SCIENCE CITY OF MUÑOZ -- Don’t look now but the lowly carabao might yet hold the key to the commercial production of biofuel in the country. The carabao, says a returning Filipino-American scientist, provides the model as well as the “mother liquor,” for the conversion of rice stubble and straw to ethanol, an alternative to crude oil-based fuels.

“The carabao is a paradigm in converting lignocellulose to ethanol,” said Dr. Fiorello Abenes, a professor emeritus of animal and veterinary sciences at CalPoly Pomona University in California.

“It has rumen fluid whose organisms can help transform rice stubble and straw and other biomass into bioethanol,” he said.

Bioethanol is a light alcohol produced by fermenting sugarcane, corn, cassava and nipa. It is one of the types of biofuel mandated for mixture with diesel and gasoline under the Biofuels Act.

The theoretical basis for this, which Abenes discussed in a lecture at the Institute of Graduate Studies at the Central Luzon State University here, was validated by experiments conducted at the Philippine Carabao Center (PCC).

“The experiments confirmed the ability of the model to produce ethanol using rumen microorganisms as first stage fermenters, followed by yeasts in the final fermenting stage,” he said.

Abenes, who obtained his doctoral degree in animal science at the University of Connecticut in 1975, worked for many years as regional swine specialist in Alberta, Canada, and at the Dairy Training and Research Institute of the Food and Agriculture Organization of the United Nations before moving to CalPoly Pomona University.

He retired at 55 years old in that university in 2005 and is now engaged in various private enterprises in the United States.

Abenes graduated with the degree of agricultural education, cum laude, from the CLSU in 1969. He was among the first Filipinos staying abroad who responded to the government’s Balik-Scientist program in 1975.

“We can extract the rumen fluid from carabao and multiply them many times for commercial production of ethanol from biomass,” he told the Inquirer before returning to the States on Jan. 18.

In his lecture at the CLSU, Abenes said the carabao is a model for a way to convert lignocellulose to ethanol. Lignocellulose is the most common molecule on earth and is found in all plants.

Converting this molecule to alcohol using purified enzymes, chemical and physical hydrolysis (or chemical breakdown) is too expensive under Philippine conditions, Abenes said.

“The carabao is known for its ability to subsist on low quality forage, including rice stubble and straw. This ability is conferred upon this animal by the rumen that digests cellulose and hemicellulose, turning them into methane and volatile fatty acids (VFAs),” Abenes said.

The methane, he said, is expelled when the carabao belches while the VFAs are parceled between the host animal and the microorganisms.

“The host animal uses the VFAs as a source of energy. The microorganisms use them to support its life functions by synthesizing glucose,” he said.

Abenes said the feasibility of the method, as suggested by the carabao paradigm, has been validated in experiments conducted by the PCC.

He said the rumen fluid can turn lignocellulose into fermentable carbohydrates and the fermentable carbohydrates can be turned into alcohol using common yeast.

Abenes, who conducted the experiment with PCC scientist Perla Florendo, said because of the promising results of the experiment they submitted a paper to a national science and technology contest in energy research and development.

“We have no illusion about winning any prize due to limited scope of the project but its submission at least documents that the first research in this area was conducted at PCC and CLSU,” Abenes said.

He said preliminary calculations based on theoretical models have indicated that as much as 117 liters of alcohol can be distilled from 1,000 kg of biomass materials.

Given the natural abundance of biomass, the use of 85 percent ethanol for flexible fuel vehicles (FFV) may be possible, he said. There is now a technology for the conversion of vehicles using engine fuel to FFV at an affordable cost, he said.

The mandated minimum 1 percent biodiesel blend and 5 percent bioethanol blend in all diesel and gasoline fuels have become controversial of late because of the statement of Nobel Prize winner in chemistry, Dr. Hartmut Michel.

Michel said investment in biofuel development is “counterproductive” as producing biofuel would sometimes entail clearing a forest that would destroy biodiversity and emit more carbon dioxide into the atmosphere.

Sen. Miriam Defensor-Santiago, author of the Biofuels Act, sought more government oversight powers over biofuel development, saying it could adversely affect the country’s ability to produce its own food.

She said biofuel production, being land-based, will eventually compete with food.

In his talk here, Abenes said the carabao model for production of ethanol could be an alternative as it uses rice straw and other biomass. He said the experience of Brazil, the oft-cited model for a thriving ethanol industry, cannot be replicated in this country.

Brazil, he said, has a vast tract of land for sugarcane production. There are less than 25 persons per square kilometer of land in Brazil compared to the Philippines’ 300 persons per square kilometer. Brazil, the fifth largest country in the world, has a land area of 8,511,965 square kilometers. The Philippines’ land area is 300,439 square kilometers.

Abenes said the commercial production of ethanol using the carabao model can involve residents of rural areas. They can be part of the factory assembly line by performing the tasks involved in the digestion process (in bioreactor containers) of the biomass material with the use of the rumen fluid that will be supplied to them.

The alcohol from the “bacterial beer” collected from the participating rural residents can be further refined through a solar distiller, he said.

The distiller is now being designed by engineers from CLSU, he said. Abenes also said residents who will be involved in this project can have added income, making the project a boost to rural economy.