Tuesday, September 27, 2005

Sacred Cow: Hydrogen fuel cells, Part II

So, hydrogen-powered cars rule. Electric motors are efficient and make it easier to design a car, so engineers love them, and fuel cells don't produce any nasty stuff, so baby pandas love them. Everything's great, right?


Unfortunately, there are problems with fuel cell vehicles. Let's start from the lesser ones:

1. Lots of water vapor means lots of humidity and rain. Not a very scary prospect for Californians, I guess that's why they love fuel cells so much. In Small Country, we've got more rain than we can handle.

2. If you put a motor inside each wheel, you increase the unsprung mass. I'll explain what this is in a later post, for now, just remember that this makes the car bounce a lot more, and is generally considered a bad thing.

3. Electric engines aren't very powerful. And even if you've got the really good ones, they will only give the car as much power as the fuel cell generator, or battery, can provide. This is why the Lexus RX400h only has 270bhp, although the petrol engine and electric motors combined are rated at almost 400bhp! The electric motors can't put out more power than the generator and battery give them, and if the engine is making all of its 211bhp, then the motors are powered by the battery, which only gives them 45 Kilowatts. They could do better, but they have nowhere to get the extra electricity.

4. Keeping hydrogen in a car is kind of complicated. It's not particularly dangerous - hydrogen has less energy density than petrol vapors (meaning that the same amount will make a lesser bang), and it dissipates in the atmosphere a lot better, meaning that it's better to have a hydrogen leak than a petrol leak. But it needs to be kept in a pressure tank, and those are heavy and bulky. More heavy and more bulky than the ones they use for cars running on natural gas/LPG. An even bigger problem is that you can't use existing gas stations; they'd need to put in all-new underground tanks, etc.

5. And the biggest problem of all, the one that makes fuel cells a useless prospect: you need to get the hydrogen from somewhere, and you probably need oil to do it. Getting hydrogen from water is actually not very efficient - hydrogen and oxygen like each other a lot, and you'd need a lot of electricity to get them to separate, much more than you could hope to get by combining them again in a fuel cell. You need an external source of electricity, which is usually a powerplant, which is usually oil- or coal-powered. You could use nuclear power, which actually only produces a small amount of radioactive materials that you can store somewhere out of the way (I propose the basement of the Kansas school board - who's gonna know the difference?), but baby pandas say that nuclear is icky. There are environmentally-friendly ways to get electricity, but not a lot of it, certainly nowhere near as much as needed. There's probably a solution to the mess, but I don't know what it is.

So, the point:
Hydrogen fuel cell vehicles do not solve the problem of pollution - they simply move it out of the cities and into the countryside where the powerplants are. They also do this at the enormous expense of changing the whole gas station infrastructure, plus forcing the manufacturers to invest in all-new cars built in all-new factories.
Who do you think is gonna be paying for all that?

If human kind makes a concerted effort to switch from oil to hydrogen, the air may get cleaner, but your fuel bills sure as hell aren't going to get smaller. Plus, it'll rain all the time.

Join me in Part III, where I try to prove that I'm not just criticizing everything without suggesting any alternatives. Don't you hate people like that?


Anonymous said...

Even if the hydrogen is isolated using energy from fossil fuels, there's still an advantage to switching.

If we can agree on an efficient, clean, safe "end-user" energy source, like hydrogen, then we can set up the distribution infrastructure (battery fabrication, refueling stations) for that technology as its own independent unit of the energy pipeline. Because of its advantages, we'll likely never need to tear down that infrastructure until we find something that completely blows it away.

In the meantime, we may have fossil fuel plants, but we can just as easily build nuclear plants when the fossils get retired, or solar if we can make it work, or wind or hydro depending on the geographic details of the region. These plants can enjoy the efficiency of mass production, they can be added to the power grid as independent modules, and we save ourselves a bundle on type-specific infrastructure.

antyx said...

Like I said, fuel cells *do* have a point - they're just not the most efficient course of action (not by a longshot). Infrastructure costs are one thing, but I'm convinced that if humanity needed it badly enough, it would underwrite something like that; the real problem with hydrogen is that it doesn't decrease pollution. It's inefficient to produce (with oil, petrol and diesel fuel output is tiny, but you get to use the waste for plastics and stuff), hard to transport, and at the end of the day it improves the air in the city at the cost of baby pandas.


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