1.   We have also seen that hydrogen is made as a byproduct of the makeup of oxygen by electrolysis of water.

2.   Environmentalists argue that hydrogen can be made using renewable sources, especially solar power cells.

3.   His techniques allow hydroelectric and geothermal energy, both plentiful in his homeland, to be used to make hydrogen for eco-friendly fuel cells.

4.   The trouble is, the only way to make hydrogen at the moment is to split water with electrical energy from polluting power stations.

5.   While oil refineries make hydrogen, for use in the refining process, the molecule is so small that it would escape from conventional pipelines.