Hybrids, full electrics, and hub motors

A promising option to further improve the efficiency of series hybrids is the use of supercapacitors. This special type of capacitors has the advantage to achieve very high energy densities, very high rates of charge and discharge, little degradation over thousands of cycles, and low toxicity of materials used. A further option is to replace the conventional electric motor with so called hub motors. These hub motors are essentially electric motors that are directly placed over the wheels. This eradicates transmission lines. It improves efficiency by 100% and reduces weight. However, further development work is required to overcome a number of technical issues such as reliability concerns, size and heat build up.

The full electric vehicle can be regarded as a possible next sequential step from the series hybrid. This configuration comes without any combustion engine at all. All the energy is stored in a large battery which can be charged from grid electricity. Although electric vehicles have a long track record, further battery development is a key issue to improve range, reduce costs, and achieve greater energy and power densities to allow higher payload for electric trucks. Additional technologies, e.g .nano-polymers, are being developed with the potential to reduce charging times to minutes and extend battery life to over 10,000 cycles. The carbon emissions in this case depend on the CO2 emission factor of the electricity provided. However, the energy efficiency of electric motors is higher compared to combustion engines and electricity can be carbon neutral when generated from renewable resources like wind power.