I confess that I didn't know what "goaf" is. Did you?

[NNadir]

I came across this paper this evening: Quantum Chemical Calculation of the Effect of NH3 on CO2 Adsorption and Storage in Goaf Chao-yu Hao, Ya-chao Zhang, Wen-hao He, and Cun-bao Deng Energy & Fuels 2022 36 (4), 1948-1959

Goaf?

Sometimes in a paper, when they'll tell you what an unfamiliar term means. Not here, they just jump right into "goaf."

As an important source of energy in the world, coal is widely used in power generation, steel manufacturing, and other industrial processes. According to the data of the world energy statistics yearbook of BP in 2019, the world coal output in 2018 was 3.917 billion tons, with an annual growth of 4.3%. (1,2) As the largest single energy source of power generation, coal accounts for the production of more than 36% of global electricity; in China, this share has reached the value of 72.83%. The spontaneous combustion of coal and gas explosion disasters during coal mining and utilization along with flue gas emissions from coal-fired power plants with related issues as a result of CO2 as a greenhouse gas have been the main problems restricting the development of the coal industry. (3?6) In flue gas emitted by power plants, the oxygen content is usually low and the flue gas injected into underground inert goafs can prevent spontaneous coal combustion and gas explosions while, at the same time, decreasing emissions to the atmosphere. (7?13) Selective non-catalytic reduction/selective catalytic reduction (SNCR/SCR) technology is generally used for denitrification of flue gas. There will be some “ammonia escape” from the flue gas as part of the denitrification process, and this will result in a more efficient NOx reduction. (14?21)

OK, now I know "goafs" are inert and underground...

No clue...

This is why the gods invented Google I guess.

goaf
in British English
(ɡəʊf IPA Pronunciation Guide)

NOUN

mining
the waste left in old mine workings
Collins English Dictionary. Copyright © HarperCollins Publisher

A British word, apparently popular with Chinese writing in English.

Who knew?

[Solly Mack]

1. I've heard miners here call it the "gob".

By "here" I mean in the United States.

[unblock]

2. Plural is goaves. Interesting.

[eppur_se_muova]

3. Well, really now ! It's not a commonly used term like "swarf".

(OT -- I think Swarf would be a great name for a robot, IRL or in SF.)

[NNadir]

4. That raises a serious philosophical question.

Is a goaf filled with swarf still a goaf?

[Chainfire]

5. I would have guessed that it was the interspecies child of a goof and an oaf.