In 2014 Aggreko began a technology evaluation to assess the effectiveness of ETC combined with the Cummins KTA50-G3, the core engine in the Aggreko rental fleet. Initial trials demonstrated a 4% additional power output and 5% improved fuel consumption. This led to the agreement of a formal programme to further explore Bowman’s bolt-on system.

Chris Weston, CEO of Aggreko said: “We are looking forward to partnering with Bowman to further evaluate and develop a high-efficiency rental solution. Our work together so far has shown great promise.”

Bowman’s ETC systems comprise a turbo charger, turbo generator and power electronics unit. The ETC recovers waste exhaust energy to improve power density and fuel efficiency. The technology is equally suited to new- build and retrofit applications, for engines in the 200 kW-2 MW range, as well as much larger engines with a waste gate, such as the Wärtsilä 34SG, a 9 MW gas engine.

In a refrofit application the existing turbo charger may be replaced with a new unit designed to match the turbo generator that follows it. It is the energy in the exhaust gas from the turbocharger that powers the turbo generator, which is coupled to a high speed alternator. The power electronics unit shapes the generator’s output to grid standard.

Generator output is converted into grid quality, 3-phase AC at 50 or 60Hz, and at a voltage suitable for feeding into a low voltage grid or local load. It can be matched to distribution systems operating at 380-480V, or fed into a step-up transformer to contribute to a medium or high voltage grid. Bowman claims that its system, which has been sold already into 700 applications around the world, can increase fuel efficiency by 4-7%, or alternatively confer a power output increase of up to 10%. It has been proven on a wide range of power units, including those of all the leading OEMs.