The twin problems of resource depletion and growing amounts of waste can be solved through the valorization of waste into chemical, fuel and material products. While future “closed-loop” manufacturing should reduce waste through in-house use of by-products and products designed for end-of-life utilization of the components, we also need to find ways to capture valuable substances from existing waste streams and landfill sites. These waste valorization technologies must themselves be green so as not to add a substantial environmental footprint to new waste-derived products. Suitable green chemical technologies include bio-chemical processing (eg fermentation of food waste), thermo-chemical including microwave processing (eg conversion of paper waste to chemical intermediates), and benign solvent extraction (eg supercritical carbon dioxide extraction of waxes from cereal straws). One exciting new case study is on orange peel waste that is widely available in large quantities and rich in chemicals such as D-limonene and materials such as pectin: these and other valuable products can be simultaneously extracted in a novel microwave biorefinery process.