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erhaps the most important impact of India’s recent rapid biomass gasification development is socioeconomic, in its capacity to bring power to rural areas that have never had it. In the past few years, the biomass gasification industry in India has ballooned, growing from plants with kilowatt capacity peppered throughout the country, to development of systems between 1 and 10 megawatts (MW) sprouting up regularly, according to Kam Patel, director of equipment provider Global Energy Collaborations. Development has increased on residential, community and industrial scales, but different technologies seem more practical in certain applications than others. Residential development has latched onto biomethanation, where a biochemical is used to generate methane gas, according to Surya Chandak, a senior program officer with the United Nations Environment Programme’s International Environmental Technology Centre in Japan. And the most common form of gasification, which Chandak calls thermal gasification, has taken root in community and industrial installations, he says. In India, biomass feedstocks have been converted to energy for decades, specifically bagasse. Back then, however, it was directly combusted in boilers for steam and power. In the late ’80s, Chandak pioneered a combustion boiler that would burn rice husks on an industrial scale. “I was working in energy and had contact with boiler manufacturers,” he explains. “They all laughed at me, ‘Ha, ha, using rice husks, what nonsense.’” At that time, farmers would pay collectors to take the rice husks and save them from securing disposal, so the plan was viable and innovative for its time, although Chandak jokes that he feels a mixture of pride and shame when thinking about his technology. “The first industrial boiler designed by me was a primitive design,” he laughs.
Winds of Change
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Direct combustion seemed to be a no-brainer, especially since bagasse and rice husks are easily burned with little ash. “If you can use a fuel directly as such, why would you want to gasify it?” Chandak says, launching immediately into a multifaceted, yet concise answer. First, converting a boiler to burn solid biomass fuels is extremely difficult and expensive, whereas modifying one to burn syngas is much simpler. Second, boilers are crucial pieces of equipment, and fuel without favorable combustion characteristics can be harmful to them. “To subject your key equipment to such difficult material would mean that you are compromising on the reliability of your equipment,” Chandak says. Instead, shift the material problem away from the boiler. “You don’t expose your boiler to difficult fuels. You expose a gasifier to a difficult fuel.” Last, different types of biomass are available at different times of the year and they all possess varying characteristics. “If you use it directly, you’ve got to adjust your main equipment very often,” he says. “Whereas if you use an intermediary gasifier, then you’ll get normalized fuel for the boiler and all the variations will be taken care of by the gasifier.” So after years of almost-exclusive direct firing of bagasse and