> The best option is to stop using straws.
Hey, I completely agree with you there!
> CO2 is the primary concern.
Why?
> Storing waste is not a problem in most parts of the world.
I didn't say anything about storage space. Storage of waste isn't even close to the primary reason to avoid plastic waste.
> The amount of steel it would require isn't important.
It absolutely is, even if you only care about CO2. This statement contradicts other things you said. You can only make claims about one being better if you compare how much it takes to produce.
I'm trying to find sources on tons of CO2 emissions per ton of plastic & steel, and as a non-expert using Google, it's hard to pinpoint. But I get the feeling that metals are 2-3x the CO2 emissions of plastic. A steel straw would be much heavier than a plastic one, so based on this guesstimation, I'd expect CO2 parity for 1 steel straw to be somewhere in the neighborhood of 20 plastic straws. If I'm anywhere close to accurate, that doesn't seem like it takes very long to beat plastic on CO2.
If you think I'm wrong, you'll have to demonstrate it by showing how much steel it would require...
> What's important is how much energy it takes
I don't buy that blanket generalization. Energy is a highly debatable potentially misleading issue, and doesn't necessarily have a high impact on C02, if renewable energy sources are used like hydro & solar. We might be emitting CO2 by burning coal today, but we don't have to burn coal in the future.
> You also need to factor in the energy and water it takes to clean the straw and the likelihood of damaging or losing it over that time.
Sure, fine. That changes the average life of the straw. Let's say it's 1 year instead of 10. For someone who uses one straw per day at lunch only on work days, we'd have to compare the carbon footprint of 1 steel straw to about 260 plastic straws. Even for CO2 emissions, the disposable ones are at a pretty severe disadvantage any way you look at it.