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The Engineering of Landfills

practical.engineering

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Re: The Engineering of Landfills

#131

Post by vel0city »

ajb wrote: post #33

"trash is an inescapable fact of the human condition" Not really. There didn't used to be anything like as much. But what we did before wasn't necessarily better. Most consumer products were made of organics, like wood, cloth and paper; metals, and clay. Organics were burned or recycled, metals recycled (as now). Only broken clay was really waste. Cities didn't collect trash - they collected ash. In Britain waste col…

> Only broken clay was really waste.

> Cities didn't collect trash - they collected ash.

So is ash broken clay or is your first statement just incorrect?

Re: The Engineering of Landfills

#132

Post by bluGill »

nobodyknowin wrote: post #90
khaki54 wrote: post #81

I wonder if in 100-500 years they will mine landfills for materials or elements that have become scarce. Or maybe they will just keep them as natural gas reactors.

It might even be sooner than that. Once oil gets too expensive to pull out the the ground, mining plastic from landfills and decomposing it back to the hydrocarbons might end up big business. The natural gas/ ch4 production follows a pretty well known curve, at about 40-50 years it's nowhere near as potent. And with the push to keep organics out of the modern landfills that might get even worse.

We can make plastics from bio sources, or directly from elemental carbon. Oil is a lot cheaper, but we can do it. In WWII the Germans were running on synthetic gas. Last I checked you can buy synthetic gas - at about 5x the cost of standard pump gasoline. (synthetic gas has more energy per gallon so sometimes it is used in a race)

Re: The Engineering of Landfills

#133

Post by cogman10 »

toomuchtodo wrote: post #126
cogman10 wrote: post #123

Earlier quoted context omitted.

The big problem with plastic waste is getting it to the landfill (or incinerator) in the first place. Once the plastics are captured, I don't see too much benefit in incinerating it beyond freeing up landfill space. But that's really not a major issue as you can always dig a deeper and wider landfill. In fact, a major downside of incinerating the plastic is you end up with greenhouse gasses as a byproduct.

Certainly, you are generating some greenhouse gasses in the process, which is a trade off to ensure immediate waste destruction. To note, you will have to flare methane from the landfill in perpetuity when landfilled. If one is so inclined, internalize the cost of direct air carbon capture into the cost of waste disposal for those emissions. https://www.epa.gov/lmop/basic-information-about-landfill-ga... > Municipal…

Point taken. Though I do wonder how much of the methane released is from plastic decomposition and how much of it is from food/biomaterial decomposition. I'd naively assume the primary emission would come from readily decomposable materials and that most plastics would remain fairly stable for a lot longer than yesterday's half eaten hamburger.

Re: The Engineering of Landfills

#134

Post by aziaziazi »

legulere wrote: post #104
aziaziazi wrote: post #17

Earlier quoted context omitted.

IIRC, ~30%[0] of ocean plastic came from fishing nests. They are huge, break often and it’s easier and cheaper to throw aboard an old one than bring it onshore for recycling. (edit) 0: 46% https://www.seashepherdglobal.org/latest-news/marine-debris-... Totally unrelated but since it’s from seashepherd I can’t help adding Paul Watson trial from extradition in Japan is tomorrow.

I think the number comes from one study about the great pacific garbage patch and cannot be generalised to all ocean trash.

You are very right:

> Approximately 46% of the 79 thousand tons of ocean plastic in the Great Pacific Garbage Patch is made up of fishing nets, some as large as football fields, according to the study published in March 2018 in Scientific Reports

While generalisations may be misleading, when people talk about ocean pollutions they often think about the patches.

Re: The Engineering of Landfills

#135

Post by tomrod »

darksaints wrote: post #31
mikojan wrote: post #26

Earlier quoted context omitted.

Landfills certainly require more power to operate than that gas scheme can provide later. It all sounds and reads like a fairytale but none of this is sustainable.

70k homes is about 84MW. You’re gonna have a tough time finding any evidence that running a landfill requires 84MW of electricity.

I think their point was the delivery of that garbage over time is subject to entropy, and from first principles probably took more energy consumption than a sustained 84MW over the time period the landfill is a viable source for energy.

I know nothing about landfill engineering here, to be frank, simply being a grease for good online gearing.

Re: The Engineering of Landfills

#136

Post by Mistletoe »

scoofy wrote: post #99
bko wrote: post #2

I found this interesting: > Another option is to put it to beneficial use to create heat or even electricity. The Puente Hills landfill I showed earlier has a gas-to-energy facility that’s been running since 1987, and even though the landfill is now closed, it currently provides enough electricity to power around 70,000 homes. And towards the end > Landfills seem like an environmental blight, but really, properly des…

I genuinely use landfills, especially with plastic waste, as shibboleth to know whether I'm talking to somebody who is an environmentalist or somebody who is an "environmentalist." Anyone who thinks recycling plastic is some sort of normative good because "waste is bad" clearly hasn't put any thought into what environmental issues need to be focused on right now.

It was so frustrating when a dude at work was trying to bust my balls for not using the recycling for my plastic bottle. I didn’t have the energy or patience to explain to him how our city has single stream recycling and there was 100% chance that bottle was being shipped overseas, dumped in the ocean or something else way more stupid than just being buried in the city landfill.

Re: The Engineering of Landfills

#137

Post by fsckboy »

Iulioh wrote: post #36
barbazoo wrote: post #28

Earlier quoted context omitted.

> I wish more environmentalists would be excited about engineering solving environmental ills and relied less on knee-jerk reactions. Are many ... not? Seems like a weird complaint, I haven't encountered an "environmentalist" (whatever that even is) that is against landfills in general or the engineering of it. I'd rather we didn't produce as much garbage as we are and I hate that our city makes me wrap my garbage in…

Probably OP is thinking of NIMBYs.

OP is thinking of people who bumper sticker "Believe Science" but never took science beyond grade school or a required "science for poets" class. People who think "chemicals are bad, but organic is good".

These are not bad people, but they don't know what they're talking about enough to form their own opinions, but they don't know that.

Re: The Engineering of Landfills

#138

Post by toast0 »

yreg wrote: post #112
renhanxue wrote: post #88

Earlier quoted context omitted.

If we didn't burn waste we'd need to burn something else to stay warm in winter. Currently we supplement the waste with _mostly_ renewables, like byproducts from the forestry industry (e.g. treetops, wood chips, sawdust) and the olive oil industry (olive pits; we import this stuff from the Mediterranean region), but we burn a bit of peat too because there aren't enough reasonably priced renewables. Burning waste real…

> If we didn't burn waste we'd need to burn something else to stay warm in winter. Why not nuclear/renewables?

People don't like it when you burn nuclear waste, burning windmills isn't very effective --- at least not the modern metal ones, and solar panels are going to be toxic if you burn them. :P

Re: The Engineering of Landfills

#139

Post by toast0 »

the_gipsy wrote: post #16
cm2012 wrote: post #9

So many people misunderstand landfills. All the garbage produced in the U.S. for the next 1000 years could fit into a landfill 100 yards deep and 35 miles across on each side. That is, landfills take a trivial amount of space. Putting stuff in a landfill is way better for global warming since its not burned, the carbon is buried. Almost all plastic waste in developed countries ends up in landfills, not the natural en…

I'd guess that it's cheaper to ship a lot of garbage to developing countries.

Oregon is a lot closer, and they accept a lot of trash from my state by rail. No need to put it on a boat.

Re: The Engineering of Landfills

#140

Post by jrmg »

breck wrote: post #56
cm2012 wrote: post #9

So many people misunderstand landfills. All the garbage produced in the U.S. for the next 1000 years could fit into a landfill 100 yards deep and 35 miles across on each side. That is, landfills take a trivial amount of space. Putting stuff in a landfill is way better for global warming since its not burned, the carbon is buried. Almost all plastic waste in developed countries ends up in landfills, not the natural en…

> All the garbage produced in the U.S. for the next 1000 years could fit into a landfill 100 yards deep and 35 miles across on each side. > That is, landfills take a trivial amount of space. Damn, I had to think about this for a second, but you are right. How the hell did I not realize this before? Can you please popularize this more? Maybe compress into a pithy phrase.

The supposed triviality of this size is not sitting well with me.

What’s described is a 100 yard deep hole. So about 27 stories. It’s 35 miles per side, so 35 x 35 = 1225 square miles in area. That’s bigger than any city in the mainland US[1].

It’s a 27 story deep hole that’s twice as big as Houston. Three times as big as the city of LA, and over half the size of the urban metropolitan LA area[2]. Four times the size of New York (or three times, if you include the water as well as the land).

This is not a trivial amount of land - and it gets worse if you were not to have it be (ridiculously!) one hundred yards deep.

I’m not arguing we’re about to run out of landfill space imminently, but calling this ‘trivial’ is not what I’d call it.

[1]: https://en.wikipedia.org/wiki/List_of_United_States_cities_b... [2]: https://en.wikipedia.org/wiki/Greater_Los_Angeles

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