Hydrogen Energy; An Overview

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 race to decarbonise and transition towards a greener future. This article explores various aspects of hydrogen energy, from how it can be utilised, to its role in shaping the future energy landscape.

How is hydrogen used for energy?

Hydrogen’s potential as a replacement for fossil fuels lies in its clean-burning properties. When combusted in a fuel cell it only produces water, meaning no harmful emissions.

Storing hydrogen

Hydrogen has excellent storage capabilities – It can be stored at extremely large scales for long durations without energy loss. This stored hydrogen serves as a reliable backup energy supply when the grid needs it. 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 the storing natural gas, however the compressed air energy storage (CAES) model pioneered using caverns for energy storage. The compressibility of hydrogen makes it a better candidate for geological storage than compressed air, since a greater volume of hydrogen to be stored in a single location. This means hydrogen is a much more efficient energy carrier. Jeff Draper, SEL Founder, explained this further: “Because hydrogen is a chemical energy, 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.” This high-density storage is crucial, especially for hydrogen’s use in transportation, where hydrogen-powered vehicles excel in long-distance travel and large vehicles, offering quicker refuelling times and greater energy density compared to batteries.

As the energy transition progresses, the demand for storage will increase, which is no problem for the geological storage model. These disused caverns are abundant across the world and can be easily formed if needed too.

Hydrogen in the energy transition

Hydrogen’s versatility makes it a valuable asset in the energy transition. Firstly, it is crucial to a number of industries, which heavily rely on hydrogen to function. For example, without hydrogen it impossible to synthetically produce ammonia, which is a key component in nitrogen-based fertiliser, (the most widely used fertiliser in large scale agricultrue). Ammonia is also needed for the production of a wide range of various industrial chemicals such as plastics, pharmaceuticals, and cleaning agents. As a multi-faceted resource, hydrogen is vital, beyond its use as an energy source, it is also economically significant.

The Colours of Hydrogen

Despite being a colourless gas, hydrogen is classified into nine different colours based on its production. Each method has a different level of environmental impact with green hydrogen being the most sustainable. When green hydrogen is produced through electrolysis, no harmful emissions are produced. Moving towards unilateral green hydrogen production is important to secure a sustainable energy landscape. Like with renewable energy sources, as time goes on and investment grows, the cost of producing green hydrogen is dropping gradually. Eventually, when it is economically feasible, renewable powered electrolysis will become the primary production method of sourcing 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 requires infrastructure changes across numerous sectors. To begin with, efficient production facilities must be developed 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 coupled with carbon capture and storage to produce low-carbon hydrogen (also called blue hydrogen).

Hydrogen transport

Additionally, 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. Long duration storage must also be implemented 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, our current petrol refuelling system could be repurposed 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, there are well developed industry standards which ensure that hydrogen infrastructure and technologies meet safety requirements, just as they do for gas and other fuels.

The vessels for hydrogen storage will be made of high-grade material to avoid leakage, ensure durability and withstand the pressure of storage. If these requirements are met, then the safety of hydrogen storage can be assured. Geological storage, such as salt caverns, provides the safest possible way to store large quantities of hydrogen. The implementation of 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.

Hydrogen’s environmental benefits

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 diffuse 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; they are able to hold between 10,000 and 200,000 times more hydrogen than a hydrogen tanker. Many industries already use these caverns for storing materials such as oil, natural gas, or compressed air. 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. However, 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.

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