Answer:
Something less than 10,000 J, depending on the efficiency of the generator.
Step-by-step explanation:
By the first law of the thermodynamics, we know that energy can't be created or destroyed, so it must be conserved, and only transformed, as heat, work or internal energy. So, the energy generated can't be higher than 10,000 J.
By the second law of thermodynamics, we know that a machine can't convert 100% of the energy in an exclusively another form (heat in work for example). So, it's not possible that the generator converts all the 10,000 J of chemical energy in work to move the turbines to produce electricity.
So, we can conclude that the energy must be less than 10,000 J, and its exact value depends on the efficiency of the generator, which can't be 100%.