Caterpillar has conducted its first field trial of a 50-tonne excavator running on solar diesel, marking a potential pathway for reducing carbon emissions in heavy construction equipment. The fuel, produced using solar energy to synthesise hydrocarbons, can be used in existing diesel engines without modification. While the trial demonstrates technical feasibility, key questions remain around fuel availability, cost competitiveness, and scalability for fleet deployment. Caterpillar has not yet announced timelines for commercial rollout or indicated which excavator model was used in the test.