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Découvrez le paradoxe écologique de la Salton Sea, où l'exploitation du lithium promet une révolution verte pour les véhicules électriques, tout en dévoilant des enjeux environnementaux majeurs liés à la pénurie d'eau et à la pollution des sédiments. Plongez dans cette aventure passionnante et complexe.
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00:03You are looking at a remarkable idea, for this is the story of the miracle sea.
00:30But a major obstacle subsiste.
00:33Without a solution, these billions will never remain empty.
00:38Let's first talk about lithium.
00:40This metal, so precious that we call it or-black,
00:44is distinguished by an exceptional light.
00:46It is, at ambient temperature, the solid, the most light of the planet.
00:50It was discovered in 1817 by a chemist suédois,
00:54but remained neglected,
00:55because it didn't seem to offer any concrete utility.
00:59Certes, it is light, pâle and eclatant,
01:02but for centuries, we didn't ignore how to use it.
01:05It is just recently that its potential,
01:07until now insoupçonné,
01:08has really started to attract attention.
01:11However, another product of lithium
01:13ends up retaining the interest of researchers,
01:16its exceptional reactivity.
01:18This metal is very easily combined with other elements,
01:21but this quality makes it also highly inflammable.
01:24If you expose it to the air, for example,
01:27it has a oxidative reaction,
01:29and can break it in a few seconds.
01:32There where some don't see any danger,
01:34scientists have found a great opportunity.
01:37The unique combination of its light and its reactivity
01:40is almost almost ideal for the concept of batteries performantes.
01:45Or, you understand easily what their role is capital today,
01:49since they aliment our phones,
01:51our cars,
01:51and even some small cars.
01:52As the global demand of lithium has suddenly fallen,
01:57the consumption stops,
01:58and nothing indicates that this trend will slow down.
02:01In 2021,
02:03the total production of 540.000 tons,
02:06but the predictions estimate
02:07that it could exceed 3 million tons
02:09in 2030.
02:11The problem is that lithium is a limited resource.
02:14In the world,
02:15there are only hundreds of miners
02:16across the globe,
02:17concentrated mainly in Australia,
02:20in Chile,
02:20and in China.
02:21Of course,
02:22the world production will continue to increase,
02:24but the demand will progress quite quickly,
02:27which could lead to a crisis in a few years.
02:30Today,
02:31the actual mines are still enough to cover our needs,
02:34but it will not last forever.
02:36In this context,
02:38discover new reserves
02:39come practically to win at the lottery,
02:41and the United States
02:42figure out
02:43among the rare
02:44big winners.
02:45In this case,
02:46the mining of Tucker Pass
02:48would be able to cover the most vast
02:50reserves inexploited lithium in the world.
02:53According to some estimates,
02:56this one site would be able to satisfy
02:57until a quarter of the world's demand
02:59with nearly 40 million tons
03:01of this precious metal
03:03for a potential value
03:05surpassing the 500 billion dollars.
03:07The exploitation will be on the extraction
03:09of lithium contained in the steel,
03:10a complex method,
03:12never realized at a high level
03:14as considerable.
03:15The challenge is important,
03:16but it remains realisable.
03:18Il y a few years,
03:19the United States
03:20have acquired a major advance
03:21in the field of lithium,
03:23the Salton Sea.
03:24This vast lake,
03:26deep deep,
03:26is located in the country
03:27of Imperial,
03:28south of California.
03:30The first estimates
03:31indicate that the site
03:33could contain
03:34more than 3,400,000 tons
03:36of lithium
03:36buried under the earth.
03:37This amount would allow
03:39to produce more than 375 millions
03:42of batteries
03:42destined to electric vehicles.
03:45This seemed already immense.
03:46But recently,
03:47some specialists
03:48discovered
03:48that they were wrong.
03:50And this time
03:51in the right sense.
03:53The real reserves
03:53could reach 18 millions
03:55of tons.
03:56Which place
03:57now the Salton Sea
03:58in the fifth
03:59world's most important.
04:02This discovery
04:04could really change
04:05the world.
04:05The United States
04:06put a lot
04:07on this minerai
04:08hoping that
04:09it will contribute
04:10to maintain
04:10the solidity of their economy
04:12for many decades.
04:14To discover
04:14this second source
04:15of lithium
04:16would have been a huge
04:17surprise,
04:18approaching the country
04:19of a greater autonomy,
04:21while the majority
04:22of its lithium
04:22still comes from Chile.
04:25We refer to it
04:26as the Saudi Arabia
04:28of Lithium.
04:28The California
04:29is proud of this
04:30perspective,
04:31seeing a real man
04:32economy.
04:33The region
04:34is already surnom
04:35the Saudi Arabia
04:35of Lithium
04:37or Lithium Valley
04:38because of its potential
04:40to dominate
04:41the chain
04:41of batteries.
04:42If the project
04:43is successful,
04:44the State
04:45will take a considerable advantage.
04:47The authorities
04:48envisage
04:48to use 80%
04:50of the revenue
04:50from the extraction
04:51of lithium
04:52for the development
04:53local
04:53and the infrastructure.
04:55The idea
04:55is to modernize
04:56routes,
04:57schools
04:57and other services
04:59publics.
04:59This initiative
05:00could create
05:01many jobs
05:02in the Imperial
05:03one of the poorest regions
05:04of California.
05:06One important question
05:07is if the lithium
05:09is found
05:09under the lake,
05:10can we really extract it?
05:12In theory,
05:13yes.
05:15Two main methods
05:15are used
05:17by the industry.
05:18The first,
05:19traditional,
05:20consists
05:20of an open
05:21and more
05:22The rock is
05:23watered,
05:24and then
05:25treated.
05:26For example,
05:27the technique
05:27used to be
05:28used to
05:31the metal
05:32of the steel
05:33The second method
05:34depends on
05:35the basses
05:35of the evaporation.
05:36A surface
05:37is formed
05:39then,
05:39the oil
05:40makes it
05:40evaporated,
05:41the metal.
05:43But,
05:43these two
05:44methods
05:44often
05:45an enormous amount of water and often causes a strong contamination,
05:49as well as an abundant waste.
05:50At Salton Sea in California, the process is a little different.
05:54Instead of creating a gigantic sea or building a vacuum of evaporation,
05:58companies exploit the natural power of the region
06:02to extract the lithium in a more proper way.
06:05This technique is called the direct extraction of lithium.
06:08Près du lac, 11 centrales geothermics
06:10a very hot and rich in minerals from the soil.
06:15Habituellement, this saumure only works to produce
06:17the vapor that trains the turbines to generate electricity.
06:21Now, companies learn to recover the lithium
06:24in this same saumure before injecting it into the soil.
06:27Since the saumure is already pumped to produce energy,
06:31the collection of lithium is not necessary
06:33any additional supplements or vessels of evaporation.
06:36This allows therefore to avoid the majority
06:38of the gaspillages of water and pollution associated with other methods.
06:42It's like obtaining a proper energy and materials for batteries
06:45at the same time, with an environmental impact much more reduced.
06:48The method seems brilliant and realisable,
06:50but it also contains some challenges
06:53which are not simple to overcome.
06:55Certes, some qualifies this technique as ecological
06:58but this appreciation is pertinent
07:00as compared with other methods of extraction of lithium.
07:03It also raises some serious concerns regarding the usage of the water.
07:07The inhabitants of California already have been faced
07:09at severe pressures, and the exploitation
07:11at large scale of lithium could increase the pressure
07:14on this limited resource.
07:15The Salton Sea is very quickly.
07:17Its level has fallen from over 3 meters
07:19over the last 25 years.
07:22This is a serious problem.
07:23The diminution of the water expose more than the water
07:26in which the sediments can contain
07:28as poisonous substances.
07:29As soon as the water is reduced,
07:31this water is exposed,
07:33and it turns out and it turns out
07:35and it turns out that it does not remain in place.
07:37The wind lifts and disperses in the air.
07:40Thus, the river in retrait of the Salton Sea
07:43liberate a toxic acid
07:44which has been associated
07:45to an increase of respiratory problems
07:47for the inhabitants of the environment.
07:49The authorities have already
07:50undergone some measures
07:51to reverse this situation
07:53in addition to the water
07:55to the areas of the Salton Sea.
07:57They fill in the water
07:58a little bit deep
07:59near the lake
08:00to create new marées.
08:02The goal is to offer
08:03an habitat sure
08:04to fish and birds
08:05and to limit
08:06the dispersion of this toxic acid.
08:08Some fear, however,
08:10that the exploitation
08:10of all this white white
08:12increase the heat
08:13and reduce the years
08:15of restoration effect.
08:17For the hour,
08:18studies indicate
08:19that the geothermal centrales
08:20are using
08:20about 4%
08:22of the water available
08:23in the region.
08:24But researchers
08:25still ignore
08:25if a larger development
08:27could increase
08:28the water problem
08:29So,
08:30what will happen then?
08:31It is too late to tell you.
08:33But one thing is certain,
08:35it is necessary
08:35to take a lot more research
08:37to understand
08:37the consequences
08:38of these projects
08:39not only for the Salton Sea
08:41but also
08:42for the future
08:42of the American economy.
08:45You frotte your eyes
08:47because you can't believe
08:48you can't believe
08:48you.
08:48You are perfectly circular
08:50at the bottom of the ocean
08:52wide of the coast of Big Sur
08:53in California.
08:55You have no idea
08:56how they could appear
08:57even if you are a marine biologist
08:59marine profession
08:59and that you practice
09:01this discipline
09:01for years.
09:02You consult
09:03an ancient dossier
09:04and you discover
09:05that these holes exist
09:06since the 1990s.
09:09In 1999,
09:10a sonar
09:11mounted on a navire
09:12a mened
09:13an investigation
09:14and found 5200
09:15of these large holes
09:16on more than 1300 km2
09:18at the bottom of the ocean.
09:19They look like
09:20a craté lunar
09:21sous-marine.
09:23You contact your team
09:24and you prepare
09:25the robot
09:26to go down
09:26to explore the place
09:27and to report
09:27some examples.
09:30With your colleagues,
09:32you gain the coast
09:32and you climb up
09:33to the boat
09:34and you climb up
09:35to the boat
09:37with a joystick.
09:39Your crew
09:39place the robot
09:40in the water
09:41and he plonges.
09:42It seems normal
09:43près of the surface.
09:45But while the robot
09:46s'enfonce
09:46in the depths,
09:48the holes start to appear.
09:50A group of boats
09:51pass at all speed
09:52in front of you
09:53which makes you lose
09:54the balance
09:54and you concentrate.
09:56The robot
09:56allume his lamp
09:57so that you can see
09:58better.
09:59But more he descend
10:00moins the image
10:01is net.
10:02When he reaches the bottom
10:03you see that the holes
10:04are lisses
10:05and almost perfectly
10:07circular.
10:08Some of these holes
10:09already visible
10:09by the sonar
10:10have a diameter
10:11of 9 m
10:12and a depth
10:12of 4,50 m.
10:14You show the images
10:16to your other co-equipiers
10:17and they are stupéfaits.
10:18The robot
10:19continues to advance
10:20and other holes
10:21continue to appear
10:22all around.
10:23Many of them
10:24are too small
10:25for the scanner
10:26to catch them
10:26from the surface.
10:28These micro-depressions
10:29are abruptes
10:30and have like a queue
10:31in a certain direction.
10:33It is possible
10:34that the sous-marins
10:35are able to play
10:35a role in their formation.
10:38Where the robot
10:39circulates,
10:39there are new holes.
10:41After a few hours,
10:43the robot
10:43goes back to the boat
10:44with the items
10:45he collected
10:46you take them
10:46to your laboratory
10:47to study them.
10:49The robot
10:50has recorded
10:51images of
10:51from the human
10:52but the images
10:54do not indicate
10:54anything alarm
10:55for the moment.
10:57One third
10:57of these pockets
10:58are filled
10:58but it doesn't
11:00always explain
11:00how they are formed.
11:03It is late
11:04in the night
11:04and the members
11:05of your team
11:06do it
11:07in your laboratory
11:08in the midst
11:09of your research.
11:11You wake up
11:12the morning
11:12and in preparing
11:13for a few hours
11:14you tell
11:14that these holes
11:15have perhaps
11:16an emanation
11:17of gas
11:18which could be
11:19nocif for the marine marine.
11:21You go to the robot
11:22and you take the route
11:23for a second time
11:24to the ocean
11:25but this time
11:26you don't even
11:27think about
11:27your team
11:28you place the robot
11:30in the water
11:31and you put it
11:31behind the screen
11:32to control it.
11:34The robot
11:34descends
11:34to the ocean
11:35and begins to be relever.
11:37Jusqu'à présent
11:38les trous
11:39semblent toujours
11:39couverts de déchets
11:41mais certains
11:42d'entre eux
11:43abritent de la vie
11:44en leur sein,
11:44des poissons
11:45et des algues.
11:47Après avoir scanné
11:48leur surface plusieurs fois
11:49et n'ayant pas découvert
11:50de bulles,
11:51tu te dis qu'il ne peut
11:52donc pas s'agir d'un gaz
11:53mais tu veux en être
11:54absolument certaine.
11:57Au bout d'un moment,
11:58tu atteins un grand trou
12:00et ton robot commence
12:01à l'analyser.
12:02Tu trouves des bulles
12:04et tu découvres leurs sources
12:05mais le robot ne peut pas
12:06aller si loin.
12:07Il tourne autour
12:08essayant de s'approcher
12:09mais ça ne marche pas.
12:11Tu ramènes le robot
12:12au laboratoire
12:12et tu le modifies.
12:14Tu y attaches des bras
12:15mécaniques
12:16pour qu'il puisse
12:17soulever des objets
12:17et les déplacer.
12:19Tu ramènes ensuite
12:20le robot au même endroit
12:21mais les bulles
12:22ne sont pas aussi fréquentes
12:23que la première fois.
12:25Tu utilises les bras
12:26pour déplacer certains déchets
12:27et tu découvres que les bulles
12:29sont en réalité
12:30produites par quelques crabes
12:31qui se reposent
12:32près d'un tas d'objets
12:33en plastique.
12:34Bingo !
12:35La mauvaise nouvelle
12:36c'est que tu n'as toujours
12:37pas la moindre idée
12:38de la raison pour laquelle
12:39ces micro-dépressions
12:40et ces trous
12:41se sont formés.
12:42Tandis que tu essaies
12:43de manœuvrer le robot
12:44pour le faire remonter
12:45à la surface,
12:46une pieuvre
12:47enroule ses tentacules
12:48autour de lui
12:48et tire le robot
12:49vers le bas.
12:50Tu t'efforces de récupérer
12:51le contrôle de ta machine
12:52en utilisant la puissance maximale
12:54mais il est impossible
12:55de faire se détacher
12:56la pieuvre.
12:57C'est une lutte acharnée
12:58entre l'animal
12:59et ton robot.
13:00La pieuvre entraîne
13:01ton robot
13:01sous un tas d'ordures
13:02pensant qu'il s'agit là
13:04de quelque chose de comestible.
13:05Mais tu utilises
13:06les nouveaux bras
13:06pour dégager ton appareil
13:08sous-marin
13:08qui remonte enfin
13:09vers la surface.
13:10Tu retournes au laboratoire
13:12encore plus perplexe.
13:13Le robot a collecté
13:15d'autres échantillons
13:15pour que tu puisses les étudier.
13:17Ton œil est collé
13:18à ton microscope
13:18et tu essaies de comprendre
13:20de quoi il retourne
13:21mais tu ne trouves rien.
13:22Tu décides de faire un test
13:24de datation au carbone
13:25pour déterminer
13:26l'âge de ces trous.
13:27Au bout d'un moment,
13:28tu vas voir les résultats
13:30et tu es encore plus surpris
13:31qu'avant.
13:32Ils indiquent que les trous
13:33ont environ 400 000 ans.
13:36Il s'avère donc
13:37que les déchets de sources humaines
13:38ne sont pas en cause.
13:40Tu passes de nombreuses
13:41mis blanches
13:42à essayer de percer le mystère.
13:44Tu rassembles ton équipe
13:45une fois de plus
13:46et tu organises
13:46une petite conférence de presse.
13:48Tu dis qu'il s'agit peut-être
13:50de quelque chose
13:50qui devrait nous inquiéter.
13:52Mais tu ne peux toujours
13:53pas en dire plus.
13:55En travaillant dur,
13:57vous découvrez que les grands trous
13:58n'ont ni changé
13:59ni été actifs
14:00depuis plus de 50 000 ans.
14:02Les trous les plus récents
14:04ont très probablement
14:05été créés par les détritus
14:06d'origine humaine
14:07qui se sont déposés
14:08au fond de l'océan.
14:09La faune marine aura recueilli
14:11certains de ses déchets
14:12comme les objets de plastique
14:13et le matériel de pêche
14:14pour se faire des abris.
14:16C'est pourquoi environ
14:184 500 de ces trous
14:19sont plus récents
14:20et contiennent des déchets.
14:21Mais cela ne répond toujours pas
14:23à la question de savoir
14:24comment les trous sont apparus
14:25en premier lieu.
14:26Tu es de retour
14:27à la case départ.
14:28La seule façon
14:29de voir ce qui se passe vraiment
14:30est de débarrasser les trous
14:31des déchets
14:32qui les recouvrent
14:33et de les étudier.
14:35Cela fait les gros titres
14:36dans la communauté locale
14:37et attire l'attention
14:38d'une équipe de nettoyage.
14:40Tu organises un voyage
14:41vers l'océan
14:42et vous commencez
14:43l'extraction des détritus.
14:45De nombreux bateaux
14:46de nettoyage arrivent
14:47et tout le monde
14:47descend un filet
14:48pour remonter ce qu'il peut.
14:50Tu envoies ton robot
14:51une fois de plus
14:51pour t'assurer que les filets
14:52descendent au bon endroit.
14:54À mesure que tout le plastique
14:56est ramassé,
14:57de nombreux animaux marins
14:58sont forcés de s'échapper
14:59et de trouver d'autres abris.
15:01Tout le monde fait en sorte
15:02de ne pas leur faire de mal.
15:04Au bout de quelques semaines,
15:06tous les trous ont été nettoyés.
15:07Avec ton sonar depuis la surface,
15:10tu vois maintenant les trous
15:11plus distinctement qu'avant.
15:13Mais tu n'as toujours
15:14pas de réponse à ta question.
15:16Tu fais d'autres recherches
15:17pour savoir si d'autres trous
15:18sont apparus dans le monde.
15:20De l'autre côté du pays,
15:22il y a un mystérieux trou bleu
15:23au large de la côte du golfe
15:25de Floride.
15:26Tu pars immédiatement
15:27pour la Floride
15:28et tu prends rendez-vous
15:29avec les scientifiques
15:30en charge de l'expédition.
15:31Les trous bleus
15:32sont des dolines sous-marines
15:34qui s'ouvrent dans le plancher
15:35océanique.
15:36C'est comme sur la terre ferme.
15:37Le monde sous-marin
15:38a lui aussi ses accidents géologiques.
15:41Ce trou en particulier
15:42porte le nom de la banane verte
15:44et se trouve à 45 mètres de profondeur.
15:47Et le trou lui-même
15:48a une profondeur de 130 mètres.
15:50Tu plonges avec un équipement spécial
15:52et le reste de l'équipe
15:53vers un plancher océanique
15:55où la vie s'est faite
15:56plus que rare.
15:57Et le trou est juste là
15:58devant toi,
15:59comme un oasis dans le désert.
16:01Avec les autres scientifiques,
16:02vous êtes surpris
16:03par la diversité de la faune marine
16:05qui s'y trouve.
16:06Des tortues de mer
16:07nagent devant toi
16:08et même des requins.
16:09Ils ne veulent pas de mal aux humains.
16:12À mi-chemin,
16:14tu atteins un passage étroit
16:15et difficile d'accès
16:16pour les humains.
16:17Mais tout le monde fait attention.
16:19Il y a des coraux,
16:21des éponges
16:21et des mollusques
16:22dans tous les coins.
16:23Tu collectes quelques échantillons
16:25et tu retournes au laboratoire.
16:27Les trous bleus,
16:28en général,
16:29sont plus riches en nutriments
16:30que les sols
16:31et ils abritent
16:32de nombreux animaux.
16:34Ils sont assez communs
16:35et ne représentent pas
16:36une menace pour qui que ce soit.
16:38Au bout de tes recherches,
16:40tu te dis que les trous
16:41au large de la côte de Californie
16:42n'ont pas grand chose à voir
16:43avec ces trous bleus.
16:45Le mystère perdure.
16:46de la côte de Californie
16:48de la côte de Californie
16:49d'acquérir de la côte de Californie
16:49de la côte de Californie
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