據(jù)世界能源網(wǎng)站7月3日報(bào)道，開發(fā)氫能作為清潔能源以減少對化石燃料依賴的追求，可能會(huì)引領(lǐng)我們走向一個(gè)意想不到的地方——煤炭（煤礦）。賓夕法尼亞州立大學(xué)的科學(xué)家團(tuán)隊(duì)發(fā)現(xiàn)，煤炭可能是一種潛在儲(chǔ)存氫氣的方式，就像電池儲(chǔ)存能量供未來使用一樣，這解決了開發(fā)清潔能源供應(yīng)鏈的一個(gè)重要障礙。

“我們發(fā)現(xiàn)煤炭（煤礦）可以成為這種‘地質(zhì)氫能電池’，”賓夕法尼亞州立大學(xué)能源與礦業(yè)工程副教授Shimin Liu說道，“我們可以將氫注入煤炭（煤礦）和儲(chǔ)存，并在需要時(shí)取用。”

“氫氣是一種清潔燃料，在我們經(jīng)濟(jì)中最耗能的領(lǐng)域——交通、電力和制造業(yè)中有著潛力。但是，要建立氫能基礎(chǔ)設(shè)施并使其成為一種經(jīng)濟(jì)實(shí)惠和可靠的能源來源，還有很多工作要做。”科學(xué)家們表示。

這些工作中包括開發(fā)儲(chǔ)存氫氣的方法，但目前的方法成本高昂且效率低下。科學(xué)家們表示，“好好利用煤炭（煤礦）的地質(zhì)構(gòu)造是一個(gè)有趣的選擇，因?yàn)樗鼈兛梢詢?chǔ)存大量氫氣，以滿足每天或季節(jié)性變化的能源需求峰谷起伏”。

“煤炭經(jīng)過了深入研究，我們已經(jīng)商業(yè)化生產(chǎn)煤氣將近半個(gè)世紀(jì)了，”Liu說，“我們對它有所了解，并且在煤炭開發(fā)所在的煤礦已建成基礎(chǔ)設(shè)施。我認(rèn)為煤炭（煤礦）將是進(jìn)行氫能地質(zhì)儲(chǔ)存的合理選擇。”

為了測試這一理論，科學(xué)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(kuò)散潛力，也就是它們能夠儲(chǔ)存多少氫氣。

科學(xué)家們在《應(yīng)用能源》雜志上報(bào)告稱，所有8種煤炭都表現(xiàn)出了可觀的吸附特性，來自弗吉尼亞東部的低揮發(fā)分無煙煤和來自賓夕法尼亞東部的無煙煤在測試中表現(xiàn)最好。

“從科學(xué)角度來看，我認(rèn)為煤炭（煤礦）極有可能是氫能地質(zhì)儲(chǔ)存的首選，”Liu說，“我們發(fā)現(xiàn)煤炭（煤礦）優(yōu)于其他地質(zhì)構(gòu)造，因?yàn)樗梢詢?chǔ)存更多氫氣，它具有現(xiàn)有的基礎(chǔ)設(shè)施，并且在全國范圍內(nèi)和人口密集地區(qū)廣泛可得。

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

“同樣地，將氫氣注入煤炭會(huì)使氫氣被吸附或附著在煤炭上。這些構(gòu)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(chǔ)，直到需要時(shí)再抽取出來。”

“很多人把煤炭定義為一種巖石，但實(shí)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(chǔ)存更多的氣體。因此，煤炭就像一個(gè)海綿，相比其他非碳材料，它可以容納更多的氫分子。”

科學(xué)家們設(shè)計(jì)了特殊設(shè)備來進(jìn)行實(shí)驗(yàn)。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(tǒng)的壓力設(shè)備無法確定吸附特性。

“我們設(shè)計(jì)了一種非常新穎且具有挑戰(zhàn)性的實(shí)驗(yàn)設(shè)備，”Liu說，“花了好幾年時(shí)間才找到正確的方法。我們必須根據(jù)我們以前對煤炭和頁巖的經(jīng)驗(yàn)，進(jìn)行試驗(yàn)和錯(cuò)誤的設(shè)計(jì)實(shí)驗(yàn)系統(tǒng)。”

根據(jù)Liu及其科學(xué)團(tuán)隊(duì)的研究結(jié)果，科學(xué)家們確定無煙煤和半無煙煤是將氫氣儲(chǔ)存在已耗盡煤層的良好備選材料，而低揮發(fā)份無煙煤則更適合將氫氣儲(chǔ)存于含氣煤層。

在煤炭采礦社區(qū)開發(fā)氫氣儲(chǔ)存技術(shù)可以為這些地區(qū)帶來新的經(jīng)濟(jì)機(jī)遇，同時(shí)利用當(dāng)?shù)匾延忻禾块_采設(shè)施，也有助于更加便捷地建設(shè)國家氫氣基礎(chǔ)設(shè)施。

“在能源轉(zhuǎn)型中，煤炭社區(qū)在經(jīng)濟(jì)上受到了最大的影響，”Liu說，“這無疑是重塑采煤地區(qū)經(jīng)濟(jì)發(fā)展形態(tài)的機(jī)會(huì)，煤炭開發(fā)地區(qū)擁有專業(yè)知識(shí)和能源工程技能人才和經(jīng)驗(yàn)。如果能夠建立基礎(chǔ)設(shè)施并給予他們經(jīng)濟(jì)發(fā)展機(jī)會(huì)，這將是我們應(yīng)該考慮的問題。”

未來的研究工作將集中在煤炭的動(dòng)態(tài)擴(kuò)散性和動(dòng)態(tài)滲透性上，這些特性決定了氫氣注入和抽取的速度，科學(xué)家們表示。

“我認(rèn)為賓夕法尼亞州立大學(xué)是進(jìn)行這項(xiàng)研究的合適地點(diǎn)——我們擁有開發(fā)煤炭儲(chǔ)量和煤層氣的經(jīng)驗(yàn)，多年來還在高等學(xué)府中持續(xù)進(jìn)行工程和經(jīng)濟(jì)方面的專業(yè)知識(shí)傳授與創(chuàng)新，”Liu說，“這是進(jìn)行這項(xiàng)研究的合乎邏輯的原因。”

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

吳奇之 譯自 世界能源網(wǎng)

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.