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Fuel Cell Powered Japanese Trains on Trial in July
ScorpFromHell writes "As per this yahoo! news item, "East Japan Railway Co. is to conduct a test run of the world's first fuel-cell-powered train in July.
The fuel cells, which generate power from a chemical reaction between hydrogen and oxygen, will help reduce environmental pollution compared to the existing electric and diesel engines, the company said."
But I wonder how much energy did it consume to produce those huge amounts of Hydrogen & Oxygen? Will it be lesser than the power generated by the reaction between them?
In other words, can this technology be used by countries with not so deep pockets as Japan?"
Combustion is a chemical reaction.
The way a fuel cell works is the same as burning straight Hydrogen. 4 Hydrogen atoms combine with 2 Oxygen atoms to form 2 Water molecules. When you burn Hydrogen, it happens all at once in one big pop (or bang!). In a fuel cell, the atoms dissolve into the water at the electrodes and combine in solution. The reaction is much more controled and generates an electric potential at the electrodes.
As far as efficiency is concerned, the seperation of Hydrogen and Oxygen (by electrolosis) from water and the subsequent recombination in a fuel cell (creating electrical energy) is over 95% efficient. That compares to around 30% for a good diesel engine.
In high school, I actully built a rudementary fuel cell as a science project.
Fuel cells are an energy storage medium, not an energy source.
You are half right. Fuel cells are neither an energy storage medium nor an energy source. The source of the electricity used to hydrolyze the water is the energy source. Hydrogen is the energy storage medium The fuel cell is an energy conversion device same as an internal combustion engine except way more efficient.
I think by "diesel and electric" they mean "diesel-electric". Basically, a diesel engine (usually with separate cylinders which can be independently replaced) drives an electric generator, or bank thereof. This in turn is used to provide power to electric motors which provide motive force for the train. The benefit is that by doing this you eliminate the need for a drivetrain, gearbox, and so on. Thus, the total weight is not changed much, but you get peak starting torque (electric motors make peak torque at 0 rpm) and you aren't constantly replacing gearboxes, drivelines, clutches, et cetera, as you would be if you were trying to put all that power through a conventional drive system. Of course, it's not exceptionally efficient. At best, the generator might be 90% efficient, and so might the drive motors, and the most efficient internal combustion engine in the world is a diesel the size of a house in a container ship that's only 50% efficient... the engines in trains are probably pretty efficient (another benefit is being able to run the engine in its powerband most of the time, except when it's running at low power and maybe at max load) but they're not even 50%.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
I think you are looking at the wrong kind of trains -- the Japanese have lots of commuter trains connecting smaller cities, and literally millions of miles of track, don't think Tokyo, think outback.
These trains are actually more like busses, they have maybe 2-4 cars and run infrequencly, so electrifying these tracks doesn't make much economic sense; or is just downright ugly and expensive to maintain. They are mostly diesel powered (with the engines located below the passenger compartments, there is no seperate loc).
For these, replacing a noisy diesel engine with much quieter electrical ones makes very good sense.
Wow...pop? dissolve?
"As far as efficiency is concerned, the seperation of Hydrogen and Oxygen (by electrolysis) from water and the subsequent recombination in a fuel cell (creating electrical energy) is over 95% efficient."
Whoa! Sure that's the efficiency of electrolysis but then you have to compress and store the hydrogen (hydrogen storage is a whole thing in itself), then you have to feed it to a fuel cell that has an efficiency much less than 95%...usually less than 50% system efficiency. Overall, the total efficiency of hydrogen fuel cells is comparable to a diesel fueled vehicle, maybe even a bit less.
Of course, that's if you make the hydrogen by electrolysis. Most hydrogen comes from natural gas at the moment, which is less efficient and produces CO2.
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A pure Fuel cells system is in the order of 70-80% Combined with an average 80% motor, you have 50-60% efficiency.
OTH, if use a reformer rather than a regular storage system, you lose the bulk of the efficiency (lowers you to 30-40%). Combine that with the 80% motor, and you are in the 24-32% efficiency.
Sadly, an autmobile is around 20% efficiency. And that is only from the Gas forward. It does not include the previous inefficiencies.
Basically, we are using one of the worse systems possible. It just got developed and marketed first.
I prefer the "u" in honour as it seems to be missing these days.