Sea glass is the pieces of old broken bottles which have been worn down into smooth pebbles by abrasion through wave action. Technically it is litter, but of a rather benign sort, since it is chemically inert and over time is worn down into sand particles. However, it can be attractive and could have numerous uses, I'm sure, given sufficient reliable supply.

Of course, one could process broken glass in a tumbling machine until an appropriate appearance was achieved, but this is energetically expensive and also very dull.

I propose the dedication of a section of low-grade shoreline to the production of sea glass in industrial quantities. This could have significant fringe benefits in contributing to the reduction of erosion.
The ideal beach for this purpose has limited ecological or recreational value, is receding, ceding valuable land due to removal of material through longshore drift, and reasonable transport links.

Glass is recyclable, however, some types of glass are more locally useful than others. In the UK, for example, clear and brown glass bottles are used for local products, while green glass is mainly from imported wine and would have to be exported for recycling.

The system works like this:
If the hinterland is particularly prone to erosion - earthen cliffs, for example - then this is reinforced for the full width of the project. (ordinarily, doing this would reduce material supply and increase erosion further down the coast, but here we're supplying an alternative).
Each year, a few thousand tonnes of waste glass is broken to pieces slightly larger than the final desired average by passing through a rolling press. This glass is deposited at the 'upstream' end of the beach, over several installments. This layer can be built somewhat higher than the initial beach, to increase protection and encourage propagation.
Over time, storms and tides tumble this glass smooth, and carry it along the shore. At the downstream end of the operation, sea glass of a desirable size is extracted, while fines are allowed to proceed on to form an attractive beach with unusual green sand, potentially a new tourist attraction.

Prior to initial commencement, it may be worthwhile to remove any surface layer of sand if this would be useful (to improve a beach elsewhere, for example).
If, over time, material accumulates on the upstream side of the emplacement, this may be occasionally removed. In this event a groyn might increase the purity of the eventual product. However, perhaps this could be avoided through judicious site selection.
-- Loris, Aug 30 2022

“It’s hard to say how long it takes for glass to become smooth and develop that dusty look – but I’d say at least a year,” said Pantano. https://www.schlitz...inding-beach-glass/
One thing is for sure – only time and exposure to the elements can create beach glass. Artificially aged or tumbled glass doesn’t take on the same appearance. “Nobody has developed a process to replicate what happens to glass in a lake or an ocean,” said Pantano. [Loris, Aug 30 2022]

Not so many beaches... https://www.cnbc.co...cial-commodity.html
[RayfordSteele, Aug 31 2022]

I think that the area should be watched over and tended by a small flock of strandbeests.
-- lurch, Aug 30 2022


This is pretty neat! I especially like the "unusual green sand" part.
-- neutrinos_shadow, Aug 30 2022


//Do you have a way to speed that up?//

No, but the process has scale instead.
-- Loris, Aug 30 2022


Swimming in broken glass has never sounded so good. [+]
-- pertinax, Aug 30 2022


From sand to sand.

Each beach in the SF Bay area has its own characteristic - I remember visiting the beach on the west side of Treasure Island just about under the bridge. For whatever reason, that beach was glass. All different colors of glass, all smooth little gems. I don't know what happened that caused it or if it is still like that.

But, you could *try* tipping a container of old bottles off the bay bridge and check up on it in a year or two. Certainly whatever happened, worked on a large scale.
-- mylodon, Aug 30 2022


+ This is wonderful. I have collected sea glass for many years from all different beaches I’ve been to. They all don’t have sea glass and I think it’s interesting that there is lots of it in some places and none in others.
-- xandram, Aug 31 2022


I'm curious as to what lake or ocean shoreline you would consider a biome of negligible value. Besides Wales, of course.
-- RayfordSteele, Aug 31 2022


Oi!
-- pertinax, Aug 31 2022


The song "Walking on Broken Glass" could have used spectacular footage in the video, no matter how you look at it.
-- 4and20, Aug 31 2022


//I'm curious as to what lake or ocean shoreline you would consider a biome of negligible value.//

Yeah, that's probably the wrong word[1]. I just meant one which wasn't specially unique or interesting, or had higher organisms involved (e.g birds nesting in the cliffs). To be fair, while installing the seawall and repeatedly adding the glass would be very disruptive to the immediate vicinity, away from that I don't think the beach being glass rocks would make much difference to most creatures.
Long-term, it's arguably conservative, supplying material to hold the coast downstream to a more constant state.

A good candidate might be somewhere with an erosion problem - which already had a seawall and/or groyns to protect a town or better still an industrial site - leading to worse erosion further along the coast.

[1] later note to clarify: I'm pretty sure the idea didn't use the word 'negligible' by the time I read Rayford's comment. I don't think (but can't quite say definitively) that it ever did. Although I have revised the idea text a number of times. The phrase in the idea is "/limited/ ecological or recreational value", which isn't the same thing.
-- Loris, Aug 31 2022


Walking on a beach in Northumberland, my better half found several pieces of sea glass. Perhaps because the east coast and houses built on it are slowly collapsing into the North sea, we also found some sea bricks and even half a sea saucer.
-- bs0u0155, Aug 31 2022


The ocean is already a giant microplastic manufacturing plant, so why not this too?
-- Cuit_au_Four, Aug 31 2022


//I'm curious as to what lake or ocean shoreline you would consider a biome of negligible value.//

Well, we do have a lot of them. Saying things like "each beach is precious and must not be touched under any circumstances" is symptomatic of excessive neuroticism.
-- Voice, Aug 31 2022


Actually I've heard that beach sand is becoming hard to come by.

Maybe you make sea breaks / walls with these for awhile to slow the climate tide.
-- RayfordSteele, Aug 31 2022


For what it's worth, I imagine that standard 'beach nourishment' is at least as bad for the creatures underneath that part of the beach at the time.
-- Loris, Aug 31 2022


//reasonable or even insufficient//

Actually, yes. I have it on good authority that a little neuroticism makes for a well-balanced human. There are serious problems with the Big 5 (if I'm very well organized and very lazy I've got the same personality as someone who is disorganized and driven? If I'm highly assertive and introverted I'm the same as someone who is meek but extroverted? I think not) but there is something useful there.
-- Voice, Aug 31 2022


//sand//

Fie. Sand, like water, is pretty much unlimited as far as ten billion humans can use. We're only limited by energy and that's only limited by how hot we're willing to make things, or how radioactive, or how many people we want studying solar panels instead of, say, aging. Given enough energy we can make all the sand we want. And all the water we want.

Water is particularly easy to solve if just a few environmentalists are ignored. How about we make the collective decision to consign a hectare or hundred of salt flats to not be in the "natural" state of saltiness and dump brine onto it. We can do the same with part of Europe you guys aren't interested in, and part of the other continents. It doesn't have to be a big deal. And it won't effect biodiversity nearly as much as all the hand-wringing whinging is going to cause in the end. FFS the whole world hasn't been in a "natural" state for a hundred years and humanity needs to untwist its collective pants and agree it's better to have living humans than dead ones even if the greater long-toed Wales bat has to be relocated or die.

But I digress. Sand can be made by crushing silicate rocks to desired smoothness, and it really is that simple. So some building materials are getting more expensive. Not good but not a grand disaster. So we need to use more energy than we used to use by simply collecting sand from convenient places. The world will still turn. So we're going to have 100,041 scars on the earth instead of 100,032. Sheesh. Everything is a flipping disaster these days to such an extent we can't even identify real disasters when they happen. Lack of sand is, among the problems humanity faces, somewhere around the level of rodent extermination, bee problems, or the need for more efficient small motors. And I don't see any headlines demanding more chemical metallurgists.
-- Voice, Sep 01 2022


Let me send you this large pile of back issues of "Chemical Metallurgy Today", before they catch fire.
-- pertinax, Sep 01 2022


I've heard of people polishing wampum and stones by putting them in a sturdy plastic jug with a bit of water and sand, and mooring it near a beach that gets good wave action. The jug bobs around, quickly grinding the contents and keeping it all together.
-- afinehowdoyoudo, Sep 08 2022



random, halfbakery