In order to be truly sustainable, energy created from renewable sources needs to be made available not only to the wealthy, industrialised world, but to the massive population in the developing world, many of which currently have little to no access to hot water, electricity or heating. In Africa, most people in rural contexts rely on firewood, a rapidly diminishing resource. Furthermore, electricity access is notoriously unreliable, if supplied at all, and diesel power generators are expensive to run.

MIT graduate Matthew Orosz noticed that in Lesotho, local health clinics are desperate for electricity and hot water in order to maintain hygienic operating conditions. The water is so cold in winter that nurses are avoiding washing their hands, which obviously can have very dangerous repercussions for germ control. According to Orosz, between 30 000 and 60 000 schools worldwide lack access to electricity yet have enough sunlight to meet their power needs. In response to this, Orosz and a team from MIT set up a non-profit organisation called the Solar Turbine Group (STG) that aims to develop new solar power technologies in the developing world.

The group has since deployed a prototype system at the Matjotjo Village Health Clinic in Lesotho that essentially operates as an air conditioner in reverse. The prototype uses parabolic mirror troughs to focus sunlight onto a tube filled with a fluid similar to that found in air conditioners. The liquid, made from organic chemicals, has a very low evaporation point. As a result, it requires little energy from the sun to be converted into gas form. The hot gas expands, and as it does so it turns a generator motor which generates electricity. Not only that, but the excess heat in the system is used to heat water. The STG system uses common air conditioner parts in order to decrease expenses and to make repair and maintenance more straightforward.

The latest version of the STG is currently undergoing tests in Florida, with five more installations planned in schools and clinics in Lesotho. The key challenge for the team is creating a system that works in a viable and sustainable way, operated and maintained by the local community.

For more information on the work and progress of the Solar Turbine Group International go to www.stginternational.org

Source: MIT

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