Country superstar Keith Urban is going green on his upcoming tour by running his tour buses on bio-diesel fuel and offering his fans a chance to buy T-shirts made from recycled plastic bottles.The singer, who is married to Hollywood star Nicole Kidman, has teamed up with environmental T-shirt firm Chaser Merchandise to make sure the gear he’s offering fans is as green as possible.He says, "While I am far from the greenest guy on the block, I do look for situations where I can make even a small difference. "And so the idea that our concert tees could retain the same look and feel, but be partly made from recycled materials appealed greatly to me."