Asia’s cement makers are cutting their fossil fuel consumption and turning to the rice paddy across the street for a greener, cheaper and potentially more abundant fuel to heat their kilns. Cement plants in the world’s largest rice exporters, Thailand and India, have started to replace coal with rice husks that would have otherwise been incinerated and dumped in landfills.
Offering savings of millions of dollars a year, other rice producers such as China - the world’s largest cement producer - Vietnam and the Philippines could soon be making the switch from coal to rice!
One of the pioneers, Thailand’s Siam City Cement, says spending 15 million baht (US$360,400) three years ago on equipment to handle agricultural waste is now saving as much as 240 million baht a year, about two percent of 2002 operational costs. "It’s a win-win solution, but you need to invest and take the effort," said Siam City’s energy development manager Choompon Lertchuwongsa. "But I can see a big opportunity in all Asian countries, especially China, Vietnam and India."
Rice husks and palm kernel residues, a by-product of palm oil extraction, now account for around five percent of Siam City’s energy needs. It buys 200 tonnes of rice husks a day from nearby mills at about 150 baht per tonne, but wants 10 times that amount. "We can take 4000 tonnes a day, but the mills can’t supply that much and it’s bulky, so transportation is difficult," Choompon said. "The mills are also starting to put up the price because they know we want it. A couple of years ago it was only 50 baht a tonne." Rice husks release about 16 joules of energy per kg, about the same as lignite but less than bituminous coal’s 25 joules. Palm kernel residue releases 19 joules per kg while rubber tyres yield around 30.
Siam City says executives from companies owned by Switzerland’s Holcim Ltd in Vietnam, the Philippines, Indonesia and Sri Lanka have visited its plant, 130 km (80 miles) north of Bangkok, to consider adopting rice husks as a fuel. Industry officials from the world’s second-largest cement producer, India, have also started using rice husks and bamboo shavings from the furniture industry. Transport costs are the main challenge for cement firms wanting to use the alternative fuels. For them, paddy fields could become as important as limestone deposits in future location decisions.