7. Hydrogen fuel

Hydrogen fuel

Unlike the other energy sources in this article, hydrogen fuel must be manufactured with a net loss of energy. When manufactured from natural gas it is, like gasoline, a derivative fuel; when produced using electricity, it is a form chemical energy storage as in storage batteries.

In using hydrogen as a fuel, there are two basic alternatives: (1) a fuel cell can convert the chemicals hydrogen and oxygen into water, and in the process, produce electricity, or (2) hydrogen can be burned (less efficiently than in a fuel cell) in an internal combustion engine.

Pros:
Hydrogen is colorless, odorless and entirely non-polluting, yielding pure water vapor (with minimal NOx) as exhaust when combusted in air. This eliminates the direct production of exhaust gases that lead to smog, and carbon dioxide emissions that enhance the effect of global warming.
Hydrogen is the lightest chemical element and has the best energy-to-weight ratio of any fuel. Because of this, hydrogen can be economically competitive with gasoline or diesel as a transportation fuel.
Hydrogen can be produced anywhere; it can be produced domestically from the decomposition of the most abundant chemical on earth: water. Consequently, countries do not have to rely on OPEC countries for fossil fuels. Hydrogen can be produced from domestic sources and the price can be established within the country.
Electrolysis combined with fuel-cell regeneration [4] is more than 50% efficient; more efficient than pumped hydro and many other forms of mechanical storage.
Stationary storage with double-walled tanks is stable over long periods of time; hydrogen which outgases from the interior can be pumped back in.


Cons:
Other than some volcanic emanations, hydrogen does not exist in its pure form in the environment, as a gas, because Earth's gravity is not strong enough to hold it at bay at the existing temperature (temperature provides the escape velocity. Helium also isn't retained.) There is concern that a hydrogen economy based on nonhydrocarbon or unreacted hydrogen sources would negatively affect Earth's overall hydrogen budget due to leaks into the atmosphere, and then from the atmosphere into outer space.
It is impossible to obtain hydrogen gas without expending energy in the process. There are three ways to manufacture hydrogen;
By electrolysis from water - The process of splitting water into oxygen and hydrogen using electrolysis consumes large amounts of energy. It has been calculated that it takes 1.4 joules of electricity to produce 1 joule of hydrogen (Pimentel, 2002).
By breaking down hydrocarbons - mainly methane. If oil or gases are used to provide this energy, fossil fuels are consumed, forming pollution and nullifying the value of using a fuel cell. It would be more efficient to use fossil fuel directly.
By reacting water with a metal such as Sodium, Potassium, or Boron. Chemical by-products would be sodium oxide, potassium oxide, and boron oxide. Processes exist which could recycle these elements back into their metal form for re-use with additional energy input, further eroding the energy return on energy invested.
There is currently a lack of infrastructure and distribution network required to support the widespread use of hydrogen as a fuel. It would cost a lot of money and energy to build hydrogen plants and to replace every car and bus with a hydrogen engine and fuel tank.
Hydrogen is complicated to handle, store, and transport. It requires heavy, cumbersome tanks when stored as a gas, and complex insulating bottles if stored as a cryogenic liquid. If it is needed at a moderate temperature and pressure, a metal hydride absorber may be needed. Transport is also a problem, because hydrogen leaks effortlessly from containers, reducing the efficiency of the fuel. These hassles make hydrogen power very expensive.
Current efficient fuel cell designs are expensive since they need Platinum as a catalyst. If we were to replace every Internal combustion engine with a Fuel cell then we could potentially use all the Earth's Platinum reserves in two years.

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