Wednesday, January 5, 2011

SiO2 or Al?

I was cooking up the last box of mac-n-cheese on Monday night and I started to think about how I'm going to need to make more things from scratch. Then I started to think about my freezer and batch cooking. I posed this question on Twitter but I thought I'd repeat it here with some detail:

What do you think is more environmentally friendly: using glass (Pyrex) containers or disposable (recyclable) aluminum containers for freezer to oven cooking?

Glass Pros:
  • Reusable.
  • Easy to clean (dishwasher safe).
  • Microwave safe.
Glass Cons:
  • Potential for thermal shock.
  • Expensive.
  • I will eventually have to move and/or sell/donate these containers when I return to Hawaii.
  • Requires storage space.
Aluminum Pros:
  • Inexpensive.
  • Recyclable.
  • Take up little storage space.
Aluminum Cons:
  • Generally a one use item.
  • Not microwave safe.
  • Not sturdy.
Does anybody know how to calculate the amount of energy used to create a glass pan vs an aluminum pan? I did a cursory search and couldn't find anything useful. I imagine that the actual manufacturing energy is less for the aluminum but what about production of the raw materials? Yes, I can buy my glass pans used...but it's hard to find tight sealing lids for the older pieces and I will want lids for freezer storage.

What do you think? Do you have any additional pros and cons? Suggestions?

Warm Wishes,


  1. Fusexd quartz (SiO2) is rarely used because it takes a LOT of energy to produce (has to be heated to 2300 degrees Celsius). Most glass is soda-lime where the quartz is doped with sodium carbonate, and calcium, magnesium, and aluminum oxides. It's about 3/4 silica by weight and only has to be heated to 1500 degrees.
    Pyrex is soda lime glass that has been heated for 24 hours to remove air bubbles.

    According to US Department of Energy Documents, container glass requires about 602 BTU per pound to prepare, melt, refine, form and post-form (temper) Most of this is from fossil fuel use (glass making requires heat and lots of it!) But it works out to about .176 kWh per pound

    Aluminum requires ~6 kWh per pound to produce. That said, recycled glass only requires ~25% less energy to produce new glass products but aluminum reduces the energy cost of production to nearly zero.

  2. Thank you for the clarification; I had a feeling that somebody would call me on my inadequately researched attempt to create a cute title. Thank you also for the link on your blog.

    I've had a chance to step back from the initial information overload I experienced while researching this topic and I am leaning towards picking up a case of aluminum pans from the restaurant supply store when I do my next run of batch cooking. Thank you again for stopping by.