Power plant that uses natural gas as a fuel to generate electricity

Consider a power plant that uses natural gas as a fuel to generate electricity. If there are 10,000 J of chemical energy contained in a specified amount of natural gas, then the amount of electricity that could be produced would be:

Equal to 10,000 J because energy cannot be created or destroyed.

Greater than 10,000 J when energy demands are highest; less than 10,000 J when energy demands are lowest.

Something less than 10,000 J, depending on the efficiency of the generator.

Greater than 10,000 J because electricity has a higher energy quality than natural gas.

Greater than 10,000 J because of the positive feedback loop of waste h