Hydrogen History Before 1960

British scientist Henry Cavendish (1731-1810) demonstrated to the Royal Society of London in 1766 that there were different types of air: ‘fixed air’ or carbon dioxide and ‘inflammable air’ or hydrogen. Cavendish evolved hydrogen gas by reacting zinc metal with hydrochloric acid. He proved that hydrogen is much lighter than air and was the first to produce water by combining hydrogen and oxygen with the help of an electric spark in the late 1770s.

In 1783, Jacques Alexander Chales, a French Scientist, launched the first hydrogen balloon flight. Known as “Charliere” the unmanned balloon flew to an altitude of 3 km. Three months later,

he himself flew in his first manned hydrogen balloon.

In 1785 Lavoisier repeated Cavendish’s experiments and proved that hydrogen and oxygen were the basic elements of water. Named by Lavoisier in 1788 Hydrogen is from two Greek words, hydro meaning water and genes meaning ‘born of’.

In 1800 William Nicholson and Sir Anthony Carlisle discovered electrolysis and initiated the science of electrochemistry. In their experiments they employed a voltaic pile to liberate oxygen

and hydrogen from water. They discovered that the amount of oxygen and hydrogen liberated by the current was proportional to the amount of current used.

In 1838 Swiss chemist Christian Friedrich Schoenbein discovered that hydrogen and oxygen can be combined to produce water and electric current- the fuel cell effect. Sir William Robert

Grove was an English scientist and judge who demonstrated in 1845 Schoenbein’s discovery on a practical scale by creating a ‘gas battery’ and earned the platitude ‘father of the fuel cell’. This led to his development of the ‘gaseous voltaic battery,” the forerunner of the modern fuel cell. The Grove cell as it came to be called, used porous platinum electrodes and sulfuric acid as the electrolyte.

Konstantin Tsiolkovsky first proposed hydrogen-fueled rocket propulsion for space flights in the late 1890s. In 1911 Carl Bosch directed the development for ammonia and fertilizer to be manufactured from hydrogen and nitrogen gases, leading to the manufacturing of synthetic fertilizers.

During the 1920s Rudolf Erren converted the internal combustion engines of trucks, buses, and

submarines to use hydrogen or hydrogen mixtures. J.B.S. Haldane produced hydrogen by using wind-generated electricity in 1923. Rudolph A. Erren, a developer of hydrogen fueled motor vehicles, demonstrated their use in fleet service during the 1930s.

In 1950 Akira Mitsui was successful in biologically producing hydrogen using special types of algae and microorganisms. In 1959 Francis T. Bacon of Cambridge University made the first practical hydrogen air fuel cell. The 5kW system powered a welding machine. He named it the ‘Bacon cell’. Hydrogen fuel cells, based on Bacon’s design have been used to generate on-board electricity, heat and water for astronauts aboard the Apollo spacecraft and all subsequent

space shuttle missions.

Hydrogen Accident & Safety

In the previous decades, severe accidents have happened involving hydrogen utilized in industrial and other applications. One of them is Hindenburg accident (1937). The accident occurred at Lakehurst, New Jersey, on May 6, 1937 and was for many years under investigation to identify the reasons that caused the ignition of the hydrogen gas used for buoyancy of the giant airship “Hindenburg”.

In that accident, the ignition of hydrogen proceeded rapidly to fire toward the tail section of the craft. The fire was almost simultaneously succeeded by an explosion that engulfed the 240 t craft causing it to crash onto the ground killing 36 people. The overall results indicated that the outer shell and the paint of the airship were flammable and could be ignited from electrical sparks. Indeed, prevailing atmospheric conditions at the time the accident occurred could generate considerable electrostatic discharge activity on the airship.

Today, the memory of the Hindenburg accident is fading, and as the safety record of hydrogen—based on its safe use in space exploration and in industry—becomes more widely known, it is also becoming accepted as a safe means of storing chemical energy.

This trend has been further encouraged by the lessons learned from accidents, such as the one that occurred in 2008 on Interstate 84 in Connecticut, where a trailer truck carrying hydrogen plunged down the embankment. If the truck had carried gasoline, we know what would have happened—a huge fireball. However, because hydrogen does not form pools on the ground, but rather escapes into the atmosphere, there was no fire and no injuries were caused by the hydrogen. Nevertheless, the wide use of hydrogen as an energy carrier will result in its use by laypersons necessitating different safety regulations and technologies that are now under development.

One of the major issues affecting the acceptance of hydrogen for public use is the safety of hydrogen installations (production and storage units) as well as its applications (i.e., as vehicle fuel or home use). The hazards associated with the use of hydrogen can be characterized as physiological (frostbite and asphyxiation), physical (embrittlement and component failures), and chemical (burning or explosion), the primary hazard being inadvertently producing a flammable or explosive mixture with air

From the safety point of view, the following are the most important properties of hydrogen when compared to other conventional fuels: When released, hydrogen quickly diffuses (3.8 times faster than natural gas) into a non-flammable concentration. It also rises 6 times faster than natural gas at a speed of almost 45 mph (20m/s). When it burns, due to the absence

of carbon and the presence of heat absorbing water vapor, the fire produces much less radiant heat than a hydrocarbon fire. This reduces the risk of secondary fires. If only hydrogen is present, an explosion cannot occur. An oxidizer, such as oxygen, must be present in a concentration of at least 10% pure oxygen or 41% air. Hydrogen can be explosive at concentrations of 18.3% to 59% while gasoline can present a more dangerous potential, because it can explode at much lower concentrations, 1.1% to 3.3%.

Generate Hydrogen from Sun

Hydrogen is an ideal, clean, carbon-free carrier of energy that produces only water vapor as a waste product and has potential applications in automobiles, airplanes, and also in home-heating.

The projected mean power generation for the years 2050 and 2100 has been estimated to be 28 and 46 terawatt (TW), respectively. By far, sunlight provides the largest of all carbon-neutral energy sources. In fact, 14 TW of solar energy falls on the earth every hour. Thus, more energy from sunlight strikes the earth in 1 h than all the energy consumed on the planet in a year.

The most successful technologies taking advantage of this resource are photovoltaics (PVs; solar electricity), a $10 billion industry that is currently growing at a rate of 35–40% each year. Continued growth of the PV sector at a rate of ~25% would increase the production level from 1.7 GW in 2005 to 380 GW in 2030, and thus would satisfy a significant fraction of the world energy demand. Moreover, among the renewable sources, PVs have the highest potential to reduce the costs compared to biomass, geothermal, wind, and solar thermal.

Photoelectrolysis of water and especially the use of semiconductor–electrolyte interfaces illuminated with sunlight for the production of hydrogen from water and other suitable solvents have been reviewed in several excellent publications. At present, only about 5% of the commercial hydrogen production is primarily via water electrolysis, whereas the other 95% is mainly derived from fossil fuels. This does not represent inhouse consumption of hydrogen such as oil refi neries and ammonia plants where the bulk of hydrogen is consumed.

There are two principal methods for the electrolysis of water to generate hydrogen viz. active, that is, photoassisted and passive or dark and nonphotoassisted. The active method consists of utilization of photogenerated charge carriers in the electrolysis of water and other products. In the passive method, the electrolysis is carried out in the dark at low (80°C) temperatures using an alkaline electrolyte such as NaOH or proton exchange membrane cells involving polymeric sulfonic acids, at intermediate (200–500°C) temperatures for which suitable electrolytes are still being sought, and at high (>800°C) temperatures using oxide electrolytes such as yttria-stabilized zirconia.

Hydrogen Storage using Slurries of Chemical Hydrides

The usual storage technologies considered for hydrogen are compressed hydrogen, liquid hydrogen, metal hydrides, and carbon-based storage systems. Over the past couple of years another method of hydrogen storage and transmission has been under investigation that offers some significant advantages over the usual hydrogen storage technologies.

Thermo Power Corporation has been developing a chemical hydride slurry approach. In this approach, a light metal hydride is used as the hydrogen carrier and storage media. Light metal hydrides such as lithium hydride, magnesium hydride, sodium hydride, and calcium hydride produce hydrogen when they react with water. These materials are typically dry solids at ambient conditions. The oil in the slurry protects the hydride from unintentional contact with moisture in the air and makes the hydride pumpable. At the point of storage and use, a chemical hydride/water reaction is used to produce high-purity hydrogen.

An essential feature of this approach is the recovery and recycle of the spent hydride at centralized processing plants to produce new hydride slurry, resulting in an overall low cost for hydrogen. This chemical hydride slurry system has several benefits:

• it greatly improves the energy transmission and storage characteristics of hydrogen as a fuel,
• it provides a hydrogen storage medium that is stable at normal environmental temperatures and pressures,
• it is pumpable and easily transported,
• it has a high gravimetric and volumetric energy density, with the use of a properly designed reactor it can provide hydrogen at elevated pressures without the use of a compressor,
• it produces the hydrogen carrier efficiently and economically from a low cost carbon source, and since the production of the hydride is a carbo-thermal process performed at a centralized plant, CO2 resulting from the carbo-thermal process for refining lithium is concentrated and amenable to sequestration.