# Technology for Green Hydrogen Production: Desk Analysis
## 2 Background of Analysis
### Types of Hydrogen
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Advantage** & **Grey Hydrogen [83; 87; 88; 89]** & **Green Hydrogen [5; 6; 90; 91; 92; 93; 94; 95; 96; 97; 98]** \\ \hline Environmental benefits & \(\bullet\) & Grey hydrogen production through SMR releases significant amounts of carbon dioxide, contributing to climate change and global warming. & \(\bullet\) & A clean energy carrier with zero greenhouse gas emissions at the point of use, as it only produces water when combined with oxygen in a fuel cell or burned for energy. \\ \hline Renewable and sustainable & \(\bullet\) & Grey hydrogen relies on finite fossil fuel resources, which are subject to depletion and price fluctuations. & \(\bullet\) & Derived from RESs, which are inexhaustible and do not deplete natural resources. \\ \hline Energy security & \(\bullet\) & Grey hydrogen production is often linked to the availability and cost of natural gas, which can vary due to geopolitical factors and market dynamics. & \(\bullet\) & By using domestic RESs, green hydrogen can enhance energy security by reducing dependence on imported fossil fuels. \\ \hline Versatility & \(\bullet\) & Grey hydrogen is also versatile. Its use perpetuates dependence on fossil fuels and the associated environmental impacts. & \(\bullet\) & Green hydrogen can be used in a wide range of applications, including transportation, power generation, industrial processes, and as a storage medium for renewable energy, providing flexibility in energy systems. \\ \hline Economic opportunities & \(\bullet\) & Grey hydrogen production is often part of established fossil fuel industries, with fewer opportunities for innovation and economic expansion in renewable energy technologies. & \(\bullet\) & The production of green hydrogen can create new industries and jobs in renewable energy and related sectors, contributing to economic diversification and growth. \\ \hline Health and air quality & \(\bullet\) & The SMR process and the combustion of gray hydrogen can release NOx and other pollutants, contributing to poor air quality and health issues. & \(\bullet\) & Green hydrogen does not produce air pollutants that can harm human health, such as nitrogen oxides (NO\({}_{x}\)), sulfur dioxide (SO\({}_{2}\)), or particulate matter (PM). \\ \hline Technological innovation & \(\bullet\) & Grey hydrogen technology is more mature and less likely to benefit from the same pace of innovation and cost reductions seen in renewable energy sectors. & \(\bullet\) & Investment in green hydrogen supports the development and improvement of renewable energy technologies, electrolysis systems, and energy storage solutions, driving technological advancements. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The advantages of green hydrogen, produced from RESs through the electrolysis of water, over grey hydrogen, which is produced from fossil fuels, typically via SMR of natural gas. more sustainable, environmentally friendly, and versatile energy source compared to grey hydrogen, with the potential to drive economic growth, improve air quality, and foster technological innovation in the energy sector. Despite these advantages, the widespread adoption of green hydrogen is currently limited by its higher production costs compared to grey hydrogen. The global hydrogen generation market size was estimated at USD 170.14 billion in 2023, and is expected to grow at a compound annual growth rate of 9.3% from 2024 to 2030 [98]. Grey hydrogen, produced from natural gas through SMR, benefits from well-established industrial processes and typically has lower production costs, often in the range of USD 1 to USD 2 per kilogram, depending on the price of natural gas and the efficiency of the production process. In contrast, green hydrogen, produced via electrolysis powered by renewable energy, can cost between USD 3 and USD 6 per kilogram or more, depending on factors such as the cost of electricity, the capacity factor of the renewable energy source, and the cost of the electrolyzer.