In 2009–2011, a comprehensive project on urban buses was carried out in coop- eration with IEA’s Implementing Agreements on Alternative Motor Fuels and Bio- energy, with input from additional IEA Implementing Agreements. The objective of the project was to generate unbiased and solid data for use by policy- and deci- sion-makers responsible for public transport using buses. The project comprised four major parts: (1) a well-to-tank (WTT) assessment of alternative fuel pathways, (2) an assessment of bus end-use (tank-to-wheel, TTW) performance, (3) combin- ing WTT and TTW data into well-to-wheel (WTW) data and (4) a cost assessment, including indirect as well as direct costs.

Experts at Argonne National Laboratory, Natural Resources Canada and VTT worked on the WTT part. The WTT emissions of various fossil fuels and biofuels were assessed by using GREET model from the United States, GHGenius model from Canada and RED methodology of the European Union. All these models follow the frame work of life cycle assessment.