Idemitsu Biodiesel 5 (B5 Diesel)

Diesel fuel is primarily used in diesel engines and plays an essential role in our daily lives. It powers large vehicles such as buses and trucks, as well as trains, ships, agricultural and construction machinery, and is also used for power generation and heating in boilers. To help reduce the CO₂ emissions generated from the combustion of such diesel fuel, B5 diesel has gained attention as a practical solution.

Idemitsu Biodiesel 5 is a B5 diesel produced under the strict quality control of Idemitsu Kosan. B5 diesel is a blend of conventional diesel fuel with up to 5% biodiesel derived from biological resources (biomass) such as used cooking oil, animal fats, rapeseed oil, soybean oil, and corn oil.　Because the plants used as raw materials for biodiesel absorb CO₂ from the atmosphere during their growth, biodiesel is regarded as a carbon-neutral fuel — one that does not increase overall CO₂ levels. As a result, compared with conventional diesel, the use of B5 diesel can reduce CO₂ emissions by approximately 5%, corresponding to the biodiesel blend ratio.

B5 diesel that meets the standards specified in Japan’s Act on the Quality Control of Gasoline and Other Fuels (the “Quality Control Act”) can be used in the same way as regular diesel. Therefore, no additional investment for vehicle modifications or inspections is required, and engine manufacturer warranties remain valid just as with conventional diesel.

In July 2025, Idemitsu commenced the supply of “Idemitsu Carbon Offset Fuel B5 (ICOF B5),” which combines B5 diesel fuel derived from biomass with Idemitsu Carbon Offset Fuel (ICOF).ICOF B5 is a product that assigns carbon credits to offset the CO₂ emissions that remain even after using the low-carbon B5 diesel. This allows not only for the 5% CO₂ reduction achieved by the biodiesel portion but also for the offsetting of the remaining 95% through carbon credits—effectively achieving carbon neutrality.

Currently, Idemitsu Biodiesel 5 and Idemitsu Carbon Offset Fuel B5 Diesel (ICOF B5) are supplied specifically for construction machinery at certain construction sites. However, Idemitsu Kosan aims to expand supply in the near future so that more customers can benefit from these products. Through the reliable supply of energy solutions such as these, Idemitsu Kosan is promoting initiatives toward carbon neutrality and contributing to the realization of a sustainable society.

Staff Interview: Flexible thinking and unyielding passion bring carbon offset fuel to society as a realistic option for decarbonization. (Published July 1, 2025)

If you would like further details about our products, please reach out to us through the  Inquiry Form (Business Inquiries) and select “Fuel Oil” as the inquiry category.