The Future Of Hydrogen

      

1.      Introduction

As the first law of thermodynamics states that “energy cannot be created or destroyed; it can only be converted from one form to another”. We have found a way to change one form of energy to another form of energy which is beneficial for us. We have burned fossil fuels, hydropower, nuclear, wind power, and many more which helps us to satisfy our needs. Energy has empowered us to run our industries, households, agriculture, science, and technology. We have reached beyond the stars with the energy revolution and still exploring how energy can be used sustainably.

When humans started using different forms of energy there was an inadequate amount of knowledge of how it will affect the environment, we live in. Coal and fossil fuels were the most used source of energy to run almost everything. Slowly we moved to more sustainable, and carbon-free sources of energy and it has become a hot topic since then. With the energy crises going on worldwide, everyone is looking for a solution. One of the ways to deal with the energy crisis is to store the energy when not needed and deliver it when needed with smart grids. For e.g. during the day, the household doesn’t require a lot of energy, but factories are running so the smart grid would provide the required amount of energy where needed and collects the data for future use. And when it's night-time, there is not much need for energy so the smart grid would store it and delivers it when needed.

There are different sustainable energy sources and different ways to store them.  In this article, we are going to talk about clean hydrogen. Since the 1800s, fuel cells and water electrolysis has been around but never have been adopted due to a lack of research.  To meet the climate targets hydrogen comes into play. Hydrogen is easy to produce from different methods using various renewable energy sources. Also, it can be produced using fossil sources with the carbon capture infrastructure. Hydrogen carries energy in the form of chemical energy (or compressed gas energy) which later can be transferred in another state like heat and electricity. Hydrogen is light and can be stored in different forms over a long period which gives hydrogen the edge on the existing energy market. It could be the alternative clean and sustainable source of energy everyone has been looking for for some time. In the 1970s when oil prices skyrocketed and there were petroleum shortages alongside air pollution, hydrogen drew attention. Since then, every country has been working on hydrogen to make it better alongside many organizations that were established like the International Energy Journal of Hydrogen and Fuel Cell Technology Collaboration Programme in 1977. Funding is provided by the government in support of hydrogen technology targeting different sectors to use hydrogen. Hydrogen and electricity are similar in many cases like versatility and can be used in different applications. They do not produce greenhouse gases, SO₂, and no ozone depletion. When used in fuel cells hydrogen only emits water.  Also, hydrogen (60%) is more efficient than gasoline (45%) and coal-fired power plant (20%).

Hydrogen can be generated from various feedstocks including fossil resources like natural gas and coal also with renewable sources like biomass and water using renewable energy sources like sunlight, wind, wave, and hydropower. Various technologies like chemical, biological, electrolytic, photolytic, and thermos-chemical which has their own benefits and challenges.

 

Figure 1: Methods in the production of Hydrogen [1]

 

 

2.      Production

Natural Gas

Most of today’s hydrogen is mostly produced using natural gas. There are three methods: steam reforming (using water as an oxidant and a source of hydrogen), partial oxidation (using oxygen in the air as the oxidant), or a combination of both called autothermal reforming (ATR) [2]. Hydrogen is extracted from natural gas and liquefied petroleum gas using steam reforming. While extracting from heavy fuel oil and coal partial oxidation is used. Carbon monoxide and hydrogen are produced which are later converted to hydrogen and CO2 (if hydrogen is a pure product). Similarly, raw material is converted into synthesis gas and then to hydrogen.

Electrolysis

Electrolysis is the process of separating water into hydrogen and oxygen. Using renewable energy sources, electrolytic hydrogen could be the option for the future. 1 kg of H2 is produced from 9 liters of water which also produces 8 kg of oxygen as a by-product. There are three kinds of electrolysis technology currently being used. They are alkaline electrolysis, proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis cells (SOECs). Water electrolysis depends upon different factors like economical and technical factors alongside operating cost and efficiency. If renewable sources like solar PV and wind systems could be used, then the cost would be cheaper. For example, in Australia and Africa where there is plenty of suns could take the price down.

Hydrogen From Coal

Coal is a well-developed energy industry used for many years to produce ammonia from chemicals and fertilizers using gasification. On the other hand, it produces so much CO2 which is twice as much as that natural gas. Due to the high emission of carbon dioxide, the carbon-capture method is used for low-carbon energy.

Hydrogen from Biomass

Biomass is used to produce heat or electricity utilizing plant-based materials like agriculture residues, wood, energy crops, etc. Also, the acids, alcohols, and fermentation processes fall under biomass. The chemical gasification of biomass produces CO, CO2, hydrogen, and methane. It turns out biomass is more expensive than solar or wind or electrolysis due to operating costs.

3.      Storage and Transport

Hydrogen faces challenges while storage since it has low volumetric energy density. 1 kg of Hydrogen has the same amount of energy density as 2.8 kg of gasoline. In comparison to lithium batteries, it has 100 times more energy density with the same amount of kilograms.  It cannot be stored and transported like fossil fuels and natural gas. But it can be converted into something easy to transport and store. In long-distance transmission, transportation is more expensive than producing hydrogen itself. Pipelines are the most cost effective and long-term option for the transportation of hydrogen. Following are the ways to store and transport hydrogen:

1.    Ammonia

2.    Synthetic hydrocarbons

a.    Synthetic methane

b.    Synthetic diesel or kerosene

c.     Synthetic Methanol

 

Figure 2: Transmission, distribution, and storage elements of hydrogen value chains [1]

 

Hydrogen can be stored as gas or liquid in tanks for small-scale applications. Also, geological storage could be used for large-scale and long-term storage.  During the 1970s and 1980s salt caverns were used in USA and UK to store hydrogen. Depleted oil reservoirs could be used which are bigger in size than salt caverns.

 

4.      Cost

The cost varies from process to process as shown below in the table.

 

Process	Energy source	Feedstock	Capital cost (M$)	Hydrogen cost ($/kg)
SMR with CCS	Standard fossil fuels	Natural gas	226.4	2.27
SMR without CCS	Standard fossil fuels	Natural gas	180.7	2.08
CC with CCS	Standard fossil fuels	Coal	545.6	1.63
CG without CCS	Standard fossil fuels	Coal	435.9	1.34
ATR of methane with CCS	Standard fossil fuels	Natural gas	183.8	1.48
Methane pyrolysis	Internally generated steam	Natural gas	–	1.59–1.70
Biomass pyrolysis	Internally generated steam	Woody biomass	53.4–3.1	1.25–2.20
Biomass gasification	Internally generated steam	Woody biomass	149.3–6.4	1.77–2.05
Direct bio-photolysis	Solar	Water + algae	50 $/m2	2.13
Indirect bio-photolysis	Solar	Water + algae	135 $/m2	1.42
Dark fermentation	–	Organic biomass	–	2.57
Photo-fermentation	Solar	Organic biomass	–	2.83
Solar PV electrolysis	Solar	Water	12–54.5	5.78–23.27
Solar thermal electrolysis	Solar	Water	421–22.1	5.10–10.49
Wind electrolysis	Wind	Water	504.8–499.6	5.89–6.03
Nuclear electrolysis	Nuclear	Water	–	4.15–7.00
Nuclear thermolysis	Nuclear	Water	39.6–2107.6	2.17–2.63
Solar thermolysis	Solar	Water	5.7–16	7.98–8.40
Photo-electrolysis	Solar	Water	–	10.36

 

Figure 3: Production Methods Comparison

 

While we are talking about production, we also need to take into consideration the storage of the energy produced. If we compare Li-ion battery storage with hydrogen storage with a max power rating of 100MW results will be as follows:

	Power Rating	Discharge time	Cycles	Watt-hour/l	Efficiency
Li-ion	100	1min-8 hrs	1000-10,0000	200-400	85-95 %
Hydrogen	100	Weeks	5-30 years	600	25-45 %

 

So, if we want to store the energy for the long run hydrogen is the option with a high cycle.

Hydrogen efficiency is less because the energy is lost in production and transportation.

If only hydrogen is used on the site of production, it could take efficiency to 75-85%. Whereas lithium-ion batteries lost only 15% of energy in transportation and from charging and discharging combined. When stored and used later around 5-10% of energy is lost in Li-ion while moving the vehicle.

 

But if we compare energy density then, hydrogen has 3500 watts per kilogram whereas li-ion batteries have 200 watts per kilogram which is almost 100 times less.

 

Figure 4: Battery cost over the years [3]

As shown above we have come a long in battery development and cost over the years. It is almost 10 times cheaper in 2023 than in 2011. Now green hydrogen costs around 2.50$- 6.80$ whereas cheap hydrogen would be between 1$ - 1.80$ which is high carbon-hydrogen.

5. Colors of Hydrogen

•       Grey hydrogen is the most common form and is generated from natural gas, or methane, through a process called “steam reforming”.

•        Hydrogen is labeled blue whenever the carbon generated from steam reforming is captured and stored underground through industrial carbon capture and storage (CCS). Blue hydrogen is, therefore, sometimes referred to as carbon neutral as the emissions are not dispersed in the atmosphere. However, some argue that “low carbon” would be a more accurate description, as 10-20% of the generated carbon cannot be captured.

•       Turquoise hydrogen refers to a way of creating hydrogen through a process called methane pyrolysis, which generates solid carbon.

•       Green hydrogen – also referred to as “clean hydrogen” – is produced by using clean energy from surplus renewable energy sources, such as solar or wind power, to split water into two hydrogen atoms and one oxygen atom through a process called electrolysis.

•       Pink hydrogen is created through electrolysis of water but the latter is powered by nuclear energy rather than renewables.

Fig: Types of Hydrogen

6.      Conclusion

Hydrogen is a quite promising technology with plenty of research going on. Several countries are already testing the use of hydrogen. The USA already has a pipeline of 750 miles to transport hydrogen. In 2020, the EU has launched 100 billion euros to European Green Acceleration Center to develop a green hydrogen economy by 2025 which would bring the cost of hydrogen to 2$ per kilogram which means 50$ per megawatt. In countries like Japan 7 thousand of fuel cell vehicles were in use as of 2022. The USA has planned to invest 7 billion dollars to develop hydrogen production to meet the need by 2030 which is 10 billion tonnes.

Hydrogen is already widely used in some industries and is yet to realize the full potential of this suitable and clean energy. Promoting and investing in R&D is necessary for the government to scale up hydrogen supply and demand.

Right now, the government has a key role to play in the advancement of hydrogen technology with challenges like cost, uncertain technology, supply and demand, and infrastructure with public acceptance. The next step would be Integration, Development, coordination, and Creation.