As introduced in the last blog regarding Micro-Turbine Range Extenders, we will continue the discussion of turbine engine applications in the automotive sector in this blog.
Looking to solve the problem of range anxiety in electric vehicles, many companies have started exploring the business model of recharging electric batteries in automotive vehicles with a parallel turbine engine driving a generator – coined under the term ‘micro-turbine range extender’ (or MTRE). As seen in the turbine-powered car programs initiated in the 50s and 60s, issues with low efficiencies, slow throttle response, and capital cost of the powertrain rendered all of these programs futile shortly after their inception. However, the revolution of electric vehicles and hybrid technologies has allowed this technology to resurface from a different direction. With battery-driven electric motors designated as the main driver, these cars are equipped with a technology that has both energy efficient low-end torque as well as groundbreaking throttle response and many of the former drawbacks during its initial iterations are solved using an electric drivetrain. The turbine-engine, instead of operating as the main driver, will now only operate at its most efficient power output mode and work to simply drive electricity through the generator, recharging the vehicle’s battery packs. Acting as an isolated thermo-mechanical system, a micro-turbine range extender can be designed and optimized without having to worry about the varying duty cycles and idling that is inherent in the vehicle’s drivetrain. The thermodynamic model of a typical micro-turbine range extender can be seen below in Figure 1.
One application within commercial vehicles that has benefitted from this technology utilizes a MTRE system developed by Wrightspeed. The specific application lies within retrofitting refuse trucks with this electric powertrain in order to help them save an estimated $35,000 a year on fuel and maintenance costs. In such heavy-duty applications, it is obvious that the potential for fuel cost and maintenance savings is much higher due to the large fuel burning needed for these vehicles as well as the harsh drive cycle a refuse truck goes through. The question in the expansion of this technology generally comes in two forms: What makes the micro-gas turbine range extender a better alternative than a normal ICE hybrid option? – and – What is the viability of scaling this for consumer vehicles given the capital cost of the drivetrain?