An internal combustion engine that uses hydrogen for fuel. Hydrogen had already been gathering attention last century as a possible replacement for fossil fuels, with many even calling it mankind's ultimate energy source. The only by-product of hydrogen when combusted is water vapor; it does not produce any carbon dioxide, a major contributor to global warming, nor any nitrogen oxides, which pollute the atmosphere. The construction of Beyond Coast, which needs to maintain its CELESS to survive, helped advance research in this area considerably. It is also possible to store large amounts of hydrogen in metal hydrides, or compounds containing hydrogen in combination with other substances; these have reduced the amount of necessary fuel storage space compared to previous combustion engines.
Its high energy conversion rate has led to the use of the hydrogen engine in the flight units of BCP's EMPS. There is also research being conducted to examine whether this type of engine can be used in motor vehicles on Beyond, which currently operate purely on electric and solar energy.