Bio-diesel, known as FAME (Fatty Acid Methyl Ester), is the most common and best-known alternative diesel fuel. It is manufactured from soybeans, canola, vegetable oils or animal fats and is blended with traditional diesel fuel to improve the overall GHG performance.

Its use, however, is limited, including the potential requirement to significantly modify vehicle fuel systems and fuel stations if the blend of bio-diesel to diesel exceeds 5%. Bio-diesel also has the potential to cause fuel filter blockages, cold weather performance issues, and some long-term storage issues.

With some limitations, Komatsu has approved using up to 20% bio-diesel blends in their engines.

Renewable diesel, or HVO (Hydrotreated Vegetable Oil), offers significant improvements over traditional bio-diesel. It can be used as a diesel substitute (up to 100%, with no blend-wall limitations) with no modifications to the vehicle fuel system or fuel station equipment. It is also stable in long-term storage and does not block fuel filters.

“HVO is appealing because it is a drop-in fuel that is very similar to diesel at a molecular level,” says McKinnon. “However, it has no sulphur, so it is considered a cleaner diesel.” The fuel density of renewable diesel is lower than standard diesel fuel. Because of this, it does result in a slight decrease in power (1-2%) and a slight increase in fuel consumption.

While the particulate emissions are lower than diesel, the tailpipe GHG emissions are similar. What is dramatically improved is NET GHG emissions, which take into account the carbon sequestered from growing the crops that produce the fuel. “It’s very similar to a fossil fuel-derived diesel,” says McKinnon. “The difference is the source used to create that diesel.”

Renewable diesel currently costs more than traditional diesel fuel, and availability is limited in many locations. However, with the rising prices of petroleum diesel and market availability set to expand rapidly, this gap is quickly getting smaller.

Komatsu has also approved paraffinic fuels (HVO, GTL, etc) for Komatsu engines as long as they follow fuel standards EN 15940 and ASTM D975.

Are paraffinic fuels ok for use in engines with DPF and SCR? Yes. Approval to use covers engines equipped with or without DPF and with or without SCR after-treatment systems. The critical point is to ensure that fuel meets the standard EN 15940.

Hydrogen is one of the most abundant resources on the planet, burns with zero carbon emissions, and can be produced from green energy. “Cummins, our diesel provider for our large class mining equipment, is working on developing a mid-term solution for an internal combustion engine to run on hydrogen,” says McKinnon. “It will be a compression ignition engine –a cross between a diesel and an internal combustion engine.” The developments of this solution will start with smaller displacement on highway engines to develop a fuel-agnostic engine.

Another important technology is hydrogen fuel cells, which generate electricity through an electrochemical reaction. They share an advantage with batteries because cells can join together to increase power output. The technology has the potential to significantly outperform batteries because energy density is higher, and instead of recharging, it is only necessary to ensure a fuel supply is available. Refuelling times will be very similar to that of diesel today. In partnership with Cummins Diesel, Komatsu is developing a hydrogen-powered mining truck.

There are, however, significant challenges. “The volumetric density of hydrogen is much lower than diesel or gasoline,” says McKinnon, “so you’d need a fuel tank about three times as large to get the same capacity and range.”

Another challenge is that most hydrogen today is produced from natural gas and is carbon intense, so green alternatives and the infrastructure to bring it to market will have to be scaled and deployed.