Energy technology: Cheaper and better solar-powered electric lights promise to do away with kerosene-fuelled lanterns

WHICH plastic gadget, fitting neatly in one hand, can most quickly improve the lives of the world’s poorest people? For the past decade the answer has been clear: the mobile phone. But over the next decade it will be the solar-powered lamp, made up of a few light-emitting diodes (LEDs), a solar panel and a small rechargeable battery, encased in a durable plastic shell. Just as the spread of mobile phones in poor countries has transformed lives and boosted economic activity, solar lighting is poised to improve incomes, educational attainment and health across the developing world.
As previously happened with mobile phones, solar lighting is falling in price, improving in quality and benefiting from new business models that make it more accessible and affordable to those at the bottom of the pyramid. And its spread is sustainable because it is being driven by market forces, not charity.
Phones spread quickly because they provided a substitute for travel and poor infrastructure, helped traders find better prices and boosted entrepreneurship. For a fisherman or a farmer, buying a mobile phone made sense because it paid for itself within a few months. The economic case for solar lighting is even clearer: buying a lamp that charges in the sun during the day, and then produces light at night, can eliminate spending on the kerosene that fuels conventional lamps. Of the 1.4 billion people without access to grid electricity, most live in equatorial latitudes where the sun sets quickly and there is only a brief period of twilight. But solar lamps work anywhere the sun shines, even in places that are off the grid, or where grid power is expensive or unreliable.
The potential savings are huge. According to a recent study by the International Finance Corporation, an arm of the World Bank, $10 billion a year is spent on kerosene in sub-Saharan Africa alone to illuminate homes, workplaces and community areas. Globally, the figure has been put at $36 billion. Flexiway, an Australian-Argentine maker of solar lamps, found in its trials in Tanzania that households often spent more than 10% of their income on kerosene, and other studies have put the figure as high as 25%. And kerosene does not merely eat up household income that could be spent on other things. It is also dangerous. Kerosene lanterns, a century-old technology, are fire hazards. The wicks smoke, the glass cracks, and the light may be too weak to read by. The World Health Organisation says the fine particles in kerosene fumes cause chronic pulmonary disease. Burning kerosene also produces climate-changing carbon-dioxide emissions.
Take a look at some of the solar lamps now available in Africa, Asia and Latin America, and their advantages are immediately apparent. Even the most basic solar lamps outperform kerosene lanterns. A typical device takes eight to ten hours to charge, and then provides four or five hours of clear, white light from high-efficiency white LEDs. The number of times solar lamps can be charged before their internal batteries wear out has improved enormously in recent years, along with their ability to cope with dust, water and being dropped. The starting price of $10 or so is still too high for the poorest customers to pay, at least up front. But as with mobile phones, prices continue to fall and novel business models are starting to provide new ways to spread the cost.
Sept 1 2012
http://www.economist.com/node/21560983