Mirrored Troughs Could Power Remote Clinics

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About 1.4 billion people in the world have absolutely no access to electricity at all and even more have extremely unreliable access. Additionally, there are some 30,000 clinics and 60,000 schools around the world that lack access to electricity.

A nonprofit start-up company, called Solar Turbine Group or STG International, run by MIT engineering PhD candidate Matthew Orosz and his colleagues has developed an alternative: a heat-powered generator that gets its energy from the sun. It's a system that uses mirrored parabolic troughs (see photo above) to capture sunlight and concentrate it on pipes at the center of the troughs. Fluid running through the pipes get heated to 320 degrees Fahrenheit.

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The heated fluid is pumped into a chamber where it expands and drives a generator that produces electricity. The hot fluid can also be used to heat water, which means the extra step of an electric heater isn't necessary. After the heat from the fluid is exhausted, the cooled fluid condenses and gets recirculated to the pipes in the trough to be heated by the sun again.

The principle behind this system is actually quite old — it was discovered in the 19th century. But only recently have engineers looked at using the sun to power it.

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The system is being tested in Lesotho, in southern Africa. Hot water is a big issue there, because in winter it gets quite cold. Without hot water, health care workers are unwilling to wash their hands.

Matthew Orosz, one of the founders, said the idea for the system came when he worked as a Peace Corps volunteer in Lesotho, and that’s where the company plans to have five fully operational systems in place for field-testing at remote health clinics. It will be, he said, a good alternative for such clinics which are too far away from cities to get reliable fuel or where there isn’t enough sunlight to power solar panels.

The research will published in an ASME Journal of Engineering for Gas Turbines and Power.

Image: STG International