At the heart of any construction alternative power discussion is … diesel.
Diesel is the go-to power on jobsites – according to the Diesel Technology Forum, 98% of construction’s energy use in the U.S. comes from diesel.
But with intense global initiatives to reduce carbon emissions to net zero by 2050, the press is on for construction industry manufacturers to find ways to lessen diesel’s carbon impact. A range of solutions is being considered: replacing the diesel engine altogether, reconfiguring the engine to run on lower-carbon fuels and making the diesel engine as efficient as possible.
All will be needed.
The challenges are many. Unlike some sectors, construction doesn’t rely on a core piece of equipment, but rather on a vast fleet that ranges from mini excavators to massive off-highway trucks. And a jobsite can be anywhere from midtown Manhattan to rural Wyoming. Which is why so many diesel alternatives are being offered, including electric, hydrogen, biodiesel and other biofuels. And, over the next decade or so, one (or more) of these alternatives will establish themselves as having the greatest long-term potential.
“What’s coming? The answer is probably all of them,” said Jeremy Harsin, construction market director at Cummins. “The combination of duty cycle and available infrastructure is going to decide what wins out, but they’re probably all going to have their place in the world.”
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“What’s coming? The answer is probably all of them. The combination of duty cycle and available infrastructure is going to decide what wins out, but they’re probably all going to have their place.” -- Cummins's Jeremy Harsin
Electric is happening.
Zero emissions, low noise, instant response, fewer components to break down, all on a platform that delivers the same breakout force of a diesel-powered unit – electric power sounds like a big win.
Which is why much of the alternative power activity in construction has centered on electric, particularly in the compact equipment segment.
“Battery power density is increasing all the time and we’re seeing a number of different technologies that make better use of battery energy,” said Ray Gallant, vice president of product management and productivity at Volvo Construction Equipment.
“Electric is happening now as machines are starting to be commercially available,” says Chris Sleight, managing director at Off-Highway Research. Although now quite expensive compared to their diesel counterparts, “at some point the economic argument will be there,” Sleight added.
Electric options are certainly growing. Volvo, for example, started selling its electric compact excavators and wheel loaders into North America this year and recently expanded its offering to five machines.
Electric has also made its way to mid-size and larger construction equipment. Examples include:
- Electric backhoes introduced by Case Construction Equipment and John Deere
- Doosan Bobcat's all-electric Bobcat T7X compact track loader
- The Liebherr 220-tonne LR 1250.1 unplugged crane
- Royal BAM Group’s conversion of a Vogele asphalt paver featuring swappable battery packs
- Volvo’s 22-ton EC230 electric excavator (not yet commercially available)
Electric machines, however, have some significant downsides. The ones most critical to contractors are limited run-time-per-charge and recharging time.
Most OEMs are now citing a 6-to-8 hour run time for “average” use on compact equipment and an 8-hour overnight charge. At those rates, without a charge top off, operators are concerned they will be unable to run an excavator with a hammer all day. However, it should be noted that electric equipment doesn't idle, but rather turns off. This changes the “run” time on electric equipment to be only when actively operating and thus extends uptime.
Although the electric charging infrastructure is the most developed of all alternative powers in the United States, today’s electric car owners still have range anxiety when they get into rural areas. Since many jobsites aren’t even on the grid, many OEMs are selling chargers with their electric machines. Solar charging is also being examined.
And electric’s strong sustainability argument can break down when one gets to the batteries themselves. First, several minerals are extracted to create the batteries, including copper, lithium and nickel.
Second, proper end-of-life battery disposal is still in question, not to mention that battery materials have residual value. Cat, for one, said it is looking at repurposing batteries from high-power applications for a lower-power second life.
Electric machines will also require a reworking of the dealer parts and service offering and technician training. “You’ve got an industry that’s built itself for decades around diesel engines and hydraulics and now it will have to shift with relative speed to batteries, motors and actuators,” Sleight said.
In addition, residual value is central to any equipment cost equation; the verdict is still uncertain whether the value of electric -- or indeed any alternative-powered machine -- will hold up in the resale market.
Hydrogen will be used in two forms.
“In addition to electric, hydrogen is one of the most talked about alternative power. It has the most near-term potential, particularly for larger machines,” Gallant said.
Current construction equipment prototypes use hydrogen in two ways: either as a fuel cell that charges a battery-electric machine or to fuel an internal combustion engine.
In a hydrogen fuel cell, hydrogen and oxygen react to produce electricity, with water as its only by-product. In the second way, hydrogen is used as a direct engine fuel, much like diesel.
“There’s definitely a lot of interest in hydrogen spark-ignited engines,” said Harsin, “and that’s a product that we’re excited about because it goes hand-in-hand with some of the diesel work we’re doing.”
While hydrogen must be compressed and transported at low temperatures, “it’s a portable fuel so you can get it to where it’s needed,” Sleight said.
But infrastructure challenges are also part of the hydrogen story. The number of hydrogen fueling stations is a hard-to-see sliver looking at this chart from the U.S. Department of Energy. Almost all of them – around 70 – are in California.
Construction equipment powered by hydrogen fuel cells and hydrogen-fueled engines are in the prototype stage. Some machines under development include:
- JCB’s 20-metric-ton 220X excavator (fuel-cell), and backhoe and forklift (engine).
- Volvo’s just-announced HX04 artic prototype (fuel-cell)
- Hyundai excavators and forklifts (fuel-cell)
- Sany dump and mixer trucks (fuel-cell)
- Mining and resources group Anglo American's nuGen Komatsu 930E 291-ton mining truck (fuel cell)
Low-carbon fuels can be used in the same basic engine.
Hydrogen-powered engines also illustrate another way to reduce engine emissions: modify a conventional engine to be able to burn cleaner fuels.
According to proponents, this approach doesn’t require wholesale changes of jobsite practices, machine componentry or fueling infrastructure.
Cummins announced this year that it would produce a range of fuel-agnostic over-the-road truck engines able to burn natural gas and hydrogen and diesel. Below the head gasket, each engine platform has similar components, while above-the-head-gasket components would change to accommodate the different fuels.
This approach offers scale, since the many of the components are similar. And it holds promise for off-highway engines since Cummins commonly adopts cross platform technologies, Harsin said.
ClearFlame Engine Technologies is another company taking an engine modification approach.
“One way you can make a diesel engine fuel agnostic is to make it hot enough that it will turn anything,” said BJ Johnson, ClearFlame chief executive officer and co-founder. “When you combine the hotter environment with the injection system you get the performance of diesel but the emission benefits of cleaner burning fuels.”
ClearFlame said 90% of the original diesel engine componentry remains the same with its modifications, which have been tested in over-the-road trucks using E98 ethanol, lowering CO2 emissions by 45% to 50%.
Off-highway engines are next. ClearFlame working with John Deere, a Series A investor, in a pilot demonstration that will use its modification on a 9-liter engine.
“It’s still just a power plant in the heart of a big machine, whether it’s a tractor versus a combine versus an excavator,” Johnson said. And while ClearFlame says its technology can run on a range of renewable fuels, the ready availability of ethanol makes it the front runner.
“There’s a lot of good work being done in the diesel space. It’s about lowering our emissions overall. Everything doesn’t have to be zero emission.” -- Volvo CE's Ray Gallant
Don’t discount the diesel engine.
Current prices and world political stability issues aside, diesel remains the construction stalwart.
Despite its “dirty diesel” perception, Cummins says it’s worth a reminder that compared with Tier 1 engines, today’s Tier 4 Final engines offer a 96% reduction of oxides of nitrogen and a 97% reduction in particulate matter.
The U.S. is also likely to see Tier 5 emissions regulations by the end of the decade, Harsin said. California has already discussed enacting a Tier 5 regulation in 2024 with implementation to start in 2028. “I’m sure that greenhouse gas regulations are coming in the off-highway space,” Harsin said.
Another consideration: the gradual retirement of construction’s aging fleet. Construction machines have a relatively long life; there are plenty of Tier 3 engine-powered machines still plugging away on jobsites. Cat, for example, estimated the average age of its field population to be 11.3 years.
The gradual retirement of this aging fleet will also reduce emissions, especially when you consider the significant reduction in emissions that occurred between Tier 3 and Tier 4, Harsin said.
“There’s a lot of good work being done in the diesel space. It’s about lowering our emissions overall. Everything doesn’t have to be zero emission,” said Gallant.
Solving this issue will require patience and experimentation.
There are several ancillary issues surrounding the search for alternative power. These include dealer service reconfigurations, technician training and end user acceptance.
Government also will play a key role, either through incentives or regulations. The recent Infrastructure Improvement & Jobs Act, for example, designated $7.5 billion to build out a national electric vehicle charging network and another $8 billion for at least four regional clean hydrogen demonstration hubs.
Above all, alternative power must make financial sense to end users, even if the cost equation is tempered with sustainability goals and incentives.
Sleight pointed out the chicken-and-egg nature inherent in alternative power: an alternative is not going to be economically viable until it reaches a certain scale, and it’s not going to reach that scale unless the economics are solid.
Gallant is a self-proclaimed optimist: “I do think that we can achieve 30 to 40 percent zero emissions in the future, but it has to be a global effort.”
Added Johnson: “It’s a testament to the diesel engine that it dominates so many applications. There’s not one solution that is going to check all the boxes, particularly in the next couple of decades. It’s not silver bullets, but rather silver buckshot.”
Want to learn more?
Many would agree that a transformation of the construction industry has already commenced. Technology is changing the way buildings are designed, equipment operates and organizations function. Renewable energies are being leveraged more often and in more ways. A generational shift in the workforce is already underway.
AEM Vision Team and Futures Council members spent countless hours discussing how these influences, among many others, could transform the construction industry over the next 10 years. For more information on The Future of Building and other trends impacting the equipment manufacturing industry and the customers it serves, visit aem.org/insights.
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