than doubled the NOx reduction on a relatively old Euro 4 bus, bringing it below the Euro 5 [emissions] level without making any changes to the catalytic system,” says Foster.
“The technology has proven extremely stable, in terms of daily operation over the course of 18 months regardless of outside temperature and driving conditions,” he continues.
“Furthermore the use of ASDS has eliminated common recurring issues, such as the formation of solid deposits in the exhaust system.”
Amminex asserts that the effectiveness of prevailing technology is hampered by low speeds and low temperatures – conditions that do not affect its aftertreatment technology.
Amminex has already retrofitted its ASDS package to 300 buses operating in Copenhagen, where on-line emissions data suggests that the system is removing 95-99% of NOx, and specifically harmful NO2, from exhaust fumes.
“The London trial as well as data from Copenhagen shows that bus operators with Euro 4 and 5 city buses can capture a major NOx benefit with an efficient, low-cost solution simply by replacing the prevailing technology,” states Tue Johannessen, chief technology officer with Amminex.
“It is not necessary to get rid of diesel-powered city buses – they just need the right emissions solution.”