More than 30 million plastic hotel key cards are manufactured every year for hotel guests. Yes, some key cards are returned to the front desk and reused, but a large majority end up in the trash. Made from PVC plastic, these cards are not biodegradable and can also be unreliable when it's time to open your door. Starwood Hotels will soon launch a new program that eliminates key cards with a new smartphone app. The app is pre-programmed at check-in and allows guests to open the door with the tap of their phone. One more way technology is helping to cut waste.