Blue hydrogen is produced mainly from natural gas, using a process called steam reforming, which brings together natural gas and heated water in the form of steam. The output is hydrogen – but also carbon dioxide as a by-product. That means carbon capture and storage (CCS) is essential to trap and store this carbon.Blue hydrogen is sometimes described as ‘low-carbon hydrogen’ as the steam reforming process doesn’t actually avoid the creation of greenhouse gases. Blue hydrogen is currently being tested as a blend in the natural gas network. One may ask why would you split up natural gas only to blend it with natural gas?