Hydrogen is the lightest of all elements and also the most common element in our universe. The major share of all hydrogen on earth is bound in water and in various hydrocarbons, a minor fraction exits as free hydrogen gas molecules (H2).
Hydrogen is combustible and the energy contents, 120 MJ/kg, is high compared to 50 MJ/kg for methane (biogas), 40 MJ/kg for gasoline and 20 MJ/kg for methanol. Hydrogen gas is not a primary energy source, but it offers an excellent method for energy storage, superior to present battery technologies and with high capacity.
Industrial scale hydrogen is produced from natural gas or biomass, but the technology of producing hydrogen gas from water by electrolysis has been known since the 19th century.
HYDROGEN GAS PRODUCTION FROM SOLAR, WIND AND WAVE ENERGY:
Utilising surplus electricity generated from solar, wind or wave power is a modern and environmentally sustainable method of producing hydrogen gas for energy supply. This form of hydrogen gas production is already common. An electric current is introduced to the water in the electrolyzer. Hydrogen gas is generated at the cathode and oxygen at the anode.
HYDROGEN GAS STORAGE
At an industrial scale hydrogen gas is stored under 200 bar pressure, but for vehicles a number of higher standard pressures are applied. All pressure vessels obey the European pressure equipment directive (PED) and national instructions of inspection and use.
THE FUEL CELL
The fuel cell is an old invention, almost the age of the steam machine. Already in 1839, the Englishman William Robert Grove designed a fuel cell producing electricity. At the end of the 19th century the theoretical outlines of the fuel cell were known. In the competition between the combustion engine, the electrical car and the fuel cell vehicle the first one outnumbered its rivals, thanks to easy handling of the energy source and the independency offered by a distribution network of fuel stations.
Development of the fuel cell lied waste for decades, while other systems were refined. In the 1970s the automotive industry resumed R&D of hydrogen technology. During the last few years membrane materials and other technologies have been developed for longer lifespans and higher efficiency.
In the fuel cell energy from hydrogen gas is converted to electricity, heat and water. Each fuel cell generates around 0,7 V. To increase power many cells are combined to a so called ‘stack’. The only exhaust gas is water steam.
There are several types of fuel cells, from alkaline (in space rockets and submarines) to modern polymembrane fuel cells (PEM) and solid fuel oxide cells.
Boats and other vehicles use one or several electrical motors supplied with electricity from the fuel cell.
Hydrogen gas is naturally present in small amounts in the atmosphere. Leakage from storage tanks or pipelines is biologically non-hazardous.
To avoid any damages as a result of the high pressure all connections and valves are pressureless when a tank is shifted to another.
A mixture of hydrogen and oxygen (oxyhydrogen gas) is explosive when the hydrogen content is in the span 18,2 – 58.9 %. Therefore, hydrogen gas is normally stored outside in open sheds, where the amount of hydrogen in the air never will be critical.
Modern and individually designed digital control systems monitor the whole chain from production and storage to combustion and power train control.