TIME REQUIRED

Two or three 50-minute lesson periods.

LESSON RATIONALE

One of the country's most pressing problems is how to dispose of solid waste in an environmentally responsible manner.  Options include incineration, deposit in local landfills, mass burning, and recycling.  There are both social and economic considerations for all options.  Presently our landfills are near capacity.   While incinerating garbage reduces the volume of waste, there are concerns about wasting energy and about emissions of pollutants.  Recycling is growing in popularity in the United States but is expensive and is only a partial solution.  The solution discussed in this lesson is mass burning, which reduces the volume of waste and at the same time produces usable energy in the form of steam.  This production of energy is especially valuable because our dependence on fossil fuels, much of which must be imported, is a major problem for the United States today.

MATERIALS

1. Classroom set of copies of student reading.
2. Burner and small boiler (kettle) to produce steam at atmospheric pressure.
3. Small, homemade paper windmill.

CONCEPTS, UNDERSTANDINGS, SKILLS

Engineering:

1. Refuse is burned to produce steam.
2. Steam has an economic value.  When it is under pressure, it can be used to drive engines or electric power generators.
3. Mass burning greatly reduces the volume of refuse.

Mathematical:

1. Use of mathematical principles to demonstrate a physical reality.
2. Solving simple equations.
3. Substituting values for variables in an equation.
4. Ratios and ratio solving.

MATERIALS NEEDED

1. Sticks of various lengths to simulate flagpoles.
2. Quantity of clay, sand, or other materials into which to put the simulated flagpoles.
3. Classroom set of copies of student reading.

LESSON OBJECTIVES

Students will:

1. Have briefly examined alternative methods of waste disposal.
2. Understand how energy can be produced from waste.
3. Understand the economics of mass burning.
4. Be aware that engineers are involved in waste disposal problems and are helping to solve environmental problems in waste disposal.

SUGGESTED PROCEDURES

1. Demonstrate how steam is produced.  With a burner and a small boiler (kettle), heat the water in the boiler until steam is generated.  If possible, utilize a tube at the steam outlet in order to concentrate the steam.  Use the steam to cause the arms of the windmill to rotate.
2. Ask students to suggest what elements are necessary for steam production. (Answer: Heat source, water, and container for the water being heated.)
3. Distributed the reading, and review the definitions with the class.
4. Point out  that if the amount of refuse is known, engineers can use mathematical formulas to find out how much steam mass burning generates.  Ask students to suggest why this information would be useful to know.
5. Go over the problem step by step.

ENRICHMENT ACTIVITIES

Give students an opportunity to discuss further questions that engineers would have to resolve: heat containment, waste products, pressure containment, energy load and capacity, etc.

If mass burning generators are available in the area, arrange a field trip, so that students can see the actual boilers in operation.  Alternatively, arrange for the class to observe the school boiler in operation and view its elements.

Divide class into two teams and have them debate and discuss the pros and cons of various methods of waste disposal, including the ethics of waste disposal.  (Students will need to do some library or internet searching to obtain information about the various methods and the problems associated with each.)

Have students research how their community disposes of waste and what the regulations governing waste disposal are.