We've compiled a list of frequently asked questions about our Electric Turbo Compounding systems, from performance and reliability to installation, operation, and maintenance.


What are the key components of the ETC system?+

Our ETC system consists of a turbo generator and a power electronics unit. For optimum system performance, we usually recommend the replacement or modification of the host engine turbocharger, but this is based on your specific requirements and host engine type, size, operating load etc.

For what engine sizes is ETC technology suitable?+

The ETC product family includes systems for engines in the 150kW-2MW range. Depending on engine type and size, either a single or twin ETC system is required. We are currently exploring solutions for engines in the 2-20MW range, and already have the capability to work with larger engines, such as the Wärtsilä 34SG, a 9MW gas engine. To see how we work with large engines view our case study.

On what engines has the ETC system been proven?+

The ETC system is suitable for integration with a wide range of engine types. We have demonstrated reliable performance on the following engines and are currently working with customers on a number of additional engines.

    • CAT 3516 TA/LE
    • Cummins KTA50-G3
    • Cummins KTA50-G8
    • Cummins QSK60
    • Cummins QSK78
    • Jenbacher J312
    • Jenbacher J320
    • MAN 2842
    • MAN D2676
    • Mitsubishi 6R41
    • MTU 4000
    • Scania DC 12
    • Volvo TAD1642
    • Wärtsilä W20V34SG
    • Wärtsilä W18V50SG

What kind of genset performance improvement does ETC provide?+

Adding ETC to your genset will increase its electrical efficiency by between 4 and 7% relative to baseline, depending on a range of parameters such as type of combustion, fuel, operating usage etc. For example, if the host genset has a baseline electrical efficiency of 38%, adding ETC could improve this to >40%.

Can I benefit from both fuel saving and additional power at the same time?+

Yes, however there will be a trade-off between optimising for fuel savings, gaining additional power, or a combination of both.

Who uses ETC technology?+

Anyone looking for better fuel efficiency or increased power output to give their business a competitive edge can benefit from our technology. This includes, engine and generator OEMs who build our ETC technology into their products, along with independent power producers and power rental companies. Read more about the markets where we work.

How quickly does the ETC system achieve payback for customers?+

Depending on the application and your commercial and technical drivers, between 6 months and 4 years.

What if the ETC system causes engine damage?+

With over 20 million running hours in the field there is no evidence that the ETC system has ever caused engine damage or decreased engine service intervals.

What is the track record for the ETC system?+

The ETC product range is rugged and reliable. Over 800 systems deployed across the world have accumulated more than 20 million running hours of smooth, reliable and robust operation in a range of harsh operating environments.

What happens if the ETC system has a fault? Can I still run my generator?+

Yes, with the ETC 1000 system thanks to a rotor lock.

How does Bowman provide local support?+

Within the UK we will support you directly in both trial and post-trial MRO requirements. Outside the UK we work with a number of channel partners that can support you in all maintenance, repair and operations requirements.

Who is responsible for installing the ETC system?+

Depending on your requirements, either Bowman or a Bowman-approved partner can install the ETC system, although you are free to do this yourself if required. View further information on installation.

Do we maintain the compression ratios in the turbocharger as a result of adding the Bowman turbo generator in series?+


What is the estimated maintenance cost per hour of the ETC system?+

£0.35 per running hour. This is based on a typical 100,000-hour schedule of around £0.15 for planned and £0.20 for unplanned maintenance costs per hour.

What additional back pressure occurs as a result of using the ETC system?+

The back pressure at the exhaust manifold is increased by between 0.5 and 1.0 bar when ETC is implemented. This varies depending on the original parameters of the host engine and how the combined engine and ETC system is being optimised. Please note, that this significantly exceeds limits normally published by the engine OEM, but these limits relate to typical turbocharger operation and we will re-match the turbocharger to work with the ETC system correctly.

I am operating a CHP plant and already recover heat from the exhaust gas, how much heat does the ETC system consume?+

Typically, and this depends on the parameters of the original genset, an ETC system will reduce the final temperature of the exhaust gas by between 60° and 80°C.

Can attachment of Bowman's ETC equipment negate de-rating of the engine itself at altitude?+

Most genset engines, depending on how they are rated under standard reference conditions, will suffer de-rating in higher ambient temperatures (usually above 45°C) or as altitude increases. This is generally caused by a reduction in the mass of air taken into the engine in these conditions, resulting in temperatures inside the engine reaching specific limits that certain components (e.g. turbochargers) can tolerate. When ETC is added to a genset, particularly to produce additional power, it can also cause temperatures to increase. However, studies into the de-rating of gensets with ETC have shown that de-rate does not occur any earlier. Given this, it can be said that applying ETC to a genset can offset a certain extent of de-rate relative to the genset before it had ETC fitted in cases where ETC is added to provide additional power.

What is the heat loss from exit of the turbocharger to exit of the turbo generator?+

Between 60° and 80°C, depending on fuel type, turbocharger type and your application.

What are Bowman's standard Terms & Conditions?+

You can read our standard terms here.

I have another question not answered above+

No problem. Please get in touch via our contact form.