Flash Joule heating has been widely used as an ultrafast, scalable, and versatile synthesis method, most prominently in the synthesis of flash graphene. Traditional methods of graphene synthesis involve purely chemical or thermal means and are far more energy-intensive and far less scalable than flash Joule heating. Herein, we demonstrate kilogram-scale flash graphene synthesis using an automated flash Joule heater. We implement a pulse width modulation system to improve graphene quality and uniformity while scaling up to larger batch sizes. We furthermore report evidence that the flash Joule heating synthesis of graphene is an electrothermal process in which the presence of charge and the resulting electric field inside the graphene precursor facilitates graphene synthesis by lowering the activation energy of the reaction. We present both through experiment and theory the thermodynamic values of the flash Joule heating transition from amorphous carbon feedstocks, to turbostratic graphene, to finally ordered graphene and graphite. We finally compare the energy, environmental, and monetary costs of flash Joule heating to other scalable methods for graphene production via life cycle and technoeconomic assessments.