Extracting natural hydrogen is a topic that’s gaining increasing attention due to the potential of hydrogen as a clean energy carrier. However, understanding the greenhouse gas implications of natural hydrogen extraction is essential for a comprehensive assessment of its environmental impact.
A group of developers have announced, in a paper called Greenhouse gas intensity of natural hydrogen produced from subsurface geologic accumulations, their intention to extract hydrogen from naturally occurring stores of the gas underground. But while this so-called gold or white hydrogen is expected to be extremely cheap to produce, it is unknown exactly how it will compare to other methods of generating the molecule in terms of greenhouse gas emissions.
In this scenario, the wells yield a daily output of 160.7 tonnes of unprocessed natural gas. However, this gas must undergo separation, dehydration, and compression processes to yield a marketable quantity of 39.1 tonnes of hydrogen.
The model assumes that a portion of the produced hydrogen is used on-site to provide power for various operational processes. The phase of gas separation presents the highest emissions intensity, with fugitive greenhouse gases and emissions resulting from venting and flaring potentially exceeding 2.25 tonnes of carbon dioxide equivalent (CO2e) per day in the initial year.
In the first year, the drilling phase also contributes significantly to emissions due to embodied emissions linked to the procurement of cement and steel for equipment. Additionally, the model takes into account the practice of reinjecting waste gas into a disposal well at a comparable pressure level to that of each productive well, rather than returning it to the original reservoir.
In conclusion, the greenhouse gas implications of natural hydrogen extraction are contingent upon the specific source and extraction methods. To harness the potential of hydrogen as a clean energy carrier, it is essential to minimize greenhouse gas emissions associated with its extraction and production. Efforts are being made to address these challenges and transition toward more sustainable hydrogen sources and production techniques in the ongoing pursuit of a low-carbon energy future.
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