Globally, the size of the hydrogen industry is expected to hit $183 billion by 2023, up from $129bn in 2017, according to Fitch Solutions. The green variant of the fuel is produced entirely from renewable sources. Green hydrogen produced from renewable sources could cost less than natural gas by 2050, as the cost of solar power continues to decline, according to research by BloombergNEF. The cost of green hydrogen, which is considered expensive to produce today, should decline by up to 85 per cent by 2050 and could fall below $1 per kilogram or $7.40 per one million British thermal units by 2050 in most markets, according to its research.