Editor’s Note: This is Part Three of an eight-part series on the evolution of construction equipment and the diesel fuel alternatives manufacturers are introducing, including hybrid machines, electric and battery-powered equipment, and hydrogen combustion and hydrogen fuel cell technology. You can read Part One in the series by clicking here. Part Two.
Ten years ago, heavy equipment and truck OEMs were scrambling to meet Tier 4 and Tier 4 Final exhaust emissions. Climate change wasn’t the top priority, air quality was.
But one of the innovations that came out of that regulatory push, the hybrid diesel-electric engine, has proven to be successful at cutting fuel use and emissions. And when you cut fuel burn and exhaust emissions, you cut CO2. And that should count for something.
Fully electric and hydrogen systems may rock our world in the future, but hybrid and natural gas engines are here now.
Hybrids, big and little
A diesel-electric hybrid is simply a machine or vehicle with a downsized internal combustion engine (ICE) that uses the flywheel to power a generator and batteries, which in turn provides electrical power to the wheels, tracks and hydraulics. Hybrids come in all sizes, from a 3,000-pound Toyota Prius to a 744,000-pound Caterpillar 798 AC mining truck.
For earthmoving contractors, there are numerous diesel-electric hybrids working successfully in the field. These include early adaptors such as Komatsu’s HB215LC-1 hybrid excavator, Deere’s 644K electric hybrid wheel loader and the Cat D7E dozer. Equipment World reported on these a little less than a decade ago. A 25 to 40 percent improvement in fuel economy was just one of the benefits customesr' claimed.
Even if you put fuel economy and climate change aside, hybrid construction machines offer plenty of advantages:
- The instantaneous response of electric motors means that your machine is always running at the optimal speed. You don’t have to rev up the engine or switch to a power mode for heavy digging.
- Traction control adjusts instantly and automatically with precise small gradations on wheeled machines.
- Regenerative braking on wheeled machines adds power back to the system whenever you travel downhill.
- Brushless motors and AC final drives require less maintenance and, as a general rule, have longer warranties than traditional transmissions.
One machine type that is well suited to diesel-electric hybrids is the telehandler. And these machines have been blazing a trail in the hybrid space for decades.
In 2017, JLG celebrated 20 years of hybrid innovation with the debut of its H800AJ, an 80-foot boom lift with an electric motor/generator that can run exclusively in electric mode by using its Tier 4 Final diesel engine to charge the batteries on demand.
And in 2018, the German engine manufacturer Deutz invited Equipment World to Cologne to see their latest development in this area. By replacing the conventional 3.6-liter diesel engines with the Deutz E-drive hybrids the company was able to power a Liebherr TL 432-7 telehandler with a 2.6-liter engine and a Manitou MT 1335 telehandler with a 2.2-liter engine. According to the company, hybrids will represent 5 to 10 percent of its market.
Powering peripherals and data
As with fully electric construction machines, hybrids can use their electrical capacity to power peripheral systems that normally draw power via the fan belt. Things like cooling fans, water pumps, oil pumps and PTOs are often termed “parasitic” draws, but with electrification they do not steal horsepower from the loading, lifting or travel functions.
Hybrids and fully electric systems also pair well with advanced control systems. “Electrification is a key enabler for automation and autonomy,” says Preston Moore, solution planner and product manager, electrified drivetrain and propulsion batteries at John Deere Power Solutions. “This will allow us to generate more customer insights to reduce operation costs on the jobsite,” he says.
Electrification also improves data capture opportunities as battery-powered equipment generates more data than diesel-only equipment and provides deeper connectivity. This leads to improved diagnostics and the development of new service and aftermarket models, Moore says.
One of the drivers behind the push for diesel-electric hybrids – again, going back to emissions regulations – is the difference between the technology required to meet EPA regulations for engines above 75 horsepower and engines below 75 horsepower. Above requires more expensive exhaust aftertreatment. Below is simpler and less costly.
If you compare specs, the 75-horsepower cutoff is particularly noticeable in skid steers, backhoes, compact track loaders and compact excavators. But by adding a battery-electric boost, OEMs can use a 75-horsepower ICE engine and ramp up horsepower another 10 or 20 percent without having to fit bigger, bulkier and more expensive exhaust treatment systems into the machine, says Jeremy Carson, off-highway director for Cummins.
“The hybrid model has been a great area of focus to improve the technology,” says Jacob Whitson, lead project manager at Calstart. “But because of advancements in the technology and the regulatory structure in California, the need for hybrid will become less and less.”
But for here and now, hybrids are a viable solution.
Equipment buyers will also need to evaluate the value and disposition of their used hybrid equipment, says Carson. A large portion of used machines sold at auction in the U.S. are bought by Latin American contractors, perhaps as much as 25 percent.
The presumption is that contractors and equipment vendors south of the border will shy away from these machines, given the need for a high level of technical know-how and limited parts and supplies in those regions. This will affect total cost of ownership not only for contractors but for the big rental companies that regularly dispose of used machines.
Contractors also need to discuss with their dealers the cost and longevity of the batteries used in these systems. Most OEMs are exploring battery recycling programs and ways to reduce the environmental footprint of battery production. But as with any other machine attribute, this cost to the contractor must be carefully built into their owning and operating calculations.