Fuels & Fuel Efficiency: The power to save

Choosing the right fuel and making sure it is used efficiently are important concerns in the construction industry.

According to Peter-Valentin Sauter, quarry industry consultant at Caterpillar, about one third of total operation costs on construction sites in Europe can be attributed to fuel. And that is just one part of the equation. It is becoming increasingly important to take into account environmental factors, with legislative measures such as EU Stage V and low emission zones (LEZ) putting pressure on the industry.

Describing Caterpillar’s method of helping end users of construction equipment reduce their fuel consumption, Sauter said, “This is done by a two-fold approach – developing very fuel-efficient equipment as product introductions of the last few years testify, and offering fuel consulting services to help our customers benefit from the most economic utilisation of their construction equipment.”

Within this, Caterpillar has developed the five pillars of fuel efficiency framework for looking at total site solutions – operator, idling, jobsite setup, equipment selection and configuration, and on/off-board technology.

Sauter said, “Where to find the greatest gains will depend on the job site, although typically, idling time comes up at the top. Idle time is a very good indicator of how efficiently an operation is run.”

To calculate this, Caterpillar takes the percentage of time the engine runs without doing any work, and compares it to the equipment total run time to get the idle time ratio.

“On average, equipment idles around 25% of the time and in quarry operations for example, idling time for trucks can exceed 50%, and so engine idling is a considerable cost factor and is often underestimated,” Sauter said.

What’s more, idling time also reflects the number of non-productive hours being added to the clock, and it drives up service intervals, increases maintenance costs and can even result in lower resale value.

Operator impact

Unsurprisingly, the operator has a big impact on fuel efficiency; a highly skilled operator can make a 30% positive difference to fuel efficiency compared to a novice operator – a figure that was mentioned not only by Sauter but also by Stefan Pettersson, application engineer within Volvo CE’s EMEA (Europe, Middle East and Africa) sales region. Volvo CE carried out a test in which 80 operators were asked to use a wheeled loader to load a truck with loose material in good conditions. The results showed a significant correlation between an operator’s competence and their fuel efficiency.

It is, therefore, important to provide operators with instructor-led of simulator-based training to hone their skills and help them to make use of a machine’s technological features that are designed to increase productivity and efficiency.

Eco Operator instructor Abraham Acosta from Volvo CE summed this up when he said, “It doesn’t matter how many sensors, systems and new technologies a machine has, our customers can’t get the most out of them unless they know how to use them.”

As a result, Volvo CE has been using the principles of virtual reality to train operators since 2011, when its Advanced Training Simulators were first introduced.

3D display

Today, these simulators feature a high-definition 3D display, coupled with an electronically-controlled full-motion platform that allows the operator to see and feel how a piece of construction equipment would react in real-life situations. They are used in the company’s Eco Operator training programme, which is aimed specifically at helping existing operators to use machines more economically.

The latest version of the simulator allows for 3D images of a real jobsite to be inputted into the programme. So this, coupled with the fact that the simulators incorporate the same software and data used by the company’s technology function for research and development (R&D) purposes, was said to make for a particularly realistic simulated experience.

Pettersson said, “Operators can practice the exact tasks and routes they will take on the jobsite so that they can fine tune their skills and become more efficient in real life.”

With this system, the operator is directly alerted to mistakes made in their virtual work and they can also see parameters such as fuel consumption and productivity.

What’s more, Volvo CE has been developing the capacity to use the data from those simulator training sessions to inform recommendations made to site managers about how their jobsites can best be configured.

At the beginning of 2018, it became possible for a number of operators to interact in the same virtual environment – known by Volvo CE as SiteSim. So by getting operators to work together virtually in a digital twin of a jobsite, Volvo CE can help managers to calculate the optimum set-up to maximise productivity.

“By trialling different routes to time, material types and densities, and machine settings, the upgraded simulator can help customers achieve maximum productivity and uptime while minimising fuel consumption and wear,” Pettersson said.

That leads into another of Caterpillar’s five pillars of fuel efficiency – job site setup. This refers to the way in which the pieces of a total site solution puzzle are fitted together – how the machines interact with one another, how the jobsite infrastructure is maintained, how schedules are organised, and so on.

Sauter said, “In quarries for example, the haul roads are the heart of the operation and their condition impacts both fuel efficiency and productivity. A poorly maintained haul road with ruts and holes forces operators to slow down and to accelerate, which of course negatively impacts fuel consumption.”

This is an issue that Volvo CE’s SiteSim programme targets by not only better co-ordinating machines but also optimising site layout.

“Moving a pile 30m closer to the crusher can have a significant impact on production over time and the cost,” Pettersson said.

Volvo CE offers an Insight Reports service, whereby site managers can be provided with analyses of various aspects of their jobsite, such as fuel efficiency, fleet hours, average fleet utilisation, utilisation by machine type and litres per hour during work. From there, a plan can be made.

Machine selection

Another pillar of fuel efficiency that relates closely to site setup is machine selection and configuration, which refers to how well a machine and its attachments are suited to a particular application.

Sauter said, “Production studies have shown that the selection of the bucket on an excavator or on a wheeled loader can easily impact fuel burn by up to 15%. Of equal importance is the selection of the GETs (ground engaging tools). Without the right tips for penetrating the material, fuel efficiency can be impacted by up to 17% – based on studies we have conducted.”

Technology is the next pillar and it refers to the way in which fuel efficiency informs the design of Caterpillar’s machines.

“For example, the recently introduced Cat 988K XE large wheeled loader benefits from a high efficiency electric drive system and generates fuel savings of up to 25% compared to previous corresponding models, and even up to 49% in face loading applications,” Sauter said. “Other examples are the 320 and 323 next generation excavators also recently introduced, which consume up to 25% less – again, compared to previous corresponding models – as well as benefiting from reduced maintenance costs and considerably boosting efficiency through integrated technology.”

Speaking specifically about Caterpillar’s engines, Alex Eden, a product and technical marketing manager at the company, said, “At the most basic level, optimising fuel efficiency comes down to delivering the right amount of fuel and air to the combustion chamber, in the right form and at the right time. It sounds simple, but it’s really very difficult to achieve.”

He said Caterpillar works with a number of fuel system component suppliers to get the best performance. Taking the example of injector nozzles, the optimum spray patterns much be created to ensure complete combustion.

“We employ sophisticated CAE and thermofluid analysis to design ultra-efficient combustion bowls in our pistons to optimise energy transfer from the burning fuel through the piston and to the crank. We work to reduce friction, heat rejection and noise because they all represent wasted energy that could be powering the machine,” Eden said.

The resulting engine is then calibrated to strike the right balance between emissions, response and fluid consumption – including diesel exhaust fluid – to deliver a product that performs at the lowest possible fuel consumption point.

Downsizing

Two examples highlighted by Eden were the new C2.8 and C3.6 engines. He said, “These engines were robustly developed and extensively validated. They deliver the benefits of downsizing with an up to 10% fuel efficiency improvement.”

These fuel efficiency improvements are enhancing the power density of new engines, giving customers the option of downsizing.

This has been noted by Alan Tolley, director of the engines programme at JCB, as a contributing factor to the reduction in fuel consumption by the company’s equipment portfolio.

He said, “JCB has had a major programme of fuel efficiency improvement since 2010. Since then average fuel consumption has been reduced by over 43%.

“This has come from design improvements to the machines as well as the powertrains, including increased engine efficiency, engine downsizing, increasing adoption of lock up torque converters on powershift transmissions, the launch of our Dualtech VT transmission on Loadalls, and hydraulic system efficiency improvements.”

Taking JCB’s Loadall telescopic handlers as an example, Tolley suggested that, with the Smart Power 55kW JCB EcoMax engine, they have been consuming just 4.1 litres/h of fuel.

The fuel efficiency figure comes from data recorded on JCB’s LiveLink telematics system, which is fitted as standard across its telehandler range.

The integration of digital technology into machines has a key role to play in fuel efficiency improvements, whether it’s incorporating sensors and electrohydraulic components into hydraulic systems or driving operator efficiency with the use of guidance systems.

To this end, Doosan is collaborating with Trimble to introduce a Trimble-ready factory option for Doosan excavators.

It will be available direct from the factory through Doosan Smart Solutions and will be for use with Trimble’s GCS900 2D and 3D Grade Control Systems.

Grade control

The Trimble GCS900 Grade Control System gives operators access to design surfaces, grades and alignments on a display inside the excavator cab.

The system uses a GNSS (global navigation satellite system), a GPS (global positioning system), and laser, sonic or total station technology accurately to position the blade or bucket in real time. This was said to reduce material overages and improve the contractor’s productivity and efficiency.

The use of a common grade control platform across an entire excavator fleet allows customers to port the system between machines and machine types.

Electric controls have also helped Kobelco to live up to its “We Save You Fuel” slogan with its Acera Geospec SK200-8 excavator, which claims up to a 20% reduction in fuel consumption in standard operating mode, when compared with an earlier model, depending of course on the type of work, an operator’s skill, weather conditions, and so on.

Compared with Kobelco’s 6 series, the new machine was said to save 4.4 litres of fuel for every hour of operation.

The engine features next-generation electronic control with a common-rail fuel injection system, and the hydraulic circuitry has been enhanced to minimise pressure loss.

The excavator has an advanced power plant that was said to reduce fuel consumption, and Auto Idle Stop comes as standard.

Diesel-direct electric drive

Kleemann has also been working to lower fuel consumption while maintaining high output with its mobile crushing plants by developing innovative diesel-direct electric drives for the jaw, impact and cone crushing plants in the company’s Evo line.

The crushing unit is driven directly via a fluid coupling from a diesel engine, while the belts, vibrating chutes and other components are driven by electric motors. Kleemann said that in this way the Evo crushing plants achieved low consumption values in their class.

Up to 30% fuel savings are claimed by the machines that use the diesel-direct electric drives, compared to crushers with hydraulic drives, and the speed setting can be matched fully automatically to the material.

The crushing plants in Kleemann’s Pro line were also said to have a powerful but economic drive. On the diesel-electric drive, all operation-related components are driven electrically. As an option, the plants can also be powered by an external power source, which can make for more effective work when using the machine continuously, such as in a quarry.

Looking at alternatives to conventional diesel, Tolley makes the distinction between air quality and climate change. For better air quality, emissions of nitrogen oxide (NOx) must be reduced, whereas CO₂ emissions are targeted in the fight against climate change.

He noted that, within Europe, there was particularly strong support for HVO (hydrotreated vegetable oil) fuels in Scandinavia.

He also pointed out that Neste – one of the companies to manufacture HVO fuel – is based in Finland.

Although the use of HVO fuel leads to improvements in air quality, those improvements are relatively small, according to Tolley.

Climate change

Biodiesel, on the other hand, is aimed at climate change because it offers lower CO₂ emissions and is a renewable fuel. However, biodiesel experienced something of a setback a few years ago.

“It was incentivised but then that drove behaviour such that farmers were substituting food crops for biofuel crops, creating lots of other problems. So, overall, environmentally it was a negative thing, going in that direction. So, you get unintended consequences.

“But I think there’s an expectation that there will be a move to creating low-carbon fuels to address global warming – not necessarily in the short term but progressively in the long term.”

A risk of biodiesel is that the quality might not be up to standard, in which case damage is caused to engines. So, although the engines of many equipment manufacturers, such as JCB, Caterpillar and Doosan, can run on HVO, it is important to have the right supervision to ensure that the fuel is of a high enough standard.