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Hydrogen Applications


Hydrogen is an energy carrier that can be produced in many different ways. Currently, over 95% of the hydrogen produced is from fossil fuels. In order for hydrogen to be green, i.e. zero-emission, the process for its production must not emit harmful emissions into the atmosphere. The most common way to produce green hydrogen is through the process of electrolysis, in which the electric molecule separates the water molecule into its constituent parts - hydrogen and oxygen. A key role in this process is the source of electricity. For the production process to be green, the source of electricity must be renewable. Such sources of energy are wind, sun, biomass, and others.

Solar energy Source: Photo by Andreas Gücklhorn on Unsplash

Solar energy

To produce hydrogen by using solar energy, two processes may be considered: water electrolysis using solar-generated electricity or direct solar water splitting. The direct water-splitting process refers to any process in which solar energy is directly used to produce hydrogen from water without going through the intermediate electrolysis step. Such processes are photochemical water splitting, high-temperature thermochemical cycles, biomass gasification, etc. All of these direct solar water splitting processes are under research because there are many impediments to be overcome. Nowadays, the electrolysis process in combination with solar-generated electricity is the most widely used green hydrogen production method. The most commonly used method for the generation of electricity from the Sun is photovoltaic (PV) this technology has been dominating the renewable electricity market for the last decade, bringing down the Levelized Cost of energy to the lowest compared to any other electricity-generating method. 

Hydropower Source: Photo by Marcus Ganahl on Unsplash


Hydropower or hydroelectric power is the usage of water to power machinery that produces energy. The machinery is usually a turbine or a generator, powered by the kinetic energy of the water that moves downstream. The produced electricity is then injected into the grid. Most experts in the energy sector consider hydropower as a renewable (water is restored by rain or melting ice), but not a sustainable energy source (vast m2 of land must be flooded in order to build dams). However, the generation of electricity via the flowing energy of the water doesn`t generate any greenhouse gases, which makes it green. A hydro plant that produces hydrogen on-site via electrolysis has an advantage over other renewable energy sources in that there is ample water availabilty and the flow of electricity is constant. That is why the production of green hydrogen on-site of the hydro plants has been a hot topic in the past few years. 

Biomass Source: 50 MW Biomass plant, France


Biomass is considered an organic renewable energy source. There are many sources that are classified as biomass such as manure, specific crops, residual waste, organic municipal solid waster, etc. In order to extract hydrogen out of the biomass, there are three main thermochemical processes that are used- gasification, pyrolysis, and aqueous phase reforming (APR). Moreover, as an alternative to thermochemical conversion,  a biological conversion may be used to produce hydrogen out of biomass. Commonly used biological conversion methods are the so-called biological water gas shift, dark fermentation, and photo-fermentation. There is also a possibility to use an electrochemical process such as electrolysis. The difference between water electrolysis and biomass electrolysis lies in the reaction that occurs at the anode. Biomass is a very promising source for the production of green hydrogen mostly due to its abundance and due to the fact that during their growing process, most plants consume carbon dioxide from the air, offsetting the carbon dioxide released from producing hydrogen through biomass gasification and resulting in low GHG emissions. 

Wind energy Source: Photo by Thomas Reaubourg on Unsplash

Wind energy

Wind is used to generate electricity by using the kinetic energy of the air in motion. Today there is more than 750 GW of installed wind capacity, (of which more than 35 GW offshore) helping avoid more than a billion tons of carbon dioxide globally. Due to the intermittency of wind power, very often it is curtailed to balance the grid. As an alternative to the curtailment, the produced electricity could be used to produce green hydrogen cheaply. Such projects are getting more traction, especially in combination with offshore wind power. 

Geothermal energy Source: Geothermal plant in Iceland, Photo by Tommy Kwak on Unsplash

Geothermal energy

Geothermal is the thermal energy that is located in the Earth`s crust. If the temperature of the heat is high enough it could be used for electricity production, otherwise it is mostly used for heating. The current installed capacity of geothermal power around the globe is over 15 GW. The most common ways to produce electricity from geothermal power are the so-called dry steam plants, flash steam plants, and binary cycle power plants. The electricity produced from geothermal power is considered renewable and so the hydrogen is classified as green. Moreover, the geothermal heat could be used for other thermochemical hydrogen production methods apart from electrolysis.