Garden grass could become a source of cheap and clean renewable energy, scientists have claimed.A team of UK researchers, including experts from Cardiff University's Cardiff Catalysis Institute, have shown that significant amounts of hydrogen can be unlocked from fescue grass with the help of sunlight and a cheap catalyst.It is the first time that this method has been demonstrated and could potentially lead to a sustainable way of producing hydrogen, which has enormous potential in the renewable energy industry due to its high energy content and the fact that it does not release toxic or greenhouse gases when it is burnt.Co-author of the study Professor Michael Bowker, from the Cardiff Catalysis Institute, said: "This really is a green source of energy.