Why be a BEV first mover?

Removing fossil fuels from sites is a must if countries – and companies – are serious about decreasing the carbon footprints of their activities.

Leading infrastructure clients in the UK recognised this fact on 29th April this year when six of them signed up to The Five Client Carbon Commitments, drawn up by the Construction Leadership Council. One of those five pledges is to phase out diesel – one of the big carbon hitters for an infrastructure project For instance, the Lower Thames Crossing project, one of the signatories to the commitments, has calculated that 19% of its carbon emissions would come from diesel (see p16). So, it plans to have zero fossil fuels on site by 2025 and zero emissions – neither fossil fuels nor biofuels – by 2027. Hydrogenated vegetable oil (HVO) in the short term, together with battery electric vehicles (BEVs) and hydrogen are all under consideration.

A Normet Spraymec 8110 SmartDrive has been deployed on the Sydney Metro.

BEVs are already in use on the UK’s HS2 high-speed rail project (see p15). UK infrastructure clients and contractors can also look to Norway for inspiration. Having incentivised people to switch from diesel to electric cars, local and national governments have now turned their attention to construction – as well as HGVs.

Seven cities in Norway – Oslo, Bergen, Trondheim, Stavanger, Drammen, Tromsø and Kristiansand – already demand that public sector construction and building activities are fossil- free, with a deadline of 2025 for them to be emissions free. Private construction projects must fall in line too by 2030. Norwegian roads authority Statens Vegvesen has looked extensively into deploying BEVs underground.

Reducing carbon emissions isn’t the only incentive to remove diesel: diesel particulate matter (DPM) is a recognised carcinogen. As well as reducing health risks, removing diesel could potentially reduce ventilation requirements underground too.

Australia is already ahead in its attitude to reducing DPM in working environments and the EU is preparing to tighten up its regulations too. “Sooner rather than later, all of us will be faced with the challenge of removing diesel particulate underground,” says Mark Ryan, VP equipment offering and new technology at Normet.

Ryan was talking at the latest roundtable event held by the SubSpace Energy Hub at the Hagerbach Test Gallery in Switzerland in May 2024. The goal of the hub is to accelerate the uptake of technologies such as BEVs, batteries and other forms of energy storage in order to cut carbon emissions more quickly.

Also speaking at the SubSpace event, Nathan Cables, senior manager new business and industrial at battery manufacturer Xerotech warned that late

adopters of BEVs could face delays due to lead times once legislation kicks in: “Regulatory compliance will really drive the change – that will happen fairly rapidly. There could be a situation where you are two years behind in the queue.”

Yet, without a carrot-and-stick approach like Norway’s, the decision to be a first mover in the deployment of BEVs underground construction is not yet an easy one. Drawing on some of the topics discussed at that latest roundtable, here are some of the possible reasons why.

1. Perceived fire risks

The risk of fire is probably the first concern that comes to anyone’s mind when considering BEVs underground. Stories about EV fires, from scooters bursting into flames on a metro to Tesla fires causing highway closures, always gain plenty of attention – and click throughs.

Aside from the fact that EV car fires are always considered more newsworthy than diesel ones, they are sometimes more difficult to extinguish once burning. They can reignite due to the phenomenon of thermal runaway, where heat from one battery cell transfers to an adjacent cell and starts a fire in that one too.

Fumes produced from BEV fires also create additional risks. Speaking at the SubSpace roundtable, Implenia’s head of mechanical engineering – tunnel construction, Uwe Stenner commented that the need for extensive clean ups after any fire that spreads to a BEV is an additional headache for a contractor. “If there is a fire in a tunnel, there are dangerous fumes and I have to clean the tunnel afterwards – that’s quite a big cost…even if the fire was not due to a battery vehicle.”

Proponents of BEVs underground point out that the batteries designed for construction machines are very different to those for cars. This is the case with Xerotech’s batteries, designed for rugged duties, says Cables: “They are encapsulated in fire resistant foam …with a ducted cooler that goes around each individual cell and keeps the batteries at a consistent temperature.”

Ross Dimmock, VP tunnelling at Normet explains that there are multiple safety measures on batteries such as those used in his company’s SmartDrive BEV vehicles: battery type, casing design, the battery management system that turns the battery off if they. “There are so many layers of fire and risk monitoring,” says Dimmock. “The fire has to breakthrough all these monitoring systems.”

Some battery chemistries are safer than others. Lithium- ion (Li-ion) batteries, such as those used for cars, can be used underground if they have an advanced battery management system. Lithium iron phosphate (LiFePO4) or lithium-titanium- oxide (LTO) batteries, which have lower fire risks may be a better choice, although each has pros and cons. And battery technology is developing fast.

The SubSurface Energy Hub is currently working on a best practice guide on how to mitigate fire risks. “It will start right at beginning, with the design of the machine and even the battery design,” says Dimmock.

Both HS2 and two consultants working on behalf of Statens Vegvesen have concluded that fire risks with BEVs are actually lower than those with
diesel vehicles. It is also worth noting that there was a fire on a passenger service vehicle in May 2022 on another contract on HS2, Align JV’s Chiltern Tunnels. The fire reignited having initially been extinguished. That vehicle was fuelled by HVO.

2. Cost

The mining industry has been much faster to adopt BEVs than the construction industry. Copper mining company Codelco in Chile has been trialling different types of BEV for five years. Savings in operation, due to lower energy costs, ventilation requirements and maintenance, mean that

– for some of the equipment

– the higher capital cost for BEVs is already balancing out, says Gonzalo Ramirez Troxler, Codelco’s corporate innovation director – decarbonation.

But while mining companies buy plant and run it until the end of its life, tunnelling contractors – especially those in joint ventures – tend to purchase plant for the duration of a project before selling them back to the manufacturer. This means there isn’t sufficient payback time.

Energy savings in operation vary hugely between countries, depending on the relative costs of diesel and electricity. Fuel savings also vary depending on the type of vehicle, the distances it is travelling and whether slopes – and therefore regenerative charging – are involved.

Stenner also raised questions about ventilation savings. He pointed out that increasing regulation on air quality in the EU might mean that ventilation can’t be cut, even without DPM present. He also wondered – for contractors such as Implenia that do buy their own plant – what the implications were for storing and maintaining BEVs between contracts.

Dimmock believes that, for BEVs, rental is the way forward. “We could ring fence a fleet if required,” he suggests. “We would offer all the support, safety checks, maintenance, spare parts to maximise equipment reliability” Contractors in the UK, and other markets, have yet to get their heads round this model, he adds.

3. Logistics

A major consideration in switching from diesel to BEV on a tunnelling project is the difference in refuelling. Whereas a diesel vehicle might need to have its tank refilled every couple of days, a BEV will need recharging far more often.

This means that times and locations for charging must be built into the logistics planning and management of a project. If zones for charging BEVs are needed underground, these must be taken into consideration when planning permission is being sought, since it might require the construction of additional areas.

Charging areas underground may make sense for logistics – but could be restricted due to fire risks, which are heightened during charging. For instance,
a fire at a charging station underground on a tunnelling project in Norway led the authorities to mandate charging above ground.

There are also options for swappable batteries which may be a good option for larger BEVs. These may have different risk profiles to permanent ones, which will need to be considered and mitigated.

Another point raised by Marc- Andre Beck, founder and CEO of Grivix which is developing technology to charge heavy duty BEVs automatically, is that the construction plant industry needs to standardise its charging infrastructure.

4. Renewable energy

Electric vehicles of any type will only lead to lower carbon emissions if they are charged with electricity from renewable sources. Today, the availability of renewable energy, in terms of both production and distribution, varies hugely between countries. Thanks to its hydropower, renewable energy accounts
for 98% of Norway’s energy generation, whereas for the EU it is around 23%. Meanwhile, China hit its 50% non-fossil fuel energy target for 2025 early, mid 2023, with just over 4 percent of that coming from nuclear power. In the US, around 21 percent of its energy comes from renewables, 19 percent from nuclear.

At the roundtable, Cables mentioned the huge surge in demand for electricity that we can expect due to electrification of construction and other industries. He cited one large contractor in Sweden which currently uses around 3 percent of the country’s electricity; when it electrifies that will rise to a whopping 33 percent.

This issue highlights some of the interconnected issues in energy transition and how clear strategies and policies are needed from governments to drive them all forward in parallel. Electrical power needs to be in place well before the start of major infrastructure projects, if carbon savings are to be realised.

5. Skills gaps

Those making decisions on plant hire and purchase were born and bred on internal combustion engines. Some have had negative early experiences with electric cars which adds to the perception of risks in using BEVs. There are some unanswered questions too; for instance, manufacturers are still working out how compressed air will impact on BEV performance.

New knowledge on performance and charging requirements will be needed to plan logistics for projects as outlined above. Health and safety plans and measures must be reviewed and updated.

Maintenance for BEVs may be more straightforward than for diesel – manufacturers are suggesting savings of between 30 and 50% – but it will need new skills too.

Normet says that it has over 75 trained professionals to support the 60-plus BEV units that are currently operating around the world, although Ryan says that the focus of that support is risk management: “The biggest part of this is not the maintenance, it’s helping the customer understand the risk and mitigate them,” he says.

6. Making the business case

One of the difficulties in making the case for a new technology is that it isn’t clear what all the benefits – or downsides – will be and how they will impact the bottom line.

There is anecdotal evidence that BEVs underground are adding more value than might be initially considered. For instance, Codelco found that with their electric LHDs, the noise and vibration was far lower than with the diesel versions which reduces health risks for operators – and bills for medical check-ups.

There will be first mover advantages to be gained for early adopters of BEVs in construction, but these can be hard to quantify in advance. And a transition of any kind often leads to some productivity hit before benefits start accruing.

For the construction sector, as for private cars, Dimmock thinks that Norway’s approach of incentivisation followed by legislation could be the best way forward.

“At the top you have organisations such as the UN and EU who are committed to cutting carbon and at the bottom you

have companies like Normet who already have the technology,” he says. “There’s something missing in the middle.”

You can watch the roundtables referenced in this article, alongside others, at the SubSpace Energy Hub channel on YouTube 

Case study: HS2, UK

On the UK’s HS2 project, contractor SCS JV is using BEV passenger vehicles in the Northolt Tunnels: electric passenger vehicles in both, electric multi service vehicles (MSVs) to transport tunnel lining segments to the TBM in the East tunnel only. “This is due to the fact that this tunnel is shorter and within the range of the BEV,” explains an SCS spokesperson.

A comparison between diesel and BEV equipment was made during procurement. Benefits of BEVs, according to SCS, were found to be removal of carcinogenic diesel fumes, less noise and a lower risk of fire – either due to engines or tyres.

However, the spokesperson adds: “Should a battery go into thermal runaway there remains a risk of fire (although significantly less than diesel powered equipment), with directional ‘jet like’ flames which is a new risk. There is also a change in risk from fire to explosion with potentially explosive vapour cloud being created if the batteries went into thermal runaway.”

Such risks have been mitigated through the design of the battery bricks, battery chemistry selection, mechanical protection and the battery management system to control temperatures. BEVs are charged outside the tunnel since the highest risk of thermal runaway is during charging.

With support from the HSE, SCS has developed a comprehensive risk assessment and specialist inspection process, with support by external specialists to ensure any updates to knowledge or best practice are quickly adopted.

SCS has employed specialists to train its mechanical and electrical teams.

SCS is now working with HS2’s Transforming Tunnel Safety working group to develop industry guidance to share lessons learnt. Smaller battery powered hand tools and the management of these will also be an important topic in the guidance.

Case study: Rogfast, Norway

Statens Vegvesen, the Norwegian public roads authority, commissioned two reports looking into the risks of using BEVs for tunnel construction. Both reports consider the Rogfast tunnel as a basis of their assessment.

Statens Vegvesen’s combined findings are summarised below with links to both reports for those wanting in-depth information.

• A battery fire is less likely than a diesel fire.
• A battery fire has the potential to last longer, but not much longer, compared to a fossil fuel fire.
• Combustion gases are generally very harmful to health and must be avoided regardless of whether it is a fire in a battery or diesel.
• New machines built for professional use in tunnels are expected to have several layers of built-in safety that reduce risk.
• Detectors can detect overheating in the battery cells before a fire occurs.
• There are battery chemistries that are extremely inflammable, such as lithium iron phosphate batteries.