Some of the manufacturers that have adopted SCR technology are now telling customers to ignore Euro 4 completely and go straight to Euro 5, he says, and argues that this is simply a ploy to outmanoeuvre the EGR camp and has no benefit for operators.
MAN has been winning new customers with its Euro 4 EGR engine. Last year it was one of the big winners with its share of the UK truck market rising from seven to nine per cent. Scania, the other enthusiast for EGR, also saw its market share rise while DAF, Mercedes, Iveco and Volvo (SCR users) were all down.
EGR is proving proved particularly attractive to the rental fleets. SCR engines need AdBlue and this is seen as a problem by many in the rental business. AdBlue is not widely available through garage forecourts making it difficult for rental customers to get hold of it.
Some European governments are offering financial incentives to move straight to Euro 5 so most manufacturers have an engine meeting this standard. However, no-one currently offers EGR engines at this level.
Financial incentives
MAN has a Euro 5 offering but is an SCR engine – it is still working on an EGR engine, which it says will be available “well before the October 2009 deadline”. Scania reckons it will have an EGR Euro 5 engine this year.
If there were financial incentives for Euro 5, then it would clearly be worth considering now, but of course there are none in the UK. Cussans argues that this means it makes more sense to go for a Euro 4 EGR engine.
There is no difference between Euro 4 and Euro 5 in terms of particle output but NOx output is about 40 per cent lower at Euro 5. However, this is not the end of the story. Cussans points to recent road tests in the trucking press that have shown MAN’s EGR engine to be about five per cent more fuel efficient in 44 tonne operation than the SCR engines from rivals. That translates directly into a five per cent reduction in output of carbon dioxide – the critical greenhouse gas. It also means a saving of some £4,000 a year on the typical fuel bill.
Cussans has a number of other criticisms of SCR engines. SCR only achieves the emission targets when it has fully warmed up – it is much dirtier during the warm up period. This is accepted and allowed for in the regulations. In contrast, he says, an EGR engine is clean from the moment is starts up.
To achieve Euro 5 with SCR means using about 50 per cent more AdBlue, making it more costly for the operator, he says.
He also questions what will happen to the trucks when they get old. The main markets for old right hand drive trucks are in Africa and Asia where summer temperatures could easily exceed 37 degrees Celsius at which AdBlue breaks down. Without AdBlue an SCR engine is effectively Euro 1 – that is, very dirty.
SCR needs a minimum exhaust gas temperature of 250ºC to work. If the temperature falls below that level – or fails to reach it at all – then the catalytic converter in the exhaust is unable to do its job and the system will simply not reduce emissions to Euro 4 standards. Should a vehicle continue to be operated in such circumstances, eventually the NOx sensor will illuminate the in-cab warning light, which means the next time the engine is switched off and on again its power output will be reduced by 40 per cent.
While this is unlikely to be an issue for long haul operations, where extended periods of motorway driving will ensure the exhaust temperature remains above the threshold, the same cannot be said for stop-start urban distribution operations.
In this scenario, low exhaust temperatures are commonplace. Indeed, in tests conducted by Scania, a city bus was found to be beneath the threshold for around half the time.
Apart from the environmental consequences, this could also tempt drivers to leave their vehicles running all day long to minimise the chance of the NOx sensor restricting the horsepower of their engines.
“There are maintenance issues associated with SCR,” says Scania technical manager, Clive Burnet. “While EGR is a largely maintenance-free system, SCR units will require regular servicing. Also, from time to time various SCR components will have to be replaced to ensure on-going Euro 4 compliance – and with catalytic converters likely to be priced in excess of £3,500 each, that could prove to be a costly exercise indeed.”
There is another matter clouding the issue as far as SCR is concerned: How widespread the availability of AdBlue will prove to be remains to be seen. Many operators are already expressing concerns over this while others – notably rental companies – are concerned that drivers may allow the AdBlue tank to run dry.
A NOx sensor due to be introduced in 2007 will seek to combat this by reducing the power output of the engine by 40 per cent. But as that will only happen once the engine has been switched off and back on again, there may be a temptation for some drivers simply to leave the engine running all day to avoid that particular problem although this will be recorded by the vehicle’s electronics and constitutes a criminal offence.
However, Scania is planning to offer SCR on its 16-litre engines. “The reason we have opted for SCR on our V8s at this time is that it provided us with the most rapid route to gaining certification under the German Maut system, which offers tax advantages to operators running low-emissions vehicles,” says Burnet.
DAF has firmly stuck its flag in the SCR camp and is using it across its Euro 5 engines. It says: “SCR Technology provides a sound basis for low operating costs and high residual values,” and says that EGR is let down by the need to re-route exhaust gases back into the engine which leads to lower NOx levels but argues that it may cause contamination of the engine oil and filters, resulting in shorter service intervals.”
It also argues that EGR Euro 4 engines require around two per cent more fuel than a Euro 3. “SCR does not interfere with the combustion process and allows ideal engine settings that give great engine performance as well as low fuel consumption.”
The availability of AdBlue has caused concern, and DAF and other manufacturers backing the technology are sponsoring AdBlue.com a web site which gives details of AdBlue suppliers and where it can be obtained. DAF argues that AdBlue consumption is around 1.5 litres per 100 kilometres for a CF or XF and with an AdBlue tank being 0between 26 to 75 litres in size, it is large enough to cover an operation covering up to 5,000 kilometres.
Mercedes-Benz has developed a fuel known as BlueTec diesel, designed to meet the needs of the Euro 4 SCR engine. Using AdBlue, BlueTec engines can cut carbon dioxide emissions by 87 per cent and nitrogen oxide emissions by 70 per cent.
Mercedes says: “Neither technology is new and Mercedes-Benz has long experience of both in other markets worldwide. Both, it believes, have their place.” Indeed, of the 35,000 commercial vehicles that Mercedes-Benz expects to sell in the UK next year, some 25,000 – Sprinter and Vito vans, and Mitsubishi Fuso Canter light trucks – will use EGR.
SCR is heavier and requires handling, but it can give better fuel consumption. That is why, for truck applications in which the potential benefit of fuel savings outweighs the cost and minimal inconvenience, Mercedes-Benz has met Euro 4 through BlueTec SCR technology.
Carbon dioxide
While the Euro 4 standard has tended to dominate thinking in the industry up until now, the issue of carbon dioxide is now taking a more central role. “Between 1970 and 2000, we halved carbon dioxide emissions per tonne-kilometre from our vehicles,” said Scania’s president and chief Leif Östling, when Tory party leader David Cameron and Sweden’s prime minister Fredrik Reinfeldt visited Scania in February. “By 2020 we will have done so again.”
Scania says it has been at the forefront of efforts to develop more efficient engines and to develop the use of bio-fuels like rape seed methyl ester and train drivers in more fuel-efficient driving practices. Scania is also working on a hybrid drive concept based entirely on existing technology. Diesel, ethanol or gas-powered engines are supplemented with an electrical motor/generator for propulsion and energy recovery, as well as ultra-capacitors for energy storage. Scania says this makes the powertrain very efficient, with potential fuel saving of 25 per cent or more.
Volvo has signed ‘The Global Roundtable on Climate Change’, which calls on governments to set targets for greenhouse gases and carbon dioxide emissions and explores ways of shaping policies on tackling climate change. “This is exactly the type of initiative in which Volvo wants to participate,” said Leif Johansson, chief executive of AB Volvo.
“If we are to be able to address the greenhouse effect, we in the transport industry in particular face major challenges. We know that we are part of the problem, but we are also convinced that we are part of the solution.”
Volvo has been researching and testing basic hybrid engines for the past 20 years, with tests showing that hybrid drive for heavy vehicles is most suitable for those needing to make many starts and stops, such as buses, distribution trucks and refuse vehicles with a potential fuel saving of as much as 35 per cent. It recently received £715,000 from the Swedish Energy Agency to help develop a new hybrid truck engine, which it will be launching at this year’s CV show.
In 2008, the engine is set to go into operation in two dustbin trucks in Gothenburg and Stockholm and hopes to achieve fuel savings of around 30 per cent. The test will last for three years at which time Volvo will continue to further develop and optimise the technology for future series production. Volvo will also install and test a new safety system for vehicles in city traffic on both trucks.
The hybrid engine, named ‘I-SAM’ consists of a combined starter motor, drive motor and alternator, along with an electronic control unit. I-SAM interacts with Volvo’s I-Shift automatic gear shifting system. The batteries are recharged by the diesel engine and whenever the brakes are applied. An electric motor offers smooth performance at low speeds, supplementing the diesel engine’s performance as speed increases. Volvo says that this solution allows the truck to accelerate under electric power alone, using less fuel and creating fewer emissions and decreasing noise.
Lars Mårtensson, environmental affairs manager at Volvo Trucks, says: “Thanks to the electric motor’s capacity, the diesel engine can be automatically switched off when the truck stops to make deliveries, pick up loads or pauses at traffic lights.”
Auxiliary functions such as the servo pump, AC compressor and so on are driven electrically in the hybrid truck instead of by the diesel engine.
With an efficient interaction between the two power sources, the vehicle can be fitted with a smaller diesel engine without compromising on performance.
Volvo is also developing a new lead acid battery for hybrid trucks, the Effpower is based on existing lead-acid technology currently used vehicles. Volvo says it has doubled the power output and at the same time reduced manufacturing costs. Volvo says: “With Effpower, the cost efficiency in electrical hybrids can be further enhanced.”
