A research project that aims to convert air-polluting diesel engines due for scrap into renewable-power storage units that can charge electric bus and lorry fleets is being carried out by the University of Nottingham (with support from Volvo Trucks).

Seamus Garvey, lead investigator for the university’s Faculty of Engineering (www.nottingham.ac.uk), said: “What can be done with end-of-life engines is an open question. One option is to melt them down to recycle the steel, but we propose to explore another possibility — re-tasking them to become machines that compress and expand air to store and release energy.

“Power is increasingly being generated from renewable sources that are intermittent by nature — chiefly, the sun and wind.

“How to store that off-grid energy for use when needed and not just when generated is a pressing issue to solve. Compressed-air energy storage (CAES) is one possibility.”

The proposition being explored by Volvo Trucks and Nottingham University is to transform existing engine hardware into reversible compressor/expander machines, for a relatively low cost per unit of power rating.

These machines compress air to put energy into storage or expand stored compressed air to release the energy again. One target application for these machines is at charging stations for fleets of electric buses and trucks.

The work is at a very early stage. Re-manufactured engine hardware from Volvo Trucks is being ‘gifted’ to the university, where engineering researchers will adapt the parts and incorporate them into new compression/expansion machines. The project will run until August 2019.

The machines will form a part of the High Performance Compression and Expansion laboratory at the University of Nottingham, which is one key element of a £60 million capital project in the Midlands called Energy Research Accelerator (ERA); this involves the Universities of Birmingham, Warwick, Nottingham, Leicester, Loughborough and Aston, as well as the British Geological Survey.