據世界能源網站7月3日報道，開發氫能作為清潔能源以減少對化石燃料依賴的追求，可能會引領我們走向一個意想不到的地方——煤炭（煤礦）。賓夕法尼亞州立大學的科學家團隊發現，煤炭可能是一種潛在儲存氫氣的方式，就像電池儲存能量供未來使用一樣，這解決了開發清潔能源供應鏈的一個重要障礙。

“我們發現煤炭（煤礦）可以成為這種‘地質氫能電池’，”賓夕法尼亞州立大學能源與礦業工程副教授Shimin Liu說道，“我們可以將氫注入煤炭（煤礦）和儲存，并在需要時取用?！?/p>

“氫氣是一種清潔燃料，在我們經濟中最耗能的領域——交通、電力和制造業中有著潛力。但是，要建立氫能基礎設施并使其成為一種經濟實惠和可靠的能源來源，還有很多工作要做?！笨茖W家們表示。

這些工作中包括開發儲存氫氣的方法，但目前的方法成本高昂且效率低下?？茖W家們表示，“好好利用煤炭（煤礦）的地質構造是一個有趣的選擇，因為它們可以儲存大量氫氣，以滿足每天或季節性變化的能源需求峰谷起伏”。

“煤炭經過了深入研究，我們已經商業化生產煤氣將近半個世紀了，”Liu說，“我們對它有所了解，并且在煤炭開發所在的煤礦已建成基礎設施。我認為煤炭（煤礦）將是進行氫能地質儲存的合理選擇。”

為了測試這一理論，科學家們分析了來自美國各地的8種煤炭，以更好地了解它們的吸附和擴散潛力，也就是它們能夠儲存多少氫氣。

科學家們在《應用能源》雜志上報告稱，所有8種煤炭都表現出了可觀的吸附特性，來自弗吉尼亞東部的低揮發分無煙煤和來自賓夕法尼亞東部的無煙煤在測試中表現最好。

“從科學角度來看，我認為煤炭（煤礦）極有可能是氫能地質儲存的首選，”Liu說，“我們發現煤炭（煤礦）優于其他地質構造，因為它可以儲存更多氫氣，它具有現有的基礎設施，并且在全國范圍內和人口密集地區廣泛可得。

“已耗盡的煤層氣儲庫可能是最佳的候選地。這些煤層包含類似甲烷的非常規天然氣，幾十年來已成為重要的化石燃料能源來源。甲烷會附著在煤炭表面，這個過程稱為吸附。

“同樣地，將氫氣注入煤炭會使氫氣被吸附或附著在煤炭上。這些構造通常在頂部有一層頁巖或泥巖，起到密封作用，使甲烷（或在這種情況下的氫氣）密封存儲，直到需要時再抽取出來。”

“很多人把煤炭定義為一種巖石，但實際上它是一種聚合物，”Liu說，“它具有高碳含量和許多小孔，可以儲存更多的氣體。因此，煤炭就像一個海綿，相比其他非碳材料，它可以容納更多的氫分子?！?/p>

科學家們設計了特殊設備來進行實驗。與其他吸附氣體如甲烷和二氧化碳相比，煤炭與氫氣的親和力較弱，因此傳統的壓力設備無法確定吸附特性。

“我們設計了一種非常新穎且具有挑戰性的實驗設備，”Liu說，“花了好幾年時間才找到正確的方法。我們必須根據我們以前對煤炭和頁巖的經驗，進行試驗和錯誤的設計實驗系統?！?/p>

根據Liu及其科學團隊的研究結果，科學家們確定無煙煤和半無煙煤是將氫氣儲存在已耗盡煤層的良好備選材料，而低揮發份無煙煤則更適合將氫氣儲存于含氣煤層。

在煤炭采礦社區開發氫氣儲存技術可以為這些地區帶來新的經濟機遇，同時利用當地已有煤炭開采設施，也有助于更加便捷地建設國家氫氣基礎設施。

“在能源轉型中，煤炭社區在經濟上受到了最大的影響，”Liu說，“這無疑是重塑采煤地區經濟發展形態的機會，煤炭開發地區擁有專業知識和能源工程技能人才和經驗。如果能夠建立基礎設施并給予他們經濟發展機會，這將是我們應該考慮的問題。”

未來的研究工作將集中在煤炭的動態擴散性和動態滲透性上，這些特性決定了氫氣注入和抽取的速度，科學家們表示。

“我認為賓夕法尼亞州立大學是進行這項研究的合適地點——我們擁有開發煤炭儲量和煤層氣的經驗，多年來還在高等學府中持續進行工程和經濟方面的專業知識傳授與創新，”Liu說，“這是進行這項研究的合乎邏輯的原因?！?/p>

 John, Willie Leone and Ang Liu作為賓夕法尼亞州立大學的能源和礦業工程系教授參與了這項研究工作。

吳奇之 譯自 世界能源網

原文如下：

Hydrogen Battery: Storing Hydrogen in Coal May Help Power Clean Energy Economy

The quest to develop hydrogen as a clean energy source that could curb our dependence on fossil fuels may lead to an unexpected place — coal. A team of Penn State scientists found that coal may represent a potential way to store hydrogen gas, much like batteries store energy for future use, addressing a major hurdle in developing a clean energy supply chain.

“We found that coal can be this geological hydrogen battery,” said Shimin Liu, associate professor of energy and mineral engineering at Penn State. “You could inject and store the hydrogen energy and have it there when you need to use it.”

Hydrogen is a clean burning fuel and shows promise for use in the most energy intensive sectors of our economy — transportation, electricity generation and manufacturing. But much work remains to build a hydrogen infrastructure and make it an affordable and reliable energy source, the scientists said.

This includes developing a way to store hydrogen, which is currently expensive and inefficient. Geologic formations are an intriguing option, the scientists said, because they can store large amounts of hydrogen to meet the peaks and valleys as energy demand changes daily or seasonally.

“Coal is well-studied, and we have been commercially producing gas from coal for almost a half century,” Liu said. “We understand it. We have the infrastructure. I think coal would be the logical place to do geological hydrogen storage.”

To put this to the test, the scientists analyzed eight types of coals from coalfields across the United States to better understand their sorption and diffusion potential, or how much hydrogen they can hold.

All eight coals showed considerable sorption properties, with low-volatile bituminous coal from eastern Virgina and anthracite coal from eastern Pennsylvania performing the best in tests, the scientists reported in the journal Applied Energy.

“I think it’s highly possible that coal could be the very top selection for geological storage from a scientific perspective,” said Liu. “We find that coal outperforms other formations because it can hold more, it has existing infrastructure and is widely available across the country and near populated areas.”

Depleted coalbed methane reservoirs may be the best candidates. These seams contain unconventional natural gas like methane and have become an important source of fossil fuel energy over the last several decades. The methane sticks to the surface of the coal, in a process called adsorption.

Similarly, injecting hydrogen into coal would cause that gas to absorb or stick to the coal. These formations often have a layer of shale or mudstone on top that act as a seal keeping methane, or in this case hydrogen, sealed until it is needed and pumped back out, the scientists said.

“A lot of people define coal as a rock, but it’s really a polymer,” Liu said. “It has high carbon content with a lot of small pores that can store much more gas. So coal is like a sponge that can hold many more hydrogen molecules compared to other non-carbon materials.”

The scientists designed special equipment to conduct the experiments. Coal has a weaker affinity with hydrogen compared to other sorbing gases like methane and carbon dioxide, so traditional pressurized equipment for determining sorption would not have worked.

“We did a very novel and very challenging design,” Liu said. “It took years to figure out how to do this properly. We had to properly design an experiment system, trial and error based on our previous experience with coals and shales.”

based on their results, the scientists determined anthracite and semi-anthracite coals are good candidates for hydrogen storage in depleted coal seams, and low-volatile bituminous coal are better candidates for gassy coal seams.

Developing hydrogen storage in coal mining communities could bring new economic opportunities to these regions while also helping create the nation’s hydrogen infrastructure.

“In the energy transition, it’s really coal communities that have been the most impacted economically,” Liu said. “This is certainly an opportunity to repurpose the coal region. They already have the expertise — the energy engineer and skills. If we can build an infrastructure and change their economic opportunities — I think that’s something we should consider.”

Future work will focus on the dynamic diffusivity and dynamic permeability of coal, features which determine how quickly hydrogen can be injected and pumped back out, the scientists said.

“I think Penn State is the right place to do all this research — we have the coal reserves, we have natural gas, we have both the engineering and economic expertise at the University,” Liu said. “This is the logical place to do this.”

Also contributing from Penn State was Ang Liu, instructor, John and Willie Leone Family Department of Energy and Mineral Engineering.