Many Filipino farmers are not fully aware that the practice of burning rice straw can significantly contribute to global warming. “Rice production also contributes to global warming as it emits methane,” said Dr. Constancio Asis, Jr., a former supervising science research specialist at the Philippine Rice Research Institute (PhilRice) in Muñoz, Nueva Ecija.
Following carbon dioxide, methane ranks as the second most critical greenhouse gas, responsible for trapping solar heat as it attempts to radiate back into space. Methane is produced naturally as a byproduct of anaerobic bacteria, which thrive in environments with little or no oxygen. These bacteria generate methane gas in waterlogged soils and wetlands, as well as in human-created environments like rice paddies.
Researchers indicate that prolonged flooding of fields deprives the soil of atmospheric oxygen, leading to anaerobic fermentation of organic matter within the soil. During the wet season, rice plants are unable to retain carbon under anaerobic conditions. The soil microbes transform the carbon into methane, which is subsequently released through the respiration of the rice plants or via diffusion from the water.
It was not until 2001 that methane received significant attention, following the submission of a report by the United Nations’ Intergovernmental Panel on Climate Change (IPCC). The report described methane as “one of the most potent greenhouse gases on Earth.”
Growing rice is one of the main culprits in why the world has become inhospitable to living. “An estimated 19% of the world’s methane production comes from rice paddies,” contends Dr. Alan Teramura, a botany professor at the University of Maryland. “As populations increase in rice-growing areas, more rice – and more methane – are produced.”
Is there a solution in sight? Craig Jamieson, a British national who moved to the Philippines in 2012, has developed a technology that uses the methane from rice straw to harvest palay and mill them into grains.
“(Through this innovation), we can transform rice into a multi-purpose food and fuel crop,” said Jamieson, who is the director of the Straw Innovations (SI), Ltd. “Rice straw is one of the world’s largest bioenergy resources and is currently being underused,” he said.
In the past, attempts to profitably collect and use rice straw for clean energy have almost all failed. That’s being turned around by Jamieson.
“I was inspired to develop the rice straw technologies because so much of it was being wasted through burning in the fields or being left to rot and release powerful greenhouse gases,” he said. “If we could just develop the technologies to harvest it, we would instantly transform that waste into a resource for the local communities.”
And that was what Jamieson did. The Rice Straw Biogas Hub is a collaboration between SI and the Laguna-based Southeast Asian Regional Center for Graduate Study and Research in Agriculture (SEARCA).
The project is expected to make clean energy accessible to remote and underserved rural communities. It will generate biogas as clean energy from waste rice straw and provide an innovative package of technology services for rice farmers.
The clean fuel is used for drying the grains and milling thereafter. “We asked farmers and their preference was to use the energy for productive purposes rather than domestic use. So, that’s what we are doing,” Jamieson told EDGE Davao.
According to Jamieson, his UK-registered group has established a rice drying service through the combustion of biogas from rice straw.
Drying is the most critical operation after harvesting a rice crop. When rice is harvested, it contains up to 25% moisture. The goal of rice drying is to reduce its moisture content to meet the recommended levels for sale, long-term storage.
But before drying, rice has to be harvested first. Here, the SI introduces a rice harvesting system that it has developed over five years. “The main problems are in getting the rice straw out of the field and to a place where it can be used,” he said.
The solution: the 5-in-1 harvesting technology, referring to a machine, which is said to be the first of its kind in the world. “Our machine performs in one pass of the field and performs the five separate operations in conventional straw collection – harvester, chopper, rake, densifier, and collection. It’s more efficient and, critically, it works even in wet conditions (muddy or flooded fields),” Jamieson pointed out.
The collected palay is then dried and brought to another machine where the grain is separated from the rice husk. “At the biogas hub, a dryer dries the rice grain with energy from the rice wastes, another removes the husk and another mills the grain to remove the bran, thus giving the final product,” Jamieson said.
The dryer takes about 12 hours for the grain to dry, Jamieson said. “The technology innovation is to use rice straw to power the process,” he said. “We give farmers the option to retain ownership of their grains throughout the process.
“In some of today’s cases, farmers only get 4% of the purchase price of rice. In our model, farmers can use our harvesting, drying, and milling services and then sell the finished products to the public. We just take our cut after the sale…”
To produce methane in the hub, water is added with the rice straw. The methane gas is a direct substitute for diesel or kerosene in conventional dryers.
“In the past, the government tried to give out free rice dryers but as soon as something broke, the dryers were no longer used,” Jamieson said. “Our business model is to own and operate our equipment and offer it as a service to farmers. They pay us a service fee but don’t need to buy or operate our equipment.”
During the process, the rice straw gets broken down into fertilizer, which can be used to fertilize the rice. Or it can be applied as organic fertilizer for crops, vegetables and fruits. “It can be used for anything,” he said.
The clean fuel produced in the biogas is only used for drying rice grains. Because that’s what the farmers in the area need. Jamieson, however, the fuel can also be used for cooking. “If that’s what those concerned farmers and communities want, why not?”
Jamieson believed the biogas hub can prevent the burning of millions of tons of rice straw as waste across the region each year. “The hub has exciting potential to bring clean energy access to the 150 million small-scale rice farmers who need it to process their crops and generate new income opportunities,” he said.
Jamieson expresses hope that the project will contribute to solving energy issues encountered by developing countries such as the Philippines. He emphasized, however, that the approach his team is taking is not the sole method for utilizing rice straw for energy; it merely illustrates one of many possible pathways.
“Once we have harvested and gathered the rice straw, the selection of its end use will be somewhat dependent on the specific site,” he noted.
Certain scientists caution that a disastrous incident could arise if methane were to react explosively with oxidizers, halogens, and specific halogenated substances. The atmosphere of the Earth is composed of 21 percent free oxygen and approximately 2 percent halogens and halogenated compounds.
An environmentalist shared this concerning information on his blog: “If global warming continues to progress without restraint, and the areas of the Earth with 5-15% concentrations of methane gas in the atmosphere reach a temperature of 53 degrees Celsius, which is the flash point of methane gas, it could lead to a spontaneous ignition of atmospheric gases, resulting in unimaginable devastation to our planet.”