Diesel fuel is the most power dense, relatively portable and reliable. Diesel fuel is also the most expensive, non-renewable and produces greenhouse gasses. A best-case diesel power scenario would be an initial generator cost of $20,000 plus $1,000,000 in fuel costs. Shipping, operation and maintenance expenses would also need to be added. Depending on load factor (BSFC) and cost of fuel, a diesel generator will make power in the range of $1 to $40 per kWhr. Maximum power is limited to 15 kW. A solar system's capacity factor is about 12%; therefore, a 100 kW system must be purchased to produce an average of 12 kW.