This is the first 20-year view of thermoelectric harvesting commercial opportunities, research pipeline and priorities needed. See activities of over 100 participants from materials to product integration. Learn the dead ends, shrewd initiatives, alternative technologies. Forecasts 2022-2042. 27 primary conclusions from PhD level multilingual analysts. Alternative technologies, two new in 2021. Industrialists' needs? Why does IDTechEx conclude that billion-dollar success is possible but not with current research priorities?