Saturday, May 25, 2013

Intriguing combination of chemicals leads to shortcut and a killer app for molten-salt reactors

By looking for some clues of what happens when calcium hydroxide and ammonia is mixed together, I found this


Then this:

Yahoo answers
So, this is a shortcut to the process that I've been looking at.

To recap, I wanted to find a way to economically obtain hydrogen for use in a fuel cell.  The problem with hydrogen, is that it is very light weight and is hard to transport efficiently.  It will need "infrastructure" for this purpose.

Now, this proposed system will not remove the need for infrastructure, but it will remove the difficulty of transporting hydrogen.  Ironically, it accomplishes this task by not transporting hydrogen at all.


Instead, it will entail the transport of solids, which at the distribution site to the consumer, will be converted into hydrogen safely and in an environmentally friendly way.   The solids are ammonium carbonate ( common smelling salts ) and calcium oxide ( quicklime).  Both processes to produce these solids are reversible and therefore "close the loop" for their production.  Aside from the initial mining to produce them, no additional mining will be necessary as the materials are recycled over and over again ad infinitum.

The process does require the production of a carbon feedstock, but this process can be biological, thus keeping it environmentally friendly.

This feedstock will produce ammonia which will be used for the production of the smelling salts.  Smelling salts are none other than the combination of ammonia with carbon dioxide.  It produces the solid which can be transported conveniently.

The quicklime is produced in kilns from limestone.  The limestone needs only to be mined once.  That's because the quicklime can be combined with water and this results in calcium hydroxide, which can absorb carbon dioxide to form calcium carbonate---the main component of limestone.  So, the quicklime is what is shipped to end distribution points for sale to consumers.

At these locations, the materials are combined with water.  Combining the resulting calcium hydroxide ( above graphic ) with the smelling salts in an aqueous solution will produce the ammonia once again.  The ammonia can be cracked into hydrogen, which is compressed and cryogenically stored and sold to consumers.  The production of hydrogen can thus be done at the point of sale, which obviates the need to transport it.

To produce the solids mentioned requires a lot of energy.  So, how do you keep that environmentally friendly?

Use a molten-salt reactor.  Now, this isn't totally waste-free, but it is a lot better than solid-fuel, water-cooled reactors that create so much waste.  Not to mention the good stuff that can be useful products as well.

The reactor will bake out the carbon dioxide from the calcium carbonate, which produces the calcium oxide that is shipped as mentioned above.

It can also produce the ammonia from biological feedstocks.

What's not to like?


Perhaps this is not as easy as I thought.  Making the ammonium carbonate is more complex than I thought.


A modified version of the Solvay Process can get you back to the point described in the above update.  You will need salt ( sodium choride ).

Still works, but it is just a little more complicated.


Part of a series, maybe one of the last parts.  Let's call it part x for now.

The series is called Killer App for Molten Salt Reactors.


The original post is here.  Call that one post # 1.  There are several posts in between, which shows the evolution of the idea.

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