The concept of the GravityLight is simple and yet very innovative. It consists in a light powered by gravity, it is charged by lifting a weight and letting its descent run the generator and the light.
Of course, it is only possible now thanks to the LED lights and other efficiency gains. With old light bulbs, the duration of the same concept would be ridicule, but now, a simple lift of 2-3 seconds can provide for almost 30 minutes of light.
The running costs are null, and compared to the alternative of kerosene lamps, the impact is enormous in reducing costs, environmental impact, as well as reducing fire risks and negative consequences of smoke on the health of the users….
Moreover, the energy return-on-energy invested on the manufacturing of this product is huge, and so is the sustainability, even compared to solar energy. The alternative of building a solar panel and battery storage, is 100 times more expensive, complicated to build and maintain. If it is only used for lighting it has no chance to be more economic, but if used for other applications, such as air conditioning or fridges it could be a better option, of course.
In fact, it has been proven in field tests, and users actually like the technology. So a new improved version, to be manufactured in Africa is under development after a second successful campaign on Indiegogo.
The target users of this technology are isolated communities with no access to electricity. (helping to achieve Sustainable Development Goal nº7) Their most important electricity use is light for studying, working or other activities that can be continued after dusk.
Another typical basic need where electricity is required is water pumping. For this use, solar pumps are probably the most sustainable option. Charging cellphones is starting to become a basic need too, even in remote locations with no access to a grid. Using this kind of solution for charging is also possible.
Part of the beauty of this concept is it focuses on the real demand for light, instead of focusing on the supply part of bringing electricity to a remote location. Meeting the real end-user needs directly and efficiently is more adaptive and resilient (as energy policy) than designing and building generation capacity to meet (mostly inaccurate) demand predictions.
Even in more developed regions, where microgrids and partial off-grid are becoming more common, using this kind of device is possible.
So, after considering the GravityLight, you may want to think about the following; what is the most sustainable source of energy for lighting and hand-held device charging? Is DC generation with human power like this example?