Sucking, up, sea water... those must some poorly designed radiators OOOR it could be a specially designed engine for space travel using a renewable resource of fuel for those hydrogen engines using electrolysis to break up the hydrogen, oxygen and sea-salt molecules; using the compressed liquid hydrogen as a fuel with oxygen quickly to create a burning reaction. The only major issues are storage tanks both for the sea water, the hydrogen gas and a light weight composite material tank designed to compress hydrogen into a liquid which requires tremendous strength and dangerous pressure levels. Also hydrogen doesn't burn as hot as other liquid or solid fuels and it almost immediately forms into water vapors as an exhaust; the light it produces is also barely visible to the naked eye. Could hydrogen explode? Yes, but the probability is extremely low since hydrogen is lighter than air, the gases will float away almost instantly. The concentration would have to be greater than the amount that it can dissipate into the air and form water molecules.
Believe it or not I did a 52 page project for my senior year graduation essay that lasted an hour and a half in 2008 about hydrogen vehicles for terrestrial, aerial and aquatic machines. I did far more visiting of companies and gathering physical research on experimental projects that were happening throughout the US; I got an A+ with a score of 98% for both knowledge and presentation. I even had two company representatives join me for my presentation to the school board, teachers and staff; it was quite a scene. Too bad I didn't get any job offers though . The hydrogen field is still new and experimental to this day. There are some companies introducing hydrogen cars to the public in California but that's about it mostly. The new BMW i-series electric car (Vision) was proposed to use a hydrogen engine instead of a gasoline or diesel fuel engine to generate electricity buuuut that idea fell off through the floor rather quickly because the technology for storing hydrogen has not advanced enough for everyday practical use; doable but still far too complex for the average person to comprehend with ease.
SO these aliens could be using advanced hydrogen engines of some sort... that's very cool!
I don't know, it's concept art.. this isn't even real and I'm not gonna waste time thinking about probabilities or the possibilities of some make believe alien race with technology that is barely understood. Yes, it is possible to turn seawater into fuel but that discovery was recently found and the process for making that fuel is inefficient at the moment. Honestly I don't care, I was simply sharing a thought; that's it.
I have a friend whose sister claims she saw a car that runs on water (though it isn't the drinkable kind) , that she even saw it being tanked. It was in Norway or some place, her friend worked for a company that had a prototype.