Turbo compounding refers to the use of a turbine to recover energy from the exhaust system of a reciprocating engine and re-introduce that energy back into the engine. There are currently two forms; mechanical turbo compounding, which was introduced in the aerospace sector during the 1940s, and electrical turbo compounding (ETC), pioneered by Bowman for use in the power generation and heavy vehicle sectors.
Bowman Power Group is a world leader in advanced exhaust energy recovery technologies for reciprocating engines, which are the dominant plant for power generation in remote areas, for renewable fuels and for biomass energy applications.
Bowman is working with leading engine manufacturers and genset integrators to increase power, improve fuel efficiency and reduce emissions.
In mechanical turbo compounding, the energy recovered from the exhaust gases (waste heat recovery) is converted into kinetic energy and fed back into the engine via a high ratio transmission. In ETC the energy is converted to electrical power and then electrically transmitted to the engine by a power electronics module.
The success of both types of turbo compounding depends on the successful redesign of the engine’s turbo charger, which must be made more efficient (by 5-10%) in order to prevent an excess of back pressure in the exhaust system when the turbo generator is fitted. The important advantage offered by ETC over mechanical turbo compounding, is that the former allows precise control of turbo generator performance via the Bowman power electronics module. This means that heat recovery can be optimised over a much wider range of engine loadings, leading to greater overall efficiency.
Over 600 ETC systems are installed on gensets in 11 countries on four continents; and in the first week of March, Bowman 10 million hours of system runtime! This is a lot of time; well over a thousand years. Bowman “thought it would be fun to work out how 10 million hours equates to power generation, fuel savings and CO2 reductions… – as the graphic shows.