By Andy Fyfe

Construction of new transport infrastructure and the fossil-fuelled vehicles that dominate the system is often criticised because of its carbon footprint. But new technologies may put highways and railways at the forefront of renewable energy solutions. Some of these technologies have already reached the pilot stage while some are at the first stages development, but all have the potential to offset the enormous amounts of carbon released in fulfilling our transport needs.

Solar roads

The idea with solar roads is that by embedding high-load bearing photovoltaic panels into roads and harvesting the energy they create, you could feed that energy it back into the electricity grid or recharge EVs. Using the vast square milage that roads already occupy, solar highways could also negate the need for giant solar farms while also creating ‘smart highways’ that warn drivers of any dangers ahead.

So far the technology hasn’t kept pace with claims companies such as Solar Roadways make for their benefits. Founded in Idaho in 2006, to date Solar Roadways have only managed to construct a relatively small pedestrian walkway in Sandpoint, Idaho, which was shut down in 2018 when problems emerged with the snow-melting capability and unexpected early fading of LEDs on certain colours.

However, despite the setbacks, the idea that billions of miles of highways could potentially become a source of renewable energy continues to excite many companies and it’s only a matter of time until the first working solar road starts to create renewable energy long term. 

Carbon-sequestering asphalt

Biochar is a form of charcoal that has long been used to enrich and aerate soil for agriculture, possibly as far back as the pre-Columbian Amazonians. It’s what is left behind by a process called pyrolysis, which uses extreme temperatures to decompose biomass without using oxygen, so it heats but never ignites. The process releases far less CO2 and methane into the atmosphere than simply burning the organic material and stores it indefinitely as stable carbon. Mix that with asphalt or even concrete and it becomes a long-term carbon sink.

Singapore company Highway International has recently signed an MoU with the Asia-Pacific subsidiary of American-based Verde Resources to develop and test mix designs. If successful, it could lead to Singapore constructing roads and even airport runways with biochar as a key component, transforming infrastructure into long-term carbon sinks.

Solar trains

Roads aren’t the only transport infrastructure that may soon benefit from new sustainability technology. Since June 2024, the Quebrada Solar Train has been running along a 46km route in the Argentinian Andes, connecting northern villages between Volcán and Tilcara that have existed since pre-Inca times. The fact that zero-emission technology is being used along one of the world’s most ancient trade and cultural routes adds a bit of romance to its practicality.

A similar solar train was launched in Byron Bay, Australia in 2018, but it operates purely for tourism along a 3km track. Both trains carry photovoltaic cells on the carriage roofs, but in the UK Network Rail has taken a different approach by partnering with Riding Sunbeams, a company pioneering direct-wire technology that powers trains with energy fed from trackside solar arrays.

So far only a small scale pilot project operates near Aldershot, but Network Rail is also working with EDF Renewables to provide solar energy for stations, offices and depots.

Solar healthcare

Perhaps the most sci-fi project comes in the form of Stella Juva, a solar powered mobile health clinic designed by students at Eindhoven University of Technology, which could revolutionise delivering quality medical care to the world’s most remote communities.

Rather than transporting patients to a hospital, Stella Juva takes the hospital to them, running purely on solar power. Already being field tested in Kenya, the ambulance covered 800km in its first few days, delivering equipment such as an X-ray machine, ultrasound for pre-natal scans and a defibrillator to over 200 people. It also carries cooling equipment for vaccines.

One response involved a six-hour journey across forbidding off-road terrain, completely powered by the on-board solar panels.

• Click here to secure your place at CIHT’s free webinar on improving net zero delivery in transport on 12 November.

• Download CIHT’s Climate Hazards and Highways Resilience guidance for local authorities here.