Ask HN: Is anyone pursuing longshot tech for recycling / remediating landfills? | Hacker News Reader

Ask HN: Is anyone pursuing longshot tech for recycling / remediating landfills?

6 pointsin_vestor7 comments

I have had a lifelong interest in cleaning up trash—-something that’s probably rooted in deep-seated aesthetics and maybe a bit of OCD.

My first career was in standard finance/tech and left me with enough flexibility to try to do something I’m really passionate about.

I have rigorously followed the academic literature and commercial development of recycling tech. It has been a disheartening journey. Recycling doesn’t work as well as people think. Promising solutions like plasma gasification had lots of engineering and economic challenges. A recent push in Europe for landfill mining went nowhere.

What is really needed is a single stream solution where almost any material can go in the front end, and out the back end comes useful elemental products or inert products.

Is anyone working on long-shot technology that would do this? If so, I would like to network. I’m not interested in something to make incremental changes around the edges. I’m interested in the type of tech that would be revolutionary.

I haven't heard of anything that actually works. I would maybe look at prevention as an alternative - things like compostsble packaging, reduction in packaging, bring your own packaging (zero waste lifestyle), etc.

See https://www.explainthatstuff.com/plasma-arc-recycling.html

This is what I referenced in my post as plasma gasification.

It has been tried in the real world. Belgium planned to use it for landfill mining, and Britain planned to built two plants to process fresh trash. But this has all been shut down at this point due to engineering challenges and economic challenges.

I’m trying to find out if there is anyone out there trying to still plug away at this and make progress?

Which post?

It's hard to believe something like that gets a net energy yield from burning the syngas, also technologies around syngas seem to struggle when competitive fuels are available.

The construction material bit is definite downcycling and even that sort of plasma torch might destroy PFAS it is (i) not going to destroy or isolate toxic metals like like and (ii) it is not going to extract various precious materials that are widely dispersed in waste: so low-value outputs can't really be good.

I've heard that the plasma torch can be tuned up to separate elements, at least coarsely, and if it could produce high value products it would be a big help.

My understanding is there really is no shortage of landfill space there is more of a political unwillingness to build more landfills. There is a huge interest in a "circular economy" but that precludes downcycling and of course making products recyclable is a start.

Another I find interesting is that very similar chemistry is being proposed for battery recycling as is used for reprocessing spent nuclear fuel, it seems a technology similar to PUREX could be tuned up to extract just about anything out of a mixture of everything in the periodic table but probably not economically. Similarly there are all the "pyroprocessing" techniques based on molten salts and such that are not so discriminatory as PUREX but more so than the plasma torch.

You basically correctly identified the main reasons plasma gasification has not been viable and why it won’t be viable until these issues are resolved.

My inquiry basically amounts to whether anyone is working on these problems. There was a big push 10-20 years ago, but it seems people have given up.

There is plenty of land for landfills, but nobody wants them nearby. The bigger problem, however, is that in the long run, the encapsulations will all fail. It’s not a matter of if; it’s a matter of when. Until then, there are ongoing maintenance costs (such as mowing because you can’t let trees get root) that can add up quickly.

Someone has to work on this technology because it will eventually be needed for remediations (it already is needed for old, unlined landfills). It needs to capture the high-value metals (as you mentioned) and it needs to be economical in terms of initial capital costs as well as being at least energy neutral.

It doesn’t necessarily have to produce net energy since it can generate revenue the same way a landfill does (tipping fees), but it would be nice to at least get close to energy break even.

Anyway, I guess people have given up on this problem for now, sadly.

I did a lot of reading about it just now and this I think is the best report

http://energy.cleartheair.org.hk/wp-content/uploads/2013/09/...

which I see as pessimistic. Although the plasma torch is using a fraction of the energy output, they are blasting oxygen or air into the reactor so pyrolysis is driven by combustion as well. The reactor is not breaking down dioxins so those need to be stripped. From an air pollution quality it looks acceptable but not great. Heterogenous feedstocks will confound the thing.

This gasification facility is in a class by itself,

https://www.netl.doe.gov/research/Coal/energy-systems/gasifi...

it was not able to pay for its capital costs but after a bail out it has been highly successfully at paying its operations costs. It is highly optimized and it is not just selling natural gas but also nitrogen fertilizer (uses the nitrogen from the liquid air factory that makes oxygen for the blast) and coal tar products and even waste CO2. It has a huge coal seam across the street so it is always consuming the same stuff so the preprocessing and cleanup are all standardized. It was “too big to fail” so people did stay the course and get it spinning like a top.

Thanks for the info. I reviewed it.

To me, it seems the problem nobody is addressing is how to recycle valuable metals without them becoming part of the slag (ie we need something that can be used to break down electronic components to their rare metals and then capture them usefully). Everything I’ve read seems to just ignore this. Have you any thoughts on this?

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