hho? A quickl spin through Wikpedia just to make sure this wasn't some new acronym for an electrical gadget and I find:
1) Herbig–Haro object
being a "distinct type of emission nebula" formed by a new star, the most I can claim for emmissions is out my Exhaust ports...... so I guess you're not trying to make one of them.....
2) Home heating oil
Mine is sufficiently old I could probaly burn the stuff & generate a couple of gee gees (I did get a clamshell to run on diesel many years ago! - a 30HP behaved like a 2.5, but it ran) I guess you don't want a refinery on board to generate the stuff, so probably not that....
3) Brown's gas and HHO are fringe science terms for a 2:1 mixture of oxyhydrogen allegedly endowed with special properties.
Oxyhydrogen - Wikipedia, the free encyclopedia
You seriously talking about this?