Senior Editor and virtual portfolio manager (2001-2012) for The Spear Report, The Spear Report Professional Edition, Spear's Security Industry Analyst, Spear's Strategic Resource Investor, Spear's ETF Investor. Private Trader since 1996 (equities and futures) Trading Coach since 2002 (daytradingpsychology.com) Contributor: CNBC, Forbes.com, Smartmoney.com, SFO Magazine, Trader Planet.
Jake Huneycutt is a former Portfolio Manager. Jake holds an MBA degree with a concentration in finance from Emory University. He earned a Master of Accounting degree from the University of North Carolina at Chapel Hill. He received his B.A. in History from East Tennessee State University. Jake is originally from Johnson City, TN and currently splits time between Boston, MA and Atlanta, GA.
Gasoline Energy Density = 11.8 kWh/kg
Typical Gas Tank Size ~ 20 Gallons = 55kg
Gasoline Engine, Transmission, Gas Tank & Exhaust System Weight = 700 kg
Gasoline Engine Thermodynamic Efficiency 25%
Typical effective energy density of gasoline system = (all the energy/all the weight)*efficiency
((11.8*55)/(55+700)) * 0.25 = 0.215 kWh/kg
Lithium Ion Energy Density 0.266 kWh/kg
Case in point Battery Size (85kWh) = 320Kg
Electric Motor, Battery Pack Structure and Inverter Weight = 100kg
Electric Drive Thermodynamic Efficiency: 90%
Typical effective energy density of state of the art electrical system = (all the energy/all the weight)*efficiency
((0.266*320)/(320+100) * 0.9 = 0.182
Put this together and we have an example of a system that is 182/215 = 85% of the effective energy density of gasoline ALREADY!!!!!!!
That means 15% away as an overall system from proving that a gasoline range extender is technologically pointless.
Considering that all of the improvements to close that gap would need to come from improved energy density cells (unlikely to reduce the weight of motors and inverters).
We are looking for an energy density improvement at the cell level of
(420/320)*.15 = 20%
That is the whole story right there, 20% improvement in battery energy density makes gasoline in all its forms unnecessary for all vehicles either as a main source of on-board energy or as a range extender.