The key challenges in construction going all-electric

The construction industry is a major contributor to climate change, accounting for 20 percent of global emissions. The problem is set to grow: Square footage is expected to grow 20 percent globally by 2030. To have a chance at net zero goals, the building sector energy intensity needs to drop nearly five times more quickly over the next 10 years than it has in the past 10, according to the International Energy Agency (IEA). Mining Excavator

Key to decarbonizing construction: electrifying heavy-duty construction vehicles.

While all-electric compact construction vehicles are already on the market (think a forklift in a warehouse), the larger the equipment (wheel loaders and excavators), the more difficult it is to electrify.

In August, I visited the Danfoss construction showcase in Denmark where engineers are trying to crack the all-electric construction machine nut. While there, I was able to get a peek at some considerations engineers are addressing as they’re electrifying equipment. 

Electrifying these machines pose a whole host of unique challenges. Central to every challenge: Batteries are very different from internal combustion engines (ICE).

Powering electric construction vehicles requires a lot of power. That means a lot of batteries. And those can be very expensive. 

For context, an ICE wheel loader I saw at the Danfoss facility cost about $150,000, all in all. The battery display the team used to power the prototype cost an additional $90,000. That’s a 60 percent addition to the cost.

A retrofitted wheel loader at the Danfoss facility with the ICE removed and 140 kilowatt hour battery display added to the back — approximately twice the amount of a standard long-range electric car

What’s more, the prototype can’t operate for the same number of hours as an ICE counterpart between charges. Realistically, the vehicle could work for four hours, according to the engineer team. To be construction site ready, it would need to secure eight hours of operation at a minimum. 

"It's not just pulling a combustion engine out and putting in, let's say, an electric motor," said Casper Olesen, senior systems engineer at Danfoss Power Solutions. "It's rethinking the whole machine."

The easiest path forward is to increase energy efficiency. While marginal efficiency gains may have been a tough sell for ICE vehicles, efficiency in all-electric equipment translates to direct savings.

"Technologies are actually becoming more attractive because now efficiency is not just making a difference if you're using 10 or 15 liters of diesel an hour," said Olesen. "It is actually, ‘Can I fit enough batteries into the machine so I can use it for my work?’"

Taking out the conventional hydraulic system and changing to something high-efficient could add an hour or two to the run time. Technologies such as variable displacement pumps and variable speed pumps can reduce idle losses — energy consumed when the vehicle is not operating. 

Other design changes are subtle but make a cumulative difference. For example, the team is programming the wheel loader’s front scooper to default at a specific angle when the machine is driving to cut down on wind resistance. 

There are many efficiencies to gain here. Today’s ICE excavator, for example, is only 30 percent efficient, meaning 70 percent of the energy supplied by the engine is wasted before the bucket hits the earth, according to Danfoss calculations. Combining electrification and efficiency means only 25 percent of energy input is needed to shift the same amount of earth. 

An example highlighting the potential in energy efficiency and electrification in a 16-ton conventional excavator, provided by Danfoss

Transitioning to zero-emissions construction equipment requires more than the vehicles. It also requires the infrastructure to charge the equipment. 

"It takes some time going from what is well known today to something that is new, because you also need to establish the service network behind the infrastructure," said Erik Westergaard, systems engineer at Danfoss. 

At new construction sites, it’s possible there isn’t an electrical hookup at all — much less high voltage options. 

"So if you're inside the city, you might be able to find a big power plug and connect," said Olesen. "But if it's spread out in the countryside, you need to ensure that you have a large enough battery capacity." 

From there, no options to charge are perfect. Operators could transport the machines to another place to charge or bring a battery bank to the site every day to recharge machines overnight.

Danfoss’s climate strategy organization, Project Zero (which paid for my trip to Denmark), recommends partnerships to plan electric vehicle infrastructure early and carefully. The team suggests involving stakeholders in communicating the reduced noise and air pollution benefits to build public support, as well as having transparent and predictable municipal processes to give long-term signals on the direction of construction standards. This can be strengthened if localities require companies to make their construction carbon-footprint available when participating in public tenders. 

New machines require a workforce that knows how to operate them. 

Today, commercial real estate developers have highly specialized ICE engineers to keep equipment going. With all-electric vehicles, projects would need to have highly specialized power electronics engineers and high voltage engineers, as well as service people. 

"So it’s a completely new engineering department they need to establish because it's not the same competencies and specialization," said Olesen.

The batteries also require a new knowledge set. Different battery chemistries have different best practices — and failure to follow those could kill a battery system. You can’t leave them full for a long time; you can’t let them get completely drained. 

"So there is quite a steep learning curve for groups and the people that use them," said Westergaard. "If you really want to have things lasting longer, there's a bit more knowledge needed."

Not only does this require retraining and new competencies, but the workforce is limited, as these machines are new. The good news is that all-electric equipments have fewer moving parts — meaning ultimately there will be less maintenance required. 

Real estate developers and the private sector can signal demand for this skill set through setting rules for public procurements, including requirements for vehicles and machinery used in construction projects. 

Original equipment manufacturers (OEMs) can also play a role here. Construction equipment manufacturers can help communicate the shift in resources needed to make an all-electric vehicle a reality. 

In these early days of all-electric construction equipment, the demand to go all electric isn’t economic. Rather, it’s coming from those prioritizing reductions in emissions, air pollution and noise. 

The mining sector is a good example. Eliminating air pollution from machines could make operations cheaper, with one of the biggest expenses being ventilation of air in the underground mines. Going all-electric eliminates the need to pull out exhaust emissions, reducing overall costs. 

The reduced air pollution and noise can be a benefit to construction projects in cities, which may have noise ordinances or pollution regulations. The public sector can help spur forward this market through requiring carbon-intensity standards within requests for proposals, or set emission standards for all construction within a municipality. 

Developers with net zero goals are also early adopters. Developer Lendlease, for example, has climate goals that extend to construction, meaning the team is navigating these all-electric vehicle challenges — and using renewable diesel when all-electric alternatives aren’t yet ready. 

Ultimately, all organizations engaging in construction can help move the needle simply by encouraging developers to account for all emissions. While the friction to achieve net zero construction may seem strong, the sector has huge, unharnessed energy efficiency potential that can lead to deep emission reductions — and get us on the road to net zero. 

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