A Look at Recycling Glass Facts and Footprint.
One of the confusing things about recycling glass facts is knowing what type of units are being discussed, and being able to convert to a standard unit.
Also, in looking at recycling glass facts, one of the most common factors that crops up is the carbon footprint. The US EPA has a report called Solid Waste Management and Greenhouse Gases.
In Chapter 2, they talk about the Greenhouse Gas (GHG) emmissions in terms of Metric Tons Carbon Equivalent per ton of product.(MTCE)
Say what? Care to explain?
Since EPA works with metric tons and kg and I think in pounds, I need to do some conversions. One of the best converters I've found is onlineconversions.com, which allows you to convert almost anything into anything.
For starters, few people express their carbon footprint in carbon rather than carbon dioxide(CO2). You can always convert CO2 to carbon by multiplying with a factor 0.27 (1000 CO2 equals 270 carbon). Or you can convert carbon to CO2 by multiplying by afactor of 3.703 (1000 carbon equals 3703 of CO2)
Now lets start looking at recycling some glass.
One recycling fact that I didn't know is that melting down cullet (ground glass from recycling) supposedly produces no CO2, whereas the melting of the limestone and soda with the sand does produce co2.
Another recycling fact is that when the cullet is used in the manufacturing of new glass, it melts at a lower temperature. Producing glass from all raw materials uses about 40% more power. Using a 23% mix of recycled glass results in saving about 600 pounds of CO2 for every ton of glass melted.
So lets look at what happens with a jar of Adams Peanut Butter. We buy the 32 ounce size, which weighs 1 lb 5.75 ounces when it's empty.
There are three areas that can be looked at for carbon release in the manufacturing of glass: the carbon released from the inputs; both virgin and recycled, the carbon released from the non-energy processing and the combination of the two. We will start with a look at the carbon released from the combination, (which includes transportation).
The Metric Ton Carbon Equivalent (MTCE) per ton of Virgin Input and transportation energy emissions for glass is 0.18. Since I want to be working in pounds and ounces, I convert by multiplying the MTCE by the short ton conversion factor of 1.1023113109 and get 0.198 Short Tons of Carbon Equivalents. Since a short ton weights 2000 pounds, there are 396.83 Pounds of Carbon Equivalents per short ton. (0.198 times 2,000). That works out to 0.2 pounds Carbon Equivalents per pound of virgin input.
The Carbon Equivalents convert to Carbon Dioxide by multiplying by a factor of 3.703, which results in 0.73 pounds of CO2 per pound of input.
Since my 32 ounce Adams Peanut Butter jar only weighs 1 lb. 5.75 ounces, that means that it is 1.36 parts of a pound (21.75 ounces divided by 16), we can multiply both the Carbon Equivalents per pound of input (0.20) and the CO2 per pound (0.73) by that factor and arrive at 0.270 pounds of Carbon Equivalent and 0.999 pounds of Carbon Dioxide that are saved for every 32 ounce glass jar that is recycled.
Now let's look at the same jar made with 100% recycled glass, adding in the non-energy factors.
If that jar was made from 1 metric ton of recycled material, it would produce 0.09 metric tons carbon equivilent (MTCE) per ton of glass. Let's see, that's 198.42 pounds of carbon equivalents per short ton, which converts to 0.10 pounds of carbon equivalents and 0.37 pounds of CO2 per pound of input.
Since recycled glass only creates 0.10 pounds of carbon equvalents and 0.37 pounds of CO2 per pound of input, our 1 pound 5.75 ounce jar would only emit 0.499 pounds of CO2.
With a 23% mix of recycled cullets and virgin inputs per ton, we end up with 352.74 pounds of carbon per short ton and our jar will create 0.24 pounds of carbon equivalents. This works out to 0.888 pounds (14.2 ounces) of CO2 per jar.
In summary, the amount of carbon dioxide (CO2) released from making a 32 ounce jar to fill with Adams Peanut Butter will be 15.98 ounces with virgin inputs, 7.99 ounces with all recycled material and 14.2 ounces with a 23% recycled mix.
Obviously, if we could create all the new jars from nothing but recycled glass, we would have a much larger savings in co2 emmissions, but that isn't realistic. We do get an 11.11% reduction in emmissions from the current mix of 23% recycled glass, though. If the amount of glass recycled increases, the amount of cullets used in new manufacturing might increase, so always recycle your glass.
Or, you could just re-use that jar. We wash out the jar and lid, and then fill the jar with our home-dried raisins every fall, store them in the root cellar and enjoy them all winter and spring.
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