Approximately 220 million tires are discarded in the U.S. each year. These tires present a disposal problem because they take up

Question

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Approximately 220 million tires are discarded in the U.S. each year. These tires present a disposal problem because they take up

space, harbor pests, and have been known to catch fire. One tire can generate about 250,000 BTUs (1 BTU = 3 x 10 -4 kWh) when it is burned. The average American home consumes about 10,000 kWh of electricity per year. How many tires would be needed to meet the annual electricity demand of ten homes for one year if the production of electricity from tires is 50% efficient?

Chemistry

1 answer:

lions [2.9K] · Answer 1 · 2026-03-08T14:41:08+03:00

Answer:

A total of 2667 tires are required to satisfy the annual power needs of ten homes.

Explanation:

According to the Second Law of Thermodynamics, not all energy produced when tires are incinerated can be effectively used due to losses associated with finite temperature differences. The energy obtainable from a tire when burned, measured in kilowatt-hours ( $E_{out}$ ), can be calculated using the efficiency definition:

$E_{out} = \eta \cdot E_{in}$

Where:

$\eta$ - Efficiency, which is dimensionless.

$E_{in}$ - Energy released from burning, measured in kilowatt-hours.

Taking into account $\eta = 0.5$ and $E_{in} = 75\,kWh$ , the yearly energy yield from a tire amounts to:

$E_{out} = 0.5\cdot (75\,kWh)$

$E_{out} = 37.5\,kWh$

Thus, the number of tires necessary to meet the electricity demand of ten homes for one year is:

$n = \frac{(10\,homes)\cdot \left(10000\,\frac{kWh}{home} \right)}{37.5\,\frac{kWh}{tire} }$

$n = 2666.667\,tires$

A total of 2667 tires are necessary to satisfy the annual power needs of ten homes.