Paul (with background)

It might seem a surprising statement, but Bowman Power Group’s Electric Turbo Compounding (ETC) technology is actually based on well established principles, some dating back to the early part of the last century.

This is not the jaded view of a disgruntled competitor – it’s direct from Bowman’s Engineering Director Paul Dowman-Tucker.

Less surprisingly, that’s not the whole story. Dowman-Tucker explains: ‘Whilst our ETC technology is unique in the market place it is entirely based on long-standing principles and technologies which have been around since the early part of the last century when people were working to improve aircraft engine efficiency with mechanical turbo compounding.

‘Here at Bowman we have been building on those principles over the last 10 years, trying to bring modern technologies to play and provide a commercially viable product for the waste heat recovery market place.’

For example, turbo machinery is now commonplace in every modern day car or diesel engine, he adds, high-speed electric machines are becoming the norm in domestic item such as vacuum cleaners, and the power conversion technology Bowman employs is widely used in wind and solar power systems.

Bowman’s unique application is for the power generation industry, converting recovered waste energy from the exhaust stream of reciprocating engines into grid-quality electrical power.

‘First of all we have to take the energy from the hot exhaust gases, which we do in exactly the same way as a turbocharger does, and convert that into electricity with the alternator part of the turbo generator,’ said Dowman-Tucker.

‘We then have to condition it as it is very high frequency AC power that we produce. We have a power electronics module which will convert that into grid quality three-phase electrical power.’

While there are some configuration complexities to ensure that the host engine operation remains optimal, fitting the ETC system is relatively straightforward. In any event, the possible benefit to efficiency is significant compared with the incremental gains achieved by engine manufacturers themselves.

‘We are doing something quite specific in terms of our technology being a waste heat recovery technology which has the potential to make a step change in their engine performance.’

Dowman-Tucker recognises that other approaches exist, such as the Organic Rankine Cycle, or ORC, though it is less compact and more costly, adding: ‘And certainly we don’t feel it has the track record that we have in the field in terms of operational units. At our latest count we had over 600 systems in operation with over 13 million running hours, and this is growing rapidly.  Furthermore our cost point is such that we can offer, in good circumstances, less than a two year payback.’

Looking ahead, Bowman’s focus remains firmly on the stationary powergen industry. However, the potential for ETC technology in other sectors is not being ignored and, in one example, the company has secured government funding to explore its use in the maritime domain.

Watch this space.