Hydrogen to the rescue of the pros

Published on 21/04/2023, updated on 15/03/2024

Hydrogen propulsion is BorgWarner’s solution for continuing to use internal combustion engines beyond 2035. Here’s how it works.
The debate surrounding the announced end of the internal combustion engine has been causing a stir ever since a consortium of 8 countries led by Germany opposed the European bill last March. As a reminder, this resulted in an agreement authorising the sale of internal combustion engine vehicles beyond 2035 on condition that they use CO2-neutral fuels. This decision opens the door to carbon-neutral synthetic fuels (efuel) and hydrogen, which contains no carbon.

Visit to BorgWarner’s technical centre in Blois

This brings us to our visit to BorgWarner (BW), which produces petrol and diesel injection systems in Blois (France) and, in this case, has developed a brand new hydrogen injection system for internal combustion engines. BMW and Mazda began looking into the subject some fifteen years ago, but their engines were sorely lacking in power compared with their petrol counterparts. Inspired by this work, BW has been quietly developing a new hydrogen injection system for the past 5 years, which would eliminate the problems encountered by BMW and Mazda.

So how does it work?
First of all, the principle involves burning hydrogen in an internal combustion engine instead of petrol or diesel. Hydrogen is injected and mixed with air in the engine’s cylinders, then compressed and finally ignited via a spark plug to start combustion.

In the case of petrol or diesel engines, the fuel is injected in liquid form, but in the case of hydrogen, it is injected in gaseous form. As the density of hydrogen is 8,000 times lower (at ambient temperature and pressure) than that of petrol and diesel, it has to be injected under high pressure to compensate for this handicap. As a reminder, in the days of BMW and Mazda, hydrogen injection solutions were based on naturally-aspirated engines (without turbochargers) and delivered fairly modest performance figures.

High-pressure hydrogen injection

The BW system solution gets round this problem by using not only a turbocharged engine but also a high-pressure direct injection system. As a leading specialist in fuel injectors (petrol, diesel and gas), BW has developed a new injector specially adapted to hydrogen, for integration into an injection system with engine management adapted to the characteristics of this gas.

The commercial vehicle in focus

In order to demonstrate the merits of its concept, BW has chosen to convert an existing engine to hydrogen, and has chosen the 2.2 HDi turbo-diesel engine from the Stellantis group, which equips the Peugeot Boxer in particular. After an initial series of tests on an engine test bench to check that the system was working properly, BW moved on to the vehicle testing stage, installing this “new” hydrogen engine in two vehicles, a Peugeot Boxer and a Citroën Jumper.

The choice of light commercial vehicles is not accidental, since they are one of the targets of this technology, which is targeting commercial applications. The reason is that almost 30% of users of these vehicles cannot be satisfied with the electric traction battery solution (which is too restrictive in terms of range and weight), while being able to cope with the additional volume imposed by the bulky hydrogen coils. This means that this technology is unlikely to find its way into compact passenger cars as it stands.

And the magic happens

Initial tests on the engine dyno showed encouraging performance and emissions figures, and after gradual improvements to the concept, BW has now achieved a promising result. In fact, not only has the main objective been achieved, with virtually zero CO2 emissions (0.4 g per km), but pollutant emissions have virtually disappeared, with the only measurable value being a very low quantity of nitrogen oxide (NOx), well below the limit of the future Euro 7 standard.

In terms of performance, the current figures for power and torque are 110 bhp and 250 Nm respectively, slightly lower than the base diesel engine. These figures are likely to improve with future optimisations. In terms of consumption, BW has obtained 3 kg of hydrogen per 100 km and a range of 300 to 500 km, while refuelling will take between 5 and 10 minutes at 350-bar hydrogen filling stations. BW has announced that the system can be upgraded to a pressure of 700 bar, which will reduce the size of the cylinders, increase range and reduce refuelling time.

The challenge that the American equipment manufacturer set itself seems to have been met, with the result being the first internal combustion engine that is as ‘clean’, or nearly so, as its electric counterpart. To underline the level of performance, BW points out that a cyclist would emit 6g of CO2 per km as a result of breathing… An unbeatable argument!

Of course, this technology will only come into its own once it is possible to obtain supplies of green hydrogen (produced from renewable energy sources) easily and at competitive prices. A development that BW has no doubt about, as it observes the promising development of the European hydrogen industry. Stay tuned!

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photo credit BorgWarner