Green Hydrogen: A Future of Alternative Energy

Abstract:
In the year 2019, global carbon dioxide emissions from fossil fuels and coal stood at 22.06 GT and 10 GT respectively. At present, the amount of carbon dioxide in the Indian atmosphere is 420 ppm, which is about 70 to 120 ppm more than the ideal condition. Hydrogen is emerging as an important source of energy as it produces zero carbon emissions and is a non-polluting source of energy. India’s hydrogen demand in the year 2022 is 9.1 million tonnes, of which over 76 per cent is being produced from natural gas, 23 per cent comes from coal and the rest is generated from the electrolysis of water. Hydrogen is highly flammable compared to other energy sources. Hydrogen has an energy density three times higher than that of petrol and diesel. The use of green hydrogen will help reduce greenhouse gas emissions and increase the share of renewable energy in total energy consumption. In the future, hydrogen will join the current electric grid system as an important energy carrier, as it can be made safely from renewable energy sources and is virtually non-polluting. Hydrogen can be produced using various techniques like water electrolysis, steam methane reforming, gasification, methane pyrolysis, partial oxidation. It will also be used as fuel for ‘zero-emissions’ vehicles, for power generation and as fuel in aircraft. Green hydrogen can be one of the major possibilities of reducing carbon emissions.

Keywords:
Green Hydrogen, Renewable Energy, Carbon Dioxide, Zero Carbon Emissions.

Introduction:
On 12th December 2015, 195 countries laid the foundation for the Paris Agreement to covers climate change mitigation, adaptation, and finance. In the 21st century, all countries agreed to keep the average global temperature below 2 degrees centigrade over pre-industrial levels. In addition, they are committed to developing technologies that can limit temperature rise to 1.5 ^o C. The global average temperature has increased by about 1.4 degrees centigrade from 1860 to 2020. Considering the last 40 years, the increase in temperature has been around 1 degree centigrade, which is the highest rate of increase. During the same period, global carbon dioxide concentration has increased from 340 to 420 ppm and is increasing at a rate of 2 ppm/year [14]. The increase in world population implies higher energy demand, which will result in greater production of carbon dioxide with the actual fossil fuel dominant energy mix. Current environmental policies are still far from meeting these conditions, with the goal set out in the Paris Agreement focusing on developing zero carbon dioxide emissions energy sources over the past decades. One of them is hydrogen, which when combusted with air does not emit carbon dioxide.

Hydrogen is abundantly available in our environment. It is stored in water (H₂ O), hydrocarbons such as methane (CH₄ ), and other organic materials. Using hydrogen as a fuel is a major challenge. Hydrogen is a chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. Under normal conditions, hydrogen is a gas of diatomic molecules with the formula H2 . Hydrogen is a colourless, odourless, tasteless, non-toxic and highly flammable gas. Hydrogen energy has the option of high energy efficiency, extreme environmental and social benefits as well as economic competitiveness. In addition, it involves the use of hydrogen or hydrogen containing compounds to generate energy for all practical uses.

Hydrogen (H₂ ) is an alternative fuel that can be produced from a variety of resources. However, the market for hydrogen as a transportation fuel is still in its infancy. Government and industry are working towards clean, economical and safe hydrogen production and distribution for widespread use in fuel cell electric vehicles. According to a TERI report, in 2020, India’s hydrogen demand stood at 6 million tonnes (mt) per year. However, studies have shown a tremendous opportunity for development in this area. It is estimated that by 2030 the cost of hydrogen will be reduced by 50 percent.
 

Currently, hydrogen can be made from water through electrolysis. This is more energy intensive but can be done by using renewable energy, such as wind or solar, and avoiding the harmful emissions associated with other forms of energy production. Almost all of the hydrogen produced each year is used for refining petroleum, treating metals, fertilizer production and food processing. Although hydrogen production can generate emissions that affect air quality, depending on the source, a fuel cell electric vehicle that runs on hydrogen emits only water vapor and hot air as exhaust and is passed to a zero-emissions vehicle. Hydrogen can be produced in many ways and by many processes. Policy also covers land in renewable energy parks can be allotted for the manufacture of green hydrogen/ green ammonia. Also set up different manufacturing zone near ports of country for exporting the green hydrogen.

Hydrogen Production Processes:

Water Electrolysis - Electrolysis is a promising alternative for producing carbon-free hydrogen from renewable and nuclear resources. Electrolysis is the process of using electricity to split water into hydrogen and oxygen. This reaction takes place in a unit called electrolyzer. The hydrogen gas released in this way can be used as hydrogen fuel, or mixed with oxygen to form oxyhydrogen gas, which is used in welding and other applications.
 

Steam Methane Reforming - Steam methane reforming is a process in which methane from natural gas is heated with steam, usually with a catalyst, a mixture of carbon monoxide and hydrogen used in organic synthesis and as a fuel. In energy, steam methane reforming is the most widely used process for hydrogen. In steam–methane reformation, methane reacts with steam under pressure 3–25 bar in the presence of a catalyst to produce relatively small amounts of hydrogen, carbon monoxide and carbon dioxide. Steam reforming is endothermic - that is, it has to supply energy for the process to proceed.

Steam Gasification – Steam gasification is considered to be one of the most effective and efficient techniques to generate hydrogen from biomass. From all thermochemical processes steam gasification provides the highest stoichiometric yield of hydrogen. There are many factors that affect the yield of hydrogen in steam gasification. Natural Gas Reform/Gasification: Synthesis gas – a mixture of hydrogen, carbon monoxide and a small amount of carbon dioxide is created by the reaction of natural gas with high temperature steam. Carbon monoxide is reacted with water to produce additional hydrogen.

Methane pyrolysis - the major sources of hydrogen are natural gas 48%, oil 30% and coal 18% while only 4% of hydrogen comes from renewable energy sources worldwide. In methane pyrolysis, hydrogen and carbon are separated. One of the benefits of methane pyrolysis is that in this process carbon dioxide, along with oxygen is produced. This is the main advantage of methane pyrolysis over conventional steam methane reforming and coal gasification processes. Natural gas has lower carbon content than coal gasification but economically the cost of natural gas is slightly higher than coal. Water electrolysis, the metal oxide cycle and the methane pyrolysis process produce CO₂ free hydrogen.

When hydrogen is produced by decomposing methane, the reaction method is known as pyrolysis or methane cracking. In this process, methane splits into its constituent elements which are H₂ and solid C. There is no combustion of carbon in this process. In this method, hydrogen is produced cheaper than steam methane reforming. In addition, CO₂ capture and storage (CCS) also occurs during this process. The reason for the cheap reaction process may be the production of solid carbon. This solid carbon is precious and therefore offsets the cost of the entire process. The process of methane pyrolysis undergoes the chemical splitting of methane. The resulting compounds include hydrogen and hydrocarbons along with solid carbon molecules [12].

CH₄ g C_(s) + 2H₂ g ΔH 298K = 74.52 kJ/mol

This process is endothermic and obtains energy from various sources. Since oxygen is not involved in the reaction, no carbon dioxide or its derivatives are produced. Hence no further separation process is required during the reaction.

Partial Oxidation - Partial Oxidation In the water-gas shift reaction, carbon monoxide reacts with water to form carbon dioxide and more hydrogen. Partial oxidation is an exothermic process that generates heat. The process is, generally, much faster than steam reforming and requires a smaller reactor vessel.

Government Policy: Government also focused on such technology that emits zero carbon. Indian Prime Minister launched the National Hydrogen Mission on 15^th August 2021. Its aims to aid the government in meeting its climate targets and making India green hydrogen hub. Government of India decided that the waiver of inter-state transmission charges shall be granted for the period of 25 years to the producer of green hydrogen from the projects commissioned before 30th June 2025.

Green hydrogen can be manufactured by a developer by using renewable energy from a co-located renewable energy plant. Green hydrogen plants will be granted open access by the government for sourcing of RE. Banking shall be permitted for a period of 30 day for RE used for making green hydrogen. Connectivity, at the generation end and the green hydrogen manufacturing end, to the Inter-State Transmission system for RE capacity set up for the purpose of manufacturing green hydrogen shall be granted on priority under the electricity rules 2021.

Land in RE parks can be allotted for the manufacture of green hydrogen. Government of India proposes to set up manufacturing zones and production plant. Manufacturers of green hydrogen shall be allowed to set up bunkers near ports for storage and export. Land for the storage purpose shall be provided by the respective Port authorities.

MNRE will establish a single portal for all statutory clearance and permission required for manufacture, transportation, storage and distribution of green hydrogen. The concerned agencies/authorities will be requested to provide the clearance and permission in a timebound manner, preferable within a period of 30 days from the date of application. In order to achieve competitive prices, MNRE may aggregate demand from different sectors and have consolidated bids conducted for procurement of green hydrogen through any of the designated implementing agencies.

Conclusion:
Nowadays, hydrogen gas is continuously proving its power as a sustainable and clean energy carrier in the current fossil fuel deployment phase with high specific energy and zero polluting energy sources. In this regard, India has a lot of biomass potential and coal reserves which have a greater tendency to consolidate higher production. All over the world are rapidly commercializing fuel cell technologies and India is still in the early stages. India is currently facing some major challenges like creating public acceptance, regulation policies, standards and codes etc. Overcoming these issues, India will be able to meet the energy demands through clean gateways in the near future. In terms of fuel savings, hydrogen fuel cell vehicles were found to deliver three times more economy than conventional internal combustion engines. In the presented paper, India has described the processes of hydrogen production. In the end, it has been found that green hydrogen will be used as a fuel for zero-emissions vehicles, for power generation and as a fuel in aircraft. Green hydrogen can be one of the major possibilities of reducing carbon emissions.
 

- Krishnadeep Sahu, Young Professional – II, Agricultural Energy and Power Division, ICAR–CIAE Bhopal
- Harsha Wakudkar, Scientist, Agricultural Energy and Power Division, ICAR–CIAE Bhopal
- Sandip Gangil, Principle Scientist, Agricultural Energy and Power Division, ICAR–CIAE Bhopal