Minecraft wiki entry for Building_a_rollercoaster, associated text: Most real-life roller coasters only use powered rails to climb the first hill, using the energy from the descent of that hill to move the car along the rest of the track. This can be achieved in Minecraft as well: simply place powered rails up the first hill (along with your choice of redstone power source) and make the rest of the track from plain rails. The minecart should be able to make it around the whole track, as long as each hill is not as big as the previous one. Note that, if you choose to follow this model, your riders will not maintain top speed throughout the entirety of the ride.