If Bermuda’s buses switched to an electric-hybrid system, there could be a cost savings. *Bermuda Sun photo
If Bermuda’s buses switched to an electric-hybrid system, there could be a cost savings. *Bermuda Sun photo

In my last article I looked at a few of the projects I came across during my travels last year that piqued my interest from an energy perspective. 

One of the initiatives I mentioned is based in the city of Oxford in central southern England. According to Wikipedia; Oxford has a population of 150,200, which makes it the 52nd largest city (by population) in the UK and covers an area of 17.6 miles, which is about 16 per cent smaller than Bermuda. 

It lies within the greater Oxford metropolitan area. Oxford is one of the UK’s fastest growing cities and has one of the most expensive real estate markets outside of London. 

The city is known worldwide as a university town and home of the University of Oxford, the oldest university in the English-speaking world. 

Oxford demonstrates examples of every English architectural period since the arrival of the Saxons, and is affectionately known as the “city of dreaming spires”, a term coined by poet Matthew Arnold in his poem Thyrsis, referring to the harmonious architecture of Oxford’s university buildings.

 With all of that history, you could be forgiven for expecting a transportation system based on steam engines and horse drawn ‘Hackney Carriages’ but oh, how mistaken you would be! 

Enlightened

In reality, Oxford has one of the most enlightened transportation systems in the entire country. It is operated by The Oxford Bus Company and here are just a few of their claims to fame: “We are proud to run the lowest emission bus fleet of its size in the UK. Providing greener travel options for Oxford.

“Oxford Bus Company aims to provide the best possible service to the people of Oxford whilst minimising our environmental impact on the historic city. We now have the highest percentage of electric-hybrid buses in a bus fleet in the UK.”

“Driving towards a greener Oxford, in January 2013, we introduced 19 brand new electric-hybrid vehicles to our fleet. This was in addition to the 18 electric-hybrid buses already in operation. This means that 36 per cent of buses used across our local and park&ride routes are now electric-hybrid buses.”

“From January 2014, Oxfordshire County Council will implement a Low Emissions Zone (LEZ) in Oxford City Centre. This means that all buses operating within the LEZ will have to meet the highest ‘Euro V’ standards for NOx (Oxides or Nitrogen) by January 2014. Oxford Bus Company is on target to be fully compliant with the forthcoming LEZ.”

So what exactly is a diesel electric-hybrid bus and how does it work?

Power

A hybrid vehicle is one that takes its power from more than one source. In the case of diesel electric-hybrid buses, the two power sources are the traditional, but much smaller diesel engine, and an electric motor/generator powered by a 600 volt lithium-ion battery.

The bus is powered using a parallel hybrid system. This enables the small diesel engine and electric motor to work independently or in combination with each other, depending on driving conditions, dramatically reducing fuel consumption and emissions. 

The battery is charged using the electric motor that also acts as a generator, to capture energy that would usually be lost as heat into the atmosphere during braking. This energy is stored in the battery for later use.

What makes the hybrid bus so different to other buses is that both units can work independently or together. 

When the bus accelerates away from a bus stop, the electric motor works independently and uses the stored energy in the battery to power the bus. During this time, the diesel engine is shut down as it is not required. Not only does this save fuel, it also removes emissions and noise pollution as the electric motor is virtually silent! It’s only when the bus reaches speeds of about 10mph (17kph) that the small diesel engine starts and works in combination with the electric motor to power the vehicle.

So what do you think Bermuda, can we learn a few lessons from the oldest university town in the English speaking world?

Comments and suggestions to info@bae.bm

Nick Duffy is the divisional manager at Bermuda Alternate Energy.