Science...

 I love reading Becky Chamber's novels, but I'm finding a common flaw in several of them - perpetual motion machines.

Sidra human form AI, in A Closed and Common Orbit, generates power by harvesting kinetic energy when she moves, but the energy cost of moving will be far greater than that harvested - and that's not allowing for the power requirement of data processing, etc.

Ships in the fleet generates energy from water flowing from the centre to the outside - the ships used to spin, so it would effectively be flowing downhill - but that same water would have to be pumped back uphill for recycling.

Similar problem with the first Monk and Robot book.  No way are a couple of small solar panels going to power his bike (which is pulling a fair size load) and the other stuff he has with him.

 

Who has spotted similar gaffes in other novels?