Written by Myriam G Layaoen


Now that the world`s energy is rather weakening than multiplying in supply, the fuel-dependent rice farming is compromised. Maximizing what’s available may sound rational but converting farm wastes into useful energy is even better. What more if you could produce two kinds from a single source?

Inspired by this conviction, PhilRice scientist and engineer, Ricardo Orge and team explored ways to recover the heat from carbonizing rice hull and utilize it as source of energy to accomplish various farm operations. While doing so, the system also produces biochar intended for soil application.  The production and utilization of biochar in farming has been considered as a way of reducing emission and increasing sequestration of greenhouse gases while delivering immediate benefits through improved soil fertility and increased crop production.

Two from one

Cogeneration is normally coined as ‘combined heat and power’ or the utilization of otherwise wasted heat to generate power.  In Orge`s study, however, it denotes the generation of two products (biochar and heat energy) from one process (carbonization or the conversion of organic substance into carbon).

Orge’s team particularly focuses on developing a system that combines biochar production with recovering and utilizing the heat generated from the RH and carbonization process.

“What we have in mind is to provide affordable and sustainable energy sources to our small-scale farmers especially those in marginalized agricultural areas. We are trying to develop a system that will generate energy for their farms using their own farm waste while continuously improving the condition of the soil for a sustainable agriculture,” Orge explained.

The system features the PhilRice continuous-type rice hull (CTRH) carbonizer equipped with heat recovery attachments for heat utilization during the carbonization process to satisfy energy needs within the farm while producing biochar. In a usual setup, the heat generated during rice hull carbonization is just wasted.

Orge`s team set up a prototype of the RH carbonizer-pump system to test the feasibility of carbonization-generated heat for pumping water. The system components include the CTRH carbonizer, mini-boiler (heat recovery component), water pump, and other accessories like piston pump and valves.

The PhilRice CTRH carbonizer maximizes heat generation since the gaseous products of partial combustion are combusted before coming out of the chimney, resulting in a smokeless emission.

Aside from successfully utilizing the heat for pumping water, the team also designed and tested various heat recovery attachments to demonstrate the use of the generated heat in providing added income opportunities for the farmers.  These include a cooking attachment for high volume cooking which, with the addition of other needed components, could also be used for extracting essential oils from medicinal plants (or other distilling-related processes) and pasteurizing mushroom fruiting bags. They also developed and oven for baking food products (pandesal, bibingka, etc.) for business of farmer housewives.

Also, through a collaborative work with a private company, the biochar-heat cogeneration system is currently being applied in poultry house heating.

“This process eliminates the use of liquefied petroleum gas (LPG)-fuelled burners while making use of biochar and chicken manure from the poultry in the production of organic fertilizer,” Orge explained.

Added benefit

Being considered as a carbon-negative technology, the biochar-heat cogeneration system proves its relevance to the world’s current climatic conditions.

“This technology can be a two-edged sword to fight climate change, that is, increasing food production or enhancing food and energy security at farmers` level while helping reduce greenhouse gas emissions through biochar application in the soil as a form of carbon sequestration,” Orge said.

Orge heads the PhilRice Climate Change Center and the program leader of the institute`s Coping with Climate Change Program. The program aims to “contribute in sustaining rice productivity by developing climate-resilient rice-based farming systems.”

Orge sees the biochar-heat cogeneration system as an answer to one of the top 100 questions in the future of agriculture, some of which are on energy, climate change, and resilience.

For the farmers

Rice researchers like Orge meet at a common end – the best for our farmers. For him, some improvements have yet to be done to realize the full potential of the system. For one, the generation and utilization of the heat must be maximized and for the carbonizer to efficiently work on other agricultural wastes usually found in the farm.

“I admit there are still a number of concerns to address before we can announce the technology’s availability. We are taking into consideration the existing status of the rice industry. While we are studying the improvements and completing the data of our research, we might also try to maximize use of the system’s other product – biochar – as this has various practical applications in farmers’ farm. For example, as soil conditioner,” Orge said.

Farmers who opt to adopt the technology may also be exposed to potential occupational hazards. Thus, they must undergo proper training prior to its use.

The cogeneration technology through rice hull is a promising tool to help address both energy and food security while mitigating climate change at the farmers` level. Just like cogeneration, solutions to rice farming dilemmas should not be limited to a single approach. It entails a multi-handed effort among rice stakeholders, the farmers included.

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Philippine Rice Research Institute (PhilRice) is a government corporate entity attached to the Department of Agriculture created through Executive Order 1061 on 5 November 1985 (as amended) to help develop high-yielding and cost-reducing technologies so farmers can produce enough rice for all Filipinos.

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Philippine Rice Research Institute