It seems that some kind of dark matter (mirror matter) allows to construct devices which act like perpetuum mobiles of the second kind without violating the Second Law -- see the indicated link.

Dark matter is a fantasy material to make the ailing big bang work. Even if it did exist, it cannot be compacted to a useful density. It is also said to be very hot though magically it does not transfer heat.

Where is it? 400x as much DM as light matter, yet the galaxy looks like it was made out of LM. Some say it's in a halo, but with that much DM outside the galaxy, then all the LM would naturally follow such a gravitational source so we'd have a doughnut instead of a spiral galaxy. Perhaps the DM idea was made by doughnuts?