Professor Jim Barber of Imperial's Department of Biological Sciences explains:

[...]

"... the problem is hydrogen doesn't exist on Earth by itself. Instead it combines with other elements such as oxygen to form water, or with carbon to form methane, coal and petroleum. However, water is very stable and for this reason cannot be used directly as a fuel. Researchers have investigated using electrolysis to split water into oxygen and hydrogen but today it costs ten times as much as natural gas, and is three times as expensive as gasoline.

"Yet nature figured out how to split water using sunlight in an energy efficient way 2.5 billion years ago. By revealing the structure of the water splitting centre we can begin to unravel how to perform this task in an energy efficient way too."

Sue Freeman, acting editor of the magazine, said: "The research shows that a 'dermatologically tested' claim on one product may mean something completely different to the same claim on another product.

"This is confusing and potentially misleading. Without standard definitions, and with companies refusing to supply details of their tests and results, these claims are meaningless, and consumers are left guessing about the benefits implied by such claims."