Lighter Than Air, Better than Gas


BISHOP-172Gasoline is pretty amazing stuff.  It has a high energy density, can be manufactured and delivered for less than the cost per ounce of bottled water and has allowed a transportation infrastructure to be developed that has reshaped the face of America.  It has changed how and where we live and work.  If it weren’t for the minor issues that we are rapidly running out of the stuff and that burning it trashes our planet, we would be good to go.

A lot of thought and research has gone into thinking about what we can replace it with for transportation.  While battery powered vehicles get a lot of press, there are some pretty fundamental limits that will restrict their use.  Basically, the problem is that batteries are mostly a terrible way to store energy.  In a world with Moore’s Law telling us that semiconductors and computers get a factor of two better every 18-24 months, progress in batteries pokes along at a pretty leisurely pace.  Your great-grandfather would recognize a “D” cell and know what it does but would have no clue about what your IPhone is.

So alternatives are being actively worked.  One serious contender is what is called the “hydrogen economy”.  Fuel cells can convert hydrogen into electricity cleanly, simply and without emitting any greenhouse gases and so one can envision powering cars with hydrogen.  The Hindenburg notwithstanding, it is not a crazy idea.  There is a lot of it on the planet, we call them the oceans, the fuel cell technology is rapidly progressing and many of the technical hurdles are being overcome.  One such area with rapid progress is in how we generate the hydrogen to begin with.

Folks at Boston University are at the forefront of this research.  Srikanth Gopalan and his co-workers are developing systems that act as catalysts for the decomposition of steam into hydrogen and oxygen.  Using membranes made of Gd0.2Ce0.8O1.9-d-Gd0.08 Sr0.88Ti0.95Al0.05O 3+/-d they have found a way to separate hydrogen and oxygen.  I know, it does look like a complicated system but that’s the kind of stuff scientists play with these days.  What happens here is that the steam is placed on one side, a hydrocarbon fuel on the other, and the membrane conducts ionic** oxygen to the other side with a balancing flux of electrons leaving free hydrogen.

There is a lot of work to be done to make it inexpensive and scalable to industrial capacities but the research has real promise.  So someday you might be driving to work using technologies developed at BU.  Now, if we could only think of a way to reduce the traffic, that would really be something.

Oh, wait, we have invented a technology that will reduce the traffic in cities.  But that is a story for another day.


Dave B.

*Electrochimica Acta 56 (2011) 6989-6996


**Two atoms were walking down the street and meet each other.  One said “How are things?” “Not so good, I’ve lost an electron.” “That’s terrible, are you sure?” “I’m positive….”