In the search for sustainable energy solutions, hydrogen has emerged as a promising contender. Its versatility and potential for zero-emission production mean it is a frontrunner in the energy transition. This article delves into various aspects of hydrogen energy, exploring its potential use, storage and role in a decarbonised future.
Why Hydrogen?
Hydrogen is an excellent potential replacement for fossil fuels due to its clean-burning properties. When combusted it only produces water, meaning energy production with no harmful emissions. Alongside its use as a fuel source, hydrogen is also very well placed for use in energy storage. Without energy storage, due to natural intermittency, renewable energy is unable to securely power the grid. If we employed hydrogen based energy storage, H2 could play a huge role in facilitating dispatchable reserves of 100% clean power.
Storing Hydrogen
Hydrogen has excellent storage capabilities; it can be stored at extremely large scales for long durations without energy loss. By using stored hydrogen to generate power, we can build a supply of reliable backup energy to bolster the grid during renewable generation deficits. In addition to its large-scale storage capacity, hydrogen can be stored at ultra-high pressure – up to 700 bar – thanks to its high compressibility. These characteristics make it ideal for geological storage in disused mines and salt caverns.
CAES and Hydrogen
Geological storage has been long employed for storing compressed air. The first energy storage plant utilising the CAES (compressed air energy storage) model began operation in 1978 in Germany. After Huntorf pioneered the model, it was followed by McIntosh Alabama in 1991. Most recently, in April 2024 China opened the world’s largest CAES plant, Hubei Yingchang.
The traditional CAES model uses compressed air for energy storage. Excess renewable energy is used to pump compressed air into a geological storage facility. When there is an energy deficit, this compressed air used to drive a generator, producing power. The traditional CAES model is a great solution to the renewable intermittency problem, however, since hydrogen is much more compressible than air, it a better option for geological energy storage. This is simply because hydrogen is able store a much larger quantity of power in a single location.
Jeff Draper, SEL Founder, explained this concept further: “Hydrogen is a chemical energy. This means it has 150 times the energy content than compressed air does. It can hold a huge amount of energy per cubic meter in a cavern.”
As the energy transition progresses, the demand for energy storage is steadily increasing. The geological storage model can accommodate this need. There are numerous suitable caverns available worldwide. These disused resources can be successfully repurposed to support the energy transition.
Understanding Hydrogen
Hydrogen is the simplest and most abundant element in the universe, consisting of just one proton and one electron. Traditionally, hydrogen is produced through a process called steam methane reforming (SMR), where natural gas is heated with steam to produce hydrogen and carbon dioxide. This method is used most commmonly, but releases significant amounts of CO2. However, in recent years, as the energy transition progresses, cleaner methods of hydrogen production are becoming more common, like Storelectric’s green hydrogen production patent.
What is hydrogen used for?
Hydrogen’s versatility is part of the reason it will be important for a decarbonised future. Firstly, it has excellent potential to replace fossil fuels as an energy source, due to its clean burning properties. Aside from this, hydrogen is essential for various industries, with one notable example being its necessity for producing ammonia. Without hydrogen it is impossible to synthetically produce ammonia. Production of nitrogen-based fertiliser, which essential for large scale agriculture, relies on ammonia. Ammonia is also necessary for producing a wide range of industrial chemicals such as plastics, pharmaceuticals, and cleaning agents.
These are just a few examples of how important hydrogen actually is across society. Green hydrogen production could revolutionise heavy industry by decarbonising traditionally fossil fuel reliant sectors.
The Colours of Hydrogen
Despite being a colourless gas, hydrogen is actually classified into nine different colours based on how it is produced. Each method has a different level of environmental impact with green hydrogen being the most sustainable (as its production does not cause any harmful emissions.
Moving towards total green hydrogen production is important to secure a sustainable energy landscape. Like with renewable energy sources, as time passes and investment grows, the cost of producing green hydrogen is dropping steadily.
Eventually, when it is economically feasible, renewable powered electrolysis will become the primary production method of hydrogen. This infographic outlines the nine current methods of producing hydrogen, and their colour classifications:
The Future Hydrogen Economy
Realising the full potential of hydrogen energy will require infrastructure changes across numerous sectors. To begin with, we need efficient production facilities to ensure a consistent and reliable supply of hydrogen.
This involves investing in electrolysis plants powered by renewable energy sources such as wind and solar (producing green hydrogen), as well as exploring alternative methods like steam methane reforming / auto-thermal reforming coupled with carbon capture and storage to produce low-carbon hydrogen (also called blue hydrogen).
Hydrogen Transportation
Establishing robust transportation networks is essential for the distribution of hydrogen from production sites to users. This includes the construction of pipelines and vehicles equipped with suitable storage facilities to ensure safe, efficient delivery. We must also implement long-duration storage to accommodate the large-scale production and distribution of hydrogen.
Hydrogen-powered vehicles, particularly fuel cell electric vehicles (FCEVs) are a promising alternative to traditional petrol and diesel cars. FCEVs also improve on battery electric vehicles, offering zero-emission transportation but with longer ranges and shorter refuelling times.
However, widespread adoption of FCEVs would require a comprehensive refuelling infrastructure located along major transportation routes and in high population density areas. Luckily, we could repurpose our current petrol refuelling system for this.
Integrating hydrogen into existing gas networks opens up the opportunity to decarbonise sectors traditionally reliant on fossil fuels, such as transport, heating and heavy industry. To fully realise the economic and environmental benefits of a hydrogen economy, we need to see a mindset shift in favour of hydrogen energy. Only through global collaboration and commitment can we lessen economic and infrastructure challenges. Hydrogen has the potential to facilitate a transition towards a secure, sustainable, low-carbon future.
Hydrogen Safety
Despite its numerous benefits, hydrogen poses unique safety challenges due to its high flammability and low ignition energy. However, well-developed industry standards ensure that hydrogen infrastructure and technologies meet safety requirements, just as they do for gas and other fuels.
Manufacturers will make the vessels for hydrogen storage from high-grade material to avoid leakage, ensure durability, and withstand the pressure of storage. Meeting these requirements assures the safety of hydrogen storage.
Geological storage in salt caverns is the safest possible way to store large quantities of hydrogen. Implementing these safety standards should inspire the same faith in hydrogen that the public has long held for fossil fuels.
It’s important to note that, like hydrogen, fossil fuels are highly reactive. However, safety regulations have successfully ensured their safe handling and storage, both below and above ground, for over a century.
While the transition to hydrogen requires a high level of safety regulation, this is no different than the standards applied to fossil fuels. While the methods for handling and storage may differ between hydrogen and fossil fuels, the commitment to maintaining safety remains just as important.
Environmental Benefits of Hydrogen
Transitioning to hydrogen offers environmental benefits, as it is a far cleaner and more sustainable energy source than combustion of fossil fuels. Hydrogen, unlike fossil fuels, rapidly dissipates in the event of a leak because its low density causes it to rise and disperses quickly in the air, eventually dissipating upwards and escaping into space.
This contrasts sharply with the environmental damage caused by an oil spill. By adopting proven safety standards, we can effectively manage the risks associated with hydrogen, as we have long done with fossil fuels, and use it safely as a low carbon solution to power the grid.
Hydrogen Storage in Salt Caverns
Salt caverns are the optimal vessel for storing large volumes of hydrogen due to their extensive storage capacity; A hydrogen tanker can hold up a single tonne of hydrogen, where a cavern can easily store two hundred! (Storage capacity data taken from one cavern in Teesside). Many industries already successfully store oil, natural gas or compressed air in caverns across the globe.
The technology for geological storage exists and has consistently proven successful. Since salt caverns, depleted gas fields, and saline aquifers have a huge range of sizes globally, they have a vast range of storage scales. This versatility means they are capable of meeting both seasonal and daily energy demands. The ability to repurpose existing caverns for hydrogen storage means this solution is replicable, flexible and most importantly, an economically viable step towards global decarbonisation.
CAES provides a scalable and geographically versatile energy storage solution and integrating hydrogen storage and production with the CAES infrastructure simultaneously addresses the challenges of energy intermittency, grid stability and green hydrogen accessibility. This is a groundbreaking innovation in the energy transition landscape. The symbiotic relationship between CAES and hydrogen storage and production is the missing link in the energy transition.
Is Hydrogen the Fuel of the Future?
Hydrogen emerges as a key player in the energy transition. Its clean-burning properties, coupled with its storage capabilities, position it as a frontrunner in the transition towards a greener future. As outlined, hydrogen’s versatility extends beyond its role as an energy source, influencing various industries and economic sectors.
The future of hydrogen energy hinges on infrastructural developments across production, transportation, and storage sectors, which is absolutely possible, but necessitates global collaboration and commitment. Despite safety challenges, established industry standards can ensure the safe handling and storage of hydrogen.
With its vast storage potential in salt caverns and synergistic relationship with technologies like CAES, hydrogen presents a scalable, flexible, and economically viable pathway towards global decarbonisation. Embracing the hydrogen economy not only promises environmental benefits but also signifies a shift towards a secure, sustainable, and low-carbon future.
