Question

One pound of bituminous coal contains 14,000 BTUs of energy. Suppose a coal-fired power plant needs 3,500 BTUs of heat to produce one kilowatt-hour of electricity. This plant has a 1 Megawatt output.
How much coal is required to produce one kilowatt-hour of electricity?

Answer 1

Answer:

$\boxed{\text{4 oz}}$

Explanation:

1. Energy needed

$\text{Energy} = \text{1 kWh} \times \dfrac{\text{3500 BTU}}{\text{1 kWh}} = \text{3500 BTU}$

2. Mass of coal needed

$\text{Mass of coal} = \text{3500 BTU} \times \dfrac{\text{1 lb coal}}{\text{14 000 BTU}} = \text{0.25 lb coal} = \textbf{4 oz coal}\\\\\text{It takes \boxed{\textbf{4 oz of coal}} to produce 1 kWh of electricity}$