This plugin adds two sets of Gyroscopes: They consume energy at all times, and can store an amount of energy. One set can produce turning force despite using no engine space, the other has a lot of energy capacity.
This plugin adds a set of Gyroscopes: They can store an amount of energy, and can produce turning force, despite not taking any engine space. But, they are dense, and constantly consume energy.
In addition, there are Flywheel Batteries: similar to the gyroscopes, except that they are dedicated batteries with no turn rate; much more powerful than a similarly sized battery, but with the mentioned downsides.