Transport is mostly powered by gasoline engines, but switching to electric vehicles may not be the best solution due to environmental concerns and the need for massive battery capacity. Coal-powered electricity could make things worse. Battery production has serious human toxicity impacts. Electric vehicles will need a lot of infrastructure and subsidies to become widespread. Gasoline engines will still be used for a long time, with some improvements. Alternative fuels will only make up a small portion of transport energy by 2040. As the energy system becomes cleaner, electric and hydrogen vehicles will play a bigger role. Hybrid vehicles will also become more common.