HUMAS USU – The Indonesian Government has officially launched B50, a biofuel consisting of 50% palm oil-based biodiesel and 50% conventional diesel fuel. According to the government, the policy is expected to reduce foreign exchange spending, lower carbon emissions, and strengthen the country's energy security.

Despite the optimism surrounding the initiative, one question continues to concern diesel vehicle owners and generator operators: Is B50 truly safe for their engines?

Providing a balanced academic perspective, Prof. Dr. Ir. Tulus Burhanuddin Sitorus, S.T., M.T., IPM, a lecturer in the Department of Mechanical Engineering at the Faculty of Engineering, Universitas Sumatera Utara (USU), shared his views on the matter.

"B50 is feasible for implementation, but it must be supported by strict quality control and continuous technical monitoring."

What Is B50 and Why Is It Being Implemented?

B50 is a fuel blend consisting of 50% biodiesel, or Fatty Acid Methyl Ester (FAME) derived from palm oil, and 50% fossil diesel. The Indonesian Government has mandated its nationwide implementation across various sectors starting in July 2026, continuing the country's biodiesel transition from B20, B30, and B40.

According to Prof. Tulus, the transition is primarily driven by the need to strengthen Indonesia's energy independence. Increasing the proportion of biodiesel will reduce dependence on imported diesel fuel, maximize the use of domestic resources, and expand the contribution of renewable energy within the national energy mix.

"The main objective is not merely to replace fossil diesel, but to build energy independence, reduce foreign exchange expenditures, increase the added value of palm oil, and lower fossil fuel-based emissions," he explained.

From a macroeconomic perspective, the projected benefits are substantial. The government estimates foreign exchange savings of approximately Rp157.28 trillion, a reduction of around 46.72 million tons of CO₂ emissions, and the creation of up to 2.2 million jobs throughout the palm oil and energy supply chains.

Is B50 Safe for Diesel Engines?

Technical testing of B50 has been conducted across six major sectors: automotive, mining heavy equipment, agricultural machinery, marine transportation, generators and power plants, and railways. The results showed that 80–90% of the evaluated parameters performed satisfactorily, while heavy equipment tested for approximately 900–1,000 operating hours experienced no significant operational issues.

However, Prof. Tulus emphasized that these encouraging results do not automatically guarantee identical performance for every diesel engine under all operating conditions.

"Diesel engines in the field vary significantly in terms of age, fuel injection technology, tank cleanliness, filter condition, rubber hose materials, and operating patterns. Therefore, while B50 is suitable for use, continuous monitoring remains essential."

He further stressed:

"B50 is safe as long as it meets official specifications, is distributed properly, and is used in engines maintained according to established standards."

Will B50 Increase Fuel Consumption?

One common concern among consumers is fuel efficiency. Since biodiesel has a slightly lower energy content per liter than conventional diesel, testing indicates that fuel consumption may increase by approximately 1–3% compared to B40, with one heavy equipment trial recording an increase of around 3.12%.

"In terms of liters per kilometer or liters per operating hour, B50 is generally slightly less fuel-efficient rather than more economical," Prof. Tulus explained.

Nevertheless, he noted that this increase is relatively small and should be considered alongside fuel prices, supply stability, and maintenance costs. At the national level, the economic benefits from reducing fuel imports remain highly significant.

Is Long-Term Storage of B50 Safe?

For generator owners who rely on reserve fuel tanks, storage stability is an important consideration. Technically, B50 can be stored safely provided that storage tanks remain clean, sealed, dry, and fuel stocks are rotated regularly. However, compared to conventional diesel, biodiesel is more susceptible to water absorption, oxidation, and microbial growth because FAME is more hygroscopic.

"The term 'fuel going bad' is scientifically more accurately described as oxidative degradation, sediment formation, increased acidity, or water and microbial contamination," Prof. Tulus explained.

For standby generators, he recommends avoiding prolonged fuel storage without rotation and regularly inspecting water accumulation at the bottom of fuel tanks as well as checking fuel filters before operating under full load.

Environmental and Health Impacts of B50

From an emissions standpoint, B50 generally offers environmental advantages. The oxygen content in biodiesel promotes cleaner combustion, while its relatively low sulfur content can reduce particulate matter (black smoke), unburned hydrocarbons, and carbon monoxide compared to pure fossil diesel. These improvements may contribute to better air quality, particularly in densely populated transportation corridors.

However, Prof. Tulus emphasized that B50 should not be regarded as a zero-emission fuel.

"Engines still produce exhaust gases, and NOx emissions remain influenced by engine load, combustion temperature, and engine calibration. Proper maintenance and emissions testing are still essential."

He also noted concerns regarding the increased demand for palm oil feedstock, including the potential risks of deforestation and land-use conflicts if governance is not properly managed. Therefore, the long-term sustainability of B50 must be supported by responsible raw material management, productivity improvements, supply chain traceability, and environmental protection.

Preparing Diesel Engines for B50

Ahead of nationwide implementation, Prof. Tulus recommended several practical steps for diesel engine users:

• Clean and inspect fuel tanks, particularly those containing accumulated sediment.
• Prepare spare fuel filters and inspect them more frequently during the transition period, as biodiesel may dissolve existing deposits inside fuel tanks.
• Drain the water separator regularly, especially on generators and infrequently used vehicles.
• Inspect hoses, seals, and gaskets, replacing any components that have become brittle or cracked, as older materials may not be fully compatible with higher biodiesel blends.
• Purchase fuel only through authorized distribution channels and apply the First-In, First-Out (FIFO) principle when managing stored fuel.
• Operate standby generators periodically to prevent fuel from remaining stagnant in storage tanks for extended periods.

He also encouraged users to maintain detailed operational records.

"Keep records of fuel consumption, operating hours, filter replacements, and any engine complaints during the first one to two months. These data will help determine whether any issues originate from the fuel, maintenance practices, or the engine's existing condition."

An Academic Perspective: Balancing Optimism with Caution

Concluding his remarks, Prof. Tulus stated that B50 represents an important strategic energy policy for strengthening national energy security and reducing dependence on imported diesel. However, he stressed that its success should not be measured solely by achieving blending targets, but also by maintaining consistent biodiesel quality, ensuring proper blending processes, establishing reliable distribution and storage systems, and promoting disciplined maintenance of diesel fuel systems.

"To ensure credibility, B50 implementation must be supported by consistent biodiesel quality, clean distribution systems, user preparedness, and transparent field evaluations," he concluded.

Frequently Asked Questions (FAQ)

What is B50?
B50 is a diesel fuel blend consisting of 50% palm oil-based biodiesel (FAME) and 50% fossil diesel, officially mandated for nationwide implementation in Indonesia beginning July 1, 2026.

Is B50 safe for diesel vehicles?
Yes, provided the fuel meets official quality standards, is distributed properly, and the vehicle is maintained according to manufacturer recommendations, including regular inspection of fuel filters, tanks, and rubber hoses.

Is B50 less fuel-efficient than B40 or conventional diesel?
Yes. Based on testing, B50 fuel consumption is approximately 1–3% higher than B40 because biodiesel has a slightly lower calorific value than fossil diesel.

Can B50 be stored safely in generator fuel tanks?
Yes, as long as the storage tank is clean, sealed, dry, and fuel stocks are rotated regularly. Prolonged storage without rotation may increase the risk of oxidative degradation and water or microbial contamination.

What should diesel engine owners prepare before the nationwide implementation of B50?
Inspect fuel tanks and filters, drain the water separator, check rubber hoses and seals, purchase fuel from authorized suppliers, and monitor engine performance carefully during the first one to two months of the transition.

(Zulfahmi Purba)