Hydrogen trains are now running in Germany. But are they really green and do they make any sense?
The first hydrogen-powered trains have entered commercial service in northern Germany, on a route normally served by diesels. The Coradia iLint trains are built by Alstom in France and are equipped with fuel cells that "convert hydrogen and oxygen into electricity, thus eliminating pollutant emissions related to propulsion." According to the Transport Minister quoted in the Alstom press release,
The emission-free drive technology of the Coradia iLint provides a climate-friendly alternative to conventional diesel trains, particularly on non-electrified lines. In successfully proving the operability of the fuel cell technology in daily service, we will set the course for rail transport to be largely operated climate-friendly and emission-free in the future.
All the blogs seem really excited about this, even though rail electrification with overhead wires has been going on in Europe for decades and, though expensive, is the tried and true method. But hey, hydrogen is clean and green, right? I must admit that I have always been a skeptic of the hydrogen economy, but is it time to admit I was wrong? Perhaps things have changed. After all, as Daniel Cooper writes in Engadget,
Hydrogen's strong energy density and relative ease of generation and transportation makes it ideal for heavy loads. And while it's currently not a clean material, the hope is that companies can push towards creating H2 with 100 percent renewables in the future.
I read that and thought, no, I am not wrong. This is classic hydrogen hype. Let's deconstruct it.
Energy Density: It's true, hydrogen has the highest energy density per mass of any fuel; the trouble is it is the lightest fuel and has a very low energy per unit volume; a gallon of diesel has many times more energy than a gallon of hydrogen. So, according to the Department of Energy, "its low ambient temperature density results in a low energy per unit volume, therefore requiring the development of advanced storage methods that have potential for higher energy density."
So you need a lot of it stored at very high pressure in expensive tanks. Or you can liquify it, which takes more energy than the hydrogen actually contains. Some are trying chemical storage, but it is still experimental.
Ease of Generation: The way they are making the hydrogen for these trains is really easy! It is called steam-methane reforming, described by the U.S. Department of Energy:
High-temperature steam (700°C–1,000°C) is used to produce hydrogen from a methane source, such as natural gas. In steam-methane reforming, methane reacts with steam under 3–25 bar pressure (1 bar = 14.5 psi) in the presence of a catalyst to produce hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide. Steam reforming is endothermic—that is, heat must be supplied to the process for the reaction to proceed.
While it's currently not a clean material: To supply the German trains, gas company Linde will provide gas from their refineries, so for now and the foreseeable future, this train is running on fossil fuels. "The plan is that hydrogen will be produced onsite via electrolysis and wind energy at a later stage of the project."
This is the one thing that has been changing in the hydrogen economy over the last decade: the massive increase in renewables. When the Province of Ontario looked at these trains last year, I thought that they might make some sense, since Ontario doesn't burn coal but has Niagara Falls and big nuclear reactors with nothing to do at night, so they could make hydrogen when electricity demand was low.
But while Germany's renewable electricity supply has grown dramatically, they still get half their power from coal and are closing their nuclear reactors. It will be a very long time before they are making hydrogen from electrolysis.
Ease of Transportation: Really? Again, the U.S. Department of Energy says, "Because hydrogen has a relatively low volumetric energy density, its transportation, storage, and final delivery to the point of use comprise a significant cost and result in some of the energy inefficiencies associated with using it as an energy carrier." That's because the molecule is so small it leaks really easily, and it actually can diffuse into the metal in the pipes, causing hydrogen embrittlement and cracking.
OK, this could be the start of something big. As the head of Linde notes in the press release, “This development will push the establishment of a hydrogen society and will create new solutions for the storage and transport of energy.” With enough renewable power or some fancy new catalyst, we might someday have enough clean hydrogen to justify this.
But I keep quoting Mal speaking to Shepherd Book in Serenity, "That's a long wait for a train don't come."