Hydrogen and Fuel Cells
Fossil and nuclear fuel reserves are becoming increasingly limited, and the world's energy future will have to include several renewable alternatives to these failing resources. A promising possibility is to exploit the energy potential of the most plentiful element in the known universe hydrogen.
We will look at how hydrogen was initially discovered and how it has been used in the past. Next we will examine methods of production, distribution, and transport of hydrogen, as well as how hydrogen can be used safely. Then we will look how hydrogen can be used safely. Lastly, we will examine the present state of the art in terms of energy applications available now, such as fuel cells and hydrogen as a combustible fuel, and we will also consider the developing ideas and technologies that will be used in our energy future.
The quest for understanding the natural world around us is as old as human consciousness. This quest continues in the present day, as scientists and researchers delve with increasing intensity into the mysteries of physics, chemistry, and biology to unlock the secrets inherent in the physical universe.
Atomic Number: 1 Atomic Weight: 1.00794 Electronic Configuration: 1
Hydrogen is a gaseous element that was first discovered by Henry Cavendish in 1766. It is the first element on the Periodic Table. Hydrogen is:
- Slightly soluble in water
- Highly explosive
Hydrogen is the most abundant element in the universe, and serves as the fuel for the fusion reactions in stars. Normal hydrogen is diatomic (two hydrogen atoms chemically paired). Atmospheric hydrogen has three isotopes: protium (one proton in nucleus), deuterium (one proton and one neutron in nucleus), and tritium (one proton and two neutrons). ( 1 )
Paracelsus (1493-1541), a Swiss physician, naturalist and alchemist, was a contemporary of Leonardo da Vinci and Copernicus. In the course of investigating what would become chemistry and medicine, Paracelsus wrote of combining sulfuric acid and iron, noting that this combination produced a gas or "air" as he conceived it at the time, and that when this air was produced it was released under considerable pressure.
Later a French chemist, Nicholas Lemery , showed that the gas produced in the sulfuric acid/iron reaction was flammable, but it was Henry Cavendish (1731-1810), a British physicist, who was credited with the discovery of hydrogen in 1766. Another French chemist, Antoine-Laurent Lavoisier (1743-1793), considered the founder of modern chemistry, described one of the component elements of water as hydrogen , from the Greek words hudor (water) and gennan (generate). It was also Lavoisier who noted that the only byproduct of burning hydrogen was water itself.
In 1802 a British chemist named Sir Humphry Davy (1778-1829) was studying the chemical effects of electricity when he found that by passing an electric current through water, he was able to cause the water to chemically decompose into its component elements of hydrogen and oxygen. This process, which later became known as electrolysis, led Davy to theorize that chemical compounds are bound together by electric energy.
Working with the concept of chemical decomposition through applied electricity, a Welsh lawyer and non-scientist who was also a knighted judge, Sir William R. Grove, expanded on the work done by Sir Humphry Davy. Grove demonstrated that the process of chemical decomposition could be reversed, and that hydrogen and oxygen could be compelled to bind together forming water. At the same time the process produced an electric current that "could be felt by five persons joining hands, and which when taken by a single person was painful." Grove's discoveries came to fruition in the form of the first hydrogen fuel cell, which he invented in 1839. While it would be over one hundred years before interest was rekindled in Grove's work, it would prove to be extremely important in fuel cell technology, which today is the main source of electric power for space vehicles.
During the latter part of the Nineteenth Century , before the advent of what we now know as natural gas, a hydrogen-rich gas was produced from coal to be used in the gas lamps and heaters of European and American homes. Known in the U.S. as "town gas," and consisting of 50% hydrogen and 50% carbon monoxide, this fuel helped lay the foundation for the safe use of hydrogen, which due to its highly volatile nature, must be handled and transported with the utmost care.
For most of us, the most infamous use of hydrogen was in the lighter-than-air zeppelin. While balloons and flying air ships had been using hydrogen for almost fifty years, it was the development in 1900, by Count Ferdinand von Zeppelin of Germany, of the rigid framed air ship that allowed for greater speed and durability in flight than had previously been possible. With its aluminum skeleton framing a solid outer shell, von Zeppelin's first ship, the LZ 1, was designed with military applications in mind, opening up the possibility of long range battlefield reconnaissance from the air, as well as opportunities for tactical options like dropping bombs.
With Germany's entrance into World War I, zeppelins were equipped with bombs and machine guns, making them dangerous targets for the fledgling efforts of early British air forces using the limited biplane technology of the time. Bombs were carried from German held bases in France , and dropped with impunity over London . While the accuracy of these attacks was very poor, they served a devastating psychological role in demoralizing Britains . By the end of the war however, improvements in airplane design and capability, as well as the innovation of the phosphorus coated incendiary tracer bullets spelled the end of the hydrogen-filled dirigible.
Following World War I , Germany and the United States both continued with the development of rigid framed air ships, enhancing their air speed and reliability. Especially in Germany , these huge dirigibles, often over four hundred feet in length, became commonplace, and were used extensively for luxurious passenger travel. In 1928, the Graf Zeppelin, designated LZ127, was launched, and would go on to fly farther than any zeppelin before or since.
Test flown initially in March of 1936, the zeppelin Hindenburg would fly into history as perhaps the most memorable air disaster of the Twentieth Century. Having made the transatlantic crossing from Germany to Lakehurst , New Jersey ten times in the year previous to May of 1937, the 804-foot air ship represented the state of the art in zeppelin design, and such trips were fairly routine.
American manufactured air ships had by this time switched to the less volatile and nonflammable lighter-than-air helium gas. However, the German ship still used hydrogen as its lift medium, a fact which still generates controversy sixty years after the events that would indelibly link the Hindenburg tragedy with the dangers of hydrogen gas.
On May 6, 1937, as the Hindenburg approached its mooring tower at the Lakehurst Naval Air Station, it burst into flames. While the fire consumed only the zeppelin's cover material at first, it quickly ignited the explosive hydrogen within the massive ship. Thirty-five of the ninety-seven people aboard the Hindenburg lost their lives that day, as well as one American Navy crewman on the ground.
The continuing controversy over the cause of the Hindenburg crash is central to the issues here, as modern historians and investigators differ in their opinions as to the chain of events leading up to the disaster. Unsubstantiated rumors of sabotage not withstanding, opinions differ as to whether the fire was started by leaking hydrogen ignited by a static electricity spark, or by static electricity starting a fire in the zeppelin's cover material. Thunderstorms were passing through the Lakehurst area that day, providing ample conditions for a static discharge, but whether it was the cover material or leaking hydrogen that provided the fire with its starting place will probably never be known.
The Hindenburg experience has actually helped ensure the safe handling of hydrogen in what are primarily industrial applications in the present. Safer storage mediums have also been developed, which will be described later, replacing earlier dangerous storage. The perception that handling hydrogen is inherently dangerous has done much to hamper the public acceptance of hydrogen research and applications. However, properly handled, hydrogen is no more dangerous than gasoline or propane. Curiously, it was reported that no fatality from the Hindenburg accident was directly attributable to hydrogen burns, as the millions of cubic feet of hydrogen burned off in less than one minute. It was the diesel fuel, which powered the air ship's drive engines, that burned many of the dead and injured that day, as well as feeding the ground fire which took several hours to extinguish.
It was in the United States that Francis Bacon, a descendant of the famous English scientist and philosopher, developed the first modern successful hydrogen fuel cell in 1932, which was refined until a 5 kilowatt fuel cell system was demonstrated in 1952. As the United States began its push for space flight in the late 1950's, fuel cell technology appealed to many scientists and engineers. It was much less dangerous than any known nuclear application, much more compact and lighter than any type of battery, as well as being simpler to deal with mechanically than any solar photo-voltaic technology available at that time. Today hydrogen fuel cells provide much of the electric power for the Space Shuttle, as well as power for electric automobiles and varied other emerging applications. With a little imagination we can see the direct line from Paracelsus five hundred years ago to the possibilities that lay in front of us in the near future.