It is a fundamentally new technology that splits natural gas or biomethane directly into the components of hydrogen and solid carbon. This process requires relatively little energy. And if it uses electricity from renewable sources, there are actually no greenhouse gas emissions. Methane pyrolysis splits CH4 directly into its components, i.e., hydrogen and carbon. Unlike other technologies that use fossil resources, such as coal gasification or steam methane reforming, the greatest benefit of methane pyrolysis is the production of CO2-free hydrogen. Solid carbon is the only by-product resulting from the thermal decomposition of methane, so neither a CO2 separation step nor its subsequent storage is needed. Methane cracking is an endothermic reaction that takes place at high temperatures. Once the temperature is higher than 3000C, methane theoretically starts to decompose into solid carbon particles and H2 gas without any catalyst, according to thermodynamics. Nevertheless, for a noncatalytic methane cracking, a reasonable high conversion can hardly be reached below 12000C. Catalytic methane decomposition occurs at a temperature in the range of 600–9000C. The carbon hence generated can be used for various purposes.
The biomethane produced in the process can be converted to
hydrogen by methane pyrolysis, which can generate solid carbon. Solid carbon in itself is a very useful material and has got its use in many dimensions. Few are listed below:
- Can be used as coke in steel plants and power plants
- Carbon black used for production of tyres, plastics, coatings etc.
- Graphite electrodes Carbon Nanofibers – composite aeronautics, sporting goods.
- When added in soil, it increases the fertility of soil by retaining moisture and nutrition and reduces the chances of landslides in hilly areas.
- Activated carbon can be used in producing clean water for all.
Research has shown hydrogen production yields of 33.6 mol/kg and hydrogen concentrations of 82% from mixed waste feedstock gasification. Biochemical methods such as fermentation can produce hydrogen up to 418.6 mL/g.
Carbon returned to soil is a boon
Solid carbon, obtained after splitting of methane to produce hydrogen can be utilised in various value added products like tyre and graphite manufacturing besides being mixed with soil to increase its fertility, water and nutrition retention, reducing the consumption of synthetic fertilizer and preventing landslide in hilly terrain.
Economies of scale for Green Hydrogen
Economies of scale for Hydrogen from Waste is expected too because of the sea change in Electrolyser Market enabling green Hydrogen from offshore wind and floating Solar PV plants.
List of Top Manufacturers/ Key Players in Hydrogen Electrolyser Market are:
- Nel Hydrogen
- Hydrogenics Corp
- McPhy Energy S.A.
- Giner Inc
- GreenHydrogen.dk ApS
- Igas Energy GmbH
- Areva H2Gen
- Next Hydrogen
- Accagen SA
- ELB Elektrolysetechnik GmbH
- Beijing CEI Technology Co.Ltd
- Tianjin Mainland Hydrogen Equipment Co. Ltd.
Electrolysis (using electricity to split water into hydrogen and oxygen) has been prevalent since 1800. With further developments it was refined into alkaline electrolysis by the middle of the 20th century. In this case, voltage passes through an electrolyte of caustic salts, thereby breaking water into hydrogen and oxygen. Lately newer methods have also emerged. Proton Exchange Membranes (PEM) brought an end to the use of liquid electrolyte. Anion Exchange Membrane (AEM) electrolysis is another method that eliminates the requirement for precious metals. There’s also high-temperature electrolysis, which separates superheated steam into oxygen and hydrogen using ceramic membranes.
The cost of producing hydrogen comprises the cost of the electrolyser including the maintenance and replacement of membranes, cost of electricity utilised to develop the high temperatures required for water to split, and subsequent costs like drying, cleaning and compression of the gas. Further there are costs involved in respect of transportation also. Among these costs, the largest contributor is electricity that accounts for as much as 70-80% of the cost of hydrogen.
As regards the electrolysers, they are getting cheaper, but are still expensive. In 2018, an electrolyser producing one cubic metre of hydrogen per hour used to cost around $7,600. With further developments by the year 2020, this cost ranged between $4,900-$6,000. There is a definite scope for further reduction. Since the sales volume is on the lower side, electrolyser manufacturing has seen little automation, some are even manufactured by hand. For quite some time, the hydrogen market was relatively well-ordered. If we look at the different regions in the world, Europe led in R&D, especially for green hydrogen, utilising technologies like PEM and AEM. China, on the other hand, has dominated production, producing the world’s cheapest alkaline electrolysers for one-fifth the cost of comparable models in Europe. To avoid a repeat of the issue with solar PV manufacturing, which was developed at a great cost in Europe before being moved to China, the EU has plan to set up at least 6 GW electrolysers by 2024. ITM Power has opened a 1 GW facility in the United Kingdom. Nel, a Norwegian electrolyser manufacturer, has announced intentions to build a new 2GW facility. But keeping up with the pace in other parts of the world, China is not lagging behind. The China Baowu Steel Group, has announced plans for 1.5 gigawatts of renewable-powered electrolysers. Fortescue Future Industries, based in Australia, has announced the construction of a factory that will manufacture up to 2GW of electrolysers starting in 2023. This scaling up may lead to cutting down of costs. Further, there are countries like Chile, Egypt, South Africa and Oman which, utilising the cheap renewable power and electrolysers made elsewhere, are trying to become hydrogen producers.
Indian researchers at IIT Bombay led by Prof. C. Subramaniam have come out with an innovative solution. It involves electrolysis of water in the presence of an external magnetic field. In this method, the same system that produces one ml of hydrogen gas required 19% lower energy to produce three ml of hydrogen in the same time. This is achieved by synergistically coupling the electric and magnetic fields at the catalytic site. The simple approach also provides the capability to retrofit any existing electrolyser (that uses electricity to break water into hydrogen and oxygen) with external magnets without drastic change in the design, leading to increased energy efficiency of H2 production. 
NTPC has already awarded a project of ‘Standalone Fuel-Cell-based Micro-grid with hydrogen production using electrolyser in NTPC Guest House at Simhadri (near Visakhapatnam)’.  It is India’s first Green Hydrogen-based Energy Storage Project. It would be a precursor to large scale hydrogen energy storage projects and would be useful for studying and deploying multiple microgrids in various off grid and strategic locations of the country. Due to this rising competition worldwide, hydrogen prices are expected to fall swiftly. With these developments green hydrogen is expected to touch $1-2 by 2030.
Hydrogen from Waste would be a key driver in the triad of energy, economy and environment, meeting the requirements for Grid Stability, Energy storage Transport and utiliziation in Micro-grids. As per our estimates, hydrogen from waste can be a third of the cost of hydrogen from electrolysis using grid-based electricity. Hydrogen from waste is greener than the green because it prevents contamination of soil, water and air, mitigates GHG and returns carbon to the soil improving fertility, preventing soil erosion and land slide.
The biggest challenge for India in this, however, is the expensive production and operation processes, heterogeneous feedstock, low process efficiencies, inadequate management and logistics, and lack of policy support. Yet, hydrogen from waste with green hydrogen from resources like solar and wind would be a win-win and the highway to deep decarbonisation in the years to come.
Suraj Prasad is working as a QA Automation Engineer at Esko, A Danaher Company. He is a graduate from Manipal Institute of Technology, in Print & Media Technology.
Dr. Bibhu Prasad Rath is a graduate in Mechanical Engineering and has worked in various functions in NTPC – including Operation & Design. He is presently the Additional General Manager in Project Engineering division. His qualifications include ICWA (Inter-1995), M.Tech (IIT Delhi-2002) and PhD (in Business Administration-2015) from Aligarh Muslim University.