Saving Waste Heat - Is It Worth It?

An electrical power company must decide whether to install the following equipment to recover waste heat that normally goes up the smokestack with the emissions. "Economizers" added to coal-fired boilers use hot flue gas to preheat water for the boilers. Heat exchangers can be installed with the air pollution control equipment. The exchangers will remove heat from hot flue gas and recycle it to heat the boiler plant. Reducing the temperature of the hot flue gas will protect the air pollution control equipment. Both economical and environmental factors must be considered when making a decision concerning the purchase and installation of the equipment.

Economic Issues

The plant burns 20,000 tons of coal in an average year. Under its current contract, the company has been paying $64.55 for a ton of coal. The "economizers" will save 850 tons of coal annually. The "exchangers" will save 325 tons of coal annually. The total cost of buying and installing the equipment is $150,000.

1. If the equipment is installed, the amount of coal the company must buy each year will be reduced. Calculate the annual savings. Show your work.

2. How long is the pay-back period-the time it takes for the savings to pay the cost of the purchase and installation of the equipment?

3. In addition to the savings from the reduction in coal used, how does the installation of the heat exchangers save money?

Environmental Issues

4. List at least three environmental impacts (positive or negative) associated with this project. Refer to your textbook, if necessary.

5. What is your position on the purchase and installation of this equipment? Justify your position.