The electrical energy used to light a house might go through the following sequence of conversion steps (assuming the fuel resource to be coal).
i) one tonne of coal is completely burned to produce steam in a boiler that has an efficiency of 86%;
ii) the hot, high-pressure steam passes through a steam turbine that has an efficiency of 34%;
iii) the spinning turbine drives a generator that has an efficiency of 98%; iv) the transmission lines from the generator to the house deliver electricity with an efficiency of 94%;
v) that delivered electrical energy powers a light bulb that converts it into visible light with an efficiency of 12%.
what fraction (expressed in %) of the primary energy in that original tonne of coal actually contributes to lighting the house? what happens to the rest of the energy?