From abandoned mines to carbon sinks: Assessing the CO2 storage capacity of Austrian low-rank coal deposits

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS
Majid Safaei-Farouji , David Misch , Reinhard F. Sachsenhofer , Max Rauscher , Nikolaos Kostoglou
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引用次数: 0

Abstract

This study represents the first assessment of CO2 storage potential in Austrian coal seams. Coal samples were taken from Fohnsdorf and Leoben abandoned coal mines, with particular emphasis on the Fohnsdorf coal since Leoben coal reserves were largely mined during previous coal production. Several methods were used to compare coal characteristics, including Rock-Eval pyrolysis (RE), organic petrography, and low-pressure N2 and CO2 sorption measurements. Both Fohnsdorf and Leoben coal samples show low sulfur and ash yields, as well as correspondingly high total organic carbon (TOC) contents. The pyrolysis Tmax and vitrinite reflectance values agree with a low coal rank for both sites. According to the N2 adsorption measurements at 77 K, low-lying mire coals from Fohnsdorf show a higher BET-specific surface area (BET-SSA) and BJH pore volume compared to raised-mire coals from Leoben. However, sapropelic shales and high-ash coals from Leoben show the highest BET-SSA and BJH pore volumes of all investigated samples and considerably exceed the N2 adsorption volumes of pure coals from both locations (N2 uptake up to 16 cm3/g; avg. for all samples 5.4 cm3/g). In contrast, the mean adsorbed CO2 uptake measured at 273 K and ∼ 1 bar followed the order of Fohnsdorf low-lying mire coals > Leoben raised-mire coals > Leoben sapropelic coals and shales, ranging at ∼0.8 mmol/g, ∼0.7 mmol/g, and ∼ 0.2 mmol/g, respectively. This shows that BET-SSA and BJH equations did not allow for adequate estimation of CO2 adsorption capacity trends in the investigated sample set. Furthermore, based on the existence of a hysteresis loop between CO2 adsorption and desorption branches for all investigated samples, the occurrence of weak chemisorption phenomena during CO2 adsorption is indicated. This effect helps to increase CO2 uptake and storage safety since the chemisorption process is not fully reversible upon pressure decrease. Ultimately, the theoretical CO2 sequestration potential of the remaining unmined Fohnsdorf coal reserves was estimated at 4.65 million tons, with an additional potential for enhanced coal bed methane production due to the gas-rich nature of Fohnsdorf coals with an estimated 1.2 billion m3 of CH4 in place.

从废弃矿井到碳汇:评估奥地利低阶煤层的二氧化碳储存能力
这项研究首次对奥地利煤层的二氧化碳封存潜力进行了评估。煤炭样本取自 Fohnsdorf 和 Leoben 废弃煤矿,重点是 Fohnsdorf 煤炭,因为 Leoben 煤炭储量大部分在以前的煤炭生产过程中被开采。比较煤炭特征的方法有多种,包括岩石热解(RE)、有机岩石学以及低压 N2 和 CO2 吸附测量。福恩斯多夫和莱奥本煤炭样本的硫含量和灰分含量都很低,总有机碳 (TOC) 含量也相应较高。热解 Tmax 和玻璃光泽反射率值与这两个地点的煤炭等级较低相吻合。根据 77 K 下的 N2 吸附测量结果,与莱奥本的高地煤相比,福恩斯多夫的低洼泥沼煤显示出更高的 BET 比表面积(BET-SSA)和 BJH 孔隙体积。不过,在所有调查样本中,莱奥本的皂质页岩和高灰分煤炭的 BET-SSA 和 BJH 孔隙度最高,大大超过了这两个地方的纯煤炭的 N2 吸附量(N2 吸收量高达 16 cm3/g;所有样本的平均值为 5.4 cm3/g)。相反,在 273 K 和 ∼ 1 bar 条件下测量的平均二氧化碳吸附量依次为 Fohnsdorf 低洼泥沼煤和 gt、Leoben 高洼泥沼煤和 gt、Leoben 皂质煤和页岩,分别为 ∼ 0.8 mmol/g、∼ 0.7 mmol/g 和 ∼ 0.2 mmol/g。这表明,BET-SSA 和 BJH 方程无法充分估计所研究样品集的二氧化碳吸附容量趋势。此外,基于所有调查样品的二氧化碳吸附和解吸分支之间存在滞后环,表明在二氧化碳吸附过程中存在微弱的化学吸附现象。由于化学吸附过程在压力降低时并不完全可逆,因此这种效应有助于提高二氧化碳吸收和封存的安全性。最终,剩余未开采的福恩斯多夫煤炭储量的二氧化碳理论封存潜力估计为 465 万吨,由于福恩斯多夫煤炭富含气体(估计有 12 亿立方米的甲烷),因此还具有提高煤层甲烷产量的潜力。
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来源期刊
International Journal of Coal Geology
International Journal of Coal Geology 工程技术-地球科学综合
CiteScore
11.00
自引率
14.30%
发文量
145
审稿时长
38 days
期刊介绍: The International Journal of Coal Geology deals with fundamental and applied aspects of the geology and petrology of coal, oil/gas source rocks and shale gas resources. The journal aims to advance the exploration, exploitation and utilization of these resources, and to stimulate environmental awareness as well as advancement of engineering for effective resource management.
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