Electrification of equipment is not new, as the industry has seen decades of electric technology in mining, as well as the hybrid diesel-electric dozers, wheel loaders, excavators, and MEWPs on job sites right now, but what is noteworthy is movement toward all-electric yellow iron.
With a couple of exceptions, most of the all-electric action so far has been with scissor lifts, compact excavators, and compact wheel loaders. Since scissor lifts do not require as much power as the other two machine categories, we will focus on excavators and loaders for the purposes of this article.
Acceptance is coming along slowly, being pulled by demand for zero-emissions indoor projects, work in urban centers where noise is a factor, and other sensitive jobs with strict emissions requirements.
Concerns among contractors and fleet managers have historically centered on matching the power of conventional machines, battery life, electricity availability for charging, and cost. The concerns seem to be melting away over time, as hybrids have been observed and experienced as powerful and fuel-saving, and battery-powered electric cars and trucks have proliferated.
Jeff Seagren, who owns his own excavation company in Elgin, Illinois, and specializes in indoor and outdoor digging, as well as concrete cutting, sees definite advantages that fit attitudes among project owners he’s worked for.
“At some point, you won’t be able to just sneak Tier 4-F equipment into a building when no one’s around,” Seagren says. “Plant and building owners have become more sensitive to fumes and noise, especially if they have employees working. As long as the power is there and the battery life is good, I could envision buying an electric compact. I know it could help me.”
Under 40 in Construction Equipment Award winner (Class of 2015) David Bolderoff, CEM, fleet manager for the Sanitation Districts of Los Angeles County, was an early adopter of electrification. He started with diesel-electric hybrid dozers in the county’s landfills, and has since bought all-electric vehicles. He continues to watch the progress.
Benefits of electric machines
“I see electrification of heavy equipment as the next radial shift in equipment design and the new challenge for equipment managers to navigate,” Bolderoff says. “Managing the new fuel type will present some unique challenges for managers, and it will be imperative to get the specifications right. Particular attention will be required in selecting the right battery packs and charging infrastructure to ensure the equipment will be available to meet operational requirements.
“Equipment managers will need to be aware of the longer planning process to build the required charging infrastructure,” Bolderoff says. “Electrifying equipment should result in less maintenance, as there will be a lot fewer parts on electric equipment, which will be a huge benefit in managing the fleet. The heavy-duty on-road trucks being prototyped are designed with 7,000 to 8,000 parts compared to a typical diesel truck that has approximately 30,000 parts.”
So far when it comes to all-electric equipment, the industry has indeed been treated to mostly prototypes, and the gap between prototype and actual sales can be wide. It was the same with hybrids eight to 10 years ago. With all-electrics, OEMs have been restricted by the limits of battery technology, and demand is limited compared to diesel, but some companies don’t mind gaining public relations points while treating end-users to visions of the technology to come.
“Since Conexpo is held only once every three years, we wanted to demonstrate our commitment to our ‘Powered by Innovation’ campaign,” says Edward Song, CEO of Doosan Infracore North America. “The Doosan DX17Z-5 Electric mini-excavator is an example of our dedication to moving the construction equipment industry forward. We are searching for technological advances to reduce the impact to the environment without affecting the machine’s productivity.
“Doosan is developing the new electric mini-excavator product because of requests from customers who work in certain applications where exhaust gases are prohibitive,” Song says. “An example of this need is interior demolition job sites. An electric machine gives excavator operators the ability to do their work with a machine they’re familiar with but without the inhibitions of diesel exhaust. The 1.7-metric-ton size class was selected for this first model because of customer requests for a mini-excavator that could work in confined spaces, requiring a machine with a narrow width to access the site.”
Instead of the traditional diesel engine, Song says, the DX17Z-5 is powered by a battery located where the machine’s engine and fuel tank would normally be placed. The battery supplies power to an electric motor that is used to operate the excavator’s hydraulic system.
Chinese manufacturer XCMG also showed a 3.5-ton electric excavator at Conexpo, with the help of Cummins. Cummins BM5.7E battery modules provide 45 kWh of battery power. Cummins says each battery module is designed for high shock and vibration, and on a single charge of less than six hours, the excavator can work an eight-hour shift. Testing is currently ongoing in China. Cummins has also partnered with Hyundai on a compact excavator using its BM4.4E flexible battery modules.
One of the biggest splashes at Conexpo 2020 in Las Vegas was the 580 EV backhoe loader from Case Construction Equipment—a machine that is actually available for purchase right now.
The 580 EV electric backhoe loader is powered by a 480-volt, 90-kW, lithium-ion battery pack (weighing 1,300 pounds) that can be charged in eight hours by any 220-volt/three-phase connection. A single battery charge will support most eight-hour workdays, says Case. The battery separately powers the drivetrain and hydraulic motors, resulting in hydraulic breakout forces equal to diesel-powered machines, says the company, and improved performance during simultaneous loader and drivetrain operation.
Two public utilities in New York State are the company’s first customers, New York State Electric & Gas and Rochester Gas & Electric. At press time, delivery had been delayed multiple times due to the state’s struggles with Covid-19.
The 580 EV Case backhoe loader will be sold at a higher initial price than conventional diesel-powered backhoe loaders, but Case expects that average fleets will see a payback on that premium in about five years. Based on a machine’s workload, the company estimates that the 580 EV could save fleets as much as 90 percent in annual vehicle service and maintenance costs, when taking into account the reduction/elimination of diesel fuel, engine oil, DEF, regular preventive maintenance, and long-term engine upkeep/maintenance (and the associated labor and downtime savings).
With the 580 EV, the company is targeting utilities and utility contractors, as well as government and public works operations that might need help satisfying initiatives aimed at lowering emissions and reducing noise in public areas. Many contractors in these sectors either drive or trailer these machines back to a central shop or yard at the end of the day, making it easier to plug into existing electrical infrastructure, or to establish charging stations in a controlled yard.
“They’re on back order,” says Case dealer salesman Dennis Tovar of McCann Equipment. “There’s a lot of interest out there now that battery size and technology has caught up with customers’ power expectations.”
Battery restrictions are a major reason why many OEMs have started their all-electric efforts with compact equipment, as well as the fact such equipment is smaller and can travel through doorways and garage doors for indoor construction.
Case has been an exception with its backhoe, as has Liebherr, which in 2019 launched the LB 16 Unplugged, a nearly emissions-free battery-powered drill rig that had been successfully tested with customers in deep foundation work. Larger batteries, and the use of battery “troughs” for multiple batteries, have allowed larger electric equipment.
The rotary drill features an electro-hydraulic drive concept and can be used without a power cable. The battery technology is designed to last one working day—that’s 10 hours unplugged—and is charged overnight using a standard construction site electric supply.
“We had doubts concerning the acceptance of a cable-powered drilling rig,” said Holger Streitz, managing director, Engineering and Design, at Liebherr’s Nenzing, Austria, plant. “Right from the start, there was the clear demand to operate for an entire working day from the energy storage unit of the machine with no cable. This was an extreme requirement and was logically tackled with our smallest drilling rig, the LB 16.
“The disadvantage here was the very limited size for positioning the many battery troughs,” Streitz said. “This problem could not be solved without an optimization strategy. For dimensioning the energy storage unit, work collectives of 34 diesel-driven LB 16s were evaluated. Our LiDAT telematics system provided the corresponding data in order to be able to define a reference working day. We decided to ignore the maximum values, as these only accounted for a small proportion overall. That’s how we defined the maximum possible battery size for the available installation space. Around 80 percent of all measured drill applications can be carried out in a 10-hour shift without any cables.”
Streitz used a comparison to the automotive industry regarding battery capacity, saying the LB 16’s battery capacity equals “around nine Tesla S models or seven Audi e-tron vehicles,” and would correspond to a range of 1,864 miles.
Some of the unit’s battery troughs are positioned on the top of the housing. “The covers, which looked somewhat bulky initially, were professionally designed,” Streitz said.
Liebherr said the batteries will last 10 years, and after 10 years will still achieve 80-percent capacity. In addition to diesel fuel savings and near-zero emissions, the LB 16 operates at an extremely low noise level, a plus for urban job sites.
Perhaps the busiest company in terms of all-electric construction machinery has been Volvo Construction Equipment. The company has sought to marry electrification and autonomy on several levels, most effectively in quarry work, and has also pledged to discontinue its diesel lines of compact excavators and compact wheel loaders by the middle of this year and replace them with all-electric equivalents.
In January 2019, the company announced that, starting with the European market, it will introduce a range of all-electric compact excavators and wheel loaders. The first machines were seen at Bauma 2019 in Munich, Germany, and have since been tested in landscaping (wheel loader) and golf course applications (compact excavator) in Germany and Paris, respectively. The excavator, an ECR25, replaces a combustion engine with 48-volt lithium-ion batteries and an electric motor that powers hydraulics to move the machine and attachments. The batteries store enough energy to power the machine for eight hours in typical applications, Volvo says. An onboard charger also enables overnight charging via a household electrical socket.
See an operator's take on the Volvo mini excavator in this promotional video.
Though the company has not committed to a timeframe for commercial availability in North America, units are slated for testing with customers in California. Volvo was recently awarded a $2 million grant for a commercial pilot of the company’s electric, zero-emission excavator and electric wheel loader in California. The grant, administered by the South Coast Air Quality Management District (South Coast AQMD), is funded by the EPA’s Targeted Air Shed Grant Program, which helps agencies develop plans and conduct projects to reduce air pollution in areas with the highest level of smog and soot in the U.S. South Coast AQMD is responsible for attaining state and federal standards by improving air quality in the South Coast Air Basin of California.
The grant aims to accelerate the deployment of zero-emission technologies for off-road mobile equipment, which is one of the major contributors to nitrogen oxide (NOx) emissions in the South Coast Air Basin. The South Coast AQMD region includes Orange County and major portions of Los Angeles, San Bernardino, and Riverside counties.
“Off-road construction equipment accounts for 43 tons per day of NOx emissions in the South Coast Air Basin,” says Wayne Nastri, executive officer for South Coast AQMD. Volvo CE’s electric compact ECR25 excavator and L25 wheel loader are currently being tested in Europe, and Volvo will adapt some configurations previously developed for the European program and demonstrate the machines in real-life applications for a minimum of six months in California.
Tests will start later this year; September for the excavator and December for the wheel loader. Three customers will be selected to test the machines. The results of these demonstrations, together with customer feedback, will be reported to South Coast AQMD.
Such testing will be important for managers to monitor. Data or anecdotal evidence on long-term performance in applications, maintenance successes or failures, the life of batteries, and the cost and frequency of replacement battery purchases will be important considerations for adding all-electric iron to a fleet.