Final answer:
Approximately 6120 homes could be heated using the waste heat from the power plant.
Step-by-step explanation:
To determine how many American homes can be heated using the waste heat from a 32% efficient electric power plant, we first need to calculate the total waste heat produced by the power plant.
The power plant produces 900 MJ of electric energy per second, and 32% of that is converted into electricity. So the waste heat produced is 900 MJ * (1 - 0.32) = 612 MJ per second.
To calculate how many homes can be heated, we need to convert the waste heat into the units used for heating. Let's assume that 20% of the waste heat is used for heating, while the remaining 80% is lost. So the waste heat available for heating is 612 MJ * 0.2 = 122.4 MJ per second.
Now we need to calculate the energy required to heat a single home. Each home requires an average of 20 kW (20,000 watts) for heating during the winter. So the energy required is 20,000 watts * 1 second = 20,000 joules per second.
Finally, we can calculate the number of homes that can be heated using the waste heat. The number of homes is equal to the waste heat available divided by the energy required per home: 122.4 MJ / 20,000 J = 6120 homes.
Therefore, approximately 6120 homes could be heated using the waste heat from the power plant.