As fleet operators increasingly aim to enhance fuel efficiency and reduce costs, natural gas company Tetra4, a subsidiary of JSE-listed energy company Renergen, has started trialling diesel dual-fuel (DDF) kits on two European brands of trucks to establish the advantages of natural gas as a fuel source.

Preliminary results of the trial show that at least 50% of diesel can be substituted with gas, says Renergen CEO Stefano Marani, who tells Engineering News that, depending on further initial results, the company aims to introduce the trucks with the DDF units in fleet operations for a similar or shorter timeframe.

The trials on the trucks, which have engine performances of 440 hp and 480 hp, are expected to run until the end of this month.

As a key focus for the company is long-haul logistics, Tetra4 then aims to present the business case for using compressed natural gas (CNG) as a fuel source for large fleet operators.

Renergen COO Nick Mitchell highlights that, while several million vehicles worldwide operate using some form of gas, the importance of the trial lies in demonstrating the results in a South African context and ensuring that the conversions are successful.

Tetra4 is supplying CNG for the trucks, as well as the making available the filling infrastructure in Virginia, also in the Free State.

The trucks have each been supplied with three 200 ℓ CNG cylinders that can currently provide a travelling range of 550 km.

“The trucks will run on a combination of routes – from the home base in Virginia to Johannesburg, in Gauteng, and to Bloemfontein, in the Free State. We will also conduct trials to Harrismith, in KwaZulu-Natal, to monitor the change in elevation,” Marani says, noting that the trucks will consistently haul heavy loads.

South Africa-based installer and distributor Vehicle Gas Solutions, which imports, supplies and fits CNG kits to all types of vehicles using petrol, diesel and/or liquefied petroleum gas, undertook the import and installation and/or conversion of the DDF kits onto the trucks, as well as the monitoring of the kit performance.

The kits are imported from Italy-based dual-fuel technology provider Ecomotive Solutions.

“Key features of the kits include a cutoff function, where the CNG will be cut off should the temperature of the engines increase significantly. Temperature breaches will also be logged by the kit,” Vehicle Gas Solutions director Clinton McGuinness says.

The technology further allows for a mixture of diesel and CNG, with the quantity of each fuel depending on the engine’s needs. This means that, as the engine requires more torque, it uses more diesel. When the units incur more static revolutions on the long road, they use more gas.

The injection timing of the diesel is cut in the dual-fuel units, thereby reducing diesel use, while the energy value is supplemented by gas. This ensures that the kilowatt output of the truck is maintained, McGuinness adds.

The kilowatt strength of the trucks is maintained to original-equipment-manufacturer (OEM) specifications.

Other benefits of the technology include fuel cost savings, as well as carbon footprint reductions.

To ensure the independence of the trial results and data analytics, Tetra4 appointed actuarial data science company Autolytix Data Science, whose speciality is vehicle life cycle cost analytics, to conduct and monitor independent trials.

Autolytix Data Science COO Wimpie Frost explains that, during the trial, the company will primarily use data generated by machines and aims to calculate the fuel consumption for diesel, based on the data provided by the telemetry and gas consumption.

The human input, such as the frequency of the fuel fill-ups, will also be calculated.

Frost enthuses that indicative results can play a significant role in the development of an alternative cost-saving methodology for fleet owners and in pursuing and encouraging fleet optimisation.

“Given the fact that there are already several logistics companies on board with the concept and we are working closely with two OEMs on natural gas as an alternative to diesel, I would see the second phase as the catalyst for at least two operators to convert a meaningful portion of their fleet to run on Tetra4 gas,” Marani concludes.