Development of fuel-efficient hybrid diesel-electric buses are seen as an important means of cutting pollution in major cities: Image by Transport for London

A United Kingdom consortium is planning to speed the worldwide growth of the hybrid diesel-electric bus market by pioneering new exhaust-energy technology that will further reduce its fuel consumption and CO2 emissions.

A bus maker, university and technology companies have been brought together in a United Kingdom initiative that promises to boost the appeal of hybrid diesel-electric buses by harnessing their exhaust heat energy to achieve new low levels of fuel consumption and CO2 emissions.

The Thermal Energy Recovery Systems initiative - funded through the UK Government Technology Strategy Board - has been conceived with the aim of reducing carbon dioxide (CO2) emissions of the latest breed of hybrid buses by another 10 per cent.

This can be achieved through the capture and use of waste exhaust heat that would otherwise be lost during bus operation, while also improving fuel consumption by halving the power consumption of the air-conditioning systems.

The three-year project is led by the Wrightbus company from Ballymena, Northern Ireland, and also involves Ulster-based Queen's University and the Ricardo and Revolve technology companies. It is said to be "a potentially important step forward in public transport technology".

The first-generation heat-recovery devices are expected to lead to a production-ready Thermal Energy Recovery Systems (TERS) system within the next six years.

The Wright Group's managing director Mark Nodder explained: "TERS brings an interesting new dimension to the development of hybrid bus technology and seeks to find responsible solutions to the world's environmental challenges. This exciting new initiative, in close cooperation with our TERS project partners, is a key strand of our on-going work to deliver the next generation of hybrid buses."

Professor Roy Douglas is the leader of the research team at Queen's University located in Belfast, Northern Ireland. He added: "In this concept, we are capturing heat energy that would normally be wasted and converting it into useful power. The challenges are huge but the potential for fuel economy improvement is also huge."

He continued: "The targets for the project are to reduce fuel consumption by 10 to 20 per cent on top of the 30 per cent already delivered by the hybrid technology. It is this new hybrid technology that is the key enabler for waste heat recovery. Queen's University has been developing this research for many years, and it is very exciting to have the opportunity to put it into practice."

The heat lost in the exhaust of a modern diesel engine can represent up to 40 per cent of the available chemical energy content of the fuel used by the vehicle, said Nick Owen, director for research and collaboration at the Ricardo technology company (www.ricardo.com) based at Shoreham, southern England.

He added: "A major current focus of Ricardo's research and development efforts is therefore on the development of robust and cost-effective solutions aimed at harnessing this currently wasted energy in order to improve fuel consumption and reduce CO2 emissions in both hybrid and conventionally powered vehicles. We are extremely pleased to be able to play an active part in the TERS project research which will see the tangible demonstration of technologies on a modern hybrid bus."

Continuing the theme, Paul Turner, technical director at Revolve Technologies from Brentwood, near London, reveals that his company has "a firm focus" on energy recovery and maximisation as well as CO2 efficiency and powertrain technologies of the future.

He reports: "Investing in state-of-the-art testing equipment and capability to meet today's stringent CO2 industry demands, Revolve has achieved immeasurable successes and gained invaluable knowledge across the automotive hybrid technologies arena.

"With the combination of shared expertise and knowledge base, this TERS research and development project will provide invaluable solutions to not just the modern hybrid bus, but to the future of all powered vehicles."

Wrightbus, founded in 1946 and still a family-owned and managed company, claims to be the UK's leading independent supplier of public transport buses and has been chosen to build a fleet of hybrid buses for London.

These will bring a new look to what is already Europe's largest low-emission bus fleet and as such are likely to be some of the first vehicles to benefit from the results of the TERS initiative.

The Transport for London organisation says the newcomers will reduce both fuel consumption and air quality emissions by 40 per cent compared with conventional diesel buses, as well as being 15 per cent more economical than the city's current hybrids. Wrightbus was the first manufacturer to introduce hybrid buses into fare-paying service in London and is also testing fuel-cell buses.

The hybrid bus, in which a conventional diesel engine is paired with an electric motor, is seen as the people carrier or superbus of the future in the world's crowded and polluted cities. London, for instance, plans to introduce 90 hybrid buses to service this year.

This will boost the UK capital's fleet of hybrids to more than 200 by the end of 2011. With the potential benefits of the new research described as "huge," the next generation of hybrids are expected to make a significant contribution to cutting London's carbon dioxide emissions by 60 per cent from 1990 levels by the year 2025.