A British company hopes to bring electric light to 1.5billion people who live off the grid with an incredible electric light that is powered by gravity.
The GravityLight uses a sack of sand to gradually pull a piece of rope through a dynamo mechanism which generates electricity to power an LED light.
A three-second pull on the rope to raise the sack will keep the LED bulb running for up to 30 minutes, its makers claim.
The light, named GravityLight,works by suspending a bag filled with a heavy substance like rocks, dirt or sand from the light.
London-based designers Martin Riddiford and Jim Reeves of Therefore.com spent four years developing the light
Most of these people rely on biomass fuels like kerosene for lighting once the Sun goes down, but such fuels can be hazardous to health - as well as posing a fire risk.
Low power: A three-second pull on the rope to raise the sack will keep the LED bulb running for a full 30 minutes, it's makers claim
The flip side of this is that relatively simple devices progressively need less energy to run, making possible a whole range of relatively simple gadgets that can be powered by unconventional means.
The GravityLight was co-invented by Martin Riddiford, who designed the Psion hardware, and Jim Reeves, both directors at London-based Therefore.
'We've done a number of projects, including the Psion products - where the requirements were incredibly efficient in terms of power usage,' Mr Riddiford told The Register.
'The digital age has made products much power hungry but now there’s a reversal of that – everyone’s chasing lower power again.'
Deciwatt.org appealed for backing from crowd funding website indiegogo.com, and have already more than tripled their goal.
With the $55,000 initially requested they had promised to fund the manufacture of 1,000 gravity-powered lights for free distribution to impoverished communities in Africa and India.
They have since been promised $183,407, with nearly a month left of their appeal.
Kerosene is responsible for thousands of deaths across the developing world every year, deciwatt.org says on the GravityLamp indiegogo page - and it can be expensive.
Sand not included: The GravityLight comes as an easy to assemble kit. Its makers say they hope to use backing from crowd funding to distribute 1,000 to impoverished communities in Africa and India
Elegant solution: The GravityLight in action. A sack containing sand or rocks gradually pulls a rope through the device's mechanism to gradually generate electricity
'Sixty per cent of adult, female lung-cancer victims in developing nations are non-smokers.
'The fumes also cause eye infections and cataracts, but burning kerosene is also more immediately dangerous: 2.5 million people a year, in India alone, suffer severe burns from overturned kerosene lamps.
'Burning Kerosene also comes with a financial burden: kerosene for lighting ALONE can consume 10 to 20% of a household's income.
'This burden traps people in a permanent state of subsistence living, buying cupfuls of fuel for their daily needs, as and when they can.'
Designers at Therefore: Left to right, Patrick Hunt, Martin Riddiford, Mario Siqueira and Jim Reeves. They say rapid advances in technology have made a range of low-powered gadgets possible
The device can also be used to power other small lights, a radio or to charge batteries
The bag is then pulled down by gravity feeding a belt through the light giving 30 minutes of power. The device can also be used to power other small lights, a radio or to charge batteries
Solar panels are expensive and only produce electricity when the Sun shines, and when there is no sunlight the energy must be stored in expensive batteries.
'Very often, when buying a low cost solar lamp with an inbuilt rechargeable battery, a full third of what you're paying for is the battery, and you will need to replace it every few years. Assuming you can get a new battery,' the company says.
The team is now investigating using the GravityLight technology to power other devices or even mobiles.
'The ultimate goal for our longer term research is to establish if/how small amounts of constant power can be utilised to provide access to the internet, from very remote locations, at incredibly low cost,' they say.