Many energy specialists see hydrogen as a key path in the energy transition. While a great deal of research and many technological advances will be needed for this vision to become reality, a clear movement is underway in a number of the world's major countries.
Jules Verne’s Prescient Vision
The possibility of using hydrogenThe simplest and lightest atom, the most abundant element in the universe. as an energy carrierA synonym of secondary energy (see definition). has been understood since the 19th century. In his novel “The Mysterious Island”, French author Jules Verne anticipated an energy revolution through the character of Cyrus Smith, an engineer: “Yes, my friends, I believe that water will one day be employed as fuelFuel is any solid, liquid or gaseous substance or material that can be combined with an oxidant... , that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heatIn the field of statistical thermodynamics today, heat refers to the transfer of the thermal agitation of the particles making up matter... and light, of an intensity of which coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from... is not capable.”
In the 1840's, hydrogen from coal gas was used for public lighting and town gas. It gained new popularity in the second half of the 20th century with the space program, as researchers looked for ways to generate energy autonomously onboard satellites and to launch rockets.
What has changed since the early 19th century is the dynamic that has spurred on teams of researchers worldwide and already resulted in the first industrial and consumer applications in countries such as Japan, South Korea, the United States and Germany 1/2. The first hydrogen cars have already reached the market; stationary installations the size of a wardrobe are starting to supply electricityForm of energy resulting from the movement of charged particles (electrons) through a conductor... and heat to buildings and stores; and some buses, trucks and lift trucks are already running on hydrogen. (See Close-Up: "The Many Uses of Hydrogen”).
Subsurface natural hydrogen seeps have been detected in certain areas, but operation is a long way off.
While hydrogen has mainly been used until now in ammonia production and oil refining, it seems destined for major development as an energy carrier.
The Problem of Production
Hydrogen’s main drawback is that it needs to be produced. It is not a primary energyAll energy sources that have not undergone any conversion process and remain in their natural state.. source like oil, gas, biomassIn the energy sector, biomass is defined as all organic matter of plant or animal origin... or wind, but rather what is known as an “energy carrier”, like electricity and heat.
To be sure, natural hydrogen seeps have been detected at the bottom of the ocean or in the center of certain continental basins, notably on the Russian plains. Hydrogen has also been found to occur naturally in gas drillingThe process of boring a hole into the ground using special equipment... sludge in Mali and the United States, where efforts have begun to capture it.
But the possibility of operating a hydrogen field is something that lies far in the future – if at all – and for now, hydrogen has to be produced by separating it from other elements such as carbon or the oxygen in water. (See Close-Up: “Hydrogen Production”). This means that hydrogen is a renewable resource. The level of CO2See Carbon Dioxid emissions depends entirely on the production method. Most hydrogen today is produced from fossil fuels, but biomass gasification and electrolysis of water appear to be real possibilities, making hydrogen a potentially “clean” fuel.
€10 per kilogram: the projected price at the pump for hydrogen in 2020, for a driving range of more than 100 km per kg
In use, hydrogen does not generate any CO2 either. In a fuel cellA device that produces electricity by oxidizing a reducing agent (fuel) in one electrode (the anode) and reducing an oxidizing agent in another... , it produces electricity and gives off water and heat. (See Close-Up: “The Different Types of Fuel Cell”).
Storage and Cost
While hydrogen has a very high mass energy densityThe amount of energy stored in an object, expressed in watt-hours per kilogram (1 Wh/kg = 3.6 kJ/kg)... (it contains three times more energy per unit of weight than dieselDiesel is the name of an internal combustion engine that works by compression-ignition... ), it is very difficult to store and distribute. It takes energy to liquefy or compress hydrogen, and because the gas is very light, its transportation is very inefficient by unit of volume (15 times less efficient than oil and three times less than natural gas). (See Close-Up: “The Onboard Applications of Hydrogen”).
Excluding distribution, the ex-plant cost of hydrogen produced via steam reforming of methane (ch4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills... stands at around €1.50 per kilogram of H2. The price is much higher for hydrogen generated by industrial electrolyzers, at between €5 and €30 per kilogram, depending on the price of electricity.3 As for the price at the pump for future hydrogen cars (i.e., after transportation and compression), a target of €10 per kilogram by 2020 is considered necessary to convince consumers4, given that a vehicle can drive for more than 100 kilometers on one kilogram of hydrogen.
(2) CEA (in French only)