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Trams running on solar power

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Trams Solar Power

Date

21 June 2021

Expertises

Sustainability, Power

A unique connection between the eco solar park ‘t Oor in The Hague and the power grid of regional operator HTM allows trams of Randstadrail 3 and 4 to run on solar power. A great story to tell today, on the longest day of the year.

HTM is a public transport company in the Netherlands operating trams, light rail and buses in The Hague. With our contribution to the development of the eco solar park we have made another step in our sustainable ambitions. Between the tracks near Mariahoeve and Voorburg, 4,700 solar panels were installed, producing over 1.5 Gigawatt hours per year. 

“We were leading in the project, connecting the customer, contractor and subcontractors. We acted as the pivot in the organisation. This kind of application of solar energy is an entirely new development. The alignment of the requirements therefore took quite some effort.” Gertjan van Keulen, Project Coordinator at the Cables and Pipelines Division of Strukton Rail Netherlands

Direct connection

On behalf of Sunprojects, Strukton Rail laid the 10 kV cables to connect the high voltage to the HTM grid. We also led the installation of the substation and were responsible for other cabling work. The high yield makes this project special. Normally, the direct current is converted into alternating current and fed into the public grid. Energy loss occurs due to the conversion and transportation of energy. We have applied an innovative method allowing the generated direct current of the solar panels to be transported directly to the overhead lines, which minimises this loss. This means a possible breakthrough for a new standard in directly supplying sustainable electricity to rail networks.

Energy transition

Gertjan is enthusiastic about the project that was done successfully last year.

“This is a unique development in the field of the energy transition that I would be happy to explore further. The plans are at an early stage, but we are definitely considering this. The opportunities are technically available for trains as well, by e.g. connecting the catenary system to solar power. Railway lines are often located on fallow pieces of land, which are highly suitable for solar parks.” Gertjan van Keulen, Project Coordinator

Want to know more?

Frequently asked questions

Find answers to frequently asked questions here.

What does sustainability mean in the rail and civil infrastructure sector?

Sustainability in rail and civil engineering focuses on reducing environmental impact across the entire lifecycle of infrastructure. This includes using emission‑free equipment, circular and recycled materials, and designing assets with a longer lifespan and lower maintenance requirements. Reusing structural components—such as circular viaduct beams or recycled copper contact wires for overhead lines—significantly reduces CO₂ emissions while conserving valuable raw materials.

How can CO₂ emissions be reduced in infrastructure projects?

CO₂‑reduction is achieved through a combination of clean construction methods and material innovation. Key strategies include:

  • Deploying zero‑emission machinery such as electric cranes, electric rail‑road vehicles (Krols), electric vans and battery‑powered locomotives.
  • Integrating circular concrete, geopolymer concrete, and recycled materials to lower embodied carbon.
  • Collaborating across the supply chain — from client to contractor to materials supplier — to scale circular and low‑carbon solutions.

These measures not only reduce carbon emissions but help create more resilient, future‑proof infrastructure.

Which sustainable innovations are being used in modern rail and civil engineering projects?

Infrastructure projects increasingly rely on advanced sustainable technologies, such as:

  • 100% recycled copper contact wire, reducing CO₂ emissions by up to 92%.
  • Geopolymer concrete, offering 50–80% CO₂ savings compared to traditional mixes.
  • Electric and battery‑powered locomotives for maintenance and logistics.
  • Circular overhead‑line foundations and poles made from low‑impact concrete.
  • The Energy Bank, an innovative click‑and‑go substation that captures and reuses regenerative braking energy.
  • Circular viaduct and bridge concepts, enabling reuse instead of demolition.

These innovations drive measurable environmental benefits throughout the asset lifecycle.

What is zero‑emission equipment in infrastructure construction?

Zero‑emission equipment refers to machinery that operates without producing exhaust gases, typically powered by electricity or batteries. Examples include:

  • Electric locomotives and battery locomotives
  • Electric cranes and rail‑road (Krol) vehicles
  • Electric vans and support vehicles

This equipment eliminates local emissions, improves air quality around work sites, reduces noise pollution and helps clients comply with increasingly strict sustainability requirements.

What does the future of sustainability in infrastructure look like?

By 2050, the infrastructure sector aims to be fully climate‑neutral. This future includes:

  • A robust, climate‑resilient infrastructure network designed for extreme weather.
  • A fully emission‑free construction fleet.
  • Circular material chains where components are reused at scale.
  • Rail as a leading sustainable mobility system, supported by smart energy management and low‑carbon construction methods.
  • Infrastructure that integrates nature, supports biodiversity and ensures safe mobility for everyone.

The transition is already underway, driven by innovation, collaboration and long‑term thinking.

Why is expanding the electricity grid essential for Europe’s energy transition?

Expanding the electricity grid is crucial to support increasing demand from renewable energy, electric mobility, gas‑free homes and growing data‑center capacity. A larger and stronger grid ensures reliability, prevents congestion and enables the seamless integration of solar, wind and other sustainable energy sources.

What civil engineering works are needed to build and upgrade energy networks?

Modern energy networks rely on extensive civil engineering works, including the construction of high‑voltage substations, transmission‑line foundations, access roads, cable routes and site preparation for electrical stations. These works form the physical backbone that allows grid operators to expand capacity safely and efficiently.

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