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Based on this equation, shouldn't high speed trains consume less energy since they travel so much slower than planes (3x speed = 9x drag)?

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Really not sure whether the person you’re replying to is actually correct, but the air is a lot denser on the ground than at cruising altitude. That’ll have an effect on energy consumption that works in the other direction.

Of course it’s not correct. A high speed train will use about 40kwh per 1000 people per mile

A plane is about 5 tons an hour, or 10kg per 300 people per mile, so 30kg of jet fuel per 1000 people per mile, or 1.2GJ

So a cruising a330 uses about 10 times the energy per passenger mile as an ICE high speed train.

Clearly the comparison of polution caused it then affected by how green the electricity source is and the extra environmental impact of burning fuel in the high atmosphere.

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