I happen to have an envelope handy:

2000 kilocalorie converts to 8.3 megajoules. This should be the amount of energy consumed per day.

8.3 megajoules / 24 hours is 96 watts. This should be the average rate of energy expediture.

96 watts * 20% is 19 watts. This should be the portion your brain uses out of that average.

96 watts * 24 hours is 464 watthours. This should be the average amount of energy your brain uses in a day.

This is why I've never found "AI" to be particularly competitive with human beings. The level of energy efficiency that our brains operate at is amazing. Our electrical and computer engineering is several orders of magnitude out from the achievements of nature and biology.

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ZiiS a day ago | parent [-]

Calculate how much energy needs to be input into acriculture and transport to provide that wattage.

	▲	themafia a day ago \| parent [-]
		To be fair we'd have to consider how much of this same secondary energy would be required to build, operate and maintain the power grid. The grid itself is not 100% efficient either so we'd need to calculate how much power is directly wasted every single day just in inserting and extracting power from those overhead lines. That's way off the envelope though.