The review of the JCB’s ongoing attempts to get hydrogen accepted as an alternative fuel for internal combustion engines (ICE) published last week here on Agriland, has drawn a response from Nick Owen of Woodford Owen Consulting Ltd, a company specialising in the automotive industry.
Owen draws our attention to the reality of the production of Nitrous Oxides (NOx) from hydrogen-fuelled engines which, he noted, is minimal and less than current diesel-fuelled ICE engines that meet the latest emission standards.
It was in 2020 that the UK government confirmed that it considered hydrogen-powered ICE engines not to be a viable alternative to carbon-fuelled units, because they emitted NOx and could therefore not be considered as non-polluting.
Minimal emission of NOx
Recently, Owen has contributed to a report prepared for the Hydrogen Delivery Council, which comes under the aegis of the UK Department of Energy, Security and Net Zero (DESNZ), the government department charged with achieving Net Zero.
In this report, there is evidence presented by Volvo, Cummins and JCB itself pointing to the fact that NOx emissions can be reduced to less than 0.001g/kWh in a hydrogen-powered engine by ensuring the right conditions are met during combustion.
It goes on to explain that NOx production is due to high temperatures. Lightening, which is the main source of natural NOx, can create local temperatures of 27,000deg C for instance, and it is the avoidance of anything like such conditions in an engine that reduces NOx emissions.
The hydrogen engines now being developed by the three companies contributing to the report employ the same basic combustion strategy to achieve this and there are two major conditions that need to be met.
Simple requirements
The first is that the the air/hydrogen mix needs to be homogenous – there need to be no pockets of hydrogen rich mix within the charge.
The second is that it needs to be lean, that is, there is a generous excess of air. This reduces combustion speed through the mix and hence the maximum temperature reached,
These conditions can be easily met when there is a constant power demand upon the engine, the challenge arrives with sudden increased demand for power such as acceleration.
Adblue still needed
As yet it has not been possible to offer a purely engineering based solution, it will require the use of Selective Catalytic Reduction (SCR) to clean the exhaust of NOx, adblue being the most common method.
The situation appears to have changed a good deal from that which existed four years ago when the UK government dismissed hydrogen out of hand over this issue, an issue which no longer exists thanks to advances in engine design.
It remains to be seen if this influences DESNZ at all, or whether it was just being used an excuse to help justify the end of ICEs altogether back in 2020.