GREEN HYDROGEN

Green hydrogen: an alternative that reduces emissions and cares for our planet

#climate change #environmental sustainability #R&D

Decarbonising the planet is one of the goals that countries around the world have set for 2050. To achieve this, decarbonising the production of an element like hydrogen, giving rise to green hydrogen, is one of the keys as this is currently responsible for more than 2 % of total global CO2 emissions. Find out how this is achieved and what its impact will be in the coming decades.

Our way of life needs an increasing amount of watts to function. The latest estimates by the International Energy Agency (IEA), published at the end of 2019, predict that global energy demand will increase by between 25 % and 30 % by 2040, which in an economy dependent on coal and oil would mean more CO2, exacerbating climate change. However, decarbonising the planet suggests a different world in 2050: one that is more accessible, efficient and sustainable, and driven by clean energies such as green hydrogen.

WHAT IS GREEN HYDROGEN AND HOW IS IT OBTAINED?

This technology is based on the generation of hydrogen — a universal, light and highly reactive fuel — through a chemical process known as electrolysis. This method uses an electrical current to separate the hydrogen from the oxygen in water. If this electricity is obtained from renewable sources we will, therefore, produce energy without emitting carbon dioxide into the atmosphere.

As the IEA points out, this method of obtaining green hydrogen would save the 830 million tonnes of CO2 that are emitted annually when this gas is produced using fossil fuels. However, there are some questions about the viability of green hydrogen because of its high production cost; reasonable doubts that will disappear as the decarbonisation of the earth progresses and, consequently, the generation of renewable energy becomes cheaper.

Iberdrola.
HOWIS
GREENHYDROGENOBTAIN?
Producing green hydrogen by electrolysis from renewable sources involves breaking down water molecules (H2O) into oxygen (O2) and hydrogen (H2).
1. The water used in the electrolysis
must contain salts and minerals
to conduct the electricity.
2. Two electrodes are immersed in the water and connected to a power source and a direct current is applied.
3. The dissociation of hydrogen and oxygen occurs when the electrodes attract ions with an opposite charge to them.
4. During the electrolysis, an oxidation-reduction reaction occurs due to the effect of the electricity.
RENEWABLEENERGIES
MEMBRANE
HYDROGEN
OXYGEN
CATHODIC REACTION
4H++4e- ➔ 2H2
ANODIC REACTION
2H2O ➔ O2+4H++4e-
Source: U.S. Department of Energy and Wood Mackenzie.

 

 SEE INFOGRAPHIC: How is green hydrogen obtained? [PDF]

HYDROGEN AS CLEAN ENERGY

Hydrogen is the most abundant chemical element in nature. As noted by the IEA, the global demand for hydrogen for use as a fuel has tripled since 1975 and reached 70 million tonnes a year in 2018. In addition, it is a clean energy source that only emits water vapour and leaves no residue in the air, unlike coal and oil.

Hydrogen has a long-standing relationship with industry. This gas has been used to fuel cars, airships and spaceships since the beginning of the 19th century. The decarbonisation of the world economy, a process that cannot be postponed, will give hydrogen more prominence. In addition, if its production costs fall by 50 % by 2030, as predicted by the World Hydrogen Council, we will undoubtedly be looking at one of the fuels of the future.

ADVANTAGES AND DISADVANTAGES OF GREEN HYDROGEN

This energy source has pros and cons that we must be aware of. Let's go over some of its most important good points:

  • 100 % sustainable: green hydrogen does not emit polluting gases either during combustion or during production.
  • Storable: hydrogen is easy to store, which allows it to be used subsequently for other purposes and at times other than immediately after its production.
  • Versatile: green hydrogen can be transformed into electricity or synthetic gas and used for domestic, commercial, industrial or mobility purposes.
  • Transportable: it can be mixed with natural gas at ratios of up to 20 % and travel through the same gas pipes and infrastructure - increasing this percentage would require changing different elements in the existing gas networks to make them compatible.

However, green hydrogen also has negative aspects that should be borne in mind:

  • High cost: energy from renewable sources, which are key to generating green hydrogen through electrolysis, is more expensive to generate, which in turn makes hydrogen more expensive to obtain.
  • High energy consumption: the production of hydrogen in general and green hydrogen in particular requires more energy than other fuels.
  • Safety issues: hydrogen is a highly volatile and flammable element and extensive safety measures are therefore required to prevent leakage and explosions.

Green Hydrogen plant.

IMPACT OF GREEN HYDROGEN

Hydrogen as a fuel is a reality in countries like the United States, Russia, China, France and Germany. Others like Japan are going even further and aspire to become a hydrogen economy. Below we explain what the impact will be in the future:

 Electricity and drinking water generator

These two elements are obtained by reacting hydrogen and oxygen together in a fuel cell. This process has proved very useful on space missions, for example, by providing crews with water and electricity in a sustainable manner.

 Energy storage

Compressed hydrogen tanks are capable of storing energy for long periods of time and are also easier to handle than lithium-ion batteries because they are lighter.

 Transport and mobility

Hydrogen's great versatility allows it to be used in those consumption niches that are very difficult to decarbonise, such as heavy transport, aviation and maritime transport. There are already several projects under way in this area, such as Hycarus and Cryoplane, which are promoted by the European Union (EU) and aim to introduce it in passenger aircraft.