Green hydrogen refers to hydrogen which is renewable energy with zero emission. As the cost of renewable energy such as solar energy drops, green hydrogen is touted as part of the energy mix that will lead the decarbonisation trend from consumer and industrial power to transport and aerospace applications. According to a study released this month by the National Renewable Energy Laboratory of the U.S. Department of Energy, U.S. demand for hydrogen is likely to increase from 10 million tons today to 22 million to 41 million tons a year by 2050. After decades of trial and error, hydrogen technology is expected to converge with low production costs, technological progress and global demand for sustainability, according to Bank of America. The company believes this will generate US$2.5 trillion in direct revenue and US$4 trillion if revenues from related products such as fuel-cell cars are included, bringing the total market potential to US$11 trillion by 2050. In Europe, the concept of hydrogen energy is emerging rapidly. The European Commission believes that the proportion of hydrogen in the European energy mix will increase from less than 2% in 2019 to 13-14% by 2050. Both German and French are actively conducting experiments in the construction of hydrogen energy bases. Jorgo Chatzimarkakis, secretary-general of the European Hydrogen Energy Alliance, a group of about 250 companies and research organizations, said the storage issue was key to achieving energy conversion. In this respect, hydrogen and hydrogen technology play a vital role. The alliance calls for 55 billion euros (US$65 billion) investment to build 3 million tons of hydrogen production capacity by 2030.