What is hydrogen energy?
Sarah Rigney
Staff Writer

In a bid to meet climate goals and targets, alternative energy sources are being examined globally. Here we take a closer look at the potential of hydrogen energy.

The world of energy is evolving and as we move towards a greener future, different energy options are being explored.

One option being considered is hydrogen energy, which offers great potential if produced in a ‘green’ manner. 

It’s an environmentally friendly alternative to fossil fuels, because it only emits water. This makes it an attractive fuel option for transportation and electricity generation applications. 

Hydrogen energy can be difficult to understand if you’re not familiar with scientific terminology. That’s why we decided to examine hydrogen and simply explain the potential it has.

What is hydrogen energy?

Hydrogen is the lightest element in the universe and the most abundant. It’s the energy that fuels the sun and the stars. However, it is not a primary source of energy. 

There are no natural reservoirs of pure hydrogen on earth, and as such it must be extracted from another substance. This is why it’s known as an energy carrier. 

Hydrogen is found in the greatest quantities in water, but it’s also found in natural gas, coal and petroleum.

Hydrogen energy can be produced using clean energy to split water molecules, producing only oxygen as a by-product.

At the moment, however, approximately 95% of worldwide hydrogen production comes from fossil fuels.

What types of hydrogen are there?

There are three main types of hydrogen: 

Grey hydrogen

This form of hydrogen is derived from natural gas using steam methane reforming. 

The process brings together natural gas and heated water, in the form of steam. During this energy-intensive process, a lot of carbon dioxide (CO2) is emitted and released into the atmosphere, making it the least renewable form of hydrogen. 

Blue hydrogen

Like grey hydrogen, blue hydrogen is also produced from natural gas using steam methane reforming, with CO2 being produced as a by-product. However, with blue hydrogen this carbon is trapped and stored, to avoid being released into the atmosphere. As the creation of greenhouse gases isn’t exactly avoided, blue hydrogen is known as ‘low-carbon hydrogen’.

Green hydrogen

Green hydrogen is produced with no harmful greenhouse gas emissions. It’s created using clean electricity from renewable energy sources, such as wind power or solar, to electrolyse water.

During this process, water is split into its components of hydrogen and oxygen, emitting zero-carbon dioxide in the process.

Due to the cost of production, green hydrogen accounts for a small portion of the overall hydrogen supply. The more common green hydrogen production becomes, the cheaper it will get.

Green hydrogen allows us to store excess energy created by wind and solar power when it’s windy and sunny, for use when it’s not. 

What do we use hydrogen energy for?

Hydrogen energy is a versatile source, as it can be used in gas or liquid form, or be converted into electricity or fuel. 

Hydrogen is highly flexible and has a variety of different applications:

To produce electricity

A fuel cell uses the chemical energy of hydrogen or other fuels to cleanly and efficiently produce electricity.

Within a hydrogen fuel cell, hydrogen combines with oxygen from the air to create electricity. The fuel cell can run continuously and generate energy as long as the hydrogen fuel is being supplied. 

The only by-products are water and heat, making it a clean source of energy.

As a fuel for transportation

Hydrogen energy can be used to fuel cars, trucks, trains, boats, and aeroplanes. In Japan, hydrogen is already being used to fuel public transport, such as buses. It can also be used to power freight trucks, trains, and even ships.

For example, in fuel cell electric vehicles (FCEV), hydrogen can be used to power an electric motor. So, instead of drawing electricity only from a battery, like a regular electric vehicle, a FCEV produces electricity using a fuel cell-powered by hydrogen.

Hydrogen is one of the best options for converting renewable energy into fuel, which can then be stored and transported over long distances. 

Similar to refilling a car with petrol or diesel, with FCEVs motorists simply attach a nozzle from a hydrogen dispenser and fill up the tank. 

For hydrogen vehicles to become more common, hydrogen fuel cells must become cheaper and hydrogen refuelling stations must become more widespread.

To heat buildings

There’s potential for hydrogen to replace natural gas as a way of heating domestic and commercial buildings if the current infrastructure is adapted. 

Industrial processes

Hydrogen is being used in a wide range of important industrial processes, including manufacturing steel, refining petrol, producing chemicals, and treating metals.

The challenges of storing hydrogen

There are a few challenges associated with hydrogen energy becoming more widespread. The main stumbling block, however, revolves around the difficulties of storing and transporting hydrogen.

Compared to natural gas, hydrogen is more flammable in the air, so it needs to be stored and transported carefully. It can be stored physically as either a gas or a liquid. 

By volume, hydrogen has one of the lowest energy contents. Due to its low density, it’s difficult to transport. It either needs to be cooled and liquefied or needs to be compressed.

As hydrogen molecules are so small, they can leak out of containers. This means that pipe networks previously used for methane gas will require upgrading before they are suitable to carry hydrogen.

Hydrogen can be transported through dedicated pipelines, in tube trailers that carry gaseous hydrogen, in low-temperature liquid tanker trucks, or by rail or barge.

Cruising towards a greener future 

The concept of hydrogen energy is shaking up a lot of industries, including the tourism industry. We decided to take a look at how the cruise sector is adapting to use hydrogen.

Cruise ships are notorious for polluting our oceans. Studies show that a large cruise ship can have a carbon footprint greater than that of 12,000 cars combined. 

According to the Cruise Lines International Association, over €20 billion has already been invested globally in new technologies and cleaner fuels to reduce air pollution.

One such company exploring hydrogen-powered cruise ships is Northern Xplorer. The company claims to have established the world’s first hydrogen-powered zero-emission cruise ship concept.

Northern Xplorer has an ambitious goal of launching 14 ships, with the first intended to be operational from 2024/2025.

How will Northern Xplorer’s ships be more eco-friendly?

According to the company, the ships will feature:

  • Clean technologies including fully electric propulsion
  • Battery energy storage
  • Hydrogen fuel cells 
  • Wind and solar power energy
  • Heating, ventilation, and air conditioning (HVAC) systems to prevent the spread of pathogens, using recyclable materials to promote circularity
  • Advanced LiDAR technology (Light Detection and Ranging) to detect marine plastic debris and raise awareness of marine pollution

The cruise vessels will accommodate up to 300 passengers and cruises will allow tourists to explore northern Europe.

More to follow suit

As well as Northern Xplorer, other cruise operators are also taking the plunge and exploring hydrogen. 

MSC Group, the world’s third largest cruise line, is designing and building an ocean-going cruise ship powered by hydrogen, which would allow zero-emissions operations.

The cruise brand will be known as Explora Journeys and will include a fleet of six cruise ships. The first two, Explora I and Explora II, are currently under construction in Italy.

What does the future hold for hydrogen energy in Ireland?

Recently, Gas Networks Ireland announced its participation in a major European project that aims to increase the use of hydrogen in Europe. 

It’s envisioned that by 2040, a 53,000 km hydrogen network will be created around Europe, forming five large-scale corridors with a multitude of branch pipelines.

Repurposed natural gas pipelines will account for 60% of the new backbone across the EU and only 40% of pipelines will be newly built, specifically for hydrogen.

It is hoped that by 2040 Ireland could be connected to the new European hydrogen backbone via a repurposed subsea pipeline to the Moffat interconnector in Scotland.

The project will help to:

  • Reach climate action goals
  • Provide Ireland with an enhanced security of energy supply
  • Maximise our renewable energy production, by offering the potential of hydrogen exports to other markets

In January 2023, Bord Gáis Energy announced that it was building two new power plants, both of which will be hydrogen enabled in a move that will cost the company €250 million. These innovative power plants can run on natural gas and hydrogen mix, with the ability to convert to 100% hydrogen in the future.

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Do you think that hydrogen energy will be beneficial for Ireland? We’d love to hear from you. 

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Main sources

afdc.energy.gov, energy.gov, energyireland.ie, fchea.org, gasnetworks.ie, hydrogenireland.org, irena.org, nweurope.eu, offshore-energy.biz.