Despite the massive cuts in emissions from heavy-duty diesel engines since Euro 1 started more than 22 years ago, one by product of combustion has stubbornly refused to be tackled. That is the arch greenhouse gas carbon dioxide.
According to the European Commission (EC), "CO2 emissions from heavy-duty vehicles [HDVs] rose by 36% between 1990 and 2010 – mainly due to increasing road freight traffic. Projections indicate that, without policy action, total HDV emissions would still be close to current levels in 2030 and 2050." The Commission further adds that this is incompatible with the goal of reducing greenhouse gas emissions from transport by around 60% below 1990 levels by 2050, as set out in the Commission's 2011 Transport White Paper and Roadmap.
So what's being done about it? Well, according to Cummins Engines' environmental management director Peter Williams, the good news is that – notwithstanding a few Euro 6 fine tuning issues (see panel) – the EC's myopic focus on NOx and particulates has now ended, so CO2 is back on the agenda.
"There's a good feeling, certainly from the manufacturers, that there's no need for another stage beyond Euro 6. Air quality emissions are under control and as long as the EC can convince itself that the urban operation of vehicles is good and robust, I think they'll find there's no need for a Euro 7. So, looking forward, the focus is shifting to fuel efficiency and particularly CO2."
Interestingly, though, Williams also reports that the EC is insisting that CO2 reduction be market-driven. Fuel is a cost, goes the argument, so operators will inevitably want to drive down consumption and hence, indirectly, CO2 emissions. Making that happen, however, requires better information, so that vehicle purchasers are better informed.
That's where VECTO (Vehicle Energy Consumption Calculation Tool) comes in. In simple terms, the Commission wants to create a database of trucks, buses and coaches according to their fuel-efficiency rating, and thus CO2 footprint – measured, for example, in gm/tonne, m³/km or gm/passenger-km. VECTO would award each vehicle a number in a manner broadly similar to the energy ratings provided on white goods. However, creating that database, which would be available for operators to use as a vehicle specification and purchasing tool, will be anything but simple.
"The first stage is improving knowledge," explains Williams. "The thinking is of two uses [for VECTO]. The first is as a sales tool – so in the dealership, people will configure their vehicles and understand what the CO2 output would be compared to another dealership offering a similar vehicle. If CO2, or fuel consumption, is a primary driver for vehicle selection, then making that information available to purchasers is likely to drive a gradual reduction [in CO2]." So Brussels, not unreasonably, expects fuel economy to remain high up the agenda for new truck buyers.
The second application for VECTO, however, will be by EU governments to track CO2 emissions in their own back yard, by monitoring new vehicle registrations and mapping them to CO2 efficiency. "That's what they are keen on, so [member states] can report on whole fleets," explains Williams.
So what data will be required for VECTO to come up with any vehicle efficiency/CO2 numbers? "The engine will be represented by a fuel-map," reports Williams. "That's from an engine on a test bed running at fixed speed and load conditions, measuring the amount of fuel it uses and CO2 it produces." Next is tyre-rolling resistance data, based on information currently available through mandatory tyre labelling. Then comes arguably the most contentious part of all – vehicle aerodynamics. "This is a defined process for measuring the air drag of the vehicle, essentially just coast-down to work out the air drag," explains Williams.
Given the plethora of bodywork and trailer types on the market, that's clearly going to be a challenge for VECTO's developers at the Technical University of Graz, who may well opt to use generic, rather than real, trailer and body types for their calculations. Either way, last but not least there's transmission and driven axle efficiency data.
With all those elements in VECTO, what should come out is a vehicle efficiency number indicating lowest CO2 outputs for truck, bus or coach buyers to choose against. That's the theory, but the question is, who will validate the VECTO input data supplied by the vehicle manufacturers and bodywork/trailer-makers? One suggestion is national type approval agencies, though that's yet to be decided.
For engine makers like Cummins, confirming the fuel map element is straightforward. "We run the fuel map at the point of type approval for the engine so it's when we do a certification," confirms Williams. Likewise, tyre rolling resistance data will be available through the existing labelling process, while air drag information will presumably come from the vehicle manufacturers. However, this is going to involve a lot of work.
Unsurprisingly, Europe's truck and engine manufacturers are keen to see the EC's legislative proposals for VECTO when they appear later this year (see panel). Meanwhile, Williams already believes there are ways to make it more robust. In particular, rather than provide one overall vehicle efficiency number, he wants engine fuel map data available separately to CO2 efficiency from other vehicle technologies.
That makes sense, not least because it would expose which engines burn the least fuel. And Williams points to the US, where CO2 engine data is already split out within the EPA 2014 emissions standard. And with stand-alone engine CO2 information, buyers would know the ultimate limit. "You've got a deliverable ceiling, and know that engine will always be under it. It allows the regulator to then set a trajectory for CO2 reduction. And, if the test cycle is robust, representative of real life and used in the World Harmonised Test Cycle [used in Euro 6], I think ... that's a good method of measuring CO2 in real-world operation."
The GEM vehicle simulation tool in the US already uses this approach, and Williams sees something similar working in Europe. "You could have an engine standard for CO2, as well as a standard that focuses on the vehicle. VECTO could be used in its current form for the vehicle side. The way the US GEM model works is that you have a generic engine and you use that to 'drive' the vehicle technologies. If they can import the concept [into Europe], that would be an effective way of doing it."
Whilst accepting that the current VECTO model, based on a holistic basket of data, could still work for operators, Williams believes an approach where all the components are listed individually is the way forward. "It's important that vehicle purchasers can understand what the CO2 output is. And from a regulator's perspective, it would give them the ability to drive the CO2 of the engine as the main source. We're not saying it should be changed: we're saying the regulation can be made more effective by adding an engine-focused element or engine plus transmission-focused element, so that VECTO [reveals] the most effective engine for the most effective vehicle."
Euro 6: you think it's all over?
Brussels is looking to tighten -up in-service conformity testing for Euro 6 engines through improvements to PEMS (Portable Emissions Measurement Systems). Through PEMS, Europe's engine makers are required to conduct real-life on-road compliance –trials, using operator vehicles, monitored around representative test routes.
"It's something we have to run through the useful life of the vehicle [typically defined as 700,000km or seven years for a heavy-duty, long-distance truck]," says Cummins' Peter Williams. "It's also a type-approval deliverable so we have to run PEMS tests at the point of certification" he adds. Clearly, as no manufacturer can demonstrate whole-life compliance at the start of a new engine introduction, PEMS testing provides ongoing confirmation.
Now Brussels wants more stringent PEMS testing, focusing on cold start and urban operations and payloads. It's also considering changing the make-up of the obligatory test routes. "Every aspect of the PEMS methodology is under scrutiny. They want to ensure that it delivers what is says on the tin," explains Williams.
Timetable for cutting CV CO2
Based on its VECTO computer simulation program, Brussels says the Commission intends to propose legislation in 2015 that requires CO2 emissions from new HDVs to be "certified, reported and monitored". Following its initial proposals, firm legislation could appear around 2016, being implemented by 2018 and focusing initially on segments such as long-haul and delivery trucks and coaches.
"These are the ones they've validated on the [VECTO] tool so far," says Cummins' Peter Williams. And he adds: "They're looking to have some impact from 2018 onwards. What we've heard is there will be a gradual process as the fleet gets turned over. They've got a plan for 2030 to see some reductions… So it's quite a long-term process."