In the heart of Nelson city, a digger with no fuel cap zaps to life, a silent roller compacts fresh asphalt and a svelte-looking loader unplugs from a mobile electrical charging trailer, batteries full for another day’s work.

This isn’t your typical New Zealand construction site. It’s Nelson City Council’s Bridge Street to Better project and contractor Isaac Construction is using the trio of electric machines to help streetscape Bridge Street and upgrade inner-city water, roading and pedestrian infrastructure for future growth.

“The initial reaction of some civil contractors is to reject electrical machinery,” says Toby O’Sullivan, who manages Isaac Construction’s Tasman operations.

“But I’d have to say a lot of our people have started to really enjoy using it and it’s changed a lot of minds.”

Toby and his team have a lithium battery trailer which can be topped up at any EV charging station and taken to worksites to re-energise equipment. The trailer costs less than $200 to charge and can hold enough electricity to fully re-power four electric machines – a price that’s considerably less than the $1,000 or so it costs to fuel their diesel equivalents.

The electric equipment Isaac Construction is using was co-funded through Energy Efficiency & Conservation Authority to support a trial requiring the Isaac team to test and report on the viability of battery electric technology in the construction industry.

The grant helped the company to purchase a 2.5 tonne electric roller, 4.5 tonne skid-steer loader, 5.5 tonne excavator, 300kg trench rammer and 80kg plate compactor.

So far, the machines have been used on projects in Christchurch, as well as Nelson.

Before the Bridge Street to Better project, they were put to work developing the Millars Acre Bus Hub, which has beefed up public transport capacity for Nelson and includes six new bus bays for electric bus services.

Isaac Construction is also using a 15-tonne electric loader purchased with help from the grant at its asphalt plant in Christchurch; a setting that Toby says demonstrates a “perfect application” for electric plant because the charging infrastructure is on site.

‘Getting used to new toys’

One of those operating the electrical machinery is Isaac Construction Foreman Anthony Duff. He has operated all the electric machines on the Bridge to Better project and is excited about seeing them used more in the years ahead.

“It’s just about getting used to new toys. The loader just feels like a normal loader and the trench compactor is awesome. The digger has had a few teething problems for the finer jobs, but the power is there. For trenching and digging, which is 99 per cent of what we use it for, it’s keeping up with the big boys.”

Anthony was born in Dunedin and worked as a train builder before making the move into civil construction nearly two decades ago.

He first experienced electric machinery during a stint in Western Australia, where he says electric heavy trucks and autonomous vehicles are becoming more common.

“It’s the way of the future, and once the machines start getting even bigger, they will be great.”

Early results are (mostly) positive

Toby says the results of the Isaac Construction electric machinery trial have been positive so far and their use is leading to a reduction in fossil fuel gas emissions and thousands of dollars in diesel fuel charge savings every month.

However, he concedes the technology still has a way to go before it can replace all heavy machinery in construction.

“The plate compactor technology isn’t quite there – it’s fine for smaller landscape jobs but its battery won’t last all day,” he said.

“The roller has a six-hour battery life, which is pretty good, and the 5.5 tonne digger is powerful, great for loading stockpiles, clearance or demolition jobs, but not so good final trimming as it doesn’t have quite as much smoothness of operation.”

Access to charging infrastructure can also be a challenge in some regions and the silent operation of electric heavy machinery means workers need to adjust to stay safe on site.

“What we’ve done is made a rule that the radio needs to be going on the electric machines when they are operating, so people know they are on.”

Despite those hurdles, Toby remains positive about the potential of zero-emission heavy machinery to become mainstream in future.

“There’s a lot more hydrogen and electrical machinery being developed and more charging infrastructure going in,” he says.

“It might be that future heavy plant is hybrid and uses both of those technologies.”