Reduce, reuse, recycle

The assignment was wide open: Design something based on the principles of 'reduce, reuse and recycle', and develop it into a prototype product. The results from seven teams of 18 students from the  US-based Massachusetts Institute of Technology ranged from simple mechanical devices to complex machines, but all served the purpose in original ways.

"A big part of it is figuring out a good problem to solve," said David Wallace, associate professor of mechanical engineering, who led the teams. "Otherwise, you could do a really nice thing that's irrelevant. So the first thing is deciding where to put your energy."

Some of the projects are already being tried in real-world settings and could soon become commercial products. One of these is a solar-powered bin that automatically sorts the recyclable bottles and cans dumped into it.

The bin, called Recycl-o-sort, is being tested in a public hotspot. The device uses a turntable system to pass each item through three different sensors, whose readings can differentiate between glass, plastic and aluminium containers, or non-recyclable trash, directing each type into a separate storage bin.

Another team addressed the problem of poorly insulated houses in places like northern India and Pakistan, where winter temperatures can be severe. They came up with a way of making insulation panels out of old plastic bottles, of which about a half million are discarded each year in the city of Karachi alone. The cost of enough panels to insulate a typical home would be paid back in fuel savings in about one year, the students calculated, and in the process would create jobs for local people while reducing local fuel needs and the amount of waste sent to landfills.

Also working to help with developing nations' needs, one team developed a way of processing the West African Shea nut into a butter that can be used both for cooking oil and cosmetics, using a bicycle-powered grinding machine. The device replaces the traditional mortar-and-pestle method or higher-priced mills, and can be built from locally available materials and labour.

The team will take their prototype to Ghana in January for field-testing. People from various villages will be invited to watch the tests, and micro-financing through local institutions will be arranged for those who want to put the system to work.

Another project that could help developing-world farmers is a system for sorting coffee beans, which must be sorted to a uniform size before roasting. Aimed at the estimated 20 million or more small-scale coffee farmers worldwide, the device, which can be locally manufactured and should pay for itself in two months, will be field-tested in January.

Addressing both water shortages and cost of water heating, one team designed a shower system that automatically reduces the water flow while a person is lathering up. It does this by using photocells to detect when the person reaches for the soap.

Another team came up with a way of avoiding the cost of constantly replacing batteries in remote controls for television sets and other electronics, as well as the environmental cost of constant battery disposal. They came up with a remote that can be powered for a couple of hours by just pulling a trigger. The team calculates that if one out of 100 remotes in the US were replaced by their units, five million batteries would be saved every year.

And finally, to alleviate the pollution caused by the disposal of old oil filters that are clogged with dirty oil, one team came up with a device that can extract the oil and allow it to be reused as a lubricant.

Wallace says these projects help in teaching students what it takes to be a technical innovator. Indeed, many of the projects from past classes have gone commercial, and he hopes the new batch will share the same success.