Motorized bicycles using electric motors have also re-entered the market. Electrically powered bicycles use batteries, which have a limited capacity and thus a limited range, particularly when large amounts of power are utilized. This design limitation means that the use of the electric motor as an assist to pedal propulsion is more emphasized than is the case with an internal combustion engine. While costly, new types of lithium batteries along with electronic controls now offer users increased power and range while reducing overall weight. Newer electric motor bicycle designs are gaining increasing acceptance, particularly in countries where increasing traffic congestion, aging populations, and concern for the environment have stimulated development and usage.