Is it a matter of the technology not existing? I understand it’s a grossly oversimplified model and I am neither an engineer nor a chemist, but I can’t imagine that we couldn’t simply set up a furnace that vents down a cooling pipe into a container or facility that captures the gasses and toxic particulate/waste for either further processing, reuse in industry, or just to stockpile.
In: Earth Science
When you burn something, it doesn’t just vanish. It changes from one state to another. So if you turn it into gas and smoke, which is just smaller particles, and then you collect it all? Why bother burning it. It’s going to weigh the same. So yeah, burning works if you don’t mind adding the gases and particulates to the atmosphere. If you don’t want to do that, then burning is a waste of resources that produces more carbon to burn it.
Well designed waste-burning plants will burn plastic waste to just water vapour and CO2 and even produce electricity and heat (to use for heating buildings) in the process. As long a we are talking about typical household plastics like polystyrole, polyethylene or polypropylene, you don’t get any toxic gases if the furnace is hot enough (though you still get CO2, of course). If other stuff is mixed in, you need good scrubbers, but these exist since at least three decades.
In my opinion, trying to recycle plastics is a mistake. It is only downcycling, there is market pressure to get it done in developing or lowly regulated countries, and then, the plastic tends to somehow end up in the oceans.
> Is it a matter of the technology not existing?
It exists. Flume gases tend to be 14% CO2, so the process isn’t efficient. You wash it down with an amine solution, and then you can collect and heat that again to release the CO2. This process consumes 25% of a coal power plant’s energy production, and it likely won’t scale down well for a smaller scale energy producer like an incinerator. This process is undertaken primarily to produce commercial CO2 than it is to reduce emissions. Last year, we captured a mere 40m tonnes of CO2 through this process. In order to meet the 2 degree C target by 2050, we would have to increase capture by 2 orders of magnitude by 2025.
Side note, coal ash is used to make cement, and desulfurization is how we make gypsum for drywall and plaster. Now you know where that stuff comes from.
> I can’t imagine that we couldn’t simply set up a furnace that vents down a cooling pipe into a container or facility
Sequestration is one of the things we do. The CO2 captured above is released into a gaseous state, then cooled and compressed into a liquid. We pump it into shale oil fields 2-3km below the ground to push the oil out, leaving CO2 behind effectively forever. Just don’t pop that cork…
But there’s not enough incentive. Not enough money. And frankly, there are better technologies. Nuclear, for example, actually has an astounding safety track record, and coal releases a shit-ton more radioactive material than nuclear ever has. We need less FUD, more education, and more direct guidance from experts. But Big CO2 producers work against any initiative or legislation that costs them money or threatens to put them out of business. And given our system of government, they have the right to do so.
We can, and it has been proposed before, but all that means is that instead of toxic solids in the environment, you have toxic pressurised gas canisters in the environment. Neither is ideal, and one is a lot more expensive than the other.
Plastic in the environment is bad, but burning it would be even worse. If the toxic cloud storage container ruptured you would have toxins in the air that would spread everywhere. At least if plastics get dumped the damage is limited to the affected area, not circulating around the entire world in the air. It’s much harder to clean the air vs picking up plastic.
* Costly
* Space – there are better uses for land than storing ever increasing amounts of gas
* What happens if there’s a leak? Vast amounts of concentrated and potentially harmful gas released. Sure, it’s less than the total quantity but it’s concentrated and localised.
We have scrubbers that clean the gas, but not always, we have ‘Energy from Waste’ so we can recover something of use from the waste, but not always. There are better, cheaper, easier, and safer options.
Not that the options we use are safe or the best, just relatively.
Transporting all the trash to one central location would use a ton of energy. Storing the exhaust gases is also difficult; without sorting what is being burned, the exhaust gas will be a huge mishmash of potentially toxic gases, potential greenhouse gases, corrosives gases, etc. That kind of mixed waste stream can be very difficult to deal with because making storage containers that are resistant to every possible waste product is complicated and expensive. Not to mention the hazards/risks associated with a leak; now you’ve liberated all those gases of unknown composition/hazard into the countryside.
The same problems apply to reprocessing; without a good idea of what the composition of the gases are, you can’t design an effective recapture/reprocessing facility. A process that can capture one compound might be fouled/disrupted by another compound. And not all of those products will be useful, so you’d need to create tons of storage for the non-useful products.
All these add up to make the proposed process extremely expensive to try to do. And no one is willing to foot the bill for something that is extremely complicated and failure prone.
We can. The problem is cost.
There is no significant problem we face that we cannot solve by simply paying enough money to do it. We can recycle plastic, use only solar power, and pick up all litter and dispose of it properly – if we are willing to spend the money to do it.
Capturing the gases initially isn’t hard. What you do with them afterwards is.
Burn plastic and what comes off is a load of toxic smoke.
Now, without meaning to sound sarcastic, there aren’t many uses for smoke. Smoke by its nature is hard to do anything with – it’s already undergone one chemical reaction that releases a lot of energy, so it generally needs a lot of energy *input* to react any further.
What about storing the gases? You could do that, but you’d need a lot of storage space. Gases are very low density, so if you burn something you get a large volume of gas. Think of the size of a cloud of smoke compared to the thing that’s burning. So you either need a large storage space or to compress the gas. You also need to make sure it doesn’t leak. Now there have been proposals to do this with CO2, pumping it deep into the ground, so it’s not *impossible*, but it’s a complicated and expensive business.
In fact, if all you want to do is store the waste products, you’re better off just storing the waste as it is. Likewise, if you want to reuse the materials in some form, it’s very likely to be easier to do that with the original materials than the byproducts of burning them.
The gases are several orders of magnitude larger than the solids you burned to make them. You’re generating vast volumes of gas that must be collected and stored.
In theory, it could be pressurized and/or condensed for storage – just not where you’re likely to ever have an earthquake or tornado.
As with most trash mitigation schemes the ultimate decider is money. It’s trash, literally so worthless you pay people to make it leave. Who’s paying for your carbon sequestration facility to incinerate something that can be buried in a big hole for much less?
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