Steam-powered automobiles continued development all the way into the early 20th century, but the dissemination of petrol engines as the motive power of choice in the late 19th century marked the end of steam automobiles except as curiosities. Whether they will ever be reborn in later technological eras remains to be seen. The 1950s saw interest in steam-turbine cars powered by small nuclear reactors (this was also true of aircraft), but the dangers inherent in nuclear fission technology soon killed these ideas. The need for global changes in energy sources and consumption to bring about sustainability and energy independence has led 21st century engineers to think once more about possibilities for steam use, if powered by modern energy sources controlled with computerized controls, such as advanced electric batteries, fuel cells, photovoltaics, biofuels, or others.