'Diesel-saving' technology could make it to market in two years

Experts with knowledge of the development are starting to talk in terms of “virtually zero-emission” diesel engines and citing ACCT as being even more important than the arrival of the common-rail diesel.

In the past decade, NOx has become an infamous problem. It springs from the fact that diesels become more efficient as they run hotter, but this heat increases their NOx output. The effect has led to rapidly rising awareness of NOx’s detrimental effect on health; current European research suggests it shortens 71,000 lives a year.  

Since 2014, the practice of injecting diesel exhausts with AdBlue via SCR exhaust catalysts has proved effective in most situations and has dramatically lowered average NOx outputs. But, as the Loughborough researchers point out, gaps in SCR’s effectiveness remain – notably when low exhaust temperatures prevent complete decomposition of AdBlue, such as when a vehicle is idling in traffic, especially in stop-start conditions. NOx outputs rise when SCR doesn’t function well, and that's the root of recent reports that even new-car exhausts sometimes produce multiples of permitted NOx levels.

As Hargrave explained, there’s a deep irony in this. While NOx has hit the headlines, CO2 continues to kill the planet. “NOx is serious,” he said, “but it’s really a point-source problem. It only matters in a tiny minority of locations.

"Solve it and you can get on with reducing CO2, which is important everywhere.”

Because of concerns over NOx, Europe’s diesel market is in near chaos. Sales of oil-burning cars have collapsed by 20%, putting pressure on margins and infrastructure. A swing to more CO2-heavy petrol vehicles means CO2 targets are being missed — at the very moment these targets are about to tighten.

For light commercial vehicles, there’s no realistic prospect of reducing diesel use in the short term. Market experts don’t believe buyers will entertain a rapid change to downsized petrol engines or hybrids. For heavy goods vehicles, the situation is much worse.

Whereas car engines are ‘dialled back’ on NOx and need only light doses of AdBlue, trucks need much more.

In cold-exhaust conditions (winter, for example), the incomplete breakdown of AdBlue leaves damaging and almost immovable exhaust deposits in complex exhaust systems that reduce power and even immobilise trucks completely. Understandably, the market in defeat devices for HGVs is lively.

The Loughborough team says it now needs a heavyweight technology partner to take ACCT to production but is wary of ceding valuable intellectual property rights cheaply.

Negotiations between the university’s IP specialists and prospective partners are in full swing. “Our sense is that we need a major supplier rather than a single manufacturer,” said Hargrave.

Whatever ACCT’s route to market, an increasing number of potential users are desperate to see its progress. It could lead to a whole new lease of life for diesels.