EM Drive.

New Earth and beyond are left without any kind of technology which uses fossil fuels. Carts and wagons are used until the first Electro Magnetic Field Drives are developed. These "Engines" merely harness and direct the flow of the Planets EM Field, basicly floating the vehicle within the field. Harnessing and directing the flow of the field through the engine at different frequencies by compression of the 64 star tetrahedral grid which is comprised of Quartz Crystals set within a titanium housing with silicon bumpers to keep the crystals in place. The Tetrahedral grid, or Core reactor, is surrounded by it's Female counter part which can be moved closer to or further away from the core in sections to increase directional flow to the desired direction and speed of the vehicle it is housed in. The only draw-back to this engine is that it will not work in pockets where the EM Field is effectively reversed during pole reversals. That is, until Stephanie Li figures out how to set the computer systems to constantly monitor the field and correct for it.