Mere plastik er på vej:Hvad det betyder for klimaændringer

Med den seneste fracking -boom, der forårsagede lave gaspriser, fossile brændstofvirksomheder søger andre måder at styrke deres overskud på - ved at lave mere plastik. Ligesom verden begynder at løse sit enorme plastforureningsproblem, disse virksomheder fordobler sig på plast, med enorme potentielle konsekvenser for klima og miljø.

Overmængden af ​​naturgas har resulteret i de laveste gaspriser siden 2016. Følgelig nogle fossile brændstofselskaber bliver tvunget til at lukke borerigge og anmode om konkursbeskyttelse. Store virksomheder som Exxon Mobil, Shell og Saudi Aramco, der ser tegn på et kommende fald i brugen af ​​fossilt brændstof, kompenserer for de lave priser ved at investere i plastproduktion, da plast er fremstillet af olie, gas og deres biprodukter. Som resultat, World Economic Forum forventer, at plastproduktionen fordobles i 2040.

Naturgas indeholder etan, som er en byggesten af ​​plast. Fordi USA har udvundet så meget ethan med sin naturgas, over 200 milliarder dollars er blevet investeret i 333 nye kemi- og plastprojekter, ved udgangen af ​​2019.

Judith Enck, tidligere regional EPA -direktør og grundlægger af Beyond Plastics, har sagt, at 2020 er et kritisk år, fordi mange af de nye plastproduktionsfaciliteter i USA er i tilladelsesprocessen; "Hvis endda en fjerdedel af disse etansprængningsfaciliteter er bygget, " hun sagde, "det låser os inde i en plastisk fremtid, der bliver svær at komme sig efter." En analytiker fra data- og analysefirmaet IHS Markit sagde, at medmindre plastproduktionen sænkes, "de finder bare noget andet at pakke ind i plastik."

Ethan -kiks

Ethan er en lugtfri og farveløs bestanddel af naturgas. For at lave plastik, virksomheder adskiller det fra naturgasblandingen og transporterer det i flydende form via rørledning til en "etan -krakker, "et stort industrianlæg, der bruger intens varme til at knække eller bryde ethanmolekyler fra hinanden. Disse molekyler reformeres derefter til ethylen, en grundlæggende byggesten i den petrokemiske industri, der bruges til fremstilling af harpikser, klæbemidler, kemikalier, og plast. I processen, etankrakere kan afgive forurenende stoffer, såsom nitrogenoxider, svovldioxid og partikler, samt benzen, som er kræftfremkaldende, og flygtige organiske forbindelser, der kan reagere med sollys for at danne ozon på jorden.

USA producerer allerede omkring 40% af verdens etanbaserede petrokemikalier og er den største eksportør af etan, sælger til Norge, England., og Skotland, og til Kina og Indien, hvor efterspørgslen efter plast stiger.

Energiministeriet (DOE) forventer, at inden 2025, det østlige USA, herunder Appalachia, vil producere 20 gange mere etan, end det gjorde i 2013.

I 2018, DOE offentliggjorde en rapport om potentialet for, at Appalachia kan blive et nyt "ethanet" på grund af dets Marcellus- og Utica -skiferressourcer, og Trump -administrationen fremhæver plast- og petrokemisk industri som den næste store ting for regionen.

Ohio, Pennsylvania, og West Virginia's andel af amerikansk naturgasproduktion er gået fra 2% i 2008 til 27% i 2017. IHS Markit projekterer, at disse tre stater, også kendt som Shale Crescent, vil levere 37% af USA's naturgas i 2040, nok til at understøtte fem store etan -kiks. Shell er i øjeblikket ved at bygge en $ 6 milliarder dollar etan krakker 25 miles nordvest for Pittsburgh.

Nye petrokemiske anlæg er også planlagt nær Gulfkysten af ​​Texas og Louisiana og Nedre Mississippi -floden, et område, der allerede kaldes "Cancer Alley" på grund af de giftige emissioner fra dets eksisterende petrokemiske anlæg. To store etan -kiks kom online på Gulf Coast i december med to mindre faciliteter planlagt til snart at åbne.

Plastisk spredning og forurening

Den årlige efterspørgsel efter plast er næsten fordoblet siden 2000. Og den voksende globale befolkning, forbedring af de økonomiske forhold og teknologiske fremskridt vil skabe endnu større efterspørgsel efter plast i fremtiden, ifølge en rapport fra International Energy Agency (IEA). I øjeblikket, USA og andre udviklede lande bruger op til 20 gange så meget plastik pr. person som Indien, Indonesien og andre udviklingslande.

USA producerer også mere plastemballageaffald pr. Indbygger end noget andet land. Denne smidige plastemballage udgør 40% af al plast, hvor de fleste ender på lossepladser; resten forbrændes eller genbruges. Et Center for International Environmental Law (CIEL) rapport, Plast &Klima, fandt ud af, at ved udgangen af ​​2015, 8, 300 millioner tons jomfruplast var blevet produceret globalt, to tredjedele af dem forbliver i miljøet.

Hvert år, næsten 10 millioner tons plastik vindes op i havet, hvor det indtages af havdyr, og plastaffald findes på strande selv på de fjerneste steder på Jorden. Plast forurener også jord, især på gårde, hvor spildevandsslam bruges til gødning.

Bisphenol A (BPA), en kemisk komponent i plastikken i nogle vandflasker og beklædningen af ​​dåser, er fundet i navlestrengsblodet hos ni ud af 10 spædbørn og i urinen hos 95% af de voksne amerikanere, der blev testet. Nogle undersøgelser viser, at det kan forstyrre hormon- og reproduktionssystemer. Mikroplast og små plastfibre er fundet i honning, sukker, øl, Forarbejdede fødevarer, skaldyr, salt, vaskepulver, flaskevand og postevand; imidlertid, sundhedseffekterne af mikroplast er stadig uklare.

Klimaimplikationerne af plastik

Plast udgør ikke kun et enormt forureningsproblem - det forværrer også klimaændringer. CIEL -rapporten advarer om, at drivhusgasemissionerne fra plastik bringer vores evne til at holde den globale temperaturstigning under 1,5˚C i fare. Hvis plastproduktionen forbliver på sin nuværende bane, i 2030, drivhusgasemissioner fra plastik kan nå 1,34 milliarder tons om året, svarende til emissionerne fra 300 nye 500 MW kulkraftværker. Det skyldes, at mere end 99% af plasten er fremstillet af fossile brændstoffer, både naturgas og råolie - og fordi plastik resulterer i drivhusgasemissioner på alle trin i sin livscyklus.

Udsugning og transport

Drivhusgasemissioner resulterer i første omgang, når skovområder og marker ryddes for at gøre plads til brøndpuder og rør til at bore efter olie og naturgas.

Hvis en tredjedel af de 19,2 millioner hektar i USA, der er blevet ryddet til ekstraktion, engang var skovbevokset, det betyder, at der er blevet udsendt næsten 1,7 milliarder tons kuldioxid som følge af skovrydning; i øvrigt, skovarealets evne til at optage yderligere 6,5 millioner tons kulstof hvert år er blevet fjernet.

Fracking -processen udsender metan, en drivhusgas, der over 20 år, fanger mere end 84 gange mere varme i atmosfæren end kuldioxid. Metan skyldes opblussen og lækage, som kan forekomme hvor som helst fra brønden til slutbrugeren.

Emissioner produceres også ved forbrænding af brændstoffet til drift af boreudstyret.

I 2015, emissioner fra ekstraktion og transport til plastproduktion var 9,5-10,5 millioner tons CO ₂ alene i USA - svarende til emissionerne fra 2,1 millioner personbiler kørt i et år.

Raffinering og fremstilling

"Plast er blandt de mest energikrævende materialer at producere, "ifølge chefen for CIEL. Ethan -revner er energikrævende på grund af den nødvendige varme, og producerer betydelige emissioner, det samme gør de kemiske raffineringsprocesser, der fremstiller anden plast.

De årlige emissioner fra den nye Shell -etan -krakker og et ExxonMobil -ethylenanlæg i Baytown, TX forventes at svare til at tilføje næsten 800, 000 nye biler til vejen. Greenhouse gas emissions from the Shell plant alone could cancel out all the benefits of nearby Pittsburgh's carbon reduction measures. And these are just two of the over 300 planned petrochemical projects being built in the U.S. mainly to produce plastic and plastic feedstocks.

Discarded plastic

After it's used, plastic is incinerated, recycled or ends up in a landfill.

Carbon from the fossil fuel feedstock is locked into plastic products and emitted when plastic is incinerated or decomposes. I 2015, 25% of global plastic waste was incinerated; in the U.S., emissions from plastic incineration were equivalent to 5.9 million metric tons of CO ₂ , equivalent to the emissions from heating 681, 000 homes for a year.

Only about 8.4% of plastic is recycled. Men, according to scientists from UC Santa Barbara, even recycling plastic produces greenhouse gas emissions, as fossil fuels are combusted to run the machines that shred plastic waste and heat it up to make other products.

Plastics in the environment, such as those that persist in landfills and litter coastlines all over the world, have been found by University of Hawaii researchers to release the greenhouse gases methane and ethylene when sunlight hits them; i øvrigt, emissions from plastic on the ocean surface increase as the plastic breaks down.

Could microplastics affect the ocean's ability to absorb carbon dioxide?

The ocean absorbs carbon dioxide from the atmosphere, thus reducing the amount of warming emissions would cause if they remained in the atmosphere. Phytoplankton in the ocean play an essential role in this process, taking carbon dioxide from the atmosphere and storing it in the ocean via photosynthesis. Scientists are currently trying to determine if microplastics in the ocean interfere with phytoplankton's ability to sequester carbon.

Joaquim Goes, a research professor at the Earth Institute's Lamont-Doherty Earth Observatory, said that although he has not seen any studies that show a direct effect of microplastics on phytoplankton, "We have seen microplastics attach onto phytoplankton under the microscope. Phytoplankton can shed extra sticky carbohydrates through photosynthesis, and plastics can attach onto the sticky material. One thing you can assume is that if you have too many microplastic particles, they compete with phytoplankton for light."

Marco Tedesco, a research professor at Lamont-Doherty Earth Observatory, who currently researches microplastic in snow and how it evolves, said that the chemicals used to make plastic could have unknown effects. "The chemicals that have been used during their lifecycle are heavily toxic and there's very little regulation about the use of these elements when it comes to plastics, " said Tedesco. "So the treatment of microplastics requires an extra level of attention because of the potential harm related to the chemicals that are used to treat plastics to make them colorful, more resilient, and impermeable. After a certain point, all the chemicals can permeate through the plastic and you don't know what the consequences are."

Faktisk, a 2019 study by researchers from Macquairie University in Australia studied how substances leached from plastic affected Prochlorococcus, a tiny type of phytoplankton considered a key player in the photosynthetic process that fixes carbon. Exposure to the leachate compromised its in vitro growth and photosynthetic capacity and resulted in changes in its genome.

There is still much that scientists don't know about microplastics, their impacts on the environment or what to do about them, but one thing we do know:"Anything that we produce that we put into the atmosphere or on our planet—microplastics and CO ₂ —are going to be around. They're not going anywhere, " said Tedesco, "You can stop producing plastics now and you can stop emitting CO ₂ nu, but the effect of what's left in the atmosphere or what's around in terms of microplastics will still be huge…. And there's really no clear technological path to the removal of microplastics at any scale."

What solutions could yield results?

Genbrug

Lige nu, plastic recycling in the U.S. is not working well. I årtier, the U.S. sent its recycled plastic to China, men i 2017, China banned certain types of solid waste—mainly plastics. Without a market for recycled plastic, recycling is no longer economically viable for many municipalities. The Plastic Pollution Coalition estimates that in 2018, only 2% of municipal plastic waste was recycled in the U.S. and six times more plastic was burned than recycled.

Det år, the U.S. sent 68, 000 shipping containers of recycled plastic to countries such as Bangladesh, Laos, Cambodja, Philippines, Turkey, Ethiopia and Senegal—countries that are not able to handle most of their own plastic waste.

Recycled plastic used to be cheaper than new plastic, but because of the boom in petrochemical production in the U.S., and because of the demand for recycled plastic from sustainable companies, virgin plastic is becoming cheaper than recycled. Som et eksempel, Nestle, which is often considered one of the world's worst plastic polluters, is going to pay above market rate for recycled plastic in an attempt to reach its goal of reducing virgin plastic use by one-third by 2025.

Plastic bans

As of 2018, 127 countries had some type of legislation regulating plastic bags, according to a United Nations Environment Programme report. These bills might involve limiting the bags' manufacture or use, taxing them or regulating their disposal. Twenty-seven countries have banned certain plastic products, such as packaging, plates, cups and straws. Sixty-three countries have required extended producer responsibility for single-use plastics, where producers of the plastic are responsible, financially or physically, to deal with their disposal.

I USA, the only federal ban on plastics is the Microbead-free Waters Act of 2015, forbidding the use of microbeads in cosmetics. Eight states have enacted other plastic restrictions, and 24 states have passed approximately 330 local plastic bag laws.

Christof Ruehl, a senior research scholar at Columbia University's Center on Global Energy Policy, is sanguine about the effectiveness of these bans and recycling. He and a colleague researched the potential impacts of a modest reduction in the demand for packaging material and a small improvement in plastic recycling. They cited three outcomes. "It brings peak oil demand forward by about five years into the mid- to late 2020s, " said Ruehl. "Secondly, it creates stranded assets because a lot of especially national companies are now heavily investing into new petrochemical facilities, because they believe plastic demand will continue rising. And thirdly—this I found really amazing—the impact of a successful campaign globally against the use of single-use plastics has a larger dent in oil demand than the dent caused by electric cars." In other words, effective regulations on plastic could reduce oil demand by at least as much as the adoption of electric cars 20 years from now.

The CIEL report studied possible solutions to the plastic pollution problem and determined that five measures would reduce greenhouse gas emissions the most and deliver environmental and social benefits:

1. Ending the production and use of single-use, disposable plastic;
2. Stopping development of new oil, gas, and petrochemical infrastructure;
3. Promoting zero-waste communities;
4. Requiring extended producer responsibility;
5. Adopting and enforcing ambitious targets to reduce greenhouse gas emissions from all sectors, including plastic production.

It's important to bear in mind, imidlertid, that even if it were possible to achieve these measures and eliminate all demand for plastic, "You will have to replace the plastic with something else, " said Ruehl. "That something else would use energy and produce carbon emissions. Glass and paper, for eksempel, are very energy-intensive. So in order to get a complete picture, you would have to study these replacements, but no one has done that yet."

Denne historie er genudgivet med tilladelse fra Earth Institute, Columbia University http://blogs.ei.columbia.edu.