Giving a view of fuels in 2020, Ann Cormack, Shell International's European fleet manager, said cleaner diesel was likely to be the preferred option for companies, especially with those that frequently have vehicles operating in cities.
She said LPG and CNG would continue to be niche fuels and biofuel was also increasingly on the agenda but its CO2 impact depended on how it was produced.
She said: 'The challenge for fleets is how to choose which fuels to use.
'There are three main concerns which we share with our customers: cost - fuel can be the majority of cost depending on vehicle portfolio; availability - the network and infrastructure need to be in place and sustainability - we don't want to put our effort into something that will run out after 25 years.'
She said improvement to existing fuels was the preferred solution as the technology was available, it would meet government and EU environmental requirements, the existing infrastructure was sufficient and there would be a minimal cost increase.
Cormack said hydrogen has the potential to be the ultimate fuel - but significant technology and infrastructure hurdles have to be overcome.
She said as a result, it would be some time before fuel cells became a reality.