Guide to the Elements - Hydrogen

(11/17/2008) - Everything in our world is constructed of basic components – elements.  There are eighty-something on Earth that are not the result of synthetic production or decomposition, and many of them play necessary roles in our lives. 

In the spirit of Stephen Colbert’s Better Know a District series, The Finite Planet presents the first installment of its 84 part series, “Guide to the Elements.”  How much is there?  What do we use it for? Can it be recycled?  These questions and more will be covered.

Guide to the Elements: Hydrogen

What is it? Hydrogen is the simplest of the elements and composes the majority of the universe's mass.  The most common form of hydrogen has one proton and one electron.  It has two isotopes, with one and two neutrons respectively.  Hydrogen is extremely reactive and, to my knowledge, is never found alone in nature. 

Why should I care? As one of the two elements that compose water and a key part of carbohydrates, proteins, and fats, there is no doubt hydrogen is essential for life.  As hydrogen is an incredibly abundant element on earth and is easily recycled by natural processes, a hydrogen-induced protein or water shortage is unlikely. On the other hand, hydrogen in its purest form, H2 must be synthetically purified before it is used in a number of important industrial settings.

One of the key industries in which hydrogen plays a part is industrial farming.  Hydrogen is combined with nitrogen (N2) and heated over an iron catalyst to synthesize ammonia, which is used as a fertilizer or combined with other chemicals to create even better fertilizers (ie. ammonium nitrate). 

Like to eat?  The entire industrial food system, which provides the vast majority of calories consumed in the United States, if not the world, relies upon ammonium-based fertilizers to deliver nitrogen to plants, without which they could not grow.  Without ammonia-based fertilizers, farmers need to use animal-based fertilizers (i.e. cow patties) or nitrogen fixing plants such as legumes to put nitrogen back into the soil.

H2 is also used to refine petroleum by removing nasty impurities like sulfur from sour crude.  Partially and fully-hydrogenated fats are produced using hydrogen, and some forms of welding use the gas as well. 

Hydrogen might also have a role in our future energy economy.  Fuel cells produce electricity by combining H2 with atmospheric oxygen to produce water vapor.  Fusion energy, as is currently being developed by projects such as ITER, will hydrogen isotopes deuterium and tritium as fuel.

Where does it come from?  Even though hydrogen consists of a substantial portion of the earth’s crust and biosphere, it is almost always combined with other elements.  The amount of free hydrogen in the atmosphere is virtually non-existent. 

The primary source of hydrogen used in human industry comes from processing hydrocarbons such as coal and natural gas.  Currently, this is by far the most economical method to produce large quantities of the gas. 

Can we recycle it?: Kinda.  Hydrogen extracted from hydrocarbons is a one-shot deal, but we can always produce hydrogen from water using electrolysis.  This isn’t exactly recycling in the usual sense, but it is close enough.  Electrolysis is currently 3 times as expensive as producing hydrogen from coal.  Using electrolysis to produce hydrogen for fuel cells is also not very efficient – 60% of the energy is lost due to a drop in voltage.  

Are there environmental concerns?  In gaseous form, hydrogen doesn’t pollute the environment or contribute to global warming.  Hydrogen is a major component of water vapor, which is a greenhouse gas.  However, I suspect that purified hydrogen gas turned into water is a very, very small source of water vapor creation.    

Excess use of ammonia-based fertilizer, however, can cause huge problems.  Fertilizers wash off of fields when it rains, polluting local water sources.  At the mouth of large watersheds, fertilizer causes algae blooms that in turn kill off most sea life in the area creating a dead zone.  The dead zone at the mouth of the Mississippi River, for example, covered 4,564 square miles in 2005.