Milk protein costs around 95 kg of CO2-equivalent emissions per kg of protein, which is apparently what was used in the production of this plastic [1]
[0] https://www.sciencedirect.com/science/article/pii/S002203022...
[1] https://ourworldindata.org/grapher/ghg-per-protein-poore
https://en.wikipedia.org/wiki/Whey_protein#Microbial_product...
It's not theoretical either. You can buy vegan dairy products made from this method today.
In addition, you'll need more cleaning/sterilization/mixing. I'd guess that it's lower, but I wonder how much lower.
And then there's the other products that generally get thrown into the mix to make up for things like missing fats. For example, a vegan cheese based on bacteria will often include coconut oil, probably to get the same fat profile.
Whey is an interesting product in general because it's a waste product of cheese making.
Feed efficiency is critical when doing these calculations as cows inherently need energy to survive not just produce milk. As such even if you use the same crop two different sources of protein can have wildly different levels of CO2 emissions embedded in their creation. https://en.wikipedia.org/wiki/Feed_conversion_ratio
You can't just throw in grass clippings into a vat and get whey. You can throw grass clippings into a cow to get milk (though, TBF, I dislike grassy milk).
That’s a lot of room for improvement which then means far less labor on growing crops.
And, as much as some powers try to convince us, not everything can be reduced to carbon footprint.
So it's not out of the question we could scale that up to meet plastics demand.
Maybe but probably not zero, from parents article: "The use of such treated fertilizers will be most relevant for reducing the carbon footprint of milk in countries such as the United Kingdom, Ireland, and the Netherlands, where N fertilizer is a major contributor to the footprint."
In case you are unaware much of the nitrogen in plant matter (food for yeast or cows) comes from fertilizer. And that is extracted using the Haber process (see: https://en.wikipedia.org/wiki/Haber_process ). This runs on natural gas, because it's effectively a waste product of other hydrocarbons being extracted.
If this is counting the methane emissions of the cow itself, that’s not a fair or complete accounting. The cow produces methane in her digestive system after eating grass, and the grass grows by, among other things, extracting CO2 from the air. Then the cow burps methane, the methane combines with atmospheric oxygen and breaks down to CO2 and water, and you have a closed loop; the cow cannot belch more carbon than she eats, and that carbon came from the air in the first place.
Does seem like a lot of carbon for a kg of plastic, though, how does that compare to normal plastic’s carbon footprint?
Why do you mix your units like that.
I'll edit a bit for clarity for you all who live in more consistent places.
But oil? That’s fine of course. Completely natural stuff.
People have figured out how to make it a hundred years ago, it's already used for food packaging, known properties, abundant and cheap - made from trees / other plants.
The article starts as if it's some breakthrough miracle which is unheard of. I can literally just buy compostable bags for organic waste made of corn starch on Amazon. It's already a product.
Journalist demonstrate less awareness than 8B LLM. Scientist tells you about a new plastic? Ask them how it's better than what's already on the market.
> Materials provided by Flinders University.
It's not that the "journalist" didn't think to ask, it's that this is a PR piece sent out to media outlets from the university that did the research. Nearly all universities have a PR team that sets fluff pieces out to the media to promote the work of the university.
The person who wrote this is being paid not to ask tough and important questions around this research.
They compost, but they don't biodegrade. The difference is whether it breaks into microplastics or dissolves/is digested in the ocean.
If it's actually 60/90 FAHRENHEIT, very few water bodies are (currently) 90 F. That's above even most equatorial temps.
Those temperatures are certainly hard to find in nature, outside of hot springs! Even if this is an error and we are talking about 90°F/60°F, the higher temperature is pretty much constrained to the tropics, so we're talking a year+ to degrade in real conditions. It is better than centuries, but not exactly rapid?
> For example, PLA is not biodegradable in freshwater and seawater at low temperatures [32,36–39]. There are two primary reasons for this: (i) The hydrophobic nature of PLA, which does not easily absorb water [40–42]. In aqueous environments, the lack of hydrophilicity diminishes the hydrolysis process, which is crucial for the initial breakdown of PLA into smaller, more degradable fragments. (ii) Resistance to enzymatic attack; the enzymes that degrade PLA are not prevalent or active under typical freshwater and seawater conditions [39,43,44]. The microbial communities in these environments may not produce the necessary enzymes in sufficient quantities or at the required activity levels to effectively breakdown PLA. Additionally, the relatively stable and crystalline domains of PLA can further resist enzymatic degradation.
Also:
> It should be emphasized that neat PLA cannot be classified as a completely biodegradable polymer, as it generates microplastics (MPs) during biodegradation.
Well, I guess it starts with the plastic being thermoplastic.
Part of the problem with waste management is that we don't really put it in the soil. Your household garbage is mostly biodegradable, but if it ends up buried in a lined pit under tons of other garbage, even paper and orange peels will probably sit there for centuries. I'm not sure it makes much of a difference what kinds or quantities of plastic end up buried in the landfill.
I think the solutions here are more on the supply side than the landfill side. The question there is what are we trying to solve.
Energy use? Most alternative packaging materials are energy-intensive too, so it's less about plastic and more about retail and consumer preferences to have everything individually wrapped and packaged in bags or boxes with colorful graphics, nutrition information, and so on.
Environmental pollution? There, the problem is the plastic that doesn't end up in a landfill. Including our "recycling" shipped overseas.
But I generally agree. The big issue here is we as a society have moved away from biodegradable packing and distribution. I get it, plastic prevents waste and mold. That's why we use it. It's also dirt cheap. It's a byproduct of oil refining (literally cheaper than water).
The ultimate solution to the plastic problem is making plastic more expensive, and the way to tackle that is by reducing oil consumption. Fortunately, that's sort of just naturally happening.
This is why nothing happens there, yet common folks receive higher and higher burden.
That said, the question I have is given the nature of calcium (and its relation to limestone), I'm wondering if the milk protein here is especially useful to plasticizing because of its calcium content? A quick search does classify calcium caseinate as both a protein and technically a calcium salt.
1) Heat 1 cup milk, not to boiling.
2) Add 4 tablespoons vinegar. Stir for a few minutes.
3) Strain out curds. Squeeze to remove as much liquid as possible.
4) Form into a shape or press into a mold, let dry.
That's 60 kg/person/year of plastic, which is a lot. Or about 4800 kg for a person living 70 years. Obviously, there is wide variation in this number across the human population.
/scnr
I know - long lived plastics are bad. We need some kind of middle ground thats as cheap as the current plastics and doesn't last as long.
Take a look at something people have been using for eons with saltwater aquariums: bio-pellets. These are tiny beads of PLA that are fluidized to allow high turnover of water through the PLA, this encourages bacteria to colonize and digest the PLA, then break off and move into the water column (the bacteria) and be removed by the protein skimmer. Because of the red field ratio, each 106 mols of carbon from PLA removed this way also removes 16 mols of nitrate, which is a major pollutant in aquariums. It also removes 1 mol of phosphate, a major pollutant as well, but that's not significant. Phosphate is best done by fluidized reactors with ferric oxide
As someone who constantly prints temporary jigs and spacers, I'm interested in compostable filament. Bonus points if it is comparable to PLA in price.
I made no claims about the speed at which PLA breaks down, only that it does. Biopellets in reactors tend to last years.
Well then it's not plastic is it? Plastic's defining characteristic is that it is not decomposable
But then I got out in the real world, and noticed plastics just falling apart all around -- including stuff that is not intended to fail and which is otherwise still within its useful life.
Like: One year, I bought some used pickle buckets from a local burger joint to use as planters. Within 6 months, they were falling apart: It was easy to break them apart in chunks with my bare hands.
Or the plastics used for cars: They often eventually turn brittle and fall apart, whether interior or exterior. Plastic lenses on USDM cars turn foggy and useless; some types of wire insulation disintegrate. (If we want to talk about environmental cost, can we also talk about the impact of building a new car?)
In some areas, we once used polybutylene water pipes. These tended to fail and damage homes. There was even a billion-dollar lawsuit about it in the 1990s. It was not good.
Meanwhile, a red Solo cup or a plastic drinking straw, once landfilled, will be there a very long time -- but eventually, they will also decompose.
And the UHMW cutting boards I use in my kitchen will probably outlive my grandchildren's grandchildren before they start falling apart on their own accord.
Plastic isn't always forever, even though some people seem fond of saying that it is. Plastic isn't necessarily cheap, either, even though "cheap plastic" is a common expression -- some plastics are very expensive and resoundingly durable (and there's only partial overlap of these two qualities on a Venn diagram).
The truth is somewhere in the middle, but is rather nuanced and variable and difficult to pin down in absolutes.
But plastic (as a noun) does, broadly speaking, have the material property of being plastic (as an adjective).
Your buckets would have lasted longer if you had painted them with outdoor housepaint or outdoor water- or oil-based urethane, because those coatings contain uv stabilizers.
It's trivial to make plastics that break, but then you have many microplastics which again don't decompose.
The breakage isn't even infinite, as the particles grow smaller, the shear resistance grows and it stops splitting, and again nothing decomposes it further
So decompose =/= break.
But molecularly, plastic is around forever. A wooden bucket will eventually breakdown to not be wood at all anymore. Products made from plastic is not what lasts forever, the plastic itself is.
In the right conditions (hot aerobic compost, which is admittedly difficult to achieve), PLA rather quickly decomposes all the way back down to lactic acid.
Lactic acid is definitely not plastic. It's liquid, and is one of the primary products of the happy little microbes that I nurture in my pepper ferments at home.
Again, it's hard to pin the long-term properties of plastic (noun) down in absolutes.
Everything goes faster in hot compost with additional preprocessing, but it's not strictly necessary to reduce things to dust.
Hydrolysis of the PLA still happens whether it is dust or something larger. After that, the chains are small enough to be available for microbes to eat fairly quickly.
They're just eating one bite at a time; they don't know that they have an entire elephant to eat.
More surface area improves immediate availability and speed, but less surface area doesn't cause the process to cease.
Oil based plastics are generally a lot cheaper than the above though, and they are typically not decomposable. Depending on your use this can be good or bad (I don't want my plastic plumbing pipes to decompose, but other plastics are used up and I want them to decompose)
Behold, a plastic! holds up a rock
Also, one of the most widely used plastics is PLA, polylactic acid. Which is made from lactic acid from sugarcane, beets, or cassava, and is biodegradable.