Hydrogen-based Rotary Engine?

Seabird99 writes: "I came across this article at one of my car related forums and thought that I'd pass it on here. I have always been intrigued by "alternative" technologies where they relate to artificial locomotion." For some reason Slashdot gets a lot of submissions of wacko energy concepts - power from nothing, power from sand, power from a black box, engines that get 500 miles to the gallon... Perhaps this is more of the same, but at least it's an interesting write-up.

Comments

Wacky?

[tomknight]

I guess that'd explain why Mazda have bothered to push money into researching this....

Here's a little more info if you weant to do some research.

Tom.

Addressed in article

[SiliconJesus]

The solar-voltaic energy stored in the garage would enable a small electrolysis machine to seperate the water into its base components (hydrogen and oxygen) for the car's fuel. Presumably this could be echoed on the commercial side, having large `plants` that would essnetially break water into its base components. Couple this with his other invention (the de-salinizer) could turn the oceans into giant fuel fields, that would be replenishing ((2)H2 + 02 = (2)H20). Infinate energy. Viola!

As envisioned by McMaster, Cicak, Guy, and others working on the MRE, the engine is the centerpiece of a revolution that reaches well beyond automotive technology to challenge basic assumptions about energy and the environment. McMaster calculates that 1,200 square feet of solar panels on the roof of a garage receiving 2,200 hours of sunshine a year could, with the help of an electrolysis device no bigger than a washing machine, produce enough hydrogen and oxygen to drive an MRE-powered car 200 miles a day. The oxygen would be bottled in scuba-like tanks that would snap into place under the hood. The hydrogen, more volatile and more dangerous, would be piped around the car's chassis through 180 feet of tubing, divided into 3-foot sections, each sealed off from the next by a set of valves.

McMaster Motor site

[kryzx]

Here's the McMaster Motor site complete with a little animation of the engine.

Looking at it helps me understand the way it works. I don't know if this will ever come to fruition, but I sure hope it does. Even if it doesn't, he's a revolutionary thinker with a significant record of success, and deserves our praise and respect for that.

Hard to compress hydrogen

[AlpineR]

LPG stands for Liquified Petroleum Gas. It's a mixture of propane and butane. The advantage of these gases is that it takes only a moderate pressure at ambient temperatures to convert them to liquids. Liquid fuel is great because it's compact and easy to transport.

Hydrogen, on the other hand, has a boiling point of 20 K at atmospheric pressure (a bone chilling -423 degrees F)! So tanks would need some serious insulation in addition to handling high pressure. Due to its smaller molecules, it also leaks easier than LNG.

The best way to store hydrogen is probably in a hydrogen-rich compound like methanol, which is liquid at ambient conditions. My research group, among many others, is studying ways to efficiently convert methanol to hydrogen + carbon dioxide + water at the point of use. This would allow us to fuel our cars, RV's, or cell phones with convenient methanol and then run hydrogen fuel cells.

Don't worry about the carbon dioxide from that reaction. The methanol would presumably come from biomass or nuclear/solar-powered synthesis that consumes carbon dioxide. The carbon is just a carrier for the hydrogen, and there is no net CO2 pollution.

AlpineR

Re:Hard to compress hydrogen

[Fenris2001]

Methanol might not be the best way to store hydrogen...

A properly designed hydrogen=powered engine would be able to burn slightly "dirty" fuel - such as hydrogen containing a few percent methane.

Adding methane "gels" the hydrogen at low temperature, making it easier to liquefy, store and transport.

This mixture woud still have the advantage of having vapors that are lighter than air, and thus rise in the event of a spill, rather than pooling in low spots and creating an explosion hazard.

Most leaks in a tank come from the seals and joints of the tank, but hydrogen leaks mainly by diffuing throught the tank walls. At high temperatures, this is significant, but at low (~50K) temps, it's hardly a show-stopper.

I'm not bashing carbon-based fuels, just pointing out that there are many alternatives we should pursue in the quest for clean energy.

Re:Next Problem

[ivan256]

The surface area of the roof of your garage doesn't collect enough sunshine (Even if you never had a cloudy day) enough to power your car if you drive more then a few miles a day.

Re:Next Problem

[plover]

Yes, a "gasoline well" doesn't exist. But the raw crude from an oil well comes complete with enough internal potential energy to crack a usable amount of it into gasoline. The refiner simply burns part of his raw product to produce the heat required to crack the rest of it.

A bottle of water doesn't have enough energy present to split it into hydrogen. You can say "yes, if it's at 30,000 feet or 99 degrees C" or whatever, but that bottle of water required EXTERNAL energy to raise it to that potential. And that external energy is the entire point. It had to come from somewhere, it's not free.

Until someone invents a way to "crack" water (with some off-the-wall fusion theory or whatever) there will always be a need for an external energy source to split it. Whether it comes from solar panels on your garage roof or a coal-fired plant in Montana over electric lines doesn't change the fact that EXTERNAL energy was required to make it useful.

John

hydrogen much maligned and misunderstood

[FreeUser]

Aviation types (of which I, as a pilot, am one) have an unreasoning, almost supersticious fear of hydrogen dating back to the Hindenberg disaster. Unreasoning because it is uncritical ... the hindenberg was painted with a metallic grey/silver compound which, it turns out, was basically rocket fuel. Yes, the derigable was painted with rocket fuel, which was ignited by a spark (probably a result of a static electrical discharg). The rocket fuel "exploded", while the hydrogen burned more slowly.

Indeed, your statement:

Hydrogen gas just doesn't pack as much punch, specatcular disasters caught on tape notwithstanding, as gasoline

catches a part of this truth, though more in passing, namely that a tank of hydrogen is less explosive than a tank of gasoline. Meaning, as you say, that there is less energy / volume in hydrogen gas than there is in petroleum liquid (gasoline). Two approaches to this problem are, as implied in this article and the designer's web page, a more effecient engine or, alternatively, an innovative use of chemistry to allow a hydrogen-rich compound to exist as a more dense liquid/solid at room temperature without binding the hydrogen so tightly as to make it useless as a source of energy.

Hydrogen is safer to store, transport, and use than gasoline, by virtue of the very fact that it packs less energy per unit than gasoline. Safety fears are really just that, fears, based on a widely debunked perception that dramatic explosions such as the hindenberg were a result of hydrogen, when in fact it was a result of painting the damn ship with a compound now used as rocket fuel, a compound much more combustible than hydrogen by orders of magnitude. That debunking aside, there remains the perception that hydrogen is this dangerously explosive gas, when in fact it burns too slowly to even explode with the same intensity that a 1972 Ford Pinto's gas tank would when rear-ended.

Explanation of engine...

[cr0sh]

I have read a lot of posts here regarding this engine, and I am not absolutely certain that everybody understands how this engine is supposed to work. To be honest, I am not completely certain on how it works, but from looking at the animations and descriptions, I want to attempt to explain it, in the interest of furthering discussion.

I have to admit, the fascinating thing is the fact that it is so simple - so simple that it looks like it could almost be homebrewed in a garage, provided the builder has sufficient machining skills and tools (ie, a metal lathe and mill would be an absolute necessity, as well as a wire-feed welder, among other tools).

Anyway, here is my explanation:

1. The engine is composed primarily of 6 parts: A shaft (1) which is fitted through a sphere (2) and two opposing, on either sides of the sphere, conical ends (3,4), a metal vane (5) which is slotted between the cones, and thus doesn't move - parallel to the shaft/sphere assembly, and perpendicular to the metal vane. Finally, there is the wobbly plate (6), which is fitted around the sphere, and has flattened ends that are up against the metal vane. This plate bisects the sphere, forming two independent combustion chambers. However, it is not attached to the sphere, it does not rotate, and it is not attached to the vane. It merely "slides" against these parts.

2. Now, imagine the metal vane lying at an angle. At the point where one end is touching the cone, and the vane, there is a fuel inlet and a glow plug. Fuel is admitted, and the glow-plug ignites the fuel.

3. As the fuel combusts, it expands, pushing against the plate and the vane, as it races around the chamber, which looks like a expanding wrapped wedge around the sphere. This expansion causes the plate the nutate (wobble) - but not rotate - around ("around" is not a good word, as it implies that the plate is rotating - I must stress that it does not rotate) the sphere. This opens up the chamber, and as the plate slides around the sphere (*), it rotates the sphere 180 degrees, which is connected to the shaft, which turns the shaft 180 degrees.

4. Once the combustion is started, of course the fuel inlet is closed. When the combustion is completed, the plate is now lying at the opposite angle. An exhaust port is opened (I would imagine the opening and closing of exhaust and inlet ports to be accomplished by solenoid valves of some sort), and the inlet port on the other side is opened to cause the other side to fire, to rotate the shaft 180 degrees more, while simultaneously pushing the exhaust out (by action of the plate) on the opposite side.

5. The cycle repeats.

(*) - Notice how many parts are sliding against each other? I can't understand how this thing is supposed to run dry - ie, no lubricant - unless the fuel is to provide the lubrication of some sort. All that friction will get it damn hot if it isn't lubricated and cooled in some manner.

Furthermore, I am not certain how the plate, rubbing up and acting on the sphere (nutating "around") spins the sphere, unless is it by some strange vector motions being imparted by friction.

The interesting thing about this, though - is if that is the case, if the motor shaft is somehow stalled for whatever reason, the engine shouldn't die - it should only become hotter than normal, which may or may not be a good feature.

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I hope this explanation helps - I hope it is right, I am pretty certain it is. Please discuss below, and comment on it - I would be pleased to know what others think...