Crossties or sleepers are an essential part of railroad tracks as they are responsible for keeping rails in their proper places and evenly distributing the loads of passing trains. Traditionally made of wood, sleepers today can be composed of different materials such as concrete and steel. In recent years, an Italian startup called Greenrail SRL has perfected a recipe for sleepers that not only includes recycled waste materials but also a solar photovoltaic (PV) generation system. Greenrail expects that their “solar-paneled” railway sleepers will be able supply substantial amounts of electricity to train stations and local grids.

Greenrail has received EU funding to begin replacing traditional sleepers with the company’s eco-friendly counterparts. With offices in Rome and Milan, Greenrail wants to raise Italy’s competitiveness in the global market for renewable energies and related green solutions.

The current generation of railway sleepers are made of pre-stressed concrete that is usually produced in a very energy-intensive process. Greenrail has introduced an alternative design for sleepers that include a combination of recycled plastic wastes from cities and rubber from end-of-life tires (ELT). The outer shell of a Greenrail’s sleeper is an elastic covering that can effectively reduce the wearing out of rails due to weight pressure. According to Greenrail’s own research, its eco-friendly sleepers have a much longer lifespan, and their overall maintenance cost is 2-2.5 times less than that of traditional sleepers. Furthermore, every kilometer of the eco-friendly sleepers consumes 35 metric tons of recycled plastics and rubber.

Because Greenrail’s solution allows for customization, the company is also developing variations to its sleepers. One version incorporates small solar PV panels and the other has a kinetic energy system that harvests power from passing trains. The solar version of the Greenrail’s sleeper is projected to generate around 150 kilowatt-hours of electricity per kilometer.

Greenrail has also inserted a monitoring system inside its sleepers. Known as Greenrail Linkbox, this monitoring system can send real-time diagnostic data to relevant parties as to ensure the safety of the railway network.

Giovanni De Lisi, who founded the Italian startup in 2012, said that the idea of using plastic and rubber wastes to make railway sleepers was initially dismissed by chemistry experts. De Lisi is now glad that years of R&D has borne fruit and attracted greater public attention. Going forward, he hopes that Greenrail’s products will eventually become the industry standards.

In addition to the integration of railways with renewable energy using solar panels, Greenrail is working with governments and companies to make customized products for railways that are being built or renovated (i.e. replacing aging, worn-out sleepers). Greenrail’s ambition is to use its innovations to disrupt the relatively closed market for railway infrastructure.

Renewable energies can take charge in powering railway networks

While the development of the renewable energy sector has always been a global issue, the steady price decline in solar PV generation over the recent years has encouraged more countries to be bolder in applying green technologies to public projects, including those related to transportation infrastructure. For example, the metro system in Chile’s capital city Santiago has been mainly powered by solar and wind generation since the start of 2017. Chile is one of the sunniest country in the world, and a huge solar power plant in the Atacama Desert is supplying 42% of the total electricity used by the Santiago metro system.

In India, six-coach trains with 16 solar panels on the rooftop of each coach were launched in July 2017. Although these trains still run on diesel, the solar panels will help conserve the consumption of the traditional fuel by powering the lights and fans inside the coaches. Additionally, the solar paneled trains have a backup energy storage system that provides electricity for up to 72 hours. Australia, where wind and solar projects have also taken off lately, also inaugurated the first short-distance train that is totally powered by solar PV in December 2017.

The installations of renewable generation systems are expected to climb as they become more reliable due to technological maturation. At the same time, the costs of electricity produced by wind farms and solar PV plants are becoming more competitive against electricity from power stations that burn fossil fuels. In the future, renewables will likely represent larger shares of total generation in communities across the globe. This in turn will drive energy transitions in other industries.

 (The above article is an English translation of a Chinese article written by Daisy Chuang.)