Table 2.

Notable achievements and milestones of the companies working on WHRS

Name	Notable achievement	Milestone
ABB89	They provide WHRSs for large vessels that employ main propulsion machinery and have a more than 20 MW mechanical output, enabling more than the standard 50% fuel efficiency.	•Founded in 1988 •Initial Public Offering (IPO) at London and Frankfurt Stock Exchange in 2005
Alphabet Energy90	They partnered with Berkeley Lab to create a cost-effective thermoelectric WHRS. Using nanotechnology licensed by Berkeley Lab, they developed advanced thermoelectric materials based on silicon nanowires with a conversion efficiency of 10% or more and the ability to operate at temperatures as high as 800°C.	•First industrial-scale TEG, the E1 in 2014 •In 2017, the company received a US$2,000,000 grant from the California Energy Commission. •Closing down in 2019
European Thermodynamics91	They worked with companies across the globe, large and small, to deliver state-of-the-art thermal management solutions with TEGs.	•Founded in 2001 •At 2022, they announced the collaboration with Toyota.
Faurecia92	Faurecia has more than 10 years of experience with WHRS. They provide compact EHRS that weighs less than 3 kg and can reduce fuel consumption by up to 7%, thus improving fuel economy and reducing CO2 emissions.	•Founded in 1998 •In 2016, they equip the all-new Hyundai IONIQ Hybrid with WHRSs.
Ferrotec93	This company is a leading brand in providing materials and machinable ceramics for manufacturing TEGs.	•Founded in 1981 •In 2022, they prepared for Shenzhen IPO.
GreenTEG94	They provide energy-efficient thermoelectric elements based on the thermocouple technology developed by the Swiss Federal Institute of Zurich.	•Founded in 2009 •They raised a fund of CHF 10 million at 2022.
Hi-Z Technology95	They provide thermoelectric materials, devices, and systems. The first large generator was integrated into a diesel truck. Afterward, they continued to provide TEGs for exhaust or waste heat recovery at levels ranging from watts to kilowatts. They have been developing a 1 kW thermoelectric generator for class eight diesel truck engines. They also designed an mW generator for radio power supply.	•Founded in 1988 •They developed thermoelectric generators under U.S. DoE and California Energy Commission funding since 1992.
II-VI Marlow96	They offer thermoelectric coolers and cooling modules, power generation technology, and thermoelectric systems. The newest product is a wireless sensors’ thermal energy harvesting system. The Defense Advanced Research Projects Agency has used II-VI Marlow thermoelectric materials and devices.	•Founded in 1973 and named Marlow •In 2014, they became a division of II-VI Incorporated and is now known as II-VI Marlow.
iMEC97	It is a research center that can design WHRS. Case studies include NuWay Tobacco exhaust heat recovery, Vitasoy and Nasoya gas dryer heat recovery, Dirats Laboratories, Weetabix compressor, Smith’s medical hospital, and steam replacement with hot water at Freudenberg-NOK.	•A non-profit organization founded in 1984 •In 2022, they had more than 5,500 expert scientists from 96 countries.
Kelk98	They provide TEG modules for various applications. Their microgeneration module is made using their proprietary high-performance material and high-density element mount technology. The maximum temperature of these three models ranges from 80°C to 280°C, the electric resistance varies from 1.15 to 7 Ω, and the thermal resistance ranges from 1.048°C to 29°C/W	•Founded in 1966 •Sales of Mini-TEC started in 2002 •The multi-purpose model supports mercury-free since 2023.
Laird99	They provide TEGs to harness the energy and convert it into an efficient power source. The power generators designed by them are well suited for inaccessible locations and spaces.	•Founded in 1991 •They provided thermoelectric cooling for project laser since 2021.
Mitsubishi Heavy Industry100	They provide WHRs for container vessels. The main features of their WHRS are its easy operation, easy installation, high reliability, compact design, and that it is economical and environmentally friendly. The max power output of the WHRS ranges from 800 to 3,500 kW. The waste heat temperature is approximately 400°C.	•Founded in 1884 •Mitsubishi Heavy completed the first unit of the latest version of WHRS for marine engines in 2010.
Novus Energy101	They provide a high-temperature 50-W TEG module. The max efficiency is 9%, and the waste heat temperature can reach 800°C. The specific power at the module level is 2.8 kW/kg.	•Founded in 2004 •They raised a fund of USD 38 million at 2010.
Otego102	A spin-off company of Karlsruhe Institute of Technology. They developed a roll-to-roll manufacturing process to decrease the cost of TEGs and provide low-cost WHRS.	•Founded in 1948 •Joined Dickson Group in 1988 •The name changed to Otego in 2020
Perpetua103	Their Power Puck energy harvesters are compatible with the wireless sensors and transmitters used by leading providers of wireless industrial instrumentation.	•Founded in 2005 •They raised a found of USD 3 million at 2014.
Phononic Devices104	This company announced that they had harnessed the thermoelectric power of phonons to revolutionize how the world cools and heats. Phononic’s ENERGY STAR–certified refrigerators deliver up to 40% energy savings versus compressor-based refrigerators, with unprecedented temperature stability and uniformity that fluctuates only ±0.5°C.	•Founded in 2008 •Chief product officer for semiconductor firm since 2022 •They raised a fund with an undisclosed amount in 2014.
RGS Development105	They invent, develop, and manufacture new and sustainable TEGs based on nanotechnology.	•Founded in 2006 •Acquisition by Dow Corning RGS in 2010.
RIF Corporation106	They provide thermo-generating batteries (TBs) and thermoelectric gas generators. TBs convert thermal energy into electricity and are a finished product used for manufacturing self-contained electrical supply sources.	•Russian company founded in 2013 •Since 2018, they have provided products to over 44 companies.
RMT Ltd.107	RMT provides miniature thermoelectric coolers for telecom, industrial, medical, and aerospace applications. More than 2000 different thermoelectric coolers are available for temperature-stable control of precision equipment.	•Founded in 1994 •All thermoelectric coolers are RoHS compliant and Telcordia GR-468 qualified in 2020
Sango108	Their fourth-generation heat collectors (debuted in 2018) are 60% smaller in size and 41% lighter in weight than traditional TEGs.	•Founded in 1928 •Changed its name to Sango in 2021
TE Technology109	They offer a complete line of thermoelectric cooling modules, temperature controllers, Peltier coolers, and power supplies.	•Founded in 1989
TEGPro110	They provide TEG modules with approximately 5%–8% efficiency.	•Founded in 2011
Tellurex111	They provide TEGs for small dc devices. The net output of approximately 0.75 W is adjustable from 3 to 14 V dc.	•Founded in 1986 •Closing down in 2018
Tenneco112	They provide heat exchangers, TEGs, and Rankine cycle systems. With Tenneco’s one-box design, the Rankine cycle system is a comprehensive system that enables direct waste heat recovery from exhaust gas.	•Founded in 1940 •Reaching to revenue of USD 18 billion in 2021 and most of them from automotive products
Thermo Electric Company113	It is a multinational company specializing in designing and manufacturing temperature measurement solutions.	•Founded in 1941 •Thermo-Electric USA certification in 2020
Valeo114	Its thermal systems provide thermal climate control, thermal powertrain, thermal compressor, thermal front end, and waste heat recovery solutions.	•Founded in 1923 •In 2016 and 2017, Valeo ranked as France’s leading patent filer
Yamaha115	They contribute know-how in procuring and manufacturing thermoelectric modules made of semiconductor materials. At the same time, the WHRS helps with design, vehicle concepts, and optimizing vehicle energy systems in developing prototype thermoelectric-generator modules.	•Founded in 1987 •In 2021, Yamaha began to offer samples of YGPTX024 TEG module for vehicle use
Yasunaga116	Yasunaga is a Japan-based company mainly developing and selling engine parts, machinery, and environmental equipment. WHRSs were studied by this company.	•Founded in 1923 •Mg-Si system thermoelectric conversion material announced by Yasunaga at 2013