{"id":8701,"date":"2024-10-01T13:57:34","date_gmt":"2024-10-01T04:57:34","guid":{"rendered":"https:\/\/www.elsi.jp\/?post_type=news_events&p=8701"},"modified":"2024-10-01T14:02:31","modified_gmt":"2024-10-01T05:02:31","slug":"osmotic_energy_conversion","status":"publish","type":"news_events","link":"https:\/\/www.elsi.jp\/en\/news_events\/highlights\/2024\/osmotic_energy_conversion\/","title":{"rendered":"Osmotic Energy Conversion Discovered in Hydrothermal Vents Provides Clues to Life’s Beginnings"},"content":{"rendered":"

Researchers experimentally demonstrated that hydrothermal vent precipitates, located deep in the ocean, contains aligned nanopores that enable selective ion transport, thus facilitating osmotic energy conversion from ion gradients. A key finding is that selective ion transport, typically associated with biological cell membranes, can occur through naturally formed inorganic nanostructures in geochemical settings. This discovery offers new insights into how life-sustaining energy harvesting processes can arise abiotically from long-lasting chemical disequilibria in deep-sea hydrothermal vents. Additionally, it highlights potential strategies for developing blue energy technologies utilising salinity gradients.<\/p>\n

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Figure 1. A deep-sea hydrothermal vent with aligned nanopores enabling selective ion transport and ion gradient energy conversion. Credit: Reproduced from Lee et al., Nat. Commun.<\/em> 2024<\/div>\n
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\nIn the deep sea, where sunlight cannot reach, massive structures known as hydrothermal vents (HVs) rise from the ocean floor. These chimney-like structures continuously release hot water containing various metal ions into the cold seawater, gradually growing over time, sometimes reaching heights of up to 60 meters. These vents also support a unique ecosystem distinct from that on the Earth’s surface.<\/p>\n

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In recent years, similar structures have been discovered not only on Earth but also on ice-covered celestial bodies like Saturn\u2019s moon Enceladus. Since HVs may exist on ancient Earth before life emerged, researchers believe they may have played a crucial role as \u201cnatural chemical synthesis systems,\u201d potentially contributing to the origin of life on Earth.<\/p>\n

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An international team led by researchers from the Earth-Life Science Institute (ELSI) and RIKEN Center for Sustainable Resource Science studied HV samples collected from the “Shinkai Seep Field,” located on the northwestern slope of the Mariana Trench, one of the deepest trenches on Earth, at a depth of approximately 5,700 meters. Alkaline hot water generated from the reaction between olivine and water forms white smoker-type HVs primarily composed of a mineral called brucite, which has a plate-like structure (Figure 2a).<\/p>\n

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Figure 2. Hydrothermal vent (HV) sample collected from the Mariana Trench. (a) Photograph of the deep-sea HV sample. (b) Optical microscope image of the sample. (c, d, e) Electron microscope images of the sample. Credit: Reproduced from Lee et al., Nat. Commun<\/em>. 2024<\/div>\n
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\nMicroscopic observations of the collected samples revealed that small plate-like crystals, approximately 100 nanometers in size, assembled to form a thick membrane, creating a pathway for hot vent water and seawater (Figure 2b). These membranes exhibited periodic stripe patterns, originating from the stacked multiple layers, and grew to a thickness of 200 to 400 micrometers (Figures 2c, d, e).<\/p>\n

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The researchers conducted synchrotron X-ray diffraction experiments to investigate the structure of the mineral membranes in detail. Multiple regions of the sample were scanned with X-rays, and the directions with the strongest diffraction intensity were indicated with arrows (Figure 3a). In this figure, the alignment direction of the brucite crystals is colour-coded. Remarkably, throughout the scanned sample, the plate-like brucite nanocrystals were found to be orderly and continuously arranged, radiating outward from the vent fluid channel to the seawater (Figure 3b). This arrangement confirmed that nanopore structures suitable for ion transport were formed throughout the entire sample, which has a height of 80 cm.<\/p>\n

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Figure 3. Structure and arrangement of the hydrothermal vent (HV) observed at various scales. (a) Microscope images and orientation of brucite crystals found inside the HV.(b) Schematic illustration of selective ion transport pathways formed by the accumulation of brucite crystals. Credit: Reproduced from Lee et al., Nat. Commun<\/em>. 2024<\/div>\n

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To validate this hypothesis, they immersed the samples in environments with varying concentrations of ions such as sodium and potassium present in seawater, examining ion transport (Figure 4a). The results showed that the surface charges of the nanopores allowed the entire HV structure to function as a selective ion transport material, converting differences in concentrations of sodium ions, potassium ions, chloride ions, and hydrogen ions into electrical energy (Figure 4b). This suggests that natural HVs may function as osmotic power generation systems, selectively transporting diverse ions from seawater to generate electrical energy.<\/div>\n
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Figure 4. Ion transport evaluation of the hydrothermal vent (HV) sample. (a) Evaluation of the power generation characteristics of the HV sample. (b) Schematic illustration of the selective transport of potassium and chloride ions in the HV sample through surface charges of nanopores. Credit: Reproduced from Lee et al., Nat. Commun<\/em>. 2024<\/div>\n
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\nAll living beings generate energy by leveraging ion concentration differences within their cells. Therefore, the question of how life began to utilise this mechanism is a crucial in the origins of life.\u00a0 The results of this study demonstrate that energy conversion utilizing ions essential for life can occur naturally through geological processes. Concentration differences of ions are widely observed in nature, and similar phenomena may have taken place on ancient Earth before the emergence of life. Additionally, recent research has confirmed hydrothermal activity on ice-covered celestial bodies. In the future, samples from these celestial bodies may be brought back to Earth for detailed analysis, potentially revealing similar structures and energy generation phenomena.<\/p>\n<\/div>\n

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Journal<\/td>\nNature Communications<\/td>\n<\/tr>\n
Title of the paper<\/td>\nOsmotic energy conversion in serpentinite-hosted deep-sea hydrothermal vents<\/td>\n<\/tr>\n
Authors<\/td>\nHye-Eun Lee1,2<\/sup>, Tomoyo Okumura3<\/sup>, Hideshi Ooka1<\/sup>, Kiyohiro Adachi4<\/sup>, Takaaki Hikima5<\/sup>, Kunio Hirata5<\/sup>, Yoshiaki Kawano5<\/sup>, Hiroaki Matsuura5<\/sup>, Masaki Yamamoto5<\/sup>, Masahiro Yamamoto6<\/sup>, Akira Yamaguchi1,7<\/sup>, Ji-Eun Lee1<\/sup>, Hiroya Takahashi1,2<\/sup>, Ki Tae Nam8<\/sup>, Yasuhiko Ohara9,10,11<\/sup>, Daisuke Hashizume4<\/sup>, Shawn Erin McGlynn1,2<\/sup>, Ryuhei Nakamura1,2<\/sup><\/td>\n<\/tr>\n
Affiliations<\/td>\n\n
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  1. RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan<\/li>\n
  2. Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan<\/li>\n
  3. Kochi University, Nankoku, Kochi, Japan<\/li>\n
  4. RIKEN Center for Emergent Matter Science, Wako, Saitama, Japan<\/li>\n
  5. RIKEN SPring-8 Center, Hyogo, Japan<\/li>\n
  6. Institute for Extra-cutting-edge Science and Technology Avant-garde Research, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan<\/li>\n
  7. Department of Materials Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan<\/li>\n
  8. Department of Materials Science and Engineering, Seoul National University, Seoul, South Korea<\/li>\n
  9. Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan<\/li>\n
  10. Hydrographic and Oceanographic Department of Japan, Tokyo, Japan<\/li>\n
  11. Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan<\/li>\n<\/ol>\n<\/td>\n<\/tr>\n
DOI<\/td>\nhttps:\/\/doi.org\/10.1038\/s41467-024-52332-3<\/a><\/td>\n<\/tr>\n
Online published date<\/td>\n25 September 2024<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":8702,"template":"","news_events_cat":[9],"acf":[],"_links":{"self":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/news_events\/8701"}],"collection":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/news_events"}],"about":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/types\/news_events"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/media\/8702"}],"wp:attachment":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/media?parent=8701"}],"wp:term":[{"taxonomy":"news_events_cat","embeddable":true,"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/news_events_cat?post=8701"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}