The UK has just started trials of a hydrogen powered train which generates electricity by combining it with oxygen. The only by-product is water, no greenhouse gases. But there was no mention of how the hydrogen was produced. Wiki says that most hydrogen production generates greenhouse gases, so what's the point? Is there a net reduction in emissions compared to diesel engines?
It's a valid question but I gather it is covered, certainly in the future. Hydrogen production for fuel cells will generally be via electrolysis which needs electricity but that could be produced via any means. The general move towards more environmentally friendly electricity production in general will pay off in the hydrogen system too. It obviously makes zero difference if we're still using diesel engines. It also has the advantage that there is no pollution at the point of use, avoiding things like particulate pollution from fuel-burning engines. Centralising the pollution cause by energy generation should make it easier to manage and reduce one way or another.
Why would hydrogen production for fuel cells be by electrolysis? That's among the most expensive ways to make hydrogen.
honestjoe mentioned nothing about pollution in his section on hydrogen generation, heust said that electrolysis (the most expensive and least efficient way to make hydrogen) would be the answer. Makes no sense.
It is also the only practical way to make it as of today. You can crack hydrocarbons but that releases even more CO2 and requires additional fuel. The only exception that I've heard is cracking methane. They can make pure carbon black instead of releasing hydrocarbons. But I don't think this has been demonstrated at commercial scale yet.
I think the point is that it is more efficient than running batteries or electric rail lines. They may also be expecting some of the new technologies to come online and make hydrogen production far more efficient; and without the need for fossil fuels to produce it. MIT was working on getting hydrogen from algae; which can also produce diesel and gasoline replacements fuels that are carbon neutral.
Water Vapor is a Green House Gas I like Hydrogen power. But, I want such power systems to be required to condense their water rather than spewing another, Green House Gas. Moi I imagine water from Hydrogen Power systems is pure as pure can be. Si?
You need to use high purity hydrogen in fuel cells or you significantly reduce their lifespan. You can obtain hydrogen via other means but not (currently) suitable for fuel cells.
Who Do And How So. PLEASE Illuminate for all Boardies here. Comparative Analysis is just a means to obfuscate by numbers.
Assuming the hydrogen is collected by running a current through water, something has to generate that current, probably something that emits CO2. So while the train is not emitting, w/e is 'making' its hydrogen is. That being said, hydrogen is a great renewable, in that it is a combustible fuel that can be 'made' from solar, wind, geothermal, etc.
Actually, it's the only way to back up your point. You have to know the effects of the current power sources. You have to know the impact of hydrogen creation and transport, what the water vapor does when the hydrogen is oxidized, etc.
This is the point then. I suppose we could look at it as a way of storing renewable energy, which can be unreliable. It's not the only way of course: batteries, pumping water to a higher level, spinning up flywheels (one of the F1 teams used this method when they introduced the hybrids), there are probably others. What could be done about the water vapour? Condense it?
I guess you've never heard of sequestering CO2. The process of making hydrogen out of natural gas isolates the CO2, allowing it to be easily sequestered in old oil wells, etc.
