 In the previous diagram, we have looked at how a boiler basically or power plant works. In here, we are looking at the efficiencies. Basically, when we have three components, like a boiler and a turbine and a generator, how would the efficiency, cumulative efficiency, when all of these components are put together, how the efficiency changes is what we're going to look at now. Look at this diagram where we are putting in chemical energy of 100 units into this boiler. Obviously, boiler is pretty good in terms of efficiency. And this is going to produce about 88 BTUs of thermal energy. So the thermal energy is 88 BTUs. And we are putting in 100 BTUs of energy. So this gives us roughly about 88% efficiency. These 88 BTUs of thermal energy are going into the turbine. So that becomes the input to the turbine. And the turbine puts out mechanical energy of about 36 BTUs. So 36 BTUs are coming out of this turbine. And 88 BTUs are going in, which means the efficiency is roughly about 40%, which means 40% of the energy that is coming into the turbine really gets converted into mechanical energy. Rest of it is going out as waste. Now, the third step takes it further. The generator takes it further. We are going to put 36 BTUs into the generator. And it is producing about 10.26 watt hours. Each watt hour, remember, these two are in different units now. Each watt hour is equal to roughly 3.4 BTUs. So when we multiply this number by 3.4, we get the number of BTUs that are coming out. We have to have them in the same units. So now the generator efficiency is equal to roughly about 35 BTUs, which is, again, 10.26 times 3.4 to convert into BTUs. This is the output that we are getting electrical output. And the input to this generator is 36 BTUs. So the generator efficiency turns out to be roughly about 97%. However, the cumulative efficiency is when we are putting in 100 BTUs in here to begin with, we are finally getting only 35 BTUs as output. So overall efficiency is only 35%. The reason is if we treat the entire power plant as 1 box, what we are putting in is 100 BTUs. And the useful output is only 35 BTUs, electrical energy. That's how we get this 35% efficiency for the overall power plant. We can also get this efficiency by multiplying the efficiency of the boiler times the efficiency of the turbine times the efficiency of the generator, 0.88 times 0.4 times 0.97. This is the efficiency of the boiler, efficiency of the turbine, efficiency of the generator. When you multiply them as decimals, it turns out, again, to be 0.35 or 35% efficient. So you can get the cumulative efficiency, overall efficiency, by multiplying the efficiencies of each of the steps as decimals. That is the lesson that we learned here.