Bill: It is not a matter of my THINKING that PEM fuel cells are less efficient than carbonate and solid oxide fc's. It is a fact. I'm sure you can find it in more than one of the available fc links.
The major reason why this is the case is that PEM cells require as a fuel ultra pure hydrogen. To extract that from natural gas or other hydrocarbon requires a reformer, which must heat the fuel up to a high temperature, inject it with steam, run it past some catalysts, and do a bunch of other things to first create a stream of mixed hydrogen and carbon monoxide, and then remove almost all of the carbon monoxide, since that stuff will poison the PEM membrane. This reformer consumes a lot of energy, which reduces the net electrical output of the fc and thus net efficiency. It also adds considerably to the capital cost.
Higher temperature fuel cells don't need a reformer - their internally generated heat is enough to split off the hydrogen that they need, so just feed them plain old pipeline natural gas and they are happy. This makes them much more efficient, and probably cheaper to buy as well, although we won't know that for sure until the various types are all in mass production.
As to why DTE and others have signed up with Plug Power, I can't say, other than they obviously believe that the technological and economic issues can be solved. Also, there is just a tiny handful of companies working on high temperature fc's, and the two major ones - ERC and Siemens - were not seeking deals with anyone. So if DTE and GE wanted to get involved with a fc company, they had to go with a PEM one, of which there are many.
One other thing to think about - DTE, GE, and Sempra are NOT fuel cell
experts; their knowledge is immense in the production and use of turbines, but a fuel cell is not a piece of rotating machinery - it is a chemical process, and these outfits are unlikely to have on staff chemical engineers with a strong knowledge of fuel cell issues.
Plug has made certain promises, and to a certain extent its investors must just take Plug's word for it. They lack the ability to be absolutely sure that Plug will deliver, because even Plug itself can't guarantee that certain problems will be solved.
The money they have invested in Plug is small change for them. It is perfectly reasonable to have placed these bets - many big companies should be doing this sort of thing, IMO, just as most conservative investors ought to have a few bucks on some attractive speculations.
That doesn't mean that every little gamble will be a winner. Look at the big drug companies who had deals with all those biotechs - the ones that work out pay off big, most of the others crash and burn, and that is all right. The drug companies would like to pick all winners, of course, but they know they can't, and they lack the specialized expertise of the biotech company that they are investing in.
In other words, don't be complacent because some big companies have tossed some petty cash Plug Power's way. It is just a reasonable gamble on their part, and that is all it is. If Plug utterly fails, the corporate investors (other than First Albany and MKTY, of course) wouldn't be hurt even to the tune of one cent per share.
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