It is not possible to determine how much fossil fuel is needed to power a light bulb for a year without knowing the specific type of light bulb and the source of energy being used to power it.
Light bulbs are available in a range of wattages, which refers to the amount of electricity they use. A higher wattage bulb will use more electricity and therefore require more energy to power it. The amount of energy needed to power a light bulb will also depend on the type of fossil fuel being used to generate electricity. Different fossil fuels have different energy densities, which means that they contain different amounts of energy per unit of weight.
As a rough estimate, a 60 watt incandescent light bulb that is turned on for 8 hours a day will use approximately 528 kilowatt-hours of electricity over the course of a year. The amount of fossil fuel needed to generate this electricity will depend on the specific type of fossil fuel being used and the efficiency of the power plant that is generating the electricity. For example, a coal-fired power plant may use more fossil fuel to generate the same amount of electricity as a natural gas-fired power plant.
It is also worth noting that using energy-efficient light bulbs, such as LED bulbs, can significantly reduce the amount of energy needed to power a light bulb and therefore reduce the amount of fossil fuel required to generate that energy.
What items would you add to your survival preps to give you a power source if the electrical grid goes down?
Could you produce enough to live off the grid with solar, wind, or hydro?