Hydrogen

     The eventual fuel for human civilization will be hydrogen. In order for this to happen without major disruption, enough time must be allowed for the transition (about 50 years), and a large and reliable source of hydrogen must be selected. This means that the source material must be renewable and big enough to not be overtaxed by the growing demand of an immense world population with increased industrialization. A review of available alternatives shows that only offshore OTEC/hydrogen meets these criteria. This does not, of course, mean that smaller and/or intermittant renewable energy alternatives should not also be included where they are available.

     The huge energy reservoir in the tropical ocean available via the OTEC process will require a transportable form of that energy to allow access by the demand centers in the Temperate Zone. The most attractive and versatile transportable energy form is hydrogen. There are several natural synergies between OTEC and hydrogen, especially liquid hydrogen (LH₂).

     This scenario was recognized in the mid 1980's by Lockheed Corporation and led to a proposal to construct several 500 MW floating OTEC plants to be located in the tropical east Pacific, the Gulf of Mexico and the tropical west Atlantic. These plants would produce electricity using closed-cycle OTEC with ammonia as the working fluid. The electricity would be used to produce hydrogen by electrolysis and the hydrogen would be liquefied and transported cryogenically via LH₂ tankers (similar to LNG tankers) to Southern California to be used as transportation fuel. The demand for such zero emission fuel was anticipated because of regulations requiring a certain percentage of vehicles in Southern California to have zero emissions. Soon after this proposal was made, Lockheed made a corporate decision to restrict its business to Defense contracts only and to drop civil projects such as OTEC hydrogen.

     The Lockheed proposal, however, proves several important concepts. First, it shows that OTEC hydrogen technology was advanced enough (even more than ten years ago) to support a design by a large and reputable engineering company. Second, it shows that the tropical ocean energy resource to be tapped by OTEC is large and accessible enough to the demand centers in the Temperate Zone to warrant such a study. Third, it shows that the economics of the OTEC hydrogen process were attractive even under the economic conditions at that time.

     Fuel cells powered by pure hydrogen are simple and reliable in comparison to those fueled by hydrocarbons. The usually cited trouble area for pure hydrogen fuel, storge, has several alternative technical solutions. There are also several very promising research avenues for hydrogen-based fuel cell storage, such as carbon bucky tubes.

     Concerns about the safety of hydrogen are sometimes brought up. An objective evaluation, however, shows that hydrogen is likely to be safer than gasoline or methane as a fuel.

A hydrogen economy will be environmentally benign, economically viable and steady, with a long-term future.