Husk Power

Recycling the lowly rice husk to power villages in India (and make a profit)

Peeled-off, tossed aside, and forgotten, the rice husk may be the world's most ubiquitous-and forsaken-form of agricultural waste. To Chip Ransler of Husk Power Systems, it's a massive clean energy supply for the world's rural poor, and one that could change the lives of hundreds of millions of people.But first-what's a rice husk? It's the hard, protective coating that covers every harvested grain of rice. These husks make up about a third of the gross weight of the harvest, so rice is generally milled locally, and the husk discarded, before the digestible product is shipped off. Farmers burn the husk byproduct to get rid of it, or often just let it rot in the field.But where others see waste, HPS sees potential. And power. Power that rural India desperately needs. Villages in rural India-and throughout the developing world, for that matter-generally exist off the grid, unserved by the massive centralized power plants that electrify cities. Villagers, meanwhile, depend on motorcycle batteries, kerosene lamps, diesel generators, and the very occasional rooftop solar array (often financed by microloans) to light up dark rooms, charge cell phones, or pump water. There's a dearth of what Ransler calls "meso-power plants," which could serve a small village's needs.Husk Power Systems is working to change that. Ransler, along with three business partners from the notoriously hard-up region of Bihar, India, have pioneered a way to build village-scaled power plants, and to run them (profitably!) on plentiful, and until now worthless, rice husks. Using a tried and true technology-gasification-Manoj Sinha and Gyanesh Pandey, the team's engineers, have built a generator fueled by biogas that's released as the husks are heated. A typical system will churn out 35 to 100 kilowatts of juice, enough to serve 600-700 households.

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In a unique twist, customers prepay for the power, tallying up the wattage of what they plan to plug in. Everyone charges cell phones first. (According to Ransler, 90 percent of rural villagers in Bihar have cell phones, "which they charge from motorcycle batteries for 25 to 50 cents each-a total ripoff.") Then they'll plug in lights, radios, fans and even pumps to irrigate crops. Businesses are connecting to the new grid as well, now free from generators and the volatile costs of diesel.The benefits to the community go on and on. Compared to solar, wind, and even coal, the cost of husk power is cheap. HPS buys the husks from local farmers-about 500 tons of the material are produced by the typical village every season-creating a sustainable local market. Each plant also employs three villagers: one to feed husks into the plant, one to maintain the equipment, and one to collect payments. Of course the biggest boost is the power itself. A teacher in one village HPS serves told the team, "We earned our independence from England 60 years ago, but today-when you came into our village-we got independence from poverty."Right now, HPS is running pilot projects in 35 Indian villages, powering more than 50,000 people's homes. And, again, each plant is profitable. They pay for themselves running even at 40 percent capacity. At 95 percent, an operation can net $22,500 a year. A couple of other potential revenue streams could help bump those numbers up. The silica ash byproduct of the gasification can be sold off to concrete manufacturers, and the HPS team is also hoping to be certified under the Clean Development Mechanism program so that they can sell carbon credits for the emissions reduced by their plants. (Besides making diesel generators redundant, gasifying the husks prevents the release of a considerable amount of methane, one of the world's most potent greenhouse gasses.)The plan is to reach 100 villages as soon as possible, and then work on scaling the idea globally. "Take a map of the world's energy-poor areas and compare it to a map of rice-producing areas," Ransler explains, "and these two maps are essentially the same."Quick to dismiss any preconceived notions that providing power for the rural poor is too difficult, that it doesn't make business sense, Ransler assures, "This can work anywhere there's rice." And nearly everywhere there's rice, people are desperate for power.LEARN MORESee Ransler and Sinha present at the Pop!Tech conference.Title image of rice farmer in Bihar from Flickr user yumievriwan, licensed under Creative Commons. Bottom image from HPS.