The transport sector's energy use can be reduced by 33 per cent by 2025 if all policy options are successfully implemented, according to a report by the World Bank.

"Fuel pricing and vehicle-standards measures can be used to introduce transport behavioural changes, yielding energy savings," said Chanin Manopiniwes, an infrastructure economist at the World Bank's office in Bangkok.

These were two of several measures proposed by the World Bank study to improve Thailand's energy efficiency in the transport sector.

The study, "Thailand: Making Transport More Efficient", was undertaken by a World Bank team under the Country Development Partnership for Infrastructure. It addresses the question of how Thailand's transport sector can become more energy-efficient, assessing the performance of the transport sector in energy utilisation as well as proposing options to improve energy efficiency.

Thailand's energy mix is vulnerable to oil price rises with little diversification of fuels, as petroleum accounts for half of the country's energy consumption, said the World Bank economist.

He said about 72 per cent of petroleum was consumed by the transport sector, of which road transport accounts for 76 per cent.

The study presents comparisons of transportation in Thailand with that in the US, Germany, China, South Korea, Japan, Malaysia and other countries for the period from 1995 to 2006.

Compared to those countries, Thailand was the least diesel fuel-efficient and among the least petrol fuel-efficient.

"However, Thailand has potential for a major improvement in road sub-sector energy use," said Chanin.

He said there were five main factors contributing to poor transport energy efficiency:

First, the spatial distribution of economic activities in Thailand is heavily concentrated in Bangkok and the Eastern Seaboard industrial region. It does not require large volumes of domestic freight transport on land.

Second, freight transport is heavily dominated by road, while rail transport is limited. The use of personal vehicles has increased rapidly, causing energy waste in the transport sector.

Third, almost all vehicles use petrol, accounting for 70 per cent in Bangkok and 76 per cent in the provinces. Half of passenger cars use petrol while almost all buses (91 per cent) and trucks (80 per cent) use diesel. Factors such as the ageing of bus and truck fleets and outdated technology have engendered inefficiency in diesel fuel use.

Fourth, there are no compulsory fuel economy standards applied to newly manufactured or imported vehicles in Thailand. Estimated at 9 kilometres per litre, the average fuel economy of in-use passenger vehicles is about 30 per cent lower than that for Europe.

Lastly, fuel prices, including taxes, in Thailand are lower than that in other places such as Japan and Europe, leading to fuel-consuming behaviour.

The World Bank study proposed policy options for improving energy efficiency in three areas of transport: intercity, urban passengers and vehicle standards.

For the first option, the study suggests investing in rail modernisation and reform. Chanin added that options for urban passenger transport were to introduce a Bus Rapid Transit system and improve and integrate public transport services.

"Meanwhile, the country should take immediate action to introduce compulsory standards for fuel consumption, limit the age of trucks and buses and use alternative fuels," he stated in the study.