A gravity light, anyone?

At last someone is trying to help people living in the Third World countries, without access to grid power and not being able to light their homes. Kerosene lamps are clearly not a solution – they use expensive fuel and can be dangerous. So what is the answer?

In the current political climate one would be inclined to look to alternative energy generation. Surely, a small photovoltaic solar panel, coupled with battery-powered lamp should be able to provide enough light for the 3-4 hours people may want to stay up after dark. No fuel required, no carbon emissions, no moving parts, perfectly sustainable – sounds like a winner. Alternatively, a darling of the Greenies – wind turbine, could also do the job in a similar setup. Or maybe even a mini hydro generator dipped in the stream nearby. One of the alternative power generation systems must be suitable as a cheap and reliable source of power for house lighting, right?

As usual with alternative power generation, the problem is cost. All the above technologies are very expensive and even a small system would be out of reach of the target market – rural populations of the Third World countries. But most importantly they all rely on battery storage which is inefficient, only lasts up to 2-3 years of daily use and is expensive to dispose of or recycle. Despite considerable effort put into research there are no solutions to the energy storage problem in sight and cars still have lead-acid batteries, same as 100 years ago.  So, is there any hope for Somali villagers keen to get some cheap and reliable lighting into their mud huts? The answer is yes but the technology which came to their rescue is not based on solar/wind/hydro but … gravity!

The linked video explains how a gravity light works:

In essence a bag filled with rocks hung high up under the ceiling spins a small generator as it descends, powering a LED light. The bag takes 30 minutes to lower and so needs to be lifted twice an hour. The light unit also has terminals to trickle charge a small appliance like transistor radio or cell phone. But the best thing is the whole unit, including the bag, costs under 5 US dollars. This is amazing value for money considering it is a fully functional self-powered light as well as a charger!

What this goes to show is that new inventions in the field of power generation – big or small – do not necessarily have to come from the field of renewable energy like solar and wind.


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