Rio leaders walk the sustainability talk WATER cups made from corn, power from biodiesel and recycled toilet paper.Welcome to the United Nations conference on sustainable development - Rio+20. The three-day conference, being attended by Prime Minister Julia Gillard, is attempting to walk the talk of sustainable development. The entire summit's greenhouse emissions are being offset by the "clean development mechanism" - part of the Kyoto protocol, which helps countries find the cheapest way to cut emissions. Drinking cups are made from corn and smell like burned popcorn. A massive and noisy generator uses biodiesel to meet the needs of 50,000 delegates and journalists. Recycled toilet paper is proudly promoted in the loos, lit by energy-efficient light bulbs, and the media centre staff take a dim view to anyone who wants something printed.