科學家明確指出找到乾淨的天然氫氣所需的條件

 原文網址：https://www.earth.ox.ac.uk/article/scientists-define-ingredients-finding-natural-clean-hydrogen

牛津大學、杜倫大學、多倫多大學的研究人員詳細列出需要哪些地質條件，才能在我們腳下找到乾淨的天然氫氣來源。此研究詳述地球本身在地質時間當中產生的天然氫氣，需要什麼條件才會累積在地殼內部，而他們也確認具備這些要素的地質環境廣泛分布在世界各地。此發現今日發表在期刊《自然評論—地球與環境》(Nature Reviews Earth & Environment)，它提供了一個方向來解決氫氣供應的難題，這有助於業界尋找並開採天然氫氣來滿足全世界的需求，進而達成減少使用碳氫化合物的目標。

美國蒙大拿州一口廢棄的水井。測量溶解在地下水的氣體或許能幫助我們發現天然氫氣。圖片來源：Chris Ballentine

在現今的社會，穩定的氫氣來源對於社會的運作相當重要：氫氣製造出來的肥料供應了全世界一半人口所需的食物。此外，若要防止人類面臨預測中最糟的氣候變遷情境，未來勢必要達到碳中和，有關於此的許多規劃當中，氫氣也是重要的能源組成之一。

目前的氫氣來源主要為碳氫化合物，製程中的廢氣佔了全世界二氧化碳排放量的2.4%。2022年對於氫氣的需求為9000萬公噸，預計到了2050年會來到5億4000萬公噸，但重要的是這些氫氣的產生過程不能排放二氧化碳。製造氫氣的方法還有埋藏二氧化碳廢氣(碳封存)或是利用再生能源(風力或太陽能)，雖然他們是未來的氫氣來源，但目前都還不具有商業競爭力。

牛津大學與杜倫大學、多倫多大學合作的新研究提供了一個解法。過去數十億年來，地球的大陸地殼製造的氫氣足以提供人類至少170,000年的能量需求。雖然當中有部分已經溢散、被用掉或者目前還無法取得，但是剩餘的氫氣還是可以作為這種天然資源的自然來源(而且是零排放)

目前為止，歷史紀錄中的氫氣採樣以及測量資料並不多，限制了科學家探討目前氫氣在地殼中的蘊藏地點與儲量。若要發現可以取得並且具有商業價值的天然地質氫氣累積，一套標準的探勘流程是相當重要的。

杜倫大學的教授Jon Gluyas是研究共同作者，他強調：「人們對於氦氣已經成功開發出一套探勘策略，而類似的『第一原理』方法也可以套用在氫氣。」

這篇研究概述了一套用來找到不同種類「氫氣系統」的探勘策略，必需含有哪些關鍵要素。這包括了每種系統會產生多少氫氣、出現在哪種環境條件與岩石種類當中、從岩石產生的氫氣如何在地下遷移、形成氣田所需的條件、造成氫氣枯竭的條件。

多倫多大學的Barbara Sherwood教授是共同作者，她說：「比方說我們知道地下微生物吃掉氫氣的速度相當快。因此要讓有經濟價值的氫氣累積保存下來，避免會把微生物帶進來的環境就很重要。」

作者概述了哪些區域對這些要素的瞭解已經相當多，並強調哪些區域還需要進行更多研究，像是探討岩石反應的效率，以及什麼樣的地質歷史可以把正確的岩石聚在一起跟水產生反應。

過去有許多人炒作並誇大某些氫氣來源，比方說從地函來的氫氣——但此研究顯示這類來源並不可靠。反之，作者表示地殼中有幾種常見的地質背景都具有形成完整的氫氣系統所需的要素。這些地質背景有些從地質上來說相當「年輕」，近期(數百萬到數千萬年)才產生氫氣；其他就真的相當古老(數億年)——但重要的是，世界各地都能發現它們。

 

Scientists define the ingredients for finding natural clean hydrogen

Researchers at the University of Oxford, Durham University and the University of Toronto have detailed the geological ingredients required to find clean sources of natural hydrogen beneath our feet. The work details the requirements for natural hydrogen, produced by the Earth itself over geological time, to accumulate in the crust, and identifies that the geological environments with those ingredients are widespread globally. These findings, published today in the journal Nature Reviews Earth & Environment, offer a solution to the challenge of hydrogen supply, and will help industry to locate and extract natural hydrogen to meet global demands, eliminating the use of hydrocarbons for this purpose.

In the modern world, a reliable supply of hydrogen gas is vital for the function of society. Fertiliser produced from hydrogen contributes to the food supply of half the global population, and hydrogen is also a key energy component in many roadmaps to a carbon neutral future, essential if we are to prevent the worst predictions of climate change.

Today, hydrogen is produced from hydrocarbons, with waste gases contributing to 2.4% of global CO₂ emissions. Demand for hydrogen is set to increase from 90 million tonnes in 2022 to 540 million tonnes in 2050, but it is vital that this hydrogen is not CO₂ emitting. Production followed by the burial of waste CO₂ (‘carbon sequestration’) or from renewable energy resources (wind or solar) are both future sources of hydrogen, but are not yet commercially competitive.

New research from the University of Oxford, in collaboration with Durham University and the University of Toronto, provides a solution. In the last billion years, enough hydrogen gas has been produced by the Earth’s continental crust to supply mankind’s energy needs for at least 170,000 years. Whilst a proportion of this has been lost, consumed, or is inaccessible today, the remaining hydrogen could offer a natural (and emission-free) source of this natural resource.

Until now, limited historical hydrogen sampling and measurement have restricted scientists’ current understanding of where, and how much, hydrogen is located in the crust. An exploration recipe is critical to find accessible and commercially viable accumulations of natural geological hydrogen.

Study co-author Professor Jon Gluyas (Durham University), notes: “We have successfully developed an exploration strategy for helium and a similar ‘first principles’ approach can be taken for hydrogen.”

This research outlines the key ingredients needed to inform an exploration strategy to find different ‘hydrogen systems’. This includes how much hydrogen is produced and the rock types and conditions these occur in, how the hydrogen migrates underground from these rocks, the conditions that allow a gas field to form, and the conditions that destroy the hydrogen.

Study co-author Professor Barbara Sherwood Lollar (University of Toronto) said: “We know for example that underground microbes readily feast on hydrogen. Avoiding environments that bring them into contact with the hydrogen is important in preserving hydrogen in economic accumulations.”

The authors outline where understanding of these ingredients is strong, and highlight areas that need more work – such as rock reaction efficiencies and how geological histories can bring the right rocks together with the water that reacts with it.

Some sources of hydrogen gas, such as from the Earth’s mantle, have fuelled much speculation and hyperbole - but this research shows that these are not viable sources. Instead, the authors showed that the ingredients for a complete hydrogen system can be found in a range of common geological settings within the crust. Some of these can be geologically quite young, forming hydrogen ‘recently’ (millions to tens of millions of years), others truly ancient (hundreds of millions of years old) – but critically are found globally.

Lead author Professor Chris Ballentine (University of Oxford, Department of Earth Sciences) said: “Combining the ingredients to find accumulated hydrogen in any of these settings can be likened to cooking a soufflé – get any one of the ingredients, amounts, timing, or temperature wrong and you will be disappointed. One successful exploration recipe that is repeatable will unlock a commercially competitive, low-carbon hydrogen source that would significantly contribute to the energy transition – we have the right experience to combine these ingredients and find that recipe.”

牛津大學地球科學系的Chris Ballentine教授是主要作者，他說：「不論在哪種地質背景當中，要讓這些要素結合起來使氫氣得以累積，就像是在烤舒芙蕾一樣——只要原料、用量、時間、溫度有任何一個環節出錯，就會讓成品失敗。一套可以重複使用的成功探勘策略可以開啟具有商業競爭力的低碳氫氣來源，這對能源轉型來說相當重要。而我們正是具有相關知識來統整這些要素，並找出探勘策略的專家。」

The potential for natural geological hydrogen has motivated the authors to form Snowfox Discovery Ltd., an exploration company with a mission to find societally significant natural hydrogen accumulations.

天然地質氫氣的潛力促使作者成立探勘公司Snowfox Discovery Ltd.，目標是要找到可以對社會產生顯著影響的天然氫氣累積。

原始論文：Ballentine, C.J., Karolytė, R., Cheng, A., Lollar, B.S., Gluyas, J.G. & Daly, M.C. Natural hydrogen resource accumulation in the continental crust. Nature Reviews Earth & Environment, 2025 DOI: 10.1038/s43017-025-00670-1

引用自：Department of Earth Science, Oxford University. “Scientists define the ingredients for finding natural clean hydrogen.”