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Engineering Trash Into Treasure

4 minutes

Corn husks burn quickly and turn to ash. These lumps burn hot like firewood, longer than charcoal, but are cleaner, greener, and less expensive than both. This is made from this, and I'll show you how.

(Describer) A sign says, “D-Lab: Development Through Dialogue, Design and Dissemination”. It’s beside doors that lead to a large workshop, with many different kinds of hardware tools hanging from walls.

About three billion people in the world use charcoal for heating and cooking. But charcoal can be expensive. It produces a lot of smoke when burned, and it's made from wood, which contributes to deforestation. In fact, 98% of Haiti's forests have been cut down for fuel.

(Describer) It’s brown beside the green Dominican Republic.

We need an alternative fuel source. Let's see how charcoal is made. Trees are cut down for wood, then placed in a closed vessel and deprived of oxygen.

(Describer) ...with flames under it.

It carbonizes into charcoal instead of burning to ash. We then mix the charcoal with a binding solution and compress that into lumps called briquettes, creating a fuel source that works but has problems. Let's hack the charcoal production process to make everything about it better.

(Describer) In the workshop, different size wrenches hang in a line and a mallet lies on a vise. The woman looks through a hole in a chamber.

Part of what makes charcoal production so expensive is the equipment. Make a simple kiln out of an oil drum

(Describer) She looks up.

with holes cut in the top and bottom. Gather large rocks to rest the kiln on, find a lid, and you have a $15 kiln. We also need a tool to mold the charcoal material from the kiln into briquettes. This is an earlier design for the hand press. We pour a mixture of charcoal and binder into the spout here,

(Describer) The spout is connected to a vertical pipe with a piston sticking out of the top.

hammer down the piston,

(Describer) She uses a mallet.

(Describer) Then she lifts the piston.

slide open the panel at the bottom,

(Describer) She pushes down the piston again.

and the briquette pops out. This design costs about $20 to manufacture. But the engineers at D-Lab wanted to do better. They changed the shape into a square to make the mold easier to manufacture and reduce the amount of material used.

(Describer) She scoops with the shorter pipe.

The mold itself is used to scoop the charcoal.

(Describer) She sets a piston inside it.

Again, we hammer the piston.

(Describer) Taking out the piston, she pushes the bottom of the mold against a piston in a block.

And the briquette pops right out.

(Describer) ...like a square puck in her hand.

This design is easier to manufacture, it creates briquettes faster and only costs about $2 to make. Now that we've made the equipment less expensive, how can we make the fuel cleaner? Burning all the smoke off while the charcoal is being made can decrease the amount of smoke when it's used. Opening the kiln at the start of the process does this.

(Describer) In the drum...

So that's why we cut a hole in the top.

(Describer) She looks up again.

Final challenge. What can we do to make this fuel more sustainable? What if we replace the wood with dried corn husks or dried corn cobs, dried beanstalks, or even dried banana peels? These agricultural waste products, or ag waste, would normally be discarded as trash. We can use them to make charcoal, and your trash becomes a precious resource. And that's how you turn trash into treasure-- less expensive, cleaner burning, more sustainable treasure.

(Describer) Titles: Science Out Loud. Made with love at MIT. Accessibility provided by the US Department of Education.

Accessibility provided by the U.S. Department of Education.

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Scientists at MIT's D-Lab are turning trash into treasure. They are using trash to heat homes and cook in developing countries. Part of the "Science Out Loud" series.

Media Details

Runtime: 4 minutes

Science Out Loud
Episode 1
4 minutes
Grade Level: 9 - 12
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Episode 2
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Episode 3
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Episode 4
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Episode 5
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Episode 8
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Episode 10
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