A three-year biofuel trial organized by Neste Oil, Helsinki Region Transport (HSL), and Proventia has recently been completed, and the results have shown that Neste Oil’s NExBTL renewable diesel can significantly reduce local emissions that have a direct impact on urban air quality. Data collected by VTT Technical Research Centre of Finland show that particulate emissions were reduced by 30% and NOx emissions by 10%.
During the initial phase of the trial, buses used a blend of 30% NExBTL renewable diesel and 70% standard diesel fuel. From 2008 onwards, some ran on 100% NExBTL. Those running solely on NExBTL renewable diesel achieved the largest reductions in emissions. In addition to lower particulate and NOx emissions, using NExBTL also results in lower emissions of aromatic PAH hydrocarbons.
No problems were encountered with vehicles’ tailpipe emissions control systems. VTT estimates that, if all the buses in Greater Helsinki were to use 100% NExBTL renewable diesel, the reduction in traffic-related particulate emissions would be the equivalent of taking a third of the buses in the region off the road.
NExBTL renewable diesel produced from currently available raw materials offers a more than 50% reduction in greenhouse gas emissions compared to fossil diesel, according to Neste Oil. NExBTL is currently produced via the hydrotreating of vegetable oil, such as palm oil and rapeseed oil, and waste fat from food manufacturers. In the future, the raw material base is set to be broader, as extensive R&D work is currently under way to develop new raw material sources.
The trial in Greater Helsinki was the world’s largest renewable diesel field trial to date, according to the company. The partners involved were Helsinki Region Transport, Neste Oil, Proventia, an expert in emission control technologies, VTT, which was responsible for measurement work, and local bus companies.
The project was part of the BioRefine research project coordinated by Tekes, the Finnish Funding Agency for Technology and Innovation. Around 300 vehicles, or more than 20% of HSL’s buses, took part in the trial, driving more than 50 million kilometers (31 million miles) in all.
Use of Neste Oil’s NExBTL renewable diesel will continue in buses in Greater Helsinki after the conclusion of the Optibio trial. Following the outcome of competitive tenders for routes in Espoo and Vantaa announced on 14 December 2010, the 2011 fall timetable will see 19 buses running on NExBTL. This was the first time that CO2 emissions were used as one of the criteria in HSL’s competitive tender process, joining other emissions that have been used previously.