I was thinking that producing the hydrogen feed stock would be most of the energy used in the process. This site [1] states that, using the current global feed stock mix of light carbon and heavy carbon sources, about half the energy used in production is feed stock energy and half is added energy. Maybe an industrial chemist could estimate how much energy this new tech could save if it could be used at the scale needed?

[1] http://ietd.iipnetwork.org/content/ammonia