New Eco-Friendly Hybrid Buses for London and Beyond
Submitting InstitutionQueen's University Belfast
Unit of AssessmentAeronautical, Mechanical, Chemical and Manufacturing Engineering
Summary Impact TypeTechnological
Research Subject Area(s)
Engineering: Automotive Engineering, Civil Engineering
Built Environment and Design: Design Practice and Management
Summary of the impact
Using powertrain system models arising from QUB research Wrightbus
Ltd developed an advanced eco-friendly hybrid diesel-electric bus
which won the New Bus for London contract worth £230M supplying 600
buses to Transport for London (commencing August 2012).
Demonstrating highly significant economic and environmental impacts the
bus has twice the fuel economy of a standard diesel and emits less than
half the CO2 and NOx. The full fleet reduces
annual CO2 emissions in London by 230,000 tonnes,
improving air quality and reducing greenhouse gases.
The company continues to develop the technology in new hybrid vehicles reaching
worldwide, including USA, Hong Kong, Singapore and China.
Engine performance simulation research has been led by Professor Douglas
since the mid 1990s. Prior to this, much of the predictions for engines
used data from prototypes and operational systems, and little existed in
reliable models which could be used effect in design. Much of the problem
relates to the complexity of performance in a typical drive cycle which
has a large number of constantly changing parameters and is therefore
difficult to extract reliable average or predictive measures. The
breakthrough was in developing the 1-D code which though of low fidelity
allowed a complete predictive model to be established with reliable
output. The work continued throughout the late 1990s with the development
and implementation of component models for Internal Combustion (IC)
engines [1,2] leading to the evolution of fully operational engine
simulation code .
The success of the 1-D simulations allowed further development to the
broader powertrain system using 2-D models (Douglas & McCullough,
joined 1999) and linking several system elements together to provide a
complete picture. This was achieved through the "Virtual Engineering
Centre"  with the theory for modelling of powertrain systems and
components , where the first simple vehicle models were developed and
tested. The team built state-of-the art test cells for validation of
performance over the full cycle. Validation of the models was a key aspect
of the development and techniques were developed both on test rigs and
on-road in vehicles and the data was compared with other published
information. This investment was a key part in improving the reliability
and accuracy of models, moving from the research environment to working
prototypes in operation.
To this point much of the work had been focused around traditional IC
engines but the capability now permitted consideration of hybrid
diesel-electric drives, which was previously too challenging with existing
approaches. Since 2005 Douglas, with co-workers Fleck and Kee, led the
final phase of this research, collaborating directly with Wrightbus on
development of techniques for modelling of vehicle powertrains for
hybrid vehicles [4,6,8]. From 2007 to 2009, full vehicle models were
constructed, tested and validated and detailed component models for items
such as batteries, motors, inverters, were developed. The models were then
assembled into useful design tools to allow Wrightbus to use them in
assessing system designs. In particular the full drive cycle was
investigated and the efficiency of each element of the system assessed.
Each element was then tuned by industry (collaborations involving
Wrightbus Ltd, Revolve Technologies Ltd) to allow maximum performance at
all phases of the drive cycle. It was the culmination of this
capability in 2009 that provided the key to the Wrightbus success,
allowing development of optimum performance across the whole system.
In the last phases, working with the industrial partners on the
development of the new generation buses extensive on-road testing was
undertaken at Millbrook testing facilities (2009), overseen by Douglas,
to capture real drive cycle data for validation and verification. The
models were extensively checked for accuracy and reliability over a range
of vehicles and over a range of drive cycles.
References to the research
1. M.G.Reid, R. Douglas. "Quasi-Dimensional Modelling of Combustion in a
Two-Stroke Cycle Spark Ignition Engine". SAE Paper 941680, SAE Off-Highway
Congress, September 1994. DOI: 10.4271/941680
2. *G. McCullough, R. Douglas, G. Cunningham and L. Foley. "The
Development of a Two-Dimensional Transient Catalyst Model for DI
Two-Stroke Applications." Journal of Automobile Engineers, Part D, Vol.
215, D8, pp 919-933, August 2001. DOI: 10.1243/0954407011528482
3. *T. Khossusi, G. McCullough and R. Douglas. "Modelling of Oxygen
Storage in Automotive Catalysts". Proceedings of the Institution of
Mechanical Engineers, Part D, Journal of Automobile Engineering, Vol. 218,
No 11, pp 1349-1362, December 2004. DOI: 10.1243/0954407042580066
4. *A. Simpson, R. Fleck, R. Douglas, R.J. Kee. D. Steele. "Development
of a Heavy Duty Hybrid Vehicle Model". SAE paper 2009-01-2933, SAE
Commercial Vehicle Engineering Congress and Exhibition, Rosemont,
Illinois, US, Oct, 2009. DOI: 10.4271/2009-01-2933
*Best 3 outputs
5. R Fleck, R. Douglas, GP Blair, "Development of the QUB Engine
Simulation Package". Funded by 6 companies, 1992 to 1996, £235,000
6. R. Douglas, R Fleck, "Modelling of Powertrain for Hybrid Buses,
£66k, jointly funded via Invest NI and Wrightbus", 2008 to 2010
7. R. Douglas, R. Fleck, G. McCullough, R. Kee et al. "The Virtual
Engineering Centre". In collaboration with 3 Engineering Schools. Funded
by SPUR, 2001 to 2006, £5,100,000
8. R. Douglas et al. "The Total Thermal Management of a Hybrid
Diesel-Electric Bus", TSB funded with Wrightbus,2010, total value £1.6m,
£569k to QUB.
9. KTP007991 £192k 2010-2013 TSB & Invest N.I "To transfer the
technology of Hybrid Modelling, enabling modelling of new configurations
of the hybrid driveline for application in new city buses worldwide".
Details of the impact
29,000 people die prematurely each year in Britain from man-made air
pollution, mostly from vehicle exhausts, with London being one of the
worst cities in Europe#. QUB technology is now being
utilised to reduce this pollution.
Wrightbus is the UK's largest bus manufacturer producing a range of
buses which it now exports globally. Wrightbus used the models and
capability arising from this QUB research to improve their range of hybrid
buses, resulting in contracts of more than £230M for 600 buses and
growth in the company to a workforce of over 1400 high value
manufacturing jobs. Most notably the work helped Wrightbus secure
the contract to replace the iconic Routemaster for Transport for London.
In tests at Millbrook Proving Ground, the engineering test vehicle emitted
only 640 grams per kilometre (g/km) of CO2 and 3.96 g/km of
Oxides of nitrogen (NOx) — less than half of the CO2
emitted by a current diesel bus (1295g/km) and under half of the NOx
emitted by a current diesel bus (9.3g/km). In testing, fuel economy
was also better than twice that of a standard diesel bus at 11.6mpg.
The hybrid bus model is a simulation of the complete vehicle which allows
designers to assess the performance of the bus (power and fuel usage) over
the whole drive cycle in a city, with its numerous stops, starts,
accelerations and decelerations. It was developed with the express aim of
assisting in the design of hybrid drivelines for city buses, to specify
components and to optimise control strategies. The model has almost 50
person years of research embedded within based on extensive theoretical
work and experimental validation. The pivotal capability is that the model
works reliability over the whole drive cycle allowing designers to tune
engine and powertrain performance at all points.
This was directly introduced to Wrightbus, Ballymena initially through
a Knowledge Transfer Partnership (KTP, commenced 2010) to implement
the model into their design process for new hybrid buses. It is now routinely
used by their engineers for specification of hybrid buses and has been
applied in a series of projects. It is accepted as an important
design tool and has been well validated for accurate prediction of fuel
economy and emissions of the Wrightbus product range. This key capability
allowed partner company Revolve Technologies Ltd., working with Wrightbus,
to develop an engine management system which controls performance and
doubles the efficiency of the vehicle.
As well as the modelling and design of hybrid bus systems, this approach
is now being applied to evaluate the performance of new technologies and
for optimising non-hybrid powertrains. Wrightbus is continually searching
for lower fuel economy and better efficiency as their global market grows.
They have now employed one of the QUB research team members who developed
the vehicle model as their technology specialist.
The economic impact of this research has therefore been more widespread
throughout the global bus industry through the vehicle modelling work in collaboration
with Wrightbus Ltd, the leading manufacturer of city buses in the UK
and an exporter across the world from Singapore and Hong Kong to Las
Vegas. The research contribution has assisted Wrightbus in improving
their range of hybrid buses, in evaluating various technologies for fuel
The New Bus for London had star billing during the London Olympics
with the first 4 prototypes operating and on display throughout 2012.
The Lord Mayor of London, Boris Johnson, has acclaimed "Christmas
has arrived early in the form of this revolutionary new bus...it is the
latest, greatest masterpiece of British engineering and design,
and I am certain it will become a much loved and iconic vehicle akin to
the legendary Routemaster from which it draws so much inspiration".
Since 2012 buses have been gradually introduced to Central London routes
and being operated by Arriva.
Moreover the bus is seen as a way to improve London's air quality. The
full fleet will reduce NOx emissions by 57% and an astounding
230,000 tonnes of CO2 every year. Air pollution costs the UK
£15bn per year, mainly from the cost of treating respiratory diseases
(e.g. asthma) and heart attacks that air pollution causes#.
The success is now attracting further investment from the partners in the
TSB supported project "The Total Thermal Management of a Hybrid
Diesel-Electric Bus" with Douglas and McCullough leading the QUB
team, and in 2012, a new development project was set up in collaboration
with Flybrid Automotive Ltd to apply the flywheel storage as used in
Formula 1 cars to city buses.
#Guardian article "All Choked Up-Why is our
air so dirty" 20th March 2013
Sources to corroborate the impact
- Company contacts relating to Wrightbus associated claims:
Engineering Director, Wrightbus Ltd, Ballymena.
- Articles on hybrid bus testing at Millbrook
- Articles on London Buses
- Article on Thermal Energy Recovery Project