Surprise! Photovoltaic railway has a potential of 239.6TWh! Will it change the energy landscape?

Recently, Italian startup Greenrail Group announced that it has begun deploying its custom photovoltaic railway sleeper solution on a railway line in Italy.

Since 2018, the company has been testing photovoltaic sleepers on railway lines. Occhipinti, the company's CEO, said that these sleepers are easy to assemble and clean. "It only takes a few minutes to clean 1 km of solar railway using a trolley with brushes and water sprayers installed below. This allows us to complete the cleaning of large surfaces in a short time, saving resources and time compared to cleaning standard photovoltaic power plants."

Greenrail has conducted a series of regular tests for six consecutive months to evaluate energy efficiency, weather resistance and the impact on railway operations. They said that the solar sleeper solution has excellent robustness and effectiveness. 1 km of solar sleepers is enough to generate 44 MWh of electricity per year. This energy can be sold to the grid or used to power train stations, level crossings and traffic lights in remote areas.

Photovoltaic panels on rails

The idea of ​​replacing sleepers with solar panels is not new. Bankset Energy in the UK and Deutsche Bahn in Germany are experimenting with adding solar cells to railway sleepers or fixing photovoltaic elements to track sleepers. They generally believe that there is a huge space between the rails, so why not use solar panels instead of sleepers, which can effectively generate electricity without hindering the movement of trains.

Among them, Swiss Sun-Ways has its own unique advantages. It is the first to develop a detachable solar system for rails. The founder believes that detachable panels are an important prerequisite for the maintenance of this system, just like railway management and maintenance personnel polish the rails when managing the tracks.

According to the inventors, their panels are more corrosion-resistant than traditional panels, and the black color of the panels and the use of anti-reflective filters will reduce interference with train drivers. Sensors can monitor the normal operation of the panels, and circular brushes placed at both ends of the train group will be able to automatically remove residual dirt accumulated on the surface of the panels, such as dust or railway ballast debris. For areas with heavy snow or low temperatures, the startup intends to develop a system to melt ice and snow.

Switzerland, like other countries, relies on renewable energy to achieve energy transformation and gradually move towards the goal of a zero-emission society. However, the scarcity of available space makes it difficult for Switzerland to build large-scale installations, and the installation of solar panels on private buildings, infrastructure or mountainous areas will be hindered by many regulations.

So this technology has great potential in Switzerland. Theoretically, Switzerland's 5,317-kilometer railway network could accommodate a solar power plant with a total area of ​​5.317 million square meters, equivalent to about 760 football fields. According to Sun-Ways, excluding tunnels or sections with insufficient sunlight, the Swiss domestic railway network can produce 1 terawatt hour of solar energy per year, accounting for about 2% of the country's electricity consumption.

Sun-Ways is supported by about 10 partner companies and the Swiss Innovation Promotion Agency. If approved by the Federal Office of Transport, the world's first mobile solar power plant will be put into operation in May.

And the startup's goals are not limited to Switzerland. Sun-Ways plans to expand in Europe, especially Germany, Austria and Italy, as well as the United States and Asia. "There are more than one million kilometers of railway lines in the world. We believe that 50% of the world's railways can be equipped with our system."

China's railway photovoltaic market and difficulties

China's railways pass through the south of the colorful clouds, adjacent to the Great Rift Valley of East Africa, and cross the surface of Lake Baikal, winding and stretching. As of August 2024, the total length of China's railways will exceed 160,000 kilometers, ranking third in the world. If all the sleepers on the track are replaced with photovoltaic panels, it will generate huge economic benefits.

Busy sections of railways consume a lot of electricity, and the northwest has good sunlight. The electricity generated by photovoltaic sleepers can be absorbed by the power system along the railway, which has huge advantages. Busy railway lines such as Beijing to Guangzhou or Shanghai or routes from Beijing to Xinjiang are the only choice for pilot projects.

According to institutional data, the total potential for photovoltaic power generation that can be developed and utilized in my country's railway network is 239.6 TWh. In the railway transportation network, the space along the railway, the canopy of large station buildings, and the top of locomotives and vehicles can provide space resources for the integration of photovoltaic power generation, and the electricity used by electrified railways and station service facilities can also provide a broad space for photovoltaic power generation.

It is estimated that by 2030, the annual power consumption of China's high-speed railways will increase to 191.9 TWh. For the photovoltaic railway application scenario, under the conditions of 5%, 10%, and 15% photovoltaic in railway transportation, the annual electricity self-consistency rate of the railway transportation system will reach 6.2%, 12.5%, and 18.7%, and the annual carbon dioxide emission reduction will exceed 12,000 tons.

However, these are perfect assumptions without considering other factors, and we still have to consider practical problems.

The first problem: Photovoltaic absorption

In recent years, with the gradual promotion of distributed photovoltaics and the continuous advancement of large-scale base projects, the problem of photovoltaic absorption has become increasingly prominent. So how to absorb the power of railway photovoltaics? In fact, it is very simple. The electricity generated by photovoltaic railways can be sold to power grids, railway stations, and nearby power consumers.

The railway station uses photovoltaic power generation to power trains and charge batteries; consumers can buy the electricity generated by photovoltaic railways for household loads; in addition, the excess electricity can be sold to the power grid company for profit, which can achieve local absorption and diversified utilization. As for the excess electricity in remote areas, it can also be stored on-site in combination with new flywheel energy storage technology.

The second problem: high cost

The photovoltaic power generation market cannot be widely popularized in the world, still limited by cost, plus the special requirements of photovoltaic railways in technology and equipment, the cost can be imagined. Sun-Ways did not disclose the cost per megawatt, but it will carry out a project pilot on a section of the public transportation railway network covering the canton of Neuchâtel in western Switzerland. The project has raised nearly 400,000 Swiss francs. If large-scale construction can be achieved in the future, the cost of railway photovoltaics may still drop significantly.

The third question: Railway companies

The final decision on whether railway photovoltaics can be promoted lies with railway companies. China Railway Corporation is basically responsible for the operation of China's railways, including the photovoltaics installed on sleepers.

Although the country is now vigorously promoting the construction of new energy to achieve the "dual carbon" goal, the prospect of combining existing railway assets with photovoltaics is bright, but if the generated electricity is to be transmitted to the overhead line to power the train, it needs to be boosted. There are problems with the supply and stability of photovoltaic power. Since the railway has high requirements for power supply reliability, how to match it with other power sources is also a problem. Considering the possible safety hazards, grassroots railway bureaus cannot make independent decisions in such key areas involving railway system safety.

China Railway Photovoltaic Examples

The railway has a large demand for electricity. With the photovoltaic power generation project, it will effectively reduce electricity costs and achieve energy conservation and carbon reduction. Although there is no precedent for laying photovoltaics on rails in my country, it has long been actively exploring the field of railway photovoltaics.

On December 25, 2021, the distributed photovoltaic power generation project on the roof of the Xiong'an Station of the Beijing-Xiongan Intercity Railway (Asia's largest high-speed railway station) was officially connected to the grid for power generation. The project adopts the "self-generation and self-use, surplus power to the grid" model, with a total installed capacity of 6 megawatts, which can provide 5.8 million degrees of clean electricity for the Xiong'an High-speed Railway Station every year.

As the largest newly built station along the Beijing-Xiongan Intercity Railway, the Xiong'an High-speed Railway Station has a total construction area of ​​475,000 square meters, and the entire station building is designed in a water drop-shaped elliptical shape. The rooftop photovoltaic power generation project lays 17,700 pieces of 42,000 square meters of polycrystalline silicon photovoltaic modules on both sides of the station roof. Looking down from a high place, it is like "a pearl on a water drop shining", which complements the roof shape.

While achieving economic benefits, the project saves 1,800 tons of standard coal and reduces carbon dioxide emissions by 4,500 tons per year, which is equivalent to planting 12 hectares of trees.

In July 2016, the Hohhot Railway Bureau in Inner Mongolia, China, completed the country's first railway system photovoltaic power generation demonstration project. Using the roofs of railway buildings and nearby spaces in the Shaliang Logistics Park under the jurisdiction of the Hohhot Railway Bureau, 6,780 photovoltaic panels were laid to complete a 2.4MW distributed photovoltaic power generation project with an annual power generation of about 3 million kWh, which is mainly used for railway transportation and production.

The "Hutie Photovoltaic" distributed photovoltaic project, which was launched at the same time as the Shaliang Logistics Park, includes: Hohhot Railway East Station, Hohhot Station, Baotou Station, etc., a total of four locations, with a total installation capacity of about 16.5MW, and is expected to generate 24.75 million kWh of electricity per year, equivalent to a power generation profit of RMB 6.73 million.

The service scope of Hohhot Railway Bureau covers thousands of railway counties in the central and western Inner Mongolia, as well as the land, houses and power supply networks on both sides of the railway line, with an average annual electricity consumption of 1.6 to 1.9 billion kWh. Train operation and traction electricity account for about 80% of the total electricity consumption, and the rest is for production and life. Huhhot Railway has carried out photovoltaic construction under the brand of "Huhhot Railway Photovoltaic", reducing railway electricity expenditure, creating corporate transformation, and actively responding to the national call for energy conservation and emission reduction.

Although photovoltaic railways still have a long way to go before large-scale promotion and application, their potential in the field of new energy development has already been revealed. Moreover, it is just a wonderful corner of the application of green energy in many fields. In the future, with the spread of green energy development and environmental protection trends, there will be closer and more innovative cooperation between renewable energy and mass transportation.