Turn straw into ... fuel

From 1 ton of straw, can produce 250kg of liquid fuel . Scientists of the Institute of Chemistry (Vietnam Academy of Science and Technology) have successfully produced bio-oil (Bio-oil) from straw by public pyrolysis technology.

The study has opened up the possibility of finding alternative sources of fuel for fossil fuels that are in danger of becoming scarce.

Burning straw = burning oil

' If burning 1 ton of straw, farmers only get an insignificant amount of ash to fertilize the field and at the same time pollute the environment. Meanwhile, 1 ton of straw can produce about 250kg of raw liquid fuel for bio-oil production . 'Assoc . Prof. Dr. Dang Tuyet Phuong, physico-chemical department, Vietnam Institute of Chemistry said.

Operating in a pyrolysis plant (photo by Tuyet Phuong); H1_ROM_Xuan Vinh: Vietnam has
More than 40 million tons of straw are generated annually, equivalent to 10 million tons of bio-oil (Photo:
Xuan Vinh)

Rice straw is one of the agricultural wastes with little use value: partly used as food for cattle, partly processed as microbiological fertilizer, while most are burned right on the field. causing waste and environmental pollution.

According to the Biofuel Development Project until 2015, the vision to 2025 was approved by the Prime Minister, by 2010, our country will produce 100,000 tons / year of E-5 biofuel and 50,000 tons / year of fuel. B-5 biodiesel, ensuring 0.4% of fuel demand in the country.

By 2015, the production of bio-ethanol and bio-diesel fuel is expected to increase to 250,000 tons / year with the goal of producing 5 million tons / year E-5 and B-5, meeting 1% of gasoline demand. of the whole country.

The research results show that each ton of paddy harvested will give 1.35 tons of rice straw in the field. From 2002 to now, our country produces over 34 million tons of rice / year on average.

This also means that more than 40 million tons of straw are generated annually. ' If converted into bio-oil with 25% efficiency, then we can get 10 million tons of bio-oil per year, ' said Dr. Dang Tuyet Phuong.

New direction for creating biofuels

Many countries have built biofuels from agricultural products such as corn (USA), sugar cane (Brazil), sugar beet (countries in Europe) . to replace fossil fuels. But the source of this material is quite expensive and unstable, not to mention that it can cause food crisis leading to food insecurity.

Meanwhile, available and cheap sources of straw account for about 66% of the total agricultural waste that has not been used effectively. Taking advantage of this source of straw to produce biofuels will be of great significance in many ways.

According to Assoc. Prof. Dr. Dang Tuyet Phuong, using straw pyrolysis method without using catalysts (at 550 degrees Celsius), liquid fuel production efficiency reaches 25-30%. If catalysts are used, the pyrolysis temperature can be reduced to 100 degrees Celsius with an oil-producing efficiency comparable to that of a non-catalyst.

Accordingly, rice straw is collected and cleaned, dried and put into pyrolysis furnace. After the pyrolysis reaction will be obtained in all three types of gas, liquid and solid. Liquid products make up the majority, contain bio-oil, can be used in many fields such as chemical production, medicine, industry, food or fuel.

Particularly in the energy field, bio-oil can be used directly as a fuel in power plants (heating boilers, furnaces .) or replacing diesel oil to run engines. Solid products (coal) can be used as activated carbon, or turned into fertilizer to improve the soil when added with some trace elements.