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Paul Aspinall

Global Hydrogen Lead

It is all very well creating a Net Zero energy building or the most advanced lightweight structure using less concrete, but if methods to construct these projects create carbon emissions, then full life cycle carbon issues are not being addressed.


Constructing a Net Zero building using existing construction methods and CO2 emitting diesel plant is just like recharging an electric vehicle from a diesel generator. Not only does it not look good, but it is also counter intuitive in society’s efforts to decarbonise.

According to Statista (July 2022), the UK produced approximately 11.4 million tonnes of CO2 emissions in 2020, down from 12.8 million tonnes in 2019 (no doubt, due to a COVID impacted year). Of this, building construction emissions accounted for 2.4 million tonnes, representing 17% of the UK’s total emissions.

The impact our construction industry has on the full life cycle assessment of the product needs to be considered, from manufacturing the materials and components, through to construction, into its operation for end of use and eventual recycling of projects.

Since the UK government ended the subsidy on Red Diesel in April 2022, the cost of operating temporary plant equipment has substantially increased. A transition away from using diesel on major projects has started an important movement and cultural shift to address these significant emissions in our industry. The goal is to decarbonise construction solutions, but what is the best way to get there?


Decarbonising Highways

National Highways have identified a three-step plan with Net Zero maintenance and construction emissions targeted by 2040. An outline roadmap has been identified to show the key steps, but how can this be practically achieved?

In discussing theses construction emissions, positive initiatives are being developed on major projects, such as Lower Thames Crossing (LTC). These initiatives can be a catalyst for the industry to set the benchmark and leave a legacy for the UK to achieve our Net Zero future.


Eliminating Construction Emissions

Construction plant and vehicles The status quo construction processes need to be replaced using new technology and zero emission processes. Replacement solutions need to be fit-for-purpose to satisfy business as usual solutions, addressing all aspects of construction operations:

  • Enabling works
  • Site compounds
  • Diesel generators / temporary power
  • Moving operatives onto site / throughout the site, to and from the workface
  • Construction plant
  • Manufacturing and materials
  • Deliveries
  • Hand / portable tools
  • Commissioning
  • Operation and handover
  • Legacy net zero solutions (for general public use)

Carbon assessment tools such as PAS 2050 certification are available to measure carbon performance of ‘goods and services’. The Construction Leadership Council body CO2nstruct Zero lead the construction industry’s zero carbon change programme. The programme considers priority areas across three themes; transport, buildings and construction activity. The first programme priority is zero emission vehicles and plant. By tackling this theme and omitting diesel from projects could save millions of tonnes of CO2 from construction projects alone. Behind the practical measures, there are fundamental areas the industry must address to allow these initiatives to germinate:

  • Cultural shift to embrace new solutions
  • Behavioural change to tackle carbon emissions costs
  • Legislation and policy updates
  • Scalability of solutions for cost competitiveness

A fuel agnostic approach to zero emission alternative fuels must be used to identify the right tools and solutions for the right task. Just as an appropriate solution would be selected and tasks risk assessed for the safety case, the correct zero emission approach for a task can be selected. For example, battery electric plant is ideally suited to small scale or intermittent construction operations that requires limited run time or can be charged back at base or where recharging timeframes are not critical. Hydrogen plant equipment may be suited to larger projects requiring longer operational activities with quick refuelling timeframes for continuous operations. A supply chain for providing hydrogen to sites as a replacement for diesel, can be replicated as the business-as-usual solution providing fuel deliveries to sites. It is clear, a mix of zero emission technologies will need to be employed, whereby electric and hydrogen powered plant equipment should be considered to achieve emission free construction processes. Considering all the highways construction projects, associated utilities operations and plant equipment in use across the UK, the sheer scale to decarbonise this specific area of construction, should be brought into focus. LTC is a major project that is directly tackling this issue focussing on omitting diesel from the construction processes.


Case Study – Lower Thames Crossing (LTC)

LTC is a major project in the South East of England, providing a relief road from the Dartford crossing connecting the M25 to the A2. The project includes the longest road tunnel in the UK stretching 2.6 miles, with 14.3 miles of new road, with around 50 new bridges and viaducts to be constructed.

The LTC carbon model identifies the project will create approximately 1.76MT of CO2 emissions, of which 16% comes from diesel. To remove diesel from the project is a major undertaking given the scale and type of plant equipment required to decarbonise the construction processes, whereby just four types of plant account for 8% of carbon emissions alone – Excavators, Articulated Dump Trucks, Piling Rigs and Concrete mixers.

Analysing one of these plant items:

  • A significant number of concrete mixers will be required for continuous concrete delivery throughout the project, substantially contributing to the project carbon emissions
  • The Carbon Model identifies that concrete mixer trucks alone will use approximately 5.1 million litres of diesel delivering the concrete to site throughout the course of the project.
  • This quantity of diesel required to transport the concrete to site, will likely cost in excess of £10 million at current UK prices.
  • Substituting diesel Concrete mixers for Zero emission plant vehicles, has the potential to save 15,000 Tonnes C02 from the project
  • Moving away from fossil fuels and investing in alternative fuels such as EV and hydrogen to transport our materials and goods for construction could potentially be commercially and environmentally beneficial (and mitigate any future potential cost impact from rising cost of fossil fuels).

Upscaling this across the four main major plant items and across our highways construction projects could represent millions of pounds and CO2 emissions saving. Imagine the impact and legacy this can leave for the wider construction industry in the UK and across all sectors


Constructing the Hydrogen Value Chain

Developing these large hydrogen plant items and necessary supply chain for refuelling solutions is a major step forward supporting the decarbonisation of the construction industry.

Replacing diesel and fossil fuels from construction sites can reduce carbon emissions and provide commercial benefits, however projects and contractors require a credible and reliable alternative fuel solutions. Developing the hydrogen value chain to generate low carbon (green) hydrogen to be stored, distributed to sites and provide effective dispensing solutions for plant equipment will be critical to support the acceleration of construction decarbonisation at scale.

Original Equipment Manufacturers (OEMs) must be engaged with and policies supported to develop hydrogen plant solutions allowing contractors and clients to be confident that a decarbonised solution will be the right solution for the project.

By implementing smart and integrated solutions for our projects during the construction processes, legacy decarbonised solutions can be left to rapidly decarbonise all aspects of society. There is a moral obligation to utilise and embrace new technology and lead the decarbonisation of construction processes, replacing fossil fuels with zero emission alternative fuels.


A balanced approach

There is a clear need to decarbonise construction processes. A balanced approach that simultaneously tackles major projects together with the significant number of ‘minor’ projects. It cannot just be left to the major projects alone to develop and distil the information and decarbonised legacy through the construction industry. Major projects like LTC however, can be an enabler to germinate and disseminate the knowledge through to all construction projects and sectors whilst gaining support from policy leaders.

Policy support, legislation updates and behavioural change will all be necessary for this step change to be implemented. With highways projects leading the decarbonisation charge, the road map to Net Zero by 2040 can be accelerated with practical and visible carbon reduction techniques.

The ten point plan for the green industrial revolution, announced by the UK government in November 2020, included the end the sale of new petrol and diesel cars and vans by 2030. Perhaps a similar target or policy should be considered for zero emissions plant and equipment across the construction industry?

Scaling up zero emission plant and equipment across the construction sector will be a crucial step towards our net zero future