Tag Archives: oxygen

Free lunch?

I know there is not supposed to be any such thing as a free lunch, but maybe chemist Karen Brewer has reduced the price considerably.

Over the past few years the ever increasing cost of gasoline, coupled with the increased scrutiny of possible changes in global climate that may be a result of man-made acivities, has once again focused our national attention on alternative sources of power, or at least alternative fuels.

I’ll take a look at some new technology for producing fuels from plant matter and such at a later time, but right now I want to look into the generation of hydrogen from sunlight.

Hydrogen can be used as a fuel for two major power generating schemes.  First, there are hydrogen burning engines.  As the name implies, these are essentially internal combustion engines that burn hydrogen instead of gasoline.  Prototypes of these  vehicles are being tested now in some places, such as this bus in Iceland and the Ford P2000 automobile.  Then there are vehicles that utilize electric drive powered by hydrogen fuel cells, which combine hydrogen and oxygen to produce electricity and waste water, as demonstrated in this fuel cell bus.

One of the bigger problems associated with hydrogen power is….well….where do you get the hydrogen?  Normally, hydrogen is produced by hydrolysis, that is by passing an electric current through water and breaking it down into hydrogen and oxygen.  But the electricity has to come from somewhere, so if you use fossil fuels to generate the electricity to generate the hydrogen, it begins to look like you are not really gaining anything.  Every time you convert energy from one form to another, you lose a little in the conversion.  So, while the burning of hydrogen is much better environmentally than burning fossil fuels, if you have to burn fossil fuel to generate the hydrogen, you still lose.

Another way to generate electricity is to use solar cells.  Sunlight falls on silicon photovoltaic cells which then produce electric current, and that can in turn be used to generate hydrogen via hydrolysis.  Of course, the solar cells have their own problems, so that efficiency thing comes back to get you.  No free lunch here.

To get around this problem, chemist Karen Brewer has figured out a way to generate hydrogen directly from sunlight.  No solar cells, no algae gardens, just plain old sunlight.

For many years Brewer has been researching how to use materials and catalysts to break molecules apart.  She has been experimenting with certain molecules that essentially perform a function like photosynthesis, except in reverse.  Instead of using light to put molecules together, she uses light to break them apart.  By adding some of her materials into a water solution, and then shining light on it, she can directly break the water molecules apart into hydrogen and oxygen without using electricity.  If you want to know more, read all the geeky details in these papers from her research group.

So, of course her work is in its early stages, but it promises to provide a pathway for more efficient hydrogen generation by eliminating the need for electrical current, which is a good thing.  Maybe not a free lunch, but at least a cheaper one.

Leave a comment

Filed under Energy, fuel, Materials