Over 1.3 billion people—20 percent of the world’s population—are without access to electricity worldwide, according to the World Bank. It’s no surprise that the majority of those people live in developing countries, including 550 million in Africa, and over 400 million in India.
In developing countries, wood, charcoal, coal and dung are used for cooking and heating, and kerosene is often used for lighting. Every year, fumes and smoke from these fuels kill approximately 1.5 million people, mostly women and children. Kerosene lamps are highly toxic and a fire risk, as well as very expensive for many struggling families.
But two British designers have come up with a novel way to generate light without the need for fossil fuels or battery packs. The premise is simple: raise a weight (about 10 kg/20 lb), and then release it slowly to power an LED lamp that can shed up to 30 minutes of light.
By using the force of gravity to power lamps, designers Martin Riddiford and Jim Reeves have tapped into a reliable, safe, sustainable, and virtually cost-free source of lighting for many rural families. Riddiford and Reeves began their project by looking at creating an LED light powered by solar energy, but quickly realized that the cost of solar panels made the finished product too expensive for a developing-world market. So they shifted their focus toward gravity.
The GravityLight—which is less than 10 dollars to purchase—has no additional running costs and villagers see return on their investment within three months of buying the light as compared to the kerosene lamp which constantly needs to be refilled.
The GravityLight comes with a cloth pouch which can be filled with rocks or dirt to create the weight. The duration of the light depends on how heavy you make the weight. The weight typically powers 30 milliwatts to half a watt with a variable drive. This isn’t much power, but it’s enough to juice a fairly bright light for a short period or a reading light for a longer period, as well as power a radio and recharge batteries.
The real innovation here is applying a force, once and swiftly, to power light, akin to a wind-up clock, where energy is stored in the spring, or a grandfather clock with weights. But there’s one fundamental problem with using gravity and weight as a power source – it’s difficult to upscale.
As Riddiford explained in a recent NPR interview, the device is almost counterintuitive. When a fire starts to burn out we naturally add more firewood to create a bigger flame, but with the GravityLight, more weight actually equals less light.
Still, it seems that several of these contraptions working together, or connected to a battery, could be a good way to turn human power into something a developing world could use: stored electricity from a ‘system’ (gravity) that is omnipresent.
And Riddiford and Reeves have big plans for their invention. They’ll be testing their light in various locations over the next six months and hope to generate some interest from first-world investors too. There’s potential for the GravityLight on the outdoors and camping markets and the designers are hopeful that they can set up a buy-one-donate-one business model similar to that of widely successful TOMS shoes an eyewear. Mobile satellite communications company Inmarsat has also shown interest in the GravityLight project.
As for all that leftover kerosene oil? A gallon of kerosene weighs about 6.6 lbs…