Hydrogen plant: the way of the future?

Removing fossil fuels from construction projects is an essential part of the industry’s journey towards net zero emissions. This is particularly challenging given the nature of plant items used across the sector, often requiring high levels of torque and engine capacity. Innovative solutions are regularly being trialled on projects, including fully electric cranes and piling rigs – although sourcing electricity often requires non-sustainable methods via generators. Hydrotreated vegetable oil (HVO) is also being used, replacing red diesel. While less carbon intensive than diesel, it remains a finite resource.

Chris Roberts

Therefore, a feasibility trial was carried out from 2022 to 2023 on the world’s first dual-fuel hydrogen piling rig. The trial was titled Zero Carbon Hydrogen Construction Equipment for Real World Use (ZECHER) and involved Ulemco and Cementation Skanska, alongside a consortium between BRE and the Department for Energy, Security and Net Zero. The aim was to adapt an existing piling rig by installing a new hydrogen engine control unit (ECU) and injection system alongside the existing HVO engine and achieve a minimum of 30% hydrogen displacement in real-world usage.

Trial – phase one

The initial trial comprised adapting an existing Soilmec SR30 piling rig for dual-fuel usage. This involved installing a new hydrogen ECU and electrical system alongside the original equipment manufacturer’s (OEM) ECU. A high-pressure hydrogen injection system was also installed onto the air inlet manifold to allow the rig to operate in either hybrid or fully HVO configuration. The hydrogen storage system was fitted onto the original piling rig chassis, with no modifications required.

To maximise engine efficiency and performance, the hydrogen fuel is utilised at a greater percentage in the lower parts of the engine’s duty cycle, with percentage replacement decreasing at higher output. This gives a wide scope for engine mapping to displace diesel, while also allowing for specific operating modes, which was important given the wide range of engine torque levels throughout the piling installation process.

When conducting the trial, the availability and production method of the hydrogen gas had to be considered. For industrial usage, hydrogen has eight typical sources, from renewable to nuclear to fossil fuels. These are all designated a colour to denote the original source of the hydrogen gas. For this trial, the original feasibility stage was conducted using green hydrogen, which is from surplus renewable sources. The on-site trial utilised grey hydrogen, which is created from natural gas, without capturing greenhouse gasses in the process. Grey hydrogen is currently the most common source of industrial hydrogen.

Real-world analysis 

Following the rig adaptation and hydrogen sourcing, a two-phase trial was conducted to measure engine performance at differing torques and fuel flow rates, to effectively simulate the real-world usage of the rig when installing piles. These trials were run concurrently with mapping the duty cycle of an identical rig on a live project to overlay site data with the trial conditions. The trial phase showed that the most efficient configuration was the hybrid injection of hydrogen and HVO fuel at high torque. When compared with site data, an average hydrogen replacement of 36% was achieved, estimating a usage of 12kg of hydrogen fuel over seven hours and a reduction of 30l of diesel.

The rig was then deployed to Granby Terrace Bridge, part of the High Speed 2 (HS2) Euston Approaches contract for Skanska Costain Strabag JV to install four 900mm diameter, 30m depth piles for the bridge replacement. The dual-fuel rig performed to the same engine efficiency as the trial, and a hydrogen replacement of 36% was recorded during the piling operations, therefore proving that the concept could be implemented in real-world situations.

Upscaling from trial phase to widespread usage will require significant developments across the industry. The current UK infrastructure for hydrogen is limited and does not yet support widespread and remote usage, due to limited specified refuelling locations. Also, the supply chain of hydrogen, particularly from fully renewable sources, is not yet robust enough to support industry wide implementation of hydrogen powered plant. However, commitments such as that by National Highways on the Lower Thames Crossing project to buy UK transport’s largest ever volume of hydrogen to replace 20M.l of diesel is a real step forward.

Simply proving through the trial that the concept of a hydrogen hybrid piling rig can be brought into a live construction environment is a significant progression towards fossil fuel free construction.