Microwave and heat pump combination offer energy breakthrough for EVs

Photo: Noya Fields

Researchers from the University of Birmingham are looking to patent a an energy storage system to stop the AC draining the batteries of EVs – which can reduce the driving range by as much as 40%.

The method, invented by Birmingham energy expert Professor Yongliang Li, couples a chemical heat pump with microwave energy, and produces heating or cooling on demand, with much higher energy density than battery packs.

The e-Thermal bank provides a secondary energy source for electric vehicles.

Professor Yongliang Li is Chair in Thermal Energy Engineering in Birmingham’s School of Chemical Engineering.  His research focuses on thermal energy processes and systems.

He said:

We predict that by replacing conventional HVAC and possibly a small portion of the battery pack, e-Thermal banks would provide efficient cabin temperature control and a range extension of up to 70%, at a lower cost than increasing battery capacity.

He added:

Heating and cooling the EV cabin requires considerable energy and is the most significant contributor to EV range reduction.  We aimed to offload these thermal management tasks to a microwave driven process.  Microwave is a fast heating method, because microwaves penetrate uniformly through materials and so deliver energy evenly into the body of the material.  The energy cost can be minimised by coupling with a smart meter to charge the system when energy is cheap, and the stored energy can then be used at any time.

The e-Thermal bank is ‘charged’ at the EV charging station by using microwave energy to dissociate a solid-vapour working pair and also to condense the vapour into liquid.  This charging process stores the microwave energy inside the car, in the e-Thermal bank.

During discharging, the process is reversed – feeding the vapour into a reactor to generate heat through an exothermic reaction, while simultaneously a liquid-gas phase change in an evaporator generates cooling.

University of Birmingham Enterprise has filed a patent application covering the e-Thermal bank system and method for storing energy and is seeking commercial partners for licensing collaboration or co-development.