Demonstration of 3 buses fuelled with ethanol with ignition improver in the Netherlands

This three year demonstration programme was initiated by OBL, a subsidiary of two Dutch sugar companies, and GADO, a public transport company. The programme was financially supported by a regional governmental organisation (ISP). In this programme, three bio-ethanol fuelled buses accumulated more than 700.000 kilometres in and around the city of Groningen. Five almost identical fuelled buses were incorporated in the programme for comparision purposes. The naturally aspirated Mercedes-Benz ethanol engines were equipped with an oxidation catalyst. About 6% ignition improver was added to the ethanol fuel to secure 'compresion-ignition' of the fuel-air mixture. Annual exhaust emission tests carried out by TNO showed a clear advantage of the ethanol fuelled buses. They complied to the Euro 2 emission limits and were on average very close to the expected Euro 3 limits. The diesel buses complied to the Euro 1 limits. During the programme the exhaust emissions of the diesel buses deteriorated somewhat while the emissions of ethanol buses remained constant. The total costs of operation of the ethanol buses were 30% higher than for the diesel buses. Two thirds of this was caused by higher fuel costs, despite the fact that the alcohol fuel was exempted from taxes. Additional maintenance costs (including the costs of lower availability for regular service) were responsible for the remainder of the higher costs of operation of the ethanol buses. Further discussed are performance, fuel efficiency, lubrication, experiences with fire and future work.