When getting a cup of hot coffee from your local joint, the greenest way to avoid disposables is to use a stainless steel mug. But do you know how many times you need to reuse it before you see any environmental savings? When you break down the amount of raw materials and energy needed to make a reusable mug versus a disposable cup, a Stanford Magazine story estimated you would need to use it at least 170 times to see any eco-savings. But that's only if you toss the stainless steel mug. When it's time to replace it, recycle it -- your green savings will be much greater.