Medical Dictionary. brachial plexus. noun. Medical Definition of brachial plexus. : a complex network of nerves that is formed chiefly by the lower four cervical nerves and the first thoracic nerve, lies partly within the axilla, and supplies nerves to the chest, shoulder, and arm.
Nonrenewable Sources of Energy. Most of the energy we use comes from fossil fuels, such as coal, natural gas and petroleum. Uranium is another nonrenewable source, but it is not a fossil fuel.Uranium is converted to a fuel and used in nuclear power plants.Once these natural resources are used up, they are gone forever.nergy is the power we use for transportation, for heat and light in our homes and for the manufacture of all kinds of products. There are two sources of energy: renewable and nonrenewable energy.
Fossil fuels can be used at reduced levels as transition fuels to a renewable energy economy, or at higher levels if carbon sinks prove to be economical. Natural gas could serve as a transition fuel to hydrogen derived from solar energy, since the infrastructure for use would be similar for the two gaseous fuels. Natural gas can be complemented by renewable energy sources such as solar energy, biomass fuels (renewably produced and used), and wind energy. Wind energy and solar energy are economical under some circumstances (such as areas with high wind speed or high insolation and low precipitation).