Embodied energy of digital technology

Re:Embodied energy of digital technology by londons_explore on Wednesday August 14, 2019 @03:08AM (#20693312)

Gas turbine powerplants are easily in the 60% + efficiency band... Coal at 30% is dying out in most of the western world.

Granted every fossil fueled device ever has quoted efficiency with the Lower Heating Value, whereas the HHV is the fairest measure. The difference consists of if you should extract energy from the humidity in the exhaust, and the clear answer is yes.

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Re:Embodied energy of digital technology by dredmorbius on Wednesday August 14, 2019 @03:40AM (#20693434)

AFAIR "easily" is a stretch -- there are highly efficient combined-cycle gas-turbine plants, and I think some of those actually get above 50% efficiency.

For most thermal generation, however, it's Carnot-cycle limits which get you down, and that's governed by hot vs. cold side efficiency.

Coal actually has some of the higher efficiencies, in some cases, exceeding 45%, though whether that's through high temps or combined cycle I'm not sure. (I'm not defending coal, just noting efficiency numbers I've encountered.)

Update: Wikipedia's language is "possibly 62%" efficiency, FWIW: https://en.wikipedia.org/wiki/Combined_cycle_power_plant

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Re:Embodied energy of digital technology by londons_explore on Wednesday August 14, 2019 @07:03AM (#20694268)

You're right - only the best ones achieve 60+% efficiency.

For example, [1] achieved 63.08% efficiency at the whole-site level (ie. including inefficiencies in startup, testing, etc. over a year)

[1]: http://interfaxenergy.com/article/30230/chubu-electric-plant...

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Re:Embodied energy of digital technology by dredmorbius on Wednesday August 14, 2019 @05:42PM (#20700262)

Thanks.

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