Electric street transport is equated with clean, breathable city air, something that opinion polls have constantly shown almost everyone wants.
The gentle whine of the electric motor is seen as a 'forward looking' friendly sound - unlike the 'roar' of the internal combustion engine.
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In addition to the absence of tail-pipe exhaust fumes, other advantages of electric buses include:-
Improved hill climbing capabilities (especially trolleybuses).
Lowest possible noise levels.
No idling motor energy losses. (ie: when calling at bus stops or stopped at traffic signals)
Better overall performance and less vibration (none whilst idling!) which results in a faster, more comfortable, smoother and hence more attractive journey experience for passengers.
For bus operators faster journeys reduces the fleet size & the number of trolleybus drivers required to operate the route - producing a notable bottom line improvement - whilst less vibration results a longer vehicle life.
Lower and more predictable operating costs - compared to the 'volatile' price and availability of imported fossil and other liquid fuels - even moreso when exchange rate issues are taken into account.
Fewer moving parts and the 'slide out / slot in' modularity of the electric traction packages which makes for simpler and cheaper maintenance.
Regenerative braking which allows them to use their motors as generators and recycle energy either into the batteries or back into the wires instead of wasting it as friction / heat via the brake pads. Regeneration brings energy savings of around 30%.
Experience gained from railway electrification which has shown that the sparks effect does attract more patronage, even if the actual journey times are not significantly improved.
Lower overall lifetime costs - although the initial investment in vehicles and (for trolleybuses) infrastructure will make electric buses appear to be a more expensive option than simply buying a few more motorbuses.
With trolleybuses the presence of the infrastructure both acts as a continuous advertisement for the system and helps instill confidence that the transport will be here today - and tomorrow(!), thereby encouraging businesses to make investments in the served corridors.
With battery electric buses recharging the vehicles during off-peak hours (typically overnight) eliminates any issue of capacity for electrical generation.
|The space age designed 'Cristalis' trolleybuses in Lyon, France.
These are the 'rigid' (non-articulated) versions.
|An articulated version on one of the high profile Trolleybus Rapid Transit routes in Lyon.
Proof Of Their Popularity Comes From Experience In The Towns & Cities Which Use Them!
In Arnhem, Holland the transport operators have seen ridership increases in the order of 17% on routes converted from diesels on a "like-for-like" basis. Their five year "Trolley 2000" Trolleybus Rapid Transit (TBRT) strategy was conceived knowing that by using trolleybuses passenger levels would be up to 21% higher than would have been expected using the best type of diesel buses. In Salzburg, Austria ridership increases have been 16% and the city is part way through a long term trolleybus expansion project which includes several brand new trolleybus routes (one of which will be an express service with the overhead wiring configured for overtaking) and converting several more diesel routes to electric operation. Another aspect of these ambitious plans is to see an almost total elimination of fossil fuel powered buses from Salzburg's streets. (This is being done for environmental reasons). Increases in ridership have also been noted in the USA, for instance Seattle and San Francisco where experiences have been even more significant because not only has it been found that electric buses will attract more passengers than the diesels but also that replacing electric buses with diesels (even temporarily) can lead to passengers pro-actively choosing to avoid the buses! (almost certainly similar would have been found here in Britain, if anyone had bothered to conduct a passenger survey)
|Salzburg, Austria takes air pollution issues seriously and is converting more diesel bus routes plus adding an express service to its already extensive trolleybus system so that within two years it will have achieved an almost total elimination of fossil fuel powered buses from its streets.||In Arnhem, Holland they found that a service which is busy enough to justify a bus every 10 minutes - six buses an hour - is cheaper to operate with trolleybuses than motorbuses.|
The San Francisco passenger survey found that while the streetcars are the overwhelming 1st choice - even for routes where they are not a viable proposition - the electric buses are considerably more popular than the motorbuses, which are actively disliked, being rated as noisy and smelly. Indeed when roadworks caused temporary motorbus substitution of some electric bus services (with service frequencies and journey times remaining unchanged) there was an 11.33% downturn in passenger patronage that can only be explained by passengers making a pro-active choice to avoid the motorbuses.
Even When The Electricity Is Sourced From Fossil Fuel There Is Still A Reduction In Global Air Pollution!
In an ideal world the electricity would be sourced from renewable sources as then the electric street transports would be truly 100% non-polluting and help humankind to follow policies for sustainable development. However in many places the electricity is sourced from fossil fuel burning power stations.
Critics often allege that by sourcing electricity from fossil fuels all that is really happening is that the pollution is being shifted up the energy chain to the power station. However, following extensive research in the University of California it has been found that even with low grade coal that produces a lot of carbon dioxide (as is used in Germany) electric traction offers an almost complete elimination of carbon monoxide and hydrocarbons, resulting in a significant global air quality benefit. Of course if the fuel used is high grade coal or natural gas (or another so called 'cleaner' fossil fuel) the benefits are even more admirable. Experience in Sweden has shown that when a type of coal-burning power station known as 'pressurised fluidised-bed' is used then the emission of sulphur oxides and nitrogen oxides are also considerably reduced; furthermore, when these facilities are linked in with combined heat and power facilities (ie: provides both electricity and hot water which can be made available to industrial and domestic consumers alike) then they are about 40% more efficient than their traditional large coal burning equivalents, (75% efficient opposed to 35% efficient) and are so clean that they can be located within cities.
As a contrast at best diesel engines are only 40% efficient and if you include idling, part loads etc., then this reduces to below 30%. Engines powered by other fossil fuels achieve even lower figures. Plus all the pollution is released in the street environment...
|Modern rigid (ie: not-articulated) trolleybus in São Paulo, Brazil.
|Trolleybuses come in many different vehicle lengths - including triple axle 15 metre rigid variants, as seen here on demonstration in Salzburg, Austria. Photograph courtesy of Bruce Lake.|
Electric Buses Are Environmentally Sound!
The environmental case for electric traction is that even with so-called 'cleaner' (but still finite) fossil fuels (eg: LPG, CNG, etc.,) the only proven viable vehicle propulsion system that will not pollute the air that we breathe in our towns and cities comes from electricity. Whilst renewable liquid fuels are available (gasohol, bio-diesel, etc.,) they still pollute their local environments so are more suited to quieter rural routes where air quality issues are less severe and economics suggests that electrification would simply not be a viable proposition.
|What a pleasant, fume free contrast to London:
Modern trolleybus in Geneva, Switzerland sharing the pedestrian zone with the trams.
|Trolleybuses also travel along part of the pedestrian zone in Neuchâtel, Switzerland.|
A video showing a seriously (air) polluted bus + taxi pedestrian zone in London plus this clean air equivalent scene from Geneva has been placed on the 'youtube' file-sharing website and can be watched (in a new window) by clicking the link below.
So, Knowing The Benefits, Why Aren't More Cities Investing In Electric Traction?
Perhaps the primary reason why more cities (outside of Britain) are not investing in electric traction is that the continuing limitations of battery technology means that the only way to obtain sufficient electrical energy for a full days' work is by making that energy available wherever the vehicle happens to be, and the only proven viable way to achieve this (and maintain safety within the street environment!) is through the installation of an overhead wire power supply system. Sadly every community has its negatively orientated 'NIMBY' (not in my back yard) people and it seems that a few of them dislike these overhead wires. Oddly enough though, these people are hardly ever heard complaining about the clean, breathable city air that electric traction brings!
Trolleybus System Installed - To Protect Urban Environment
As part of a policy for cleaner urban air, and having investigated all the alternatives and the financial benefits from reduced healthcare costs, in March 2005 the Italian capital city of Rome opened its fist trolleybus route since 1972.
These vehicles also feature powerful batteries giving them an expected 10km off-wire range. The reason for this is that within Rome city centre there is a 3km unwired section and in an effort to maintain urban air quality the use of diesel (or other fossil fuel) power systems was felt to be undesirable. The extra long range of the batteries is also to ensure that they have the endurance to cope with traffic delays in stop start (rush hour) travel conditions and to guarantee power to the brake compressor & air conditioning. Battery mode operation will usually include 5-15 minutes laying over between journeys at the central bus terminus in Rome city centre.
Recharging takes place whilst running under the wires.
In January 2008 Rome announced the creation of a 60 vehicle trolleybus system serving another part of the city.
|Rome trolleybus operating in battery mode just after leaving its stand at the "Termini" bus station in the city centre.||Rome trolleybus in overhead wire mode travels along a segregated Bus Rapid Transit lane in Via Nomentana.|
Why The 'Double-Standards?'
|Zürich, Switzerland, where as part of environmental policies designed to protect the health of city-dwellers by minimizing urban air pollution motor buses are generally restricted to
outer suburban and rural services.
Trams (streetcars) are almost always electrically powered - indeed this feature is often touted as one of their major benefits - and there really is no reason why buses should not be equally city (and town!) friendly.
It really is most strange that so many transport 'experts' (operators, environmental advocates, lobby groups etc.,) have such double-standards with respect to air quality (or lack of) and bus / tram propulsion systems
Bus Derived Air Pollution Is The Easiest To Solve
Whilst it is true that motor buses are not the only vehicles which create tail-pipe pollution (cars, lorries, motorcycles and taxis do too) bus derived air pollution is the easiest to solve. This is because buses generally follow fixed routes along comparatively few of the roads in a cities' overall street network. Effectively this means that significant air quality gains can be achieved by equipping just a few roads for trolleybuses.
Whilst modern trams (streetcars) usually collect their power from a single overhead wire via a pantograph fitted to the vehicles' roof (with electrical return being via the running rails) electric buses will use a pair of overhead wires (one each for power & return) and twin 'trolley' poles fitted to their roofs. This explains why they are called "trolleybuses".
In North America they also use other terms, such as trolleycoaches; etb's / electric trolley buses (to distinguish them from diesel-powered 'trolley' buses that look like an old fashioned "trolley-car" as is often used in the leisure industry) & trackless trolleys - "trolley" is another American term for "tram" or "streetcar" so a trackless trolley is a "trolley car" that collects power from overhead wires using "trolley poles" but travels without rails.
Although there are upfront investment costs associated with new trolleybus networks - and because they tend to be built in small batches the vehicles themselves are more expensive to purchase - experience has shown that once operational trolleybuses can be cost competitive with diesels if you take a "lifetime" view of an installation (20 years or so) and factor in their expected longer life, lower maintenance costs, increased availability, increased attractiveness to passengers (higher revenues), better energy efficiency, etc. In Arnhem (Holland) the management of the trolleybus system have quoted about six vehicles per hour (10 minute headways) as about the break even point when it becomes more economic to operate a service with trolleybuses than diesels.
|Modern rigid (ie: not-articulated) trolleybus in Wellington, New Zealand
|Some very busy trolleybus routes in Lüzern, Switzerland are served by 'rigid' trolleybuses which haul unpowered low-floor easy-access trailers. This is because increasing demand meant that overcrowding was becoming an issue so larger (articulated) trolleybuses were needed, however as the existing vehicles were not life-expired it was decided that using trailers would provide a cost effective solution which both increased passenger capacity and introduced low floor accessibility for the first time.|
|High capacity three-section double-articulated LighTram trolleybuses such this were designed to increase passenger capacity on busy trolleybus routes - as an alternative to converting them to (steel wheel) trams.
These image come from the Swiss cities of Geneva left, and Zürich below - the latter image comes from Wikipedia..
Similar vehicles are also used in the Swiss cities of Lucerne (Lüzern) & St Gallen.
As of Spring 2007 Geneva decided that to both cater for the increasing numbers of passengers travelling and reduce urban air pollution it will convert its busiest trolleybus routes to tram - and then use the displaced trolleybuses and LighTrams to both lengthen existing trolleybus routes and electrify more motorbus services. In Geneva they have found that the sight of the overhead wires is seen as a positive advantage, because "people see the wires and know that quality public transport comes here" (ah, so different to this country).
Trolleybuses Are Flexible Enough To Avoid Road Obstructions!
Trolleybuses can travel with the overhead wires either directly above or to one side of the vehicle. Usually their ability to 'wander' is by as much as four metres, which equates to three traffic lanes.
Apart from helping them to fit in with existing traffic flows this ability to switch lanes also gives them an ability to around obstructions, such a broken down cars.
Trolleybuses have the flexibility to go around obstructions, such as broken-down cars! Esslingen, near Stuttgart, Germany.
The above image is a video-still - click the image or the projector icon to download a 17 second video clip named 'Esslingen-go-around320.mpg' which shows the action being described as well as a duo-bus running with its trolleypoles down.
|Flexibility also means easily coping with having to use the other side of the road when road reconstruction results in single alternate lane working under the control of temporary traffic signals. Solingen, Germany.|
|Gdynia, Poland. Because trolleybuses can use several traffic lanes so at bus stops with dedicated pull-ins the overhead wires just need to be slewed towards the pull-in to be suitable whether the trolleybuses
are calling here - or not
|A simple passing loop in the overhead wires allows a moving trolleybus to pass a stationary trolleybus. Lausanne, Switzerland.|
Extending Beyond The Wires...
Many modern trolleybuses are also equipped with either a low power fossil fuel engine or batteries so that if they need to travel away from their wires they can do so, albeit perhaps at reduced speed. Another use for these secondary power systems is in the depôt, giving them the ability to gain access to every part of the facility without having to provide sufficient wiring.
In most instances these APU's will only be for emergency (& depôt) use allowing the vehicle to travel a short distance around an obstruction (eg: a road traffic accident) at reduced speed. However in some cities they use more powerful alternative power systems as this can give the possibility of scheduled operation of longer distance off-wire travel too.
In Landskrona, Sweden (which opened a small brand new system in late 2003) the depôt is unwired and around 1km away from the nearest wiring. The first vehicles in the fleet use batteries to power the trolleybuses to and from the service wiring, but when high passenger numbers resulted in fleet expansion it was decided that the extra trolleybus should be equipped with a low power apu instead.
Rome's new trolleybuses feature batteries powerful enough to allow as much as 3km of unwired operation through the heart of the city centre. The option which Rome did not want to follow is to use what is known as a duo-bus (see below) - this was for reasons of air quality.
In Beijing, China, all the routes crossing the main east-west boulevard or operating through the central shopping streets do so using powerful batteries which permit quite smart acceleration and several kilometres range at 30-40 kph. After crossing the visually sensitive areas the trolleybuses are driven into a marked box on the highway where the driver depresses a button to raise the trolley booms hydraulically into inverted V-shaped re-wiring troughs on the overhead. As with Rome's trolleybuses the batteries are recharged during the remainder of the journey.
Rome trolleybus raising its trolleyarms to switch from battery to overhead-wire power. In the view on the right the pick-up has yet to properly locate itself around the overhead wires.
Duo-buses are 200% power vehicles which can operate freely - at full power - in either electric or fossil fuel modes. When in electric mode they operate as trolleybuses, collecting power from overhead wires via twin trolleypoles.
Used in a few cities globally, duo-buses are usually fitted with motorised trolley poles, so changing between modes is simply a case of the driver stopping and pressing some buttons - (s)he does not even have to leave the cab! When raising the trolley poles correct placement is ensured by fitting inverted 'V' shaped wiring guides to the overhead wires, naturally for them to be effective the vehicle must stop in the correct location, so it is very important to prevent illegal parking at the up-points. Lowering the poles can take place anywhere, even when the vehicle is moving. In either case modal changeover takes less than a minute so when it is located at bus stops the only delay to the service comes from the time taken for the passengers to pay the driver as they board.
Duo-buses are more suited on routes where buses need to operate significant distances beyond the range of the overhead wires but the route is infrequent and therefore electrification is not commercially viable. Apart from the effects of the waste gases the primary disadvantage of the duo-bus is that the weight of the two drive systems increases their unladen weight and if this brings them close to the legal weight limit for buses it potentially could reduce the passenger carrying capacity.
|Esslingen, Germany duo-bus using its auxiliary diesel engine to go around a maintenance crew working on the overhead wires.||Massachusetts Bay Transportation Authority (MBTA) Silver Line Dual-mode bus departing South Station to serve SL2 Waterfront Line in Boston.
In the late 1980's and early 1990's the German city of Essen had a fleet of duo-buses which mostly ran as diesel buses when on surface sections of route and as trolleybuses when travelling through part of the city's underground tram / light rail system.
More information on the former underground operation of duobuses in Essen can be found on these pages...
This image shows one of the duo-buses raising its trolleyarms whilst stopped on a tunnel entry ramp.
NB: The clickable large image has been sourced from S-VHS-C videotape and is a little fuzzy.
Click the projector icon (or here) to see a 12 second video clip named 'Essen-eastern-ramp-arms-up320.mpg' showing this action taking place.
Other Types of Electric Buses.
Battery Electric Buses.
Many people know what batteries are about - after all, who has never used a torch / portable radio / music player / telephone / communications device (etc)? All of these use batteries and it would seem logical that if these work well then buses should be able to be powered from batteries as well.
Ah, if only life were that simple!
Real-world reality is such that battery technology is simply not the whole answer. This is because (especially for large buses) batteries do not carry enough energy to power the bus for a full day. If this were not so then both diesel and overhead wire trolleybuses would already have been replaced with battery buses.
Whilst simply carrying a few more batteries may seem a logical enough solution the reality is that batteries add weight, which increases energy consumption, and since there are usually legally mandated weight limits for buses / all road vehicles so using heavier buses would reduce the total number of passengers they are allowed to carry. Batteries also take up valuable passenger space inside the bus. Whilst it is true that buses could tow battery trailers behind them, if this was a real-world viable solution then many bus systems would already be doing it. This is not the place to discuss future trends, so all that will be said on that score is that the situation will only change once we start using magnetics and other energy technologies. However in tandem with those changes will be changes to our transport solutions.
Where battery technology has been proven viable is with small buses which are used on relatively short routes with the batteries benefitting from either 'top-up' charging during the day or the battery packs being replaced with fresh fully charged batteries during the day.
The use of rechargeable batteries also pose financial issues. Over time batteries degrade, which means that they reduce the amount of charge they can carry, and the reality is that (at present) none of the known battery technologies has created a battery with the same longevity as the buses. Some battery technologies are still too new to be sure of exact facts but it is looking likely that all electric buses which use batteries to power the vehicles will need their battery packs replacing at least once during their commercial lives. When the cost of the batteries is also bourne in mind this can be expensive! Often after a few years use batteries can be reconditioned, but this process only adds working life to them, it does not return them to full 'as new' condition.
Money is not the only issue. Making / half-life reconditioning / disposing of spent batteries also has environmental consequences. Of course where there is the will to do things properly the environment is easily respected.
Note however that the operational, financial and environmental challenges related to battery buses are still easier to resolve than dealing with the human (ill)health consequences of fossil fuel exhaust fumes.
Charging The Batteries.
Most battery electric buses use 'conductive charging', which is also known as 'direct wired contact' or 'direct coupling'. This well tried and proven system involves plugging a cable into a socket on the vehicle.
A variant of conductive charging sometimes sees the batteries being removed from the vehicle for recharging. If several sets of batteries are available then immediately replacing them with a fully charged set of batteries would mean that the bus could be back in service within minutes / without having to wait for the removed batteries to be recharged.
In addition to 'conductive charging' another way to charge the buses' batteries is via electromagnetic 'inductive charging'. This is further explored under the Roadway Power heading below.
Battery Electric Bus Examples.
In the early 1990's Oxford, England, trialled a fleet of four electric minibuses. A report on their first 500 days of operation found that compared to similar diesel buses (and after
taking account of extra emissions at the power station) there was:-
Maintenance costs were comparable to diesels, but because of high design and development costs which were spread over just four vehicles they were twice as expensive to purchase. Their lead-acid batteries weighed-in
at 2 ¼ tonnes, making them about 2 tonnes heavier than the regular diesel buses.
Oxford, England. A long wheelbase 'Optare MetroRider' electric minibus 'tops up' its batteries while awaiting its next scheduled journey.
This was done by means of a cable from a roadside unit plugging in to a socket located on the bus.
Despite the environmental advantages the use of battery electric buses in British towns and cities is virtually zero. This is most likely because to Britain's cut-throat deregulated bus industry (where finance is seen to be the only thing which matters) such innovation does not make (financial) sense.
One of the British conurbations which does use battery electric buses (in 2011) is St Helens, Lancashire. These are operated under the auspices of the Merseyside Passenger Transport Executive (Merseytravel) who have contracted out to private bus companies the operation of three free bus services which use a mix of mini and micro battery electric buses.
|One of the six St Helens Tecnobus Gulliver microbuses. Seen at Woodside Ferry Bus Station which connects with the Mersey Ferry.
© Copyright Colin Smith and licensed for reuse under the Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) Creative Commons Licence.
|Also used in St Helens are six of these battery electric Tecnobus Pantheon minibuses. Note the twin axle rear wheels.
Small fleets of similar battery electric buses are also used in several towns and cities around the globe, where they are often seen to provide a very effective transport solution in pedestrianised and so called environmentally sensitive areas.
(Surely our entire 'living space' aka: the whole planet should be regarded as being 'environmentally sensitive' - not just a few streets in a city centre?)
|Bordeaux, France, running on a city centre service through narrow streets which despite its small size it still only just manages to negotiate.||Amalfi, Italy. These Tecnobus Gulliver buses can carry up to 20 passengers, 10 of which are seated.
|Seen at the City Ferry terminal passengers board one of the 8 Tecnobus Gulliver electric microbuses which are operated by the Réseau de transport de la Capitale in the Old City district in Québec, Canada.
|One of the Seoul Metropolitan Government (SMG) battery electric buses which are used on the Mt. Namsan circular routes, as detailed below.
Image sourced from SMG promotional material.
Claiming it to be the first commercial all-electric bus service the Seoul (Korea) Metropolitan Government (SMG) in conjunction with Hyundai Heavy Industries and Hankuk Fiber has overseen the creation and introduction of some distinctively styled 'large' battery electric buses.
The electric buses on the Mt. Namsan circular routes are 11.05 metres in length (about 12 yards / 36¼ ft) and can travel as far as 83km (about 52 miles) on a single charge. Using high-speed battery chargers they can be fully charged in less than 30 minutes and have a maximum speed of 100 km/hr (about 62 mph). Four battery charges are being provided. They use high-capacity lithium-ion batteries and regenerative braking. The press release references collecting "energy generated from brakes when running downhill" which suggests that the route includes significant portions of hilly terrain which can be very beneficial for regenerative braking.
To reduce their weight and help maximise the distance they can travel between charges these buses make extensive use of carbon composite materials, instead of metal. They are also of a low floor design and are equipped with automatic slant boards for wheelchair users. The enhance their visual appeal and create an aura of being 'different' they are shaped like a peanut and decorated with designs symbolizing the Namsan Tower and landscapes of Mt. Namsan.
Initially December 2010 saw just five of these buses being introduced, however the aim is a phased replacement of all 14 diesel buses on this service with the new electric buses. Their phased introduction is to ensure that any teething issues minimise any inconvenience which may be caused to passengers.
Batteries + Capacitors = A Marriage Made In Heaven?
Although batteries are often used to absorb regenerative braking energy they are not best suited to this function, as they prefer slower more regular charging. By way of a contrast, capacitors are excellent for capturing large amounts of sudden and powerful bursts of electricity such as comes from regenerative braking, but less good at retaining sufficient energy for even medium time periods.
The Chinese saw the potential benefits of combining these two very different electrical storage media in ways which the Europeans and Americans failed to do, and in late 2009 introduced in the city of Shanghai a small experimental fleet of 10 such buses.
Early reports are indeed very encouraging. Using lithium iron phosphate batteries and ultra-capacitors, it is reported that overnight charging of the batteries only requires 3 -5 hours (typically 4 hours, this being half that of other types of battery bus) and that their daytime range between charges is at least 160km (100miles) with the air-conditioner switched on, and as far as 250km (155miles) to 300km (186miles) with the air conditioning switched off. A driver on bus route No.825 revealed that on an average day the electric buses (s)he drives typically cover 154km (95miles) and consume about 170 kilowatts electricity, which makes running these buses cost about a third of a diesel engined bus. As an aside, these buses have a maximum speed of 130Km/h (80mph).
In addition to 'conductive charging' another way to charge the buses' batteries is via electromagnetic 'inductive charging'.
Induction chargers typically use an induction coil to create an alternating electromagnetic field from within a charging base station, and a second induction coil in the portable device takes power from the electromagnetic field and converts it back into electrical current to charge the battery. The major advantage of the inductive approach over conductive charging is that there is no possibility of electrocution as there are no exposed conductors.
Inductive charging is well known for low power domestic electrical items - such as toothbrushes and wet/dry electric shavers - where the reasons why it is favoured include that the battery contacts can be completely sealed to prevent exposure to water.
A drawback with inductive charging is that it is a relatively slow way to charge batteries - which admittedly is not an issue for toothbrushes and shavers as they can be left on charge at all times - unlike buses and other transports which generally need to be in service as much as possible during their working day.
|Induction charged battery electric mini buses in Turin, Italy. Depending on various sources of information there are either 28 or 30 vehicles of this type operating in several Italian cities, with there being 22 in Turin (purchased 2002) and 8 in Genoa (purchased 2000 - although some sources suggest that the entire fleet dates from 2002).|
Closer views of the induction charging facility. The bus must stop accurately so that the charging plate can be lowered over the correct portion of roadway. Of course this is only possible when there are no other (illegally) parked vehicles blocking this road surface facility.
In autumn 2008 a major transport vehicle manufacturer announced proposals for an inductive system which would be installed under the road along (much of) the transports' route, with the vehicles drawing power as they drive over it. Although primarily promoted as being for trams it was stated as being suitable for electric buses too, and for buses an extra feature will be the ability to travel in battery-electric mode over other sections of road away from the power supply.
The concept is not new, as in the early 1990's 'proof-of-concept' trials were carried out with a 35 seat Roadway Powered Electric Vehicle (RPEV) at the University of California Richmond Field Station. The trials saw the burying of power conductors under a 700ft (about 213m) test track and an operational RPEV which featured a needle dial so that as the vehicle travelled along the road the driver could see the 'strength' of the charging current being received and accurately locate the vehicle above the under-road power supply.
The RPEV system was shown on television as being able to draw enough power from below the road surface that it could also roam away from the power source, so that perhaps a main road serving many bus routes would be electrified
but they would be able to make short scheduled detours in battery electric mode. However despite the technology still being in need of refining before it would be ready for full commercial exploitation once these trains had been completed
the project became stalled. Perhaps this was because between 1992 and 2000 the USA had a President who was a member of the oil industry - if so then the lack of further development is not at all surprising. A report on these trials
can be bought from this link which opens in a new window:-
But whilst the American leadership did everything it could to roll back further development in electric transports (in favour of more use of fossil fuel energy sources) further development work in Korea resulted (in March 2010) in a more advanced variant of the RPEV being launched in Seoul, Korea. Known as the On-Line Electric Vehicle (OLEV) the technology is being tested on a 2.2km route at Seoul zoo which is served by a 'road train' that had previously been criticised for its diesel exhaust fumes.
Researchers at KAIST (Korea Advanced Institute of Science and Technology) succeeded in refining the technology so that it offers power transmission pick-up capacity of 62kw, at up to 74% efficiency, over an air gap between the road surface and the bottom of the vehicle of 13cm (a little over 5").
In Seoul zoo the OLEV train travels along 2.2km route which is equipped with four sections of under road power supply equipment.
Sections 1, 2, and 3 are each 122.5 metres in length, whilst Section 4 is just 5 metres in length.
This makes for a total length of subterranean power supply cables of 372.5 metres, which is just 16% of the 2,200 metre route.
The OLEV trail 'train' at Seoul Zoo comprises of one engine and three passenger carriages.
Image sourced from Kaist publicity material at 'kaist.ac.kr' link below.
If the technology proves viable it will be installed along the bus lanes in many city streets, as since buses account for 30% of all city traffic so electrifying them is being seen as providing a significant impact in reducing urban
air pollution. Kaist estimate that only about 20% of a route's entire length would need electrifying, although if evidence from the OLEV is correct then this would include bus termini so that buses could be recharging their batteries whilst
stationary between journeys.
In 2000 a 'roadway power' technology which was specially designed for buses was tested with several electric buses in the Italian city of Trieste. Unfortunately however it seems that the trials coincided with a change of local government - and whilst it seems that the outgoing politicians were keen to see the system expanded to more routes the new politicians were not.
Perhaps at least in part this was because the trials were on one of the cities' busiest bus routes and there was some disruption, especially when it was being installed.
|A demonstration section of the experimental 'Stream' road surface power trackage and collection skate as seen at the 1999 UITP exhibition in Toronto, Canada. On this display version the red light on the skate illuminates to demonstrate that power (low voltage in this instance) is being received.||Stream road surface power trackage in Trieste.
(link opens in a new window).
Image by Luca Fascia sourced from the free online "Wikipedia" encyclopædia under a license which requires the photographers' name and this text
(C) riproduzione vietatato to be quoted.
These two images include a view of the power collection skate as seen from inside the bus. When the bus is in motion the skate tracks the power trackage by wandering from side to side under the bus.
These two images were sourced from publicity material given out by the system's manufacturers.
The technology was based on twin metal conductors located on the road surface. To ensure safety and avoid the possibility of electric shock the conductor that carried the live power was split into short sections that would only be live when the bus was actually over them. As yet this system has existed in experimental form only, however one specific technical problem which the Trieste trials identified was that the metal (of the power conductor) on the road surface could be slippery, especially when wet.
Prototype Shanghai super-capacitor electric bus at a recharging station. Note the use of pantographs for power collection. It is of course of the utmost importance that other vehicles do not park illegally, blocking the recharging facility.
Photographs and information courtesy of Zachary Jiang.
However to properly evaluate the technology a further batch of super-capacitor buses has been built, and on 28th August 2006 was placed into experimental service. These more extensive commercial trials involve Shanghai's route 11, which is a short circular trolleybus route of just 5.5km in length. This route is noted for lower levels of traffic congestion than the others, a constant passenger volume and high flow rate, with most passengers only travelling for three to five stops.
The trials involve super-capacitor buses travelling on the clockwise loop only, with conventional trolleybuses remaining on the counter-clockwise service. Furthermore, the trolleybus overhead for the clockwise circle is still being properly maintained, so that if the trials prove to be unsuccessful then conventional trolleybuses can return immediately.
Advance testing has shown that in theory the air-conditioning is not in use then the super-capacitor buses should be capable of completing a complete loop on only one charge. However, to reduce the risk of a bus delayed in traffic congestion dissipating all its stored energy (and hence becoming stranded) plus to allow the air conditioning to be used there are in fact seven charging stations located around the loop.
The super-capacitor buses cost as much as 800,000 RMB each (approximately £6,600) a figure which includes the research cost. It is estimated that if the trials prove successful and super-capacitor buses go into mass production then the cost will go down to 650,000 RMB; in comparison an air-conditioned Sunwin trolleybus costs only 400,000 RMB!
Hmmm, not a good start. Within a week of the trials commencing five out of the seven super-capacitor buses had already broken down, so to rescue the service some regular trolleybuses had to be reinstated. Apparently the problems have been blamed on the capacitor overheating under Shanghai's scorching heat. Even though it was officially autumn the weather was still hotter than had been expected. However by the end of September some of the failing super-capacitor buses had returned to service, with clock-wise services now being provided by a mixed fleet of super-capacitor and trolleybuses.
In addition, the super-capacitor bus drivers have been told that when travelling between route 11 and the garage they should use roads equipped with trolleybus overhead; this is because whilst theoretically they should be able to make the journey without recharging the high unpredictability of Shanghai's extremely congested streets makes it desirable to 'play safe' and not leave the safe haven of the overhead power lines. Although not planned as a regular feature in an emergency a super-capacitor bus can recharge from trolleybus overhead.
Reports from a visitor to Shanghai in February 2007 suggest that the trials are proceeding reasonably well. He also said that it is perhaps just as well that there are as many as seven charging stations along the loop, as buses traversing the loop are not always able to charge at every one of them. Apparently route 11 encompasses Shanghai's oldest historic relics and tourist attractions and tour buses often inadvertently park so that they block the charging points. He added that accurate docking is also essential because the charging process requires the charging facility to detect sensors on the super-capacitor bus - and this is only possible when it is stopped close to the footpath.
The visitor also reported that compared to normal trolleybuses the super-capacitors had slower acceleration and were smoother to ride - especially above 30km/h [20mph].
Perhaps the most significant issues (apart from the overheating when the trials commenced) is that because of the lack of recharging facility when returning to the garage bus drivers must drive to conserve the stored energy, which means switching off the air-conditioning, very modest use of the accelerator pedal, etc. Whilst in theory it is possible to recharge from the trolleybus wires the reality is somewhat more complicated. One issue is that with the trolleybus wires being located over the centre of the road so to reach them the super-capacitor bus would have to block the traffic flow. Another issue is that the trolleybus wires are often much higher than the charging stations, so that even when fully stretched the pantographs on the buses might not reach them.
Click the projector icon (or here) to see a video clip (opens in a new window) on 'youtube' showing a Shanghai super-capacitor bus raising its pantograph to charge the capacitors, plus other vehicles - including the trolleybuses operating in the opposite direction around the loop. The video was made by a visitor from Japan.
In connection with the 2010 World Fair (EXPO) being held in Shanghai 40 super-capacitor buses are being used on a special Expo bus service designed to also showcase Chinese technology. However things did not go well once the summer arrived, with the super-capacitors overheating causing some of the buses to break down. It seems that the super-capacitors work best when below 40 degrees C, whilst when they reach 50 degrees C an automatic safety lock is applied to the buses. Reports talk of dry ice being used in an attempt to keep the temperature down, however costing in excess of 500 Yuan per day per bus this represents an expensive solution. In addition, it has been found that the buses use more electricity when operating in higher temperatures, and therefore with the buses needing to be charged more often Shanghai Bus Co has also had to install more charging facilities along Expo Avenue. To allow for charging buses now spend 30 - 45 seconds at each bus stop.
On 27th January 2011 a super capacitor which had been caught at some traffic signals on a busy but narrow two lane road somehow managed to create havoc by bringing down the trolleybus wires which it had been using to recharge. Exactly why remains unknown but it is possible that the bus driver starting moving without ensuring that the charging device had lowered. Witness reports suggest that the incident caused the twin overhead wires to collide with each other, resulting in a loud bang and lots of sparks. It is probable that the accident damaged the buses' super capacitors, as after the accident it was unable to move away under its own power.
This incident caused significant traffic congestion and when other super capacitor buses approached the area they spent so long in the traffic that (unable to recharge) their stored energy dissipated and they became stranded as well.
Shanghai's trials with super-capacitors are reminiscent of a system trialled in the 1950's with what was known as a gyrobus.
The gyrobus concept was developed by Oerlikon (of Switzerland), with the intention of creating an alternative to battery-electric buses for quieter lower frequency routes where full overhead wire electrification could not be justified. The buses were equipped with a large flywheel that spun at speeds of up to 3,000 rpm, gradually slowing as the stored energy was used to provide electricity for the buses' traction motor. Power for charging the flywheel was sourced by means of three booms mounted on the vehicle's roof which contacted charging points located as required / felt desirable (eg: bus stops en route, at termini, etc).
Fully charged a gyrobus could (typically) travel as far as 6km on a level route at speeds of up to 50 - 60km/h (depending on vehicle batch as top speeds varied from batch to batch) The installation in Yverdon (Switzerland) sometimes saw vehicles needing to travel as far as 10km on one charge, although it is not known how well they performed (or otherwise!) towards the upper end of that distance. Charging a flywheel took between 30 seconds and 3 minutes, and in an effort to reduce the time this took the supply voltage was increased from 380 volts to 500 volts. It can only be speculated whether such frequent delays would have been acceptable had the gyrobuses survived - in commercial service - into the modern era. Especially on longer routes where several charging stops could have been required or on busy, heavily trafficked roads.
In all three locations used gyrobuses in full commercial service, these being Yverdon, Switzerland, Gent, Belgium and Léopoldsville in Zaïre (former Belgian Congo and currently known as Kinshasa in the Democratic Republic Congo). Whilst the technology worked reasonably well for various reasons none of these systems lasted for more than seven years - at most.
|Gent, Belgium gyrobuses Nos 1453 and
1452 at an intermediate charging point where contact was made to a three phase AC supply on a projecting arm via three spring booms on the roof of the gyrobus. Although not seen here the photographer suggests
there were also two auxiliary contact arms that moved sideways from the gyrobus to make contact part way down the post.
Photograph is dated to 24 August 1958, and is courtesy of Noel Reed.
Additional Gyrobus Information.
The gyrobuses used an asynchronous three-phase electric motor with condensers fitted on a common shaft. The motor was built on to a flywheel which (on the demonstrator) was 1.6m in diameter and weighed 1.6 tonnes.
This was housed in an enclosed hydrogen-filled air-cooled casing.
And In Britain?
In 1986 a planned trolleybus scheme in Bradford was scuppered because the British deregulated bus operating regime - which actively encourages cut throat 'free-for-all' competition between private bus companies often plying the same streets - encouraged a 'spoiler' company to split the fare base by introducing a rival service (along the same route) which would compete by providing part-time services using cheapo secondhand minibuses. A negative side affect of this was that the perhaps little-known proposals for trolleybuses in the nearby towns of Doncaster and Rotherham were also scrapped, although the planned tramway in Sheffield is now a reality.
With the Doncaster and Rotherham schemes in mind a prototype double deck trolleybus was built and a short stretch of overhead wiring erected between a bus garage and the nearby Doncaster racecourse, with these trials proving that it would be possible to build a trolleybus at very low cost with virtually no changes to the chassis and coachwork of what was otherwise a 79 seater diesel double deck bus.
Since then it has become pretty obvious that the free-for-all system of bus operations actively inhibits serious fixed-infrastructure transport investments - indeed it also lead to the near bankruptcy of the Sheffield tramway when rival bus companies set out to compete with the trams by offering low quality secondhand buses and dirt cheap fares.
The only city on the British mainland where cut-throat 'free-for-all' deregulation does not apply is London - here the competition is for the right to operate pre-defined bus routes under contract to the London-wide regional government body for transport, this being known as "Transport for London" (TfL).
So What About London?
London Buses Ltd in its publication "Cleaner Air for London - London Buses leads the Way" estimated that the cost of (human) health care which results from diesel bus air pollution equates to an equivalent of €0.20 (ie: 20 Euro cents) per km. Meanwhile, a different report prepared at the Roma Tre university in Rome suggested the cost as being €1.20 per km. As most readers will instantly note, the Italian figure is significantly larger! Using this figure helps justify for the investment in the new "filobus" (the Italian word for trolleybus) network detailed above because it suggests that installing the electric street transports would result in significant financial benefits in reduced health care costs.
At a presentation given by the TfL Managing Director for Surface Transport he made it quite clear (in a response to a question I asked him) that his primary duty is to run a cost effective transport system and that it would not be commercially viable to care about environmental issues, which in his view are for the government to decide. (He included issues which affect human health in this comment). Then he added that obviously if the government introduced new legally binding standards and / or someone else came up with the dosh (cash) then the situation could change.
It is a most terrible (even criminal?) indictment of our present-day system of government that under British financial criteria the Italian proposals would be seen as "uneconomic". Do we in Britain not value human health? (rhetorical question, of course we the people do, even if our leaders and decision makers just pay lip service to the issue) or is it because of the insane way in which the British government allocates funds to its various departments, with health care costs coming from a different 'pot' which is (not only) totally independent of the transport 'pot' but actually (at a governmental level) competes vigorously for funds against the transport 'pot'?
Poor health caused by air pollution is a big problem in London and with as many as 7000 diesel buses on London's streets it stands to reason that they must be part of the problem - with zero-emission (at point of use) electrically powered trolleybuses being part of the solution. In 1999 more Londoners died of air pollution related illnesses than in road traffic accidents. According to a report published by the Chartered Society of Physiotherapy - CSP - the PM10 air particles which are emitted mainly by diesel engines pose such a serious threat to public health that the World Health Organisation (WHO) believes there is NO SAFE exposure limit. The CSP's analysis revealed very high levels of this dangerous pollutant - not just in London but throughout the UK. The full story can be found at the link below.
Data sources: Road deaths - http://www.tfl.gov.uk/assets/downloads/casualties_in_greater_london_during_2005.pdf
The Electric Tbus Group has conducted a detailed study which suggests that for London the conversion of the busiest bus routes (eg: those with a frequency of every 5 minutes or more) would offer significant financial and environmental benefits. Thanks to the network effect where multiple routes operate along the same roads the situation would soon arise whereby many subsequent conversions would entail less additional wiring - both increasing the cost effectiveness of existing wiring and reducing the cost of the electrification of additional routes.
Plus of course Londoners would benefit from the significantly cleaner air in the streets where they live, work and play.
|Modern British trolleybus built in the 1980's to promote new trolleybus schemes in the South Yorkshire towns of Doncaster and Rotherham. Because of bus deregulation these failed to happen and this vehicle now lives at the Sandtoft trolleybus museum.||Artist's impression of a trolleybus for the East London Transit scheme (see below). This picture comes courtesy of the Electric Tbus Grouphttp://www.tbus.org.uk.|
In the late 1990's a serious proposal was made for using trolleybuses in London, but only as part of a small local area "rapid transit" scheme (named East London Transit) where the sole reason for suggesting
trolleybuses was because the projected ridership would have been too low to justify the cost of installing a new tramway. According to the "East London Transit - Summary Report" (published by TfL in July 2001) the use
of trolleybuses on this 33 mile (53km) high-profile Bus Rapid Transit system for east London & metropolitan Essex would provide the most financially beneficial option, generating revenues 24% higher than a comparable diesel bus scheme.
To avoid duplication and side-tracking further information about ELT and modal choice political machinations are on the A Bus For London. page.
The Need For Trolleybuses In Britain!
According to a Government report issued by the Committee on the Medical Effects of Air Pollutants air pollution hastens the deaths of between 12000 and 24000 British people a year and is associated with 14000 and 24000 hospital admissions and re-admissions - causing sufferers and their families untold amounts of misery and costing our health service & taxpayers £billions.
In February 2010 the House of Commons Environmental Audit Committee was informed that the fatality rate is actually at least 35,000 people a year, and based upon some EU studies possibly even as high as 51,000 people a year.
Yet whilst motoring offences (especially speed related) seem to be attracting ever more diligent attention by the various authorities the issue of air pollution only receives the metaphorical "lip service".
In Britain more people die from air pollution than in motor vehicle accidents. The total deaths from road traffic accidents (including pedestrians knocked down) is approx 2,538 (DfT figures, 2008) - and whilst obviously even one fatality is too many the figures are still considerably fewer than the number of casualties which can be attributed to air pollution.
So, 50 years after the clean air legislation resulted in the ending of coal sourced smogs the air that we breathe in our towns and cities is yet again so heavily polluted that people are
suffering ill health (and even dying) from it.
Many of the most severe sufferers are our children, who when in the street environment are at the right height to breathe in large quantities of particulates as they are blown about by passing traffic. It is no wonder that the incident rate of childhood asthma is now at a record high in our towns and cities.
So (once again) maybe its time to take urban air pollution seriously???
Introducing trolleybuses into British towns and cities would help Britain meet its commitment to cutting carbon dioxide emissions by 20% by 2010. The House of Commons environmental audit committee says that carbon emissions from transport are 'still moving in the wrong direction' but apart from clobbering motorists with yet more taxes the govt. has failed to find effective ways to entice people out of their cars. Amazingly with respect to new tram schemes the government has actually taken pro-active steps to make the installation of new systems more expensive - see the Enough Stick! How about Some Carrot page for more information.
By attracting car users who would not switch to a motor bus electrification of Britain's urban bus routes could help reverse this upward trend. This would also help reduce overall road traffic levels too.
A nationwide programme of bus electrification here in Britain would help us justify to the other members of our planet-wide family of nations the urgent need for similar policies for improving both the global and their local environments. It would also "add value" to people's daily lives - something which current British government transport & environmental policies totally fail to do.
Government Action Urgently Required!
In an email from a major British operator they stated that (apart from the problems caused by bus deregulation, as detailed three sections above click link to go backwards) a significant impediment to trolleybus introduction and operations in Britain - including London - could be easily removed if the government really so desired...
"Trolley Bus systems require complex approval processes bringing further business risks and potential delays. The environmental benefits of alternative fuel technologies are difficult to quantify in cash terms making this benefit difficult to sell to Government when seeking capital funding for projects."...
It could be said that the optimum solution for us here in Britain would be to use the same planning processes as are already used for highway improvement schemes, the introduction of bus lanes, bus stop shelters, new traffic signalling systems, replacement of street lighting etc. After all, the works for installing trolleybuses - erecting the overhead wires, building substations (etc) to power these wires and arranging connections to the national grid - will be considerably less disruptive to other road users than road works and about the same as the replacement of street lighting poles.
If new trolleybus systems were installed in conjunction with local government declaring the route a "high profile quality bus scheme" (such as already exist in a few locations) it should be possible to prevent spoiler companies from introducing rival services using cheapo secondhand motor buses designed solely to split the fare base and push the quality buses off the road.
Detailed Studies Of Costings...
Detailed studies of costings for new trolleybus systems in Britain have shown that installing the physical infrastructure (overhead wiring and substations) will work out at around £500,000 per kilometre. Of this about half would be for the wiring and support poles, etc., and about half the substation, feeder, etc. The costs of manufacturing and planting the (steel) support poles usually represents the largest item of the actual wiring costs, although once installed they would be expected to last for many decades (....indeed many of the poles planted in the 40's and 50's in towns around the country are still in use for street lighting and the aborted Bradford trolleybus proposals of 1986 would have re-used some of the still extant poles in that city in this way).
To reduce street clutter it is often possible to hang wires from wall rosettes on buildings - although unfortunately only certain types of buildings are suitable for this. Alternatively it should be possible for the same poles to carry both overhead wires and street lighting - but this would still require the installation of new support poles as ordinary street lighting poles will not be strong enough to support overhead wiring (and the extra work involved in this latter option could see costs rise).
It is very possible that an enterprising electricity supply company would be interested in a mutually beneficial financial arrangement with respect to physical infrastructure and long term electricity supplies.
Something else which could affect the overall cost of the overhead wiring would be whether the trolleybuses are equipped with auxiliary power units (APUs - either battery packs or diesel generator sets) which allow the vehicles to operate away from the overhead wires. APU's will increase vehicle costs but then there probably wont be a need to install wires for access to the depôt - which could result in a substantial financial saving as to wire a depôt internally can require a great deal of 'special work' - points / switches / frogs, crossings, etc. - which are always very expensive compared with plain wiring.
The nature of the wiring and its source can also cause costs to vary. 'Elastic' overhead wiring from, for example Swiss sources could result in costs working out more than the £500,000 per km quoted above, which assumed British sources.
Yorkshire, A Glimmer Of Hope?
In Summer 2007 the city of Leeds announced proposals for an electric BRT (Bus Rapid Transit) system using trolleybuses. However there is a story here which in many ways demonstrates everything that is wrong with British Government transport policies. Originally Leeds wanted a tram system, however despite much encouragement from the (national) government suggesting that they would look favourably to a request for finance, and after spending £millions of taxpayer's money drawing up proposals, the national govt. happily 'pulled the plug' financially - leaving the local politicians with nothing. So trolleybuses are being looked at in an attempt to salvage something from the otherwise wasted monies spent on the tramway proposals. The idea seems to be to maintain the same clean air benefits as the trams would have provided and follow virtually the same routes too - just that the transports would be rubber tyred and not steel wheeled. However even by November 2011 the national politicians were still stalling on this proposal, with the trolleybus scheme now having to compete against other British transport schemes for a slice of the small 'pot' of available government money.
The case for NOT using Ultra Low Sulphur "clean" Diesel fuel and Regenerating Particulate Traps
Additional information gratefully obtained from the Electric Tbus Group www.tbus.org.uk (link to an external site which opens in a new window)
Why even so called "clean diesel" is still an environmental disaster!
Diesel exhaust has been found to contain over 41 different toxins, many of which form part of the particulate. These toxins are still present in "clean diesel" powered vehicles which use Ultra Low Sulphur Diesel fuel (ULSD) and Continuously Regenerating Particulate Traps (CRT). Vehicle emissions have their greatest impacts on those directly exposed, i.e. pedestrians, transit users, those living on busy transport corridors. Electric buses produce no in-street emissions. Unless all the emissions diesels release into the surrounding air can be completely eliminated, the diesel can never be competitive with an electric bus in terms of emissions impacts. This should not imply that efforts to reduce diesel emissions are wasted. Since diesel engines will continue to be used for a variety of purposes, every effort should be made to make them as clean as possible. But one needs to realize that making an internal combustion engine cleaner does not make it a universal substitute for an electric vehicle.
So called 'cleaner' diesel increases greenhouse gases!
Currently available data from the British Freight Transport Association (FTA, 1999) indicates that the production of Ultra Low Sulphur Diesel fuel (ULSD) [at refineries] results in some 20 tonnes more CO2 equivalent than the production of regular diesel. Indications are that powering a vehicle with ULSD requires more fuel than with regular diesel, meaning that, while some emissions may be reduced, the amount of CO2 released by the vehicle is likely to be greater
In Lyon, France trolleybus route No. 6 operates over some narrow, twisting, hilly roads which are unsuitable for full-size buses so uses a fleet of half a dozen specially constructed 27 seat (53 passenger total capacity) 9.7m long, 2.4m wide midi-trolleybuses. The significance of this is that in the bus building industry (as in many other industries) the cost per item (bus in this instance) is quite a bit higher when only a few are built compared to large productions runs when a lot are built. Yet despite this it was found more desirable to use trolleybuses than fossil-fuelled buses.
Using Continuously Regenerating Particulate Traps has serious Negative Environmental Repercussions of global proportions!
The environmental benefits of exhaust after-treatment devices was recently called into question when researchers discovered heavy metals from catalytic converters embedded in the ice in remote regions of Greenland. A European Commission study found that vehicle exhausts actually erode the metals in these devices, ejecting microscopic particles into the air. Some of these metals have also been linked to asthma and lung conditions. Researchers noted that some of these particles are soluble, meaning that they can be readily absorbed by vegetation and enter the food chain. New Scientist magazine concluded that this is already a problem is of global proportions.
Scientists say the release of heavy metals from exhaust treatment devices is a global problem that also stands to threaten human health.
|Nancy, France. These innovative three-section double-articulated TVR trolleybuses were designed to give a tram-style ambiance to rubber tyred road vehicles - something which they have achieved admirably.
The TVR concept allows for the vehicles to operate in either driver-steered mode (as regular trolleybuses) or pseudo-tram mode using a proprietary guidance system which is totally independent of the vehicle's propulsion system. Unfortunately some unenlightened transport pundits have quite incorrectly used this latter feature to suggest that ALL trolleybuses are 'guided' (aka self steering) buses.
Worse still, they are hoodwinking the general public into believing this blatant untruth.
Click the projector icon (or here) to see a 14 second video clip named 'Nancy-unguided-S-bend320.mpg' showing the TVR making this 's' shaped manoeuver (plus hear the above photograph being taken - oops!).
So called 'cleaner' diesel fuelled vehicles still emit lung-damaging particulates!
Trap devices such as the CRT primarily focus on reducing the amount of particulate matter that diesels spew into the surrounding air; there is also some concurrent reduction in hydrocarbon emissions. Some traps claim to reduce particulate emissions by up to 90% in tests, although their performance in real-world conditions may vary considerably. In any case, some particulate is still released, and because "clean" diesel particulate is so much finer than that from conventional diesel engines (and invisible to the naked eye) these toxins have an easier time entering our bodies and penetrating the linings of the lungs. There is no safe level of exposure. German researchers insist the toughest diesel emission standards are not tough enough. (PM10 particles with mass less than 10 microgrammes). The Daily Mail of December 27, 2000 reported that such particulate was found deeply imbedded in the lungs of very young children, in particular children who lived in homes located along busy roads. This particulate is believed responsible for an increase in lung disorders and asthma and has also been linked to heart disease. The incidence of asthma in children under five has doubled in Britain in the last ten years and is on the rise in many other countries. There is also strong evidence for a causal link to cancer, although the research as not (yet) established this beyond doubt..
In spite of trap devices Oxides of Nitrogen (NOx) still form a major component of diesel exhaust and pose significant health risks. Oxides of Nitrogen essentially comprise a mixture of Nitric Oxide (NO) and Nitrogen Dioxide (NO2). NOx is transportation's principal contributor to urban smog and poor air quality. In combination with the moisture in the lungs, Nitric Oxide (NO) forms nitric acid. This acid results in inflammation, leading to chronic respiratory problems. Eventually, all Nitric Oxide emissions are converted to Nitrogen Dioxide (NO2) in the atmosphere. Nitrogen Dioxide is a corrosive and very poisonous gas. At concentrations above 150 ppm it leads to death. The CRT (Continuously Regenerating Trap) uses a catalyst to convert Nitric Oxide in the exhaust stream to NO2 because it needs the NO2 for a reaction that 'burns off' particulate matter and hydrocarbons. There is a strong likelihood that the proportion of NO2 in the NOx emitted by CRT equipped engines operating in real world conditions will be greater than is the case with non-CRT equipped diesels. If so, it would put a greater quantity of the more poisonous constituent of NOx emissions directly into the airways of pedestrians, transit users and area residents than would be the case with conventional diesels, where the a slower process of oxidation in the atmosphere would be required to yield the same quantity of NO2. In other words, there is every possibility that ULSD in combination with the CRT may actually intensify some of the health effects of diesel exhaust.
|MBTA trolleybus operating near Harvard Square in Cambridge, Massachusetts (USA). The offside door is used at Harvard station in the bus tunnel.
|Trolleybuses make light work of steep hills - San Francisco, USA.|
The case for NOT using fossil fuel engines which meet "Euro 4" standards for urban bus services.
Being introduced in 2006 are regulations called "Euro 4" which has the aim of enforcing a reduction in the output of harmful particulates and NOx nitrous oxide from motor bus exhaust (waste) gases. Euro 4 can be seen as a stepping stone to "Euro 5" which in 2009 will cut NOx pollution (but not particulate emissions) even further. Both regulations will apply to new buses only - existing vehicles can continue to operate with their older even dirtier engines.
Of course it is right to use the propulsion systems which create the least pollution - and for rural areas where the cost of electrification plus maintenance of the infrastructure would simply render the bus service uneconomic then by using sustainably sourced biofuels in engines which meet the "Euro 4" and "Euro 5" standards is a logical solution. But there really is no justification for using the "less dirty" option for urban services - not when a clean alternative choice exists.
However apparently 'clean' Euro 4 / 5 diesels may appear to be it need be remembered that the supposed performance is measured on new vehicles / engines in tip top condition on test cycles. No matter how clean they are when new, experience with existing engines suggests that as they age their emissions performance will deteriorate.
Whilst optimal regular maintenance will help keep the engines cleaner this reflects extra expense and "downtime" spent in the garage instead of being on the road earning revenues. The fleet will also need to be larger to cover for the extra time spent in the garage.
In an effort to meet the new regulations motorbus suppliers are following two competing routes. These are known as EGR (Exhaust Gas Recirculation) and SCR (Selective Catalytic Reduction).
There are no such things as clean diesel vehicles. Just "less dirty".
Why biodiesel is not an alternative solution for urban bus services
The use of biodiesel does not turn buses into quiet zero emission vehicles - indeed very few people would notice any significant difference, apart possibly from the smell, which especially if recycled cooking oil is being used might result in the buses smelling like fast food outlets! However for buses operating on quieter routes and especially in rural areas (where electrification is simply not a viable option) then because it can be sustainably sourced so there is a good case for using biodiesel to fuel buses.
When compared with mineral diesel the use of pure biodiesel to fuel a conventional motor bus engine results in a reduction of some pollutants and an increase in others. Biodiesel fuelled buses are just as noisy with the same levels of vibration as mineral diesel fuelled buses.
Because the carbon in biodiesel emissions is recycled from carbon that was already in the atmosphere [rather than from "new" carbon from oil that was sequestered in the earth's crust] so net emissions of carbon monoxide (CO) and carbon dioxide (CO2) are lower. The emissions particulates are also lower. Biodiesel contains fewer aromatic hydrocarbons (benzofluoranthene & benzopyrenes). However there is an increase in the harmful nitrogen oxide (NOx) emissions.
It is perhaps worth noting that the CO2 emissions from diesels into the streets only affects global climate change - it is not a direct human health issue. However emissions from diesel or other combustion engines into the streets of CO, NOx or particulates are human health issues. So whilst biodiesel may well have a part to play in reducing the use of fossil fuels and therefore reducing CO2 emissions, it is not a solution for reducing the noxious emissions like NOx from diesel bus exhaust pipes.
Biodiesel has a tendency to gel at low temperatures (less than 4 deg C), it also suffers from issues with micro organism growth and water absorption. Because of the potential severity of these problems biodiesel is usually deployed mixed with regular diesel, perhaps on an 80-90% mineral diesel and 20-10% biodiesel basis. In this format the use of biodiesel has been found to extend the life of various engine components. This is at least partly because of biodiesel's higher lubricity index compared to mineral diesel.
Some forms of biodiesel (eg: ethanol) have a lower 'energy' rating which means that for mile for mile more liquid fuel is consumed than with regular diesel.
In late 2007, a bus company which operates local buses in the English town of Reading bought 14 new ethanol fuelled double deck buses to replace the existing fleet of biodiesel powered vehicles. At the time this was the largest order for ethanol fuelled buses in the UK. These buses were introduced into service in May 2008.
However, in October 2009 it was discovered that instead of the ethanol fuel having been sourced from sugar beet grown in the English county of Norfolk (as everyone in Reading had been led to believe) it was actually made from wood pulp imported from Sweden. On learning this Reading Borough councillors launched an investigation into how they, the Reading Transport Board - which runs Reading Buses - and the people of Reading could have been deceived.
In a press release issued by Reading Borough Council on 2009-10-15 it was stated that the use of ethanol would be terminated, although the reasons cited were primarily
financial, and not because of the deception. The press release points out that although the current cost of a litre of ethanol is just 2.61% more expensive than biodiesel, the ethanol powered
buses are a massive 44.5% less fuel-efficient, making them more than twice as expensive to run than the biodiesel powered buses. The press relase can be read here
(link to an external site which opens in a new window).
Often touted as cleaner fossil fuels are liquefied petroleum gas (LPG) and compressed natural gas (CNG). However these fuels also have both financial and environmental drawbacks -
So, not only have bus operators who use them found them to be financially less viable than diesel buses but despite all the politically-correct hype their use means that the global environment suffers a significantly worse 'hit' than it currently receives from diesel buses.
In 1990 the Canadian city of Toronto introduced a fleet of CNG s replacements for both electric trolley and other buses. At the time they were hailed as being 'no-pollution replacements' (sic) the trolleybuses, however withing five years CNG operation had been withdrawn from the city. Whilst 50 buses were converted to diesel, 75 had very abbreviated lives and went straight to the scrap pile. It seems that few people want to talk about what has become seen to have been a disastrous money-wasting fiasco.
When a Swiss city introduced CNG buses to its fleet it also had to spend SFr400,000 (Swiss Francs) on the bus garage, including installing a gas detection system, creating an anti-explosion zone, modifying the ventilation system and improving both the fire detection and alarm systems. In addition SFr1 million was spent installing gas distribution, compression and storage facilities.
In December 2003 London received three experimental Hydrogen powered "fuel-cell" buses. This was as part of a global series of trials being carried out under the European Union’s CUTE (Cleaner Urban Transport for Europe) project. In all 9 EU cities were involved plus Reykjavik (Iceland), Perth (Australia) and Beijing (China). The reasoning behind the ‘CUTE’ program was to test the buses to see how they coped in different traffic and climatic conditions - which implied rigorous usage to test endurance, reliability, to look for weaknesses, etc. London was a key city in these trials because of its extreme stop-start traffic conditions where travelling for much more than a minute without stopping is fairly unusual. The trials in these 11 cities were part of a long-term development programme which previously saw the testing of one fuel-cell bus in the Canadian city of Vancouver.
In theory fuel-cell technology sounds wonderful. The hydrogen "fuel" stored on the bus is converted into electricity, with the only waste product being water vapour (ie: steam!). This means that these are electrically driven buses - and there is no pollution at point of use.
Fuel-cell technology is still very much experimental and is so energy inefficient that whilst using these buses would have resulted in a reduction in air pollution in the areas they served, (ie: their 'local environment') producing their hydrogen fuel would have still negatively impacted upon the global environment. According to information obtained from oil company BP when renewably sourced electricity is used to produce the hydrogen emissions of the harmful greenhouse gas CO2 increase by 582 tonnes for every Gwh of power generated. Furthermore, for every 9Gwh of energy invested just 1Gwh of usable power will reach the buses wheel - generating, compressing & storing the hydrogen will waste the rest of the energy. As a contrast trolleybuses are a tried, tested and proven technology successfully used in over 350 towns & cities globally. They are also very fuel efficient - when sourced renewably over 90% of the electricity actually gets usefully through to drive the vehicle. When trialled in Vancouver, Canada they found that one fuel-cell bus consumes as much power as a dozen trolleybuses and unlike trolleybuses which can work 24+ hour duties without even needing to be refuelled (OK, so occasionally they do change the bus drivers!) the fuel-cell buses needed refuelling after just 4.5 hours - barely half a workday! So for this plus other reasons resulting from their comparative trials they are now buying a fleet of 230 brand new low-floor trolleybuses.
Another issue for these fuel-cell buses is that they were so heavy that their unladen weight was roughly similar to that of a diesel bus carrying a full complement of passengers. Since governments usually set legal limits on how much a bus may weigh (partly to reduce wear & tear on the road surfaces) the net result is that their passenger capacities were lower than fossil fuel or trolleybuses of comparable size.
As with CNG buses, hydrogen buses must be equipped with leak detectors because hydrogen is extremely volatile.
Considerably more information on fuel-cell buses can be found here (link to an external site which opens in a new window)
As an aside, the CUTE trial was extended for an additional 13 months from the initial completion date of December 2005, and finished on 12 January 2007. Because of their unique nature once the London hydrogen fuel-cell buses were withdrawn from service they were donated to museums, albeit without their hydrogen equipment - which was reclaimed by the manufacturers for further development works. They have gone to the London Transport Museum, The Science Museum and the Beith Collection in Ayrshire, Scotland. Being modern buses which in no way could be considered to be ‘life - expired‘ it is unfortunate that further use could not have been found for them, perhaps as battery electric or trolleybuses at one of the living museums.
As part of the HyFLEET:CUTE project June 2009 saw a German bus company unveiling the first of an experimental fleet of fuel-cell hybrid buses which use lithium-ion battery packs. They are being seen as successors to the CUTE buses described above and the idea is that a small fleet will be supplied to several towns and cities to evaluate the technology. As with the CUTE buses the 'greeness' of these vehicles largely depends on how their hydrogen fuel is sourced - typically (at present) it comes from fossil fuels and requires so much fuel to be used that when comparing the total energy input these vehicles consume even more energy / result in more air pollution than ordinary diesel buses.
Because London's decision makers are more interested in possible future solutions for 20+ year‘s time and not seriously working to reduce air pollution ‘right now‘ further trials were proposed, this time using ten hydrogen powered buses, of which five would be fuel cell buses and five would be hydrogen powered internal combustion engine (ICE) motor buses. In addition the plans included some other types of fuel cell vehicles (such as dustcarts and taxis) ‡ and London's senior transport managers issued a stern rebuke to the various fuel cell bus manufacturers for making them so expensive(!)
All this was proposed under the auspices of TfL and the London Hydrogen Partnership's 'London Hydrogen Transport Programme'. Since TfL allowed the hydrogen filling station used by the previous fuel-cell buses to be decommissioned so the plans had to include building a replacement.
‡ In August 2008 a different Mayor (Mr Boris Johnston) who won the Mayoral election earlier in the year decided that as part of a policy of reducing expenditure and not increasing the local taxation levied on the people of London he would scale back his predecessor's plans and deleted the ICE buses. Later he was able to secure EU funding to add an extra 3 fuel fell buses to the scheme, so that there is expected to be a total of eight such buses.
The first of this next tranche of fuel cell buses was expected to enter service in December 2010 but because of snowy weather this was delayed until late January 2011. The buses were built by Wrightbus of N. Ireland using a specially modified version of its Pulsar 2 body structure on the VDL SB200 chassis. They feature ISE hybrid-electric drive and Ballard fuel-cell technologies. To help reduce overall energy consumption they regenerate their braking energy using ultracapacitors. 12m in length they are 11' 2" [3.4m] high, they seat 34 passengers, have space for one wheelchair and weigh 11,597kg.
Funding for London's new hydrogen bus experiment has jointly come from Transport for London (TfL), the Department of Energy and Climate Change (DECC) and the European Union via the Clean Hydrogen in Cities (CHIC) project.
A video of this fuel cell bus has been placed on the 'youtube' film sharing site and can be watched (in new windows) by clicking either the projector icon or the link below. It is very much suggested that you turn on your sound, so as to fully appreciate the very different sounds of this bus. http://www.youtube.com/watch?v=Mm7o61OQg2w
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