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A salt spreader HGV retrofitted with a hybrid hydrogen system. (Image: Balfour Beatty)

Angela Pllu, Balfour Beatty’s environmental sustainability manager, said the initiative was developed in mind for the ‘wider construction industry’ to promote decarbonisation.

In conjunction with establishing Scotland’s first construction hydrogen hub, Pllu said the project collaborated directly with three other organisations and the Scottish government – which provided nearly £250,000 (US$326,811) – to produce a prototype retrofit solution with hybrid hydrogen power.

“In a nutshell, we’re retrofitting heavy vehicles with a hybrid hydrogen system, aiming to achieve a 30% of reduction in carbon emissions,” explained Pllu, who added that the programme, thus far, has fitout two salt spreader heavy goods vehicles (HGV) and one impact protection vehicle (PIV).

The project also includes setting up accessible green hydrogen supply and onsite material storage and refuelling infrastructure.

“[We] are now analysing our road test data to identify further improvements,” said Pllu, who said early results were “promising”.

“Our spreaders are showing around a 26% carbon reduction during road tests, whilst the IPV is also running with reduced emissions, albeit at a slightly lower rate,” she said.

The retrofit vehicles can use two sources of engine power: diesel fuel and hydrogen.

Hydrogen use kicks in when the vehicle’s engine reaches optimum running temperature and when engine regeneration is not happening, said Balfour Beatty.

The equipment can operate in “diesel-only” mode, as well, which Balfour Beatty said helps reduce risks associated with hydrogen availability and technology adoption.

“However, it is less useful for vehicles used intermittently where the engine does not stay at an optimum temperature for extended periods,” said Balfour Beatty, which suggests the tech is best used on continually running heavy transport machines as opposed to task-based units like excavators, skid steers or other off-highway machinery.

M77 programme puts emphasis on refuelling

A hydrogen gas nozzle inserted into a vehicle’s intake valve. (Image: Adobe Stock)

Citing “safety first”, Balfour Beatty noted the biggest change to machine operations on an M77 retrofit vehicle is refuelling.

“The refuelling process is new for our operatives and requires careful attention and an understanding of hydrogen gas as the refuelling area is classified as an ‘ATEX’ zone, a designated area where there is a risk of explosion due to the presence of flammable gases, vapours, or dust,” explained Balfour Beatty.

To mitigate the risks associated with refuelling the fitouts, the company said its operators are provided with antistatic clothing to prevent static electricity from igniting the hydrogen gas.

“We have also partnered with Hydrasun, a leading international provider of integrated fluid transfer, power, and control solutions, who specialise in handling high-pressure gasses to provide comprehensive hydrogen gas training to ensure our teams can follow the required safety protocols,” added the contractor.

Balfour Beatty partnered with Logan Energy to develop a mobile refuelling solution, which it said will be “vital for the construction industry” especially for remote and off-highway applications when “offsite refuelling causes costly downtime.”

Hybrid hydrogen fitout not yet perfect

Photo: Grispb via Adobe Stock

There’s still a long way to go with the emerging power solution that is hydrogen, and Pllu recognised that reality.

“It hasn’t all been plain sailing,” she said. “The main challenge we encountered is the cost of retrofit and the current limited availability of hydrogen refuellers and hydrogen gas.”

Pllu said the hydrogen supply in Scotland is expected to increase from 2026, which should ease some accessibility concerns in the long-term.

“Transporting hydrogen is also a significant challenge and the transient nature of the construction industry does not fit the current hydrogen rollout model, where investors and suppliers seek guaranteed consumers within the local area via dedicated pipework,” added Balfour Beatty. “We are working with suppliers to address this and ensure they understand the importance of mobile hydrogen deliveries to our construction sites.”

Balfour Beatty recognised that a hybrid solution isn’t the “ultimate” technology for decarbonising the industry, but it said the solution is “effective, fast, and straightforward” and can be implemented today.

“It delivers a substantial reduction in tailpipe carbon emissions,” said the firm, “making it a valuable interim measure as we work towards our carbon reduction targets.”

Balfour Beatty also sees the retrofit solution as a small but meaningful step – holistically – for the construction industry.

“Retrofitting is an effective way to gradually build demand for hydrogen,” said the company. “This allows for the supporting hydrogen infrastructure, such as supply and refuelling technology, to grow to the necessary capacity that will be needed and avoids a sudden need for large volumes of hydrogen that the market may not be ready to supply.”

What’s next for Balfour Beatty’s M77 hydrogen project?

“As we move forward, we will host quarterly lessons learned sessions and visits to our M77 depot starting in September,” said Pllu.

In addition to three direct partners on M77 (ULEMCo, Logan Energy and Plus Zero), Pllu said entities like the Aberdeen City Council and First Bus Aberdeen were “invaluable”, and the firm said it will maintain its collaborative nature going forward.

“Navigating the evolving hydrogen technology market requires flexibility and patience,” said Pllu. “Information sharing under Non-Disclosure Agreements and aligning safety systems between hydrogen and construction industries were essential yet time-consuming steps.”

The programme hopes to test spreaders during its winter maintenance cycle and will continue to analyse its IPV data to find optimal fuel displacement strategies.

Pllu added, “Additionally, we plan to leverage funding to support our supply chain in transitioning to hydrogen, sharing risk assessments, cost information, and management plans to ease the adoption process.

“To ensure the economic sustainability of this transition, we will actively engage with the industry, build new connections, and advocate for competitive green hydrogen fuel rates.”