ZERO CO2 FOOTPRINT
Green hydrogen offers better ways to decarbonise a range of hard-to-abate sectors – including long-haul transport, chemicals, and even food processing– where it is proving difficult to significantly reduce emissions. It can also help improve air quality and strengthen energy security.
Technologies already available today enable green hydrogen to produce, store, move and use energy in different ways. Its production is carbon free by using 100% renewable energies instead of fossil resources. It can be transported as a pressurised gas or in liquid form by pipelines, ships or trucks, much like liquefied natural gas (LNG). It can be transformed into electricity and methane to feed industry and power houses, and into fuels for cars, trucks, ships and planes. Hydrogen and hydrogen- based fuels can transport energy from renewables over long distances – from regions with abundant renewable resources to energy-hungry clients thousands of kilometres away.
Green hydrogen is produced from the regenerative energy carriers by the safe means of water electrolysis (in this case, the compound H2O molecule is split into its component hydrogen and oxygen in an electrolyser with the help of electric current). The electricity provided for the hydrogen electrolysis is obtained exclusively from renewable sources (i.e. hydropower, wind power, solar energy, geothermal energy, biomass, landfill gas and sewage gas). Hy2gen AG produces green hydrogen in large scales to address the increasing commercial demands.
Green hydrogen produced by Hy2gen AG by means of Alkaline electrolysis or polymer electrolyte membrane (PEM).
Using green hydrogen produces no greenhouse gases, particulates, sulphur oxides or ground level ozone
“WATER IS THE COAL OF THE FUTURE.
THE ENERGY OF TOMORROW IS WATER …”
– Jules Verne, 1870
This is a mature and commercial technology. It has been used since the 1920s, in particular for hydrogen production in the fertilizer and chlorine industries. The operating range of alkaline electrolysers goes from a minimum load of 10% to full design capacity.
Alkaline electrolysers operate via transport of hydroxide ions (OH–) through the electrolyte from the cathode to the anode with hydrogen being generated on the cathode side. Electrolysers using a liquid alkaline solution of sodium or potassium hydroxide as the electrolyte have been commercially available for many years.
(Image: AWE Module / ThyssenKrupp)
(polymer electrolyte membrane)
PEM systems were first introduced in the 1960s by General Electric to overcome some of the operational drawbacks of alkaline electrolysers. They use pure water as an electrolyte solution, and so avoid the recovery and recycling of the potassium hydroxide electrolyte solution that is necessary with alkaline electrolysers. They are relatively small, making them potentially more attractive than alkaline electrolysers in dense urban areas. They are able to produce highly compressed hydrogen for decentralised production and storage at refuelling stations (30–60 bar without an additional compressor and up to 100–200 bar, compared to 1–30 bar for alkaline electrolysers) and offer flexible operation, including the capability to provide frequency reserve and other grid services. Their operating range can go from zero load to 160% of design capacity and offers very high gas purities (99,999%).
In the PEM electrolyser, the electrolyte is a solid specialty plastic material.
· Water reacts at the anode to form oxygen and positively charged hydrogen ions (protons).
· The electrons flow through an external circuit and the hydrogen ions selectively move across the PEM to the cathode.
· At the cathode, hydrogen ions combine with electrons from the external circuit to form hydrogen gas.
Anode Reaction: 2H2O → O2 + 4H+ + 4e–
Cathode Reaction: 4H+ + 4e– → 2H2
(Image: Silyzer 300 – PEM Module / Siemens)