Conversion technology tackles emissions by retrofitting diesel vehicles to burn liquefied natural gas
The auto industry is a major contributor to atmospheric pollution. Internal combustion engines that burn liquid fossil fuels, including diesel and petrol, release CO2, nitrogen oxides (NOx), hydrocarbons and particulates. These pollutants are toxic substances and have a negative impact both on health and global warming. Cleaner power-generating alternatives to fossil fuels, such as natural gas, biofuel, hybrid and electricity, already exist. However, these options don’t offer a rapid transition to a noticeably cleaner atmosphere. This is because the rate of replacement of fossil fuel-powered vehicles by new vehicles using these cleaner fuels is very gradual. The EU-funded BLUESKY project “addressed the problems resulting from the slow replacement of diesel-powered vehicles with new ones,” says Chief Technical Officer Olivier Marchand at the Center for Research in Thermal Machines (CRTM), the French-based company responsible for coordinating the partners. To achieve this, it developed hardware and software to enable diesel engines to burn liquefied natural gas (LNG). “Retrofitting existing diesel vehicles to burn cleaner fuel is now a practical and effective way to reduce pollutant emissions.” Long before the project began, CRTM studied, homologated , developed and tested the BLUESKY system with excellent results. Currently, there are 500 natural gas vehicles in France, Italy and the United Kingdom running on the initial version. “The switch from diesel to LNG has paid dividends over the years,” he notes. Nantes, a city in western France, installed the system in 130 buses. In 2014, it took home the first prize at the Palmarès des Mobilités awards that celebrate the most innovative urban mobility initiatives. Improvements fuelled by technology The project team developed a set of technologies aimed at the diesel-powered vehicles of the public transport and goods transport sectors. Such vehicles include heavy lorries and city buses. BLUESKY enables the conversion of older Euro IV and V diesel vehicles to burn LNG and meet the recent Euro VI emission standards. Technically, this conversion consists of four main subsystems. These comprise an engine management system, a special exhaust catalyst, a revised fuel tank, and the vehicle’s modification, testing and validation under real-duty cycles. Lessening costs and pollutants Further to meeting the most stringent Euro norms, the project’s technology helps achieve several improvements. Typically, a 20 % reduction in fuel and maintenance costs, the compression of CO2 emissions by 20 %, the complete elimination of particulate emissions and the tenfold reduction of NOx pollutants. Another important upgrade is engine noise reduction, especially in urban surroundings. Project partners developed a kinetic energy recovery subsystem for city buses that helps reduce fuel consumption. This will further improve the emission profile of the vehicles by several percent. The subsystem will also allow Euro IV and V vehicles to remain relevant, especially if converted to LNG. “The BLUESKY innovation that converts diesel or petrol engines into efficient natural gas engines with greater performance and a much cleaner exhaust system makes possible access to urban centres and low emission zones without limitations,” concludes Marchand. “There’s real potential to reduce on a large scale the emissions of heavy-duty engines and vehicles.”
Keywords
BLUESKY, liquefied natural gas, emissions, engines, diesel vehicles, diesel-powered vehicles, pollutants
