Which themselves are being, albeit slowly, replaced by mobile technology, surface-type screens, computers attached to projectors, etc. I imagine the market for chalk are all die-hards, like say, vinyl record enthusiasts today. If you were to use internet outrage as your own metric you'd think it was a huge market. Its not.
Chalk is two generations behind at this point. Its probably not too great to be breathing in all day either, at least for some of the population:
The study, published in the journal Indoor and Built Environment, ruefully concludes: "Though real-time airborne chalk dust generation was found to be low in this study … and did not contain toxic materials, chalk dust could be harmful to allergic persons and may cause lacrimation and breathing troubles in the long run and certainly is a constant nuisance in classrooms as it may soil clothes, body parts, audiovisual aids and study materials."
surface-type screens, computers attached to projectors, etc
These have their place, certainly, but I'd find it hard to believe that power-consuming electronic replacements (also considering the environmental impact from raw materials and waste products, and energy used to manufacture them) are a "better" choice than a chalkboard in many cases.
Power is also required to mine chalk (giant limestone mines), process it, package it, ship it, etc and its completely non-renewable. It becomes dust and then you place another order.
A PC with a projector can last a decade in use and depending on the region may be powered by mostly or all renewables.
One of the interesting notes in the article is that they apparently use a lot of oyster shells. I would assume the shells are typically a waste product in other (likely food) industry processes. That's pretty darn green. Besides, we have a lot of limestone, veritable rock-oceans of it.
That's part of why it's incredibly difficult to talk about waste on industrial scales. One plant's garbage is frequently another's input. Waste is expensive, so plants will always try to reduce it to the bare minimums, and if possible make money off it, in the case of certainl classes of recyclables.
>Besides, we have a lot of limestone, veritable rock-oceans of it.
Sure but the amount of carbon you burn to get to that rock, excavate it, process it, move it, etc, etc is non-trivial. A computer and projector on 8 hours of day is a drop in a bucket to that.
Yeah but in order to manufacture that computer and projector you needed vast amounts of energy, water, minerals, plastics, rare earths, compounds that don't exist naturally in our planet, pollution disposal, such as heavy metal contamination & arsenic compounds, waste acid, strong bases.
In fact the cost things like PECVD or dry etching is so disproportionate compared to drilling a hole in the ground, that I'm willing to bet a computer is the equivalent of hundreds of years worth of a blackboard with chalk.
Exactly. Having worked on vacuum systems for physical vapor deposition, I can assure you that there's an enormous amount of energy going into gently wafting the materials onto other materials. (The wide area glass coater I worked on had a 2MW substation running dozens of 150-200kW power supplies (not full tilt all at once, obviously).)
Really, I recommend anyone look into this stuff. Just to get silicon to the purity and precise structure to just start chip fabrication:
https://en.wikipedia.org/wiki/Czochralski_process
Imagine the whole supply chain, from smelting metal for wires and cases to plastic molding to storage, economies of scale truly are vast.
Sure but that one time cost has a 10 year depreciation. A lifetime of chalk is endless mining because you go through it so quickly. You're constantly buying chalk. You're not constantly buying projectors.
>that I'm willing to bet a computer is the equivalent of hundreds of years worth of a blackboard with chalk.
As someone who grew up near a limestone mine, I think you greatly underestimate how much work it takes to get rocks from the earth. I've seen some of the largest machines in the world working there. Its an huge operation.
Chalk is two generations behind at this point. Its probably not too great to be breathing in all day either, at least for some of the population:
The study, published in the journal Indoor and Built Environment, ruefully concludes: "Though real-time airborne chalk dust generation was found to be low in this study … and did not contain toxic materials, chalk dust could be harmful to allergic persons and may cause lacrimation and breathing troubles in the long run and certainly is a constant nuisance in classrooms as it may soil clothes, body parts, audiovisual aids and study materials."
http://www.theguardian.com/education/2011/nov/28/chalk-dust-...