Plastic, Metal and Glass, Oh My!: Essential Answer

Photo: Stefan Szczelkun

How are plastic, metal and glass recycled and reused and how efficient is the process?

Asked by Shilpa Sarkar, ’11 Houston, Texas.


We all know the mantra of household waste management: Reduce, reuse, recycle. But what happens to the contents of your recycle bin after they’re collected depends on the material.

In general, recyclables are sorted, cleaned and processed into basic materials that can be reused in manufacturing new products. For descriptions of the different processes that glass, metal and plastic undergo, see the Nitty Gritty Answer, where you'll also find recycling statistics and the answer to the question: What on Earth is a nurdle? 

For the most part, recyclables are remade into something like their original form. Nine out of ten recycled glass containers end up as more containers, aluminum cans are typically turned into more cans, and anything made of steel can be recycled into anything else made of steel. Plastic is usually reborn as a different type of product, such as faux-wood lumber for decking, that is more difficult to recycle. In contrast, glass and metal can be recycled ad infinitum without decreasing their strength and quality.

What’s more, glass melts at a lower temperature than its constituent ingredients, so making a bottle from recycled glass uses 25 to 30 percent less energy than producing one from scratch. Likewise, reusing steel is 60 to 74 percent more energy efficient than creating it anew from iron ore, and—as an environmental bonus—saves habitats from the ravages of mining. And the energy savings of recycling aluminum into new products is a whopping 95 percent.

Plastic deserves special attention because it is typically made from fossil fuels. In all, around two pounds of oil or natural gas go into creating one pound of new plastic. That’s in addition to the energy consumed in the manufacturing process itself. Plastic recycling is usually very energy efficient, though, using 90 percent less fuel than new plastic.

But recycling is just one aspect of a sustainable approach to waste. To increase your positive impact, follow the first two Rs whenever possible. Glass is easy to reuse, so wash out your bottles and jars and give them new lives as food storage, drinking glasses or whatever else you can dream up. Plastic’s recyclability only goes so far; once it’s a deck, the next stop may be the landfill. So for maximum eco-friendliness, reduce the amount that you use in the first place.

You can dig deeper into the three Rs by visiting the EPA’s resource conservation website or read on to the Nitty Gritty Answer.