John Deere offers diesel engines for underground applications   

PowerTech™ E 4.5L MSHA-certified engine
The PowerTech™ E 4.5L engine features two ratings certified by the Mine Safety and Health Administration (MSHA) for underground use: 63 kW (85 hp) at 2400 rpm and 74 kW (99 hp) at 2400 rpm. The PowerTech E 4.5L offers full-authority electronic controls, 2-valve cylinder heads, a high-pressure common-rail fuel system with electronic fuel injection, and a fixed-geometry turbocharger in turbocharged or air-to-air aftercooled aspirations.