The end of thermoelectric generators in automotive waste heat recovery
may come as a surprise to some, but for those who have been observing the signs over the past few years, it's probably not so unexpected. However, one of the most shocking predictions in this report is the bad news regarding waste heat recovery in vehicles: According to IDTechEx, we are not expected to see the deployment of thermoelectric generators in vehicles. The excitement of previous years and the investment of nearly $250 million in projects led by automotive OEMs that partnered with thermoelectric companies did not continue after 2014. Grants ended, project deliveries revealed issues with mechanical robustness and materials development systems—requirements that would still take several more years before they were "deployment-ready." No follow-up work was announced, and a reduction in press releases and marketing from automakers ensued.
The anticipated 3-5% reduction in fuel consumption, with power output potentially reaching 1200 W, became a fleeting dream that ended with the advent of vehicle electrification. While electric vehicles won't completely replace internal combustion engine vehicles in the immediate future, Volvo's 2017 announcement of its intention to offer electric and hybrid versions of all its models starting in 2019 indicates that timelines for the complete replacement of ICEs are already in place. This would make investing in the development of counterproductive thermoelectric generators, as the ICE exhaust is actually the ideal location for the generator due to the high temperature difference between it and the surrounding environment—a difference that doesn't exist at all in an electric vehicle.
For these reasons, IDTechEx believes that future work in this space will eventually shift towards industrial applications, with stationary high-temperature processes in such scenarios, providing a segment with less stringent robustness requirements for energy harvesters.
What about thermoelectrics in wearables?
As for the news in the wearables sector, it doesn't look much better: Harvesting thermoelectric energy in consumer electronics remains the market most developers would like to target, but it's largely in the conceptual stage. The idea here is that the temperature difference between ambient air and the human body will generate enough energy for some electronic devices—for taking a sensing measurement and transmitting the data, for example. However, the small temperature difference and the resulting power output limit of approximately 30 W/cm² are limiting factors, as is the need to use heat sinks to dissipate heat and maintain the highest possible temperature difference, which adds bulk to the final product. These limitations point to some fitness monitoring devices and low-power wearables (i.e., those with reduced functionality) as potential applications, where powering low-power wireless sensor nodes and radios becomes viable. Matrix Industries is launching its crowdfunded smartwatch next month, with 10,000 or more units reaching supporters of its vision a few months later than initially expected, but the difficulties Matrix has had to deal with in order to make this smartwatch a reality only verify how difficult it is to tap into this market.
By Dr. Harry Zervos, Principal Analyst, IDTechEx
