Re:Ask HN: Can we get rid of plastic?
by PaulHoule on Wednesday December 02, 2020 @11:30AM
(#25278002)
What is your concern about plastics?
The one plastic that is an outright poison is PVC. Widespread use of PVC is why they stopped burning trash in most places: when it burns the HCl produced eats the incinerator from the inside out.
I live in a place has zero sort-recycling which is great environmentally for aluminum cans and the biaxial PETE soda bottle in the 1-liter, 2-liter, and other form compared to alternatives such as new materials, or recycled glass or paper. (Glass involves high temperatures but is not fast, paper fibers break down permanently from reuse.)
Our recyclables are a quality product that is usually in demand, but as a commodity there is always the problem that prices go up and down.
Even with electric cars, there will be demand for hydrocarbon fuels for air travel and other use. The chemistry of that is depressing for many reasons, largely that the reactions that break large chains down to methane or that build up huge chains (such as polyethylene plastic molecules) proceed very quickly under many conditions so to get medium-size chains you have to get conditions just so and that means low reaction rates and a very big machine to make a relatively small amount of fuel. It has trouble competing with $100/barrel oil even with the best coal, reprocessing plastic into hydrocarbons cannot win.
Disposing large quantities of plastic into megastructure landfills is a possible strategy for carbon storage if we were to remove it from the atmosphere. The main concept today is to capture CO2 and inject it into a saline aquifer which is probably safe but concerning enough and not available everywhere. There is a "CarbFix" process that involves injecting 10 parts water for every part CO2 that turns the CO2 to rock but that is a lot of water.
The one plastic that is an outright poison is PVC. Widespread use of PVC is why they stopped burning trash in most places: when it burns the HCl produced eats the incinerator from the inside out.
I live in a place has zero sort-recycling which is great environmentally for aluminum cans and the biaxial PETE soda bottle in the 1-liter, 2-liter, and other form compared to alternatives such as new materials, or recycled glass or paper. (Glass involves high temperatures but is not fast, paper fibers break down permanently from reuse.)
Our recyclables are a quality product that is usually in demand, but as a commodity there is always the problem that prices go up and down.
Even with electric cars, there will be demand for hydrocarbon fuels for air travel and other use. The chemistry of that is depressing for many reasons, largely that the reactions that break large chains down to methane or that build up huge chains (such as polyethylene plastic molecules) proceed very quickly under many conditions so to get medium-size chains you have to get conditions just so and that means low reaction rates and a very big machine to make a relatively small amount of fuel. It has trouble competing with $100/barrel oil even with the best coal, reprocessing plastic into hydrocarbons cannot win.
Disposing large quantities of plastic into megastructure landfills is a possible strategy for carbon storage if we were to remove it from the atmosphere. The main concept today is to capture CO2 and inject it into a saline aquifer which is probably safe but concerning enough and not available everywhere. There is a "CarbFix" process that involves injecting 10 parts water for every part CO2 that turns the CO2 to rock but that is a lot of water.