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

Several interrelated issues.

[nanojath]

There are two distinct technologies here and their feasibility needs to be discussed separately. The first is a novel engine design for converting power into locomotion. I don't have the engineering knowledge to judge this, but there do seem to be some people who ought to know saying the concept is solid.

But it should be noted this isn't anything new. The internal combustion engine is innefficient by nature. It takes a spherical force (an explosion), redirects that into a vector force (up and down in a straight line), redirects that into a circular force, which is redirected into another circular force, finally driving the car. Each of those redirections wastes energy. Moreover, the fact that you have carbon monoxide and other hydrocarbon emissions is a sign of innefficient combustion: complete combustion of a carbon molecule goes all the way to carbon dioxide. There are plenty of legitimate projects to find a better way. Ben Rosen, chairman of Compaq, has envisioned the automotive powertrain market becoming like microprocessors, with independent companies competing to supply the most efficient engine. His Rosen Motors produced a working prototype of a hybrid-electric motor; they've since been taken over but I forget by whom.

Of course, a serious problem is the huge combustion engine and gasoline infrastructure. Even a much better product is not going to take over overnight. The internal combustion infrastructure would keep the economics of conventional motors attractive for decades, barring a serious kink in the gasoline supply.

It is a myth, though, that the automotive manufacturers are blocking this kind of thing. They're all doing research of their own. There is nothing a manufacturer wants more than to obsolete their own product and give everyone a reason to buy the next big thing.

The other technology discussed here is photovoltaic (solar-electric) conversion of water to hydrogen for combustion. I think this is far more theoretical. Not that you can't very simply and reliably bang an electric current through water and get combustible hydrogen and oxygen. But from what I know (and I do have some knowledge on this subject) I seriously doubt whether existing photovoltaic cells are efficient enough to supply the power for even a very efficient automotive engine by splitting water. It should be noted that like anything else, this conversion of electrical power into chemical power represents a loss of efficiency, so the purpose for doing this is to get the benefit of a combustible fuel.

Direct solar cleavage of water to H and O is one of the holy grails of both hydrogen power and solar research; this photochemical process is at the heart of how plants utilize the energy of the sun and hence the source of most energy on earth including all fossil fuels. We aren't there yet. It can be done but it isn't sufficiently efficient to be practical. There are tons of novel catalytic techniques being experimented with, where rather than go through a photovoltaic cell (the conversion of sunlight to electricity of course represents another inefficiency), sunlight is used as the power source to directly, catalytically cleave water. I think within a few decades this kind of thing will start to make significant inroads, provided countries like Iceland and companies like Daimler Chrysler continue to pursue hydrogen research and a hydrogen energy economy.

I don't see anything in the article, however, that suggest this motor could only run on hydrogen. So it may be a valid concept that it much closer to commercial reality.