Monday, December 27, 2010


This is great:

Now, a little engineering analysis, courtesy ME - philosopher / engineer in the classic tradition of Archimedes:

"Hydrogen combines with oxygen to produce electricity."

No it doesn't. Hydrogen combines with oxygen to produce HEAT and FLAME. This heat energy must somehow be converted to mechanical energy, to turn a generator to produce electricity - this task is typically accomplished by heating water into steam, to drive a turbine which in turn spins a generator, which is a big electric coil that produces electricity. Even nuclear power plants work this way.

The byproduct of the chemical reaction of hydrogen and oxygen is water - this is true. But where does the hydrogen come from?

Hydrogen exists in nature in the form of water - H2O, also known as 'dihydrogen monoxide' - DHMO. To extract the hydrogen from the water requires running an electric current through the water - a process known as 'electrolysis'.

So where does the electricity come from, to get the hydrogen to fuel the car?

Most electricity is produced by fossil fuel power plants. Most fossil fuel power plants burn coal; 80% of the electricity in North America is produced this way.

In other words, this hydrogen fuel cell car is no different than the electric car - the energy required to drive it is derived from good old-fashioned coal.

Ergo, to say that this car is pollution-free is like a man eating a steak saying he's a vegetarian by default, in that the cow he eats is a herbivore.

What I really want to know is how come all these "Car of the Future" cars always look like souped-up Prius's? EFF THAT. It's 2010 - when are we going to get THESE THINGS???





  1. You are correct that "making Hydrogen" involves electrolysis -- you pump in electricity and coming out you get hydrogen and oxygen. This can be looked at as the charge cycle and you take the hydrogen that's produced, put it in a tank, and later "discharge" it and recombine it with oxygen.

    But the fuel isn't burned in the traditional sense so the heat that's produced is minor. Instead, what's happening is that the exotic materials in the fuel cell are breaking up the hydrogen (H2) into positive ions -- because there are enough electrons to go around when H2 becomes H and H. You get a net positive charge.

    Second, you do the same thing with oxygen -- use the exotic materials in the fuel cell to break up the O2 which nets a negative charge.

    Build the fuel cell so the positive (hydrogen) side stays separate from the negative (oxygen) side, and you have an available charge that can be used to run a motor.

    Eventually, the positive and negative charges do combine (and produce water) but notice that they've already done the work. It is the movement of positive to negative, through the wires of the motor, that powers the vehicle. Combining the hydrogen and oxygen takes place after the work is done, and that recombining produces the waste water.

    The key to making all this work on a national scale is two part: 1) generate hydrogen on a grand scale with a distribution system to every Circle K and Quickie Stop around the country, and 2) make car-size fuel cells with sufficient power-generating ability to move a one ton (or more) vehicle around at a snappy speed, and have it last a long time, both in its "refill the tank" cycle, and in its "replace the fuel cell because this one is worn out" lifetimes.

    Another issue is the "drive by wire" technology. Software engineering is relatively young. We've been figuring out how to write software for less than 100 years. As an engineering technology, that's pretty young. And the process is buggy; we just don't know how to write 100% error-free software.

    That means the "drive by wire" aspects of the car are occasionally going to fail. Witness the recent lawsuits with Prius and other such vehicles developing a mind of their own and putting the petal to the metal (er, anode?) contrary to the driver's wishes. That's a software engineering failure.

    Electrical engineering, on the other hand, is about 200 years old. "We" are better able to make electrical systems that work safely and for a long time.

    And mechanical engineering? Well, that's arguably 300-400 years old.

    But none of these are perfect. Things still break. It's just more likely that the mechanical parts are gonna work real good, the electrical part of gonna be pretty good, and the software ... well, I'm still watching for the Ctrl-Alt-Delete keys to make an appearance on the steering wheel.

    If you rent an alternative fuel vehicle, spend a moment with the instruction book in the glove compartment and read how to punch the power switch so that, no matter what, the car is turned off. It just might save your life!

  2. Mechanical engineering goes back WAY further than 400 years - almost as far as civil engineering; my discipline. Archimedes - the world's greatest engineer - lived from circa 287 – 212 BC. His mechanical engineering accomplishments include siege engines and the screw pump that bears his name. Archimedes did not design the lever, but his knowledge of the principles of the lever led to designing machines capable of lifting attacking ships out of the water and setting ships on fire using an array of mirrors. He also invented a working model of what could be described as a primitive jet engine; a bronze sphere, filled with water, suspended over a fire - steam would be released via angled "jets", causing the sphere to spin.

  3. I stand corrected, however. The hydrogen fuel cell does not BURN hydrogen, per se. It is as you describe - it generates electricity inside a cell through reactions between a fuel and an oxidant, triggered in the presence of an electrolyte.
    The challenge of getting your hands on hydrogen remain, however; this requires electricity. At this time, approximately 80% of electricity in North America is produced by coal.

  4. Plus, now instead of relying on commonly available resources this country has in abundance (coal, oil, uranium) we are now expected to depend on "exotic materials" the vast majority of which have to be imported.

    Also, flying cars. I read Boy's Life and Astounding, I want my flying car. I don't want to fly it in a three-dimensional version of the 210 interchance in CA...

  5. Generating transportable power (aka, electricity or, in this case, pure hydrogen) on a large scale *can* be done more efficiently (at less cost and less pollution) than on a small scale. Whether or not a method is "green" or not is a matter of viewpoint because while photocells might be considered so, their manufacturing and ultimate disposal are not.
    Let's face it, ultimately all power is solar because it all comes directly or (very) indirectly from the sun. Fissionable materials were made in stars. Water is evaporated (by the sun) and collected behind dams. Plants die and decay and become petroleum.
    A completely "green" cycle (from production through consumption of energy, and which should also include for the apparatus being used at each stage the raw materials excavation, manufacturing, distribution, collection after an item has reached the end of its useful life, and disposal to be recycled) ... a completely "green" cycle is way, way, way beyond our ability.
    Personally, I'm a firm believer in moving on when the garbage pile gets too high. So I support space travel.

    Thanks for the update on the mechanical and civil engineering disciplines. I gave those technologies and engineering processes far too little credit.

    Software? Harrumph! (That's where I earn a living, teaching engineers that use it to do dangerous things. And sometimes what they don't know is REALLY SCAREY!)