Consider the following with reference to Hydrogen:

1. Green Hydrogen: Produced using renewable energy, such as wind or solar power.

2. Grey Hydrogen: The electricity used to produce it, may have been generated by fossil fuels and it emits GHGs when burned.

3. Blue Hydrogen: Produced using electricity generated by burning fossil fuels, but paired with carbon capture and storage (CCS) technologies, which prevent GHGs from entering the atmosphere.

Which of the above definitions are correct?