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Hybrid EV
Chemical-electric power
Chemical energy is a common independent energy source. Chemical energy is
converted to electrical energy, which is then regulated and fed to the drive
motors. Chemical energy is usually in the form of diesel or petrol. The liquid
fuels are usually converted into electricity by an electrical generator powered
by an internal combustion engine or other heat engine. This approach is known as
diesel-electric or gas-hybrid locomotion.
Another common form of chemical to electrical conversion is by electro-chemical
devices. These include fuel cells and batteries. By avoiding an intermediate
mechanical step, the conversion efficiency is dramatically improved over the
chemical-thermal-mechanical-electrical-mechanical process already discussed.
This is due to the higher carnot efficiency through directly oxidizing the fuel
and by avoiding several unnecessary energy conversions. Furthermore,
electro-chemical batteries conversions are easy to reverse, allowing electrical
energy to be stored in chemical form.
Despite the higher efficiency, electro-chemical vehicles have been beset by many
technical issues which have prevented them from replacing the more cumbersome
heat engines. Heat engines have been easier to scale up, with the largest
electrical generators always being driven by heat engines. Fuel cells are
fragile, sensitive to contamination, and require external reactants such as
hydrogen. Batteries require highly refined and unstable chemicals that could be
harmful to the environment and must be recycled to minimize their impact and
maximize their sustainability through material reuse. Both have lower energy and
power density than heat engines. However, recent advances in battery efficiency,
capacity, materials, safety, toxicity and durability are likely to allow their
superior characteristics to be widely applied in car-sized EVs,
For especially large electric vehicles, such as submarines and aircraft
carriers, the chemical energy of the diesel-electric can be replaced by a
nuclear reactor. The nuclear reactor usually provides heat, which drives a steam
turbine, which drives a generator, which is then fed to the propulsion.
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