Jakarta. Indonesia’s push for Bobibos, a straw-based biofuel promoted as an ultra-low-emission alternative, is drawing scrutiny from experts who warn that its technological fundamentals and cost assumptions remain unclear.

Leopold Oscar Nelwan, a mechanical and biosystems engineering lecturer at IPB University, said publicly available information on Bobibos’ conversion technology is still limited. The lack of clarity, he noted, poses a major hurdle, especially given the high energy cost of converting lignocellulosic biomass such as rice straw into fuel.

“Some literature shows that producing one liter of fuel via the Fischer–Tropsch process from coal alone costs around $0.8 to 1.6. In some cases, the process cost can exceed four times the coal price,” he said, as quoted from IPB’s official site on Monday.

Leopold said Bobibos’ claim of low production costs should be reassessed by factoring in energy requirements and capital expenditure. The technology may only become competitive, he added, if fossil fuel prices rise or if their usage becomes more restricted.

He emphasized that the fuel in question must be a hydrocarbon, not ethanol or biodiesel, to meet commercial standards for engines. Hydrocarbon chains, he explained, determine the fuel type,  with gasoline typically in the C5–C12 range and diesel in the C12–C20 range.

Multiple pathways exist to convert lignocellulosic biomass into hydrocarbons, but most remain at the research scale. These include thermochemical routes such as gasification followed by Fischer–Tropsch (FT) synthesis, and fast pyrolysis producing bio-oil for further hydrotreating. Biochemical routes involve converting sugars directly into hydrocarbons or producing ethanol for alcohol-to-hydrocarbon processes.

“Of all these pathways, gasification and FT are the closest to commercialization because the principles have already been applied in coal conversion,” Leopold said. Still, he noted that both thermochemical and hydrolysis-based methods demand specialized catalysts and operate under high temperature and pressure, resulting in significant energy costs.

Global experience also shows the hurdles. In Romania, a commercial-scale cellulosic ethanol plant in Podari was shut down in 2022 after persistent losses, according to Biooekonomie. The facility, operated using the sunliquid process with straw feedstock, was deemed no longer economically viable despite extensive review. Operator Clariant said the project would require massive additional investment to meet its operational targets.

The closure marked the end of what had been Europe’s largest straw-based biorefinery project, underscoring the financial and technological risks that still surround advanced biofuels.