Powerelectronics 697 Leland Teschler910 0

Which is more energy efficient, the garbage can or the recycling bin?

Nov. 1, 2010
My friend Terry and I had each finished off a bottle of beer. I looked around for a recycling bin while Terry just pitched his bottle in the trash

My friend Terry and I had each finished off a bottle of beer. I looked around for a recycling bin while Terry just pitched his bottle in the trash.

Was Terry indifferent to the environment? Nah. He works at one of the biggest breweries in the U.S. and knows first-hand what happens to recycled glass. “We can’t use recycled glass for making bottles. It’s just too brittle. So glass put in recycling bins generally ends up in landfills anyway,” he explains.

Terry knows what he’s talking about. Canada’s National Post reports that all the glass collected last year by recycling programs in Calgary, Edmonton, and several other Canadian cities ended up landfilled because there were no buyers for it. The situation is similar for plastic. Reports are that Germany has millions of tons of recyclable plastics piled up in fields because nobody wants the stuff. And it is literally more expensive to collect some recyclables than to just pitch them. San Francisco’s Dept. of Waste figures it pays $4,000/ton to recycle plastic bags for which it receives $32/ton.

There is a more efficient alternative to the massive deployment of special trucks and personnel that collect recyclables which ultimately wind up in landfills. Improved technology makes incinerators a ‘greener’ bet than consumer recycling. The updated word for incinerators is waste-to-energy units. Modern WTE facilities burn waste at super-high temperatures. The heat drives steam turbines to generate electricity. The residue from the WTE units is an ash that takes up about 90% less space in landfills than the original waste material.

Even better, WTE plants don’t eliminate the opportunity to pick out metals in the waste stream, for which there is a large and profitable recycling market. Automated machinery can sift through the sludge and do the job – no special trucks or recycling bins required.

As an example, consider the SEMASS WTE facility in Rochester, Mass. It was a finalist in a Columbia University competition for best worldwide WTE facilities. The SEMASS plant burns about a million tons of garbage and generates nearly 600 million kW-h of electricity annually. It also recycles about 40,000 tons of metal in a year. The energy that plants like the SEMASS unit generate is considered renewable because it comes from natural resources. In that regard WTE power is continuous and thus has a leg up on solar and wind sources. It easier for utilities to plan for the electricity that WTE generates.

Unfortunately, some environmentalists trash-talk WTE plants. They claim, among other things, that the plants put toxins into the air. Real-world results, though, indicate such concerns are overblown. Again using the SEMASS plant as an example, Columbia University Earth Engineering Center director Nickolas Themelis says the plant’s toxic dioxin emissions are less than a half gram annually, about the weight of a cigarette butt. Themelis also says the facility’s emissions are well below EPA and EU standards.

Still, many see WTE facilities as less environmentally friendly than recycling, I suspect because there’s little understanding of what really happens to much of the waste dubbed “recyclable.”Often times, the recycling bin is just a meaningless gesture. As my friend Terry says of empty bottles, “Go ahead and put them in a blue bin if it makes you feel better.”

— Leland Teschler, Editor

Sponsored Recommendations

Design AI / ML Applications the Easy Way

March 29, 2024
The AI engineering team provides an overview and project examples of the complete reference solutions based on RA MCUs that are designed for easy integration of AI/ML technology...

Ultra-low Power 48 MHz MCU with Renesas RISC-V CPU Core

March 29, 2024
The industrys first general purpose 32-bit RISC-V MCUs are built with an internally developed CPU core and let embedded system designers develop a wide range of power-conscious...

Asset Management Recognition Demo AI / ML Kit

March 29, 2024
See how to use the scalable Renesas AI Kits to evaluate and test the application examples and develop your own solutions using Reality AI Tools or other available ecosystem and...

RISC-V Unleashes Your Imagination

March 29, 2024
Learn how the R9A02G021 general-purpose MCU with a RISC-V CPU core is designed to address a broad spectrum of energy-efficient, mixed-signal applications.


To join the conversation, and become an exclusive member of Electronic Design, create an account today!