The latest patch for space engineers introduced artificial mass blocks which when powered created mass which is affected by gravity. The Gravity drive uses gravity generators to create a gravity field facing towards the front of a ship and artificial mass blocks to push the ship forwards. This is a surprisingly effective means of powering a ship and even leaves it capable of steering normally. After doing some not very accurate calculations the gravity drive uses 31.32 MW, the 8 large thrusters normally driving the ship use 53.76 MW so the gravity drive is actually quite energy efficient as well as having the added benefit of producing a forward deflector shield for any gravity based weaponry as the field should push any blocks affected by gravity back the way they came. Oh and it also accelerates much much faster then regular thrusters!