Railroad - Railroad experts: overhead line is the best solution
In the search for eco-friendly alternatives to the emissions-producing diesel locomotives on Germany's railways, according to railway experts, the familiar overhead wire is the best solution. Alternative train propulsion systems, such as hydrogen, battery, and vegetable oil, are significantly more expensive. "The best efficiency is achieved through electrification with overhead wires," says Professor Markus Hecht from TU Berlin.
In Germany, according to the Alliance for Trains, only 62% of the federal railway network is electrified. In comparison, Europe's role model is Switzerland, where the entire railway network is electrified. Austria, Italy, and the Netherlands also have over 70% electrified railway lines.
Expensive hydrogen trains
Bavaria plans to begin the long-planned test operation of hydrogen trains in Allgäu in the fall. "Bavaria aims to be climate-neutral by 2040. This includes the fact that from 2040, no diesel-powered vehicles will be in operation in the Bavarian rail passenger transport," says Transport Minister Christian Bernreiter (CSU). The preferred solution is electrification. For lines without "electrification perspective," the state government therefore plans to use battery and hydrogen trains.
However, even high-tech hydrogen trains are viewed with skepticism by critics. "Hydrogen is the most expensive solution and has a lower efficiency than diesel," says the Berlin railway technology professor Hecht. The fuel cells generate not only water and electricity but also a lot of waste heat.
Cooling is a major problem for hydrogen vehicles
"They have to cool down strongly in the summer and require electricity for the climate control systems to cool the passenger compartments," says the researcher. "In winter, they can use the waste heat to heat the passenger compartments. It's absurd that the hydrogen train uses less energy in the winter than in the summer." Due to the poor efficiency, energy consumption is always much higher than with all other technologies.
The Berlin professor is not alone in his assessment: The TU Dresden compared the advantages and disadvantages of alternative drives for the Bavarian Railway Company in reports in 2017 and 2020. Hydrogen performed worse than batteries, even in terms of the CO2 balance. However, Bavaria is a significant chemical location. Therefore, the state government plans to build a hydrogen network, which could also benefit the railway.
Lower Saxony has already tested hydrogen - and subsequently decided to buy over 100 battery trains instead, as battery propulsion is cheaper in operation. "Battery trains are also significantly more expensive in operation than pure electric trains," says Hecht. The efficiency is lower, the vehicles are heavier. The battery has a finite lifespan, must be heated in the winter, and cooled in the summer.
Even battery trains are not ideal.
Battery trains can only travel short distances, it's usually around 80 kilometers today. Then another charging station is required. A solution to this are hybrid trains: power collectors and batteries combined. These trains can charge empty batteries on track sections with overhead power lines. In Germany, there are many tunnels that are too narrow for overhead power lines - these are the ones where tunnel upgrades for the power line through battery-electric driving can save costs, according to Hecht.
Used cooking oil - from the fryer to the tank
The third option: used plant and cooking oil as a substitute fuel for diesel locomotives, known in technical jargon as HVO 100. Since diesel locomotives can run on used cooking oil without major technical modifications, this has the advantage that no new locomotives need to be bought: "Diesel vehicles can be operated without extensive modifications with the climate-friendly fuel," says a spokesperson from DB Regio Bayern. "This allows us to operate them until the end of their service life, save the climate, and conserve resources."
However, the question of how climate-friendly HVO is remains in doubt. "As much CO2 is emitted from the exhaust of HVO as with diesel," says Hecht. "The environmental benefit only arises through the certification of the HVO fuel. This requires proof that the fuel comes from biological material, that all the CO2 that comes out of the exhaust comes from the air beforehand."
But there are two big elephants in the room: "The certificates can be falsified, and then a scandal arises suddenly. And the second thing is: we don't know what happens to the material otherwise." The concern is that the HVO fuel for trains in Germany could then be replaced by coal or oil or other CO2-emitting materials elsewhere.
Practical concerns also exist. "HVO has an environmental advantage, but it is currently still about 30 percent more expensive than regular diesel," says a spokesperson from the Lower Saxony Transport Ministry. "Furthermore, the engines must be approved for the new fuel, and the availability must be ensured. This is particularly difficult or impossible for older engines."
A lasting solution will be electrification
The passenger rail advocacy group Pro Bahn sees HVO as a transitional solution. "We can't eat that much potatoes to switch all diesel vehicles," says the Bavarian state chairman Lukas Ifflaender, who is an IT professor by profession at the Dresden University of Technology and Economics in his main job. Compared to hydrogen, HVO is the more sensible transitional solution for diesel locomotives with a diesel engine and power collector.
With increasing electrification of the rail network, hybrid drive with batteries and power collectors, according to Ifflaender's assessment, will also be a practical solution in freight transport. "That's why we assume that full electric propulsion will prevail." Where not with overhead power lines, the range problem will be solved with batteries. "Almost all lines that then still pose problems and have regular freight traffic are slated for electrification."
- Despite Germany's efforts to electrify its railways, only 62% of the federal network is currently electrified, making it lag behind countries like Switzerland, Austria, Italy, and the Netherlands.
- Bavaria, aiming for climate neutrality by 2040, plans to test hydrogen trains in Allgäu this fall and potentially switch to these trains for lines without an electrification perspective.
- Professor Markus Hecht from TU Berlin, a railway expert, expresses skepticism towards hydrogen trains, arguing that they are more expensive and less efficient than diesel locomotives.
- Hydrogen trains generate waste heat and require significant cooling systems in the summer, significantly increasing energy consumption compared to other technologies.
- The Berlin professor Hecht and the TU Dresden have both concluded in their reports that hydrogen performs worse than batteries in terms of CO2 balance and efficiency.
- In contrast, Lower Saxony opted for battery trains after testing hydrogen, citing their cheaper operation compared to hydrogen trains.
- Battery trains have their own limitations, including a maximum travel distance of about 80 kilometers before requiring recharging and the need for hybrid trains for long-distance travel.
- One alternative to diesel locomotives is the use of used plant and cooking oil, known as HVO 100, but its climate benefits are uncertain due to potential certification issues and concerns about replacement materials.
- HVO is currently more expensive than regular diesel and requires engine modifications, making it a less practical solution in the short term.
- Pro Bahn, a passenger rail advocacy group, sees HVO as a transitional solution for diesel locomotives but believes that a lasting solution will be the increased electrification of the rail network and the use of hybrid drive with batteries and power collectors in freight transport.
