Currently even the most efficient of combustion engines can only convert about one-third of the energy from fossil fuels into kinetic energy, the rest is lost, at least half of it as heat. And it is this wasted heat that BMW is looking to make use of.
Through a number of research projects, the German car maker is looking at ways to recover this lost heat. Among the most promising innovations are the turbosteamer, thermoelectric generator, engine encapsulation and a waste heat exchanger for oil heating.
The Turbosteamer and Thermoelectric Generator (TEG) projects are focused on generating electric current from waste heat to improve overall engine efficiency, although each project follows a different approach.
In the Turbosteamer Project, research and technology specialists of the BMW Group are working on a heat recovery system that is based on the principle of a steam process. It mimics the process used in large-scale power plants to recover wasted heat, but scaled down to be useable within a modern car. BMW has now installed a working prototype with a BMW 5 saloon.
Meanwhile in the Thermoelectric Generator (TEG) Project; two alternative systems have been developed – one unit is designed for the exhaust system, while the other is intended for the exhaust gas recirculation system. The development phase focused on integrating units in the exhaust system has led to considerable component improvements, especially in terms of weight and size.
The thermoelectric generator converts heat directly into electricity. The engineers of the BMW Group basically refined a technology that has been used to power space probes for more than four decades by NASA. The principle behind this technology is known as the Seebeck Effect, namely that an electrical voltage can be generated between two thermoelectric semiconducters if they have different temperatures.
Researchers forecast that TEGs could lead to fuel consumption savings of up to 5 per cent under real everyday driving conditions in the future.
