There is an average of about 9.8 kilowatt-hours (kWh) of energy in a liter of diesel. This is a rough estimate, as the exact energy content of diesel can vary depending on various factors, such as the quality of the diesel and environmental conditions. It is important to note that the energy content of diesel can be converted to kilowatts (kW) or kilowatt-hours (kWh) to measure the power output or energy consumption of a specific device or vehicle.