Vietnam's O Mon I power plant switches from diesel to LNG as part of the Lô B–Ô Môn gas-to-power project, aiming for 2027

Within the largest investment in Vietnam's oil and gas sector history, the O Mon I power plant (660 MW) is entering the most important fuel transition in its more than 15 years of operation: converting from diesel to liquefied natural gas (LNG) from Block B. The project targets delivering the first clean gas in Q3 2027 from the Block B gas field offshore in the Southwest Vietnam region, which holds about 107 bcm of gas.

Fuel conversion and expansion into a gas-fired complex

This fuel conversion is not only a change of fuel but a comprehensive upgrade that will allow O Mon I, together with O Mon II, III, and IV, to operate as a gas-fired power complex with total installed capacity of 3,810 MW. The plant is part of the downstream segment of the Lô B-Ô Môn gas-to-power project, which has total investment of $12 billion—described as the largest in Vietnam's oil and gas industry history.

Project investment and funding

Baodauthau reports that the total investment for the O Mon I fuel-switch project is 2,207 billion VND. Funding comes from EVNGENCO2’s counterpart funds and commercial loans.

Technical scope: deep overhaul and SCR system

To switch from diesel oil (DO) to LNG, O Mon I must undergo a deep overhaul of the boiler firing system. Because the boiler uses a traditional firing system (not a gas turbine), the conversion focuses on changing the firing method.

A key highlight is the installation of an advanced Selective Catalytic Reduction (SCR) system, supplied by Mitsubishi Power.

How the SCR system works

Mitsubishi Power states that it is a leading SCR manufacturer with more than 40 years of experience. It has delivered over 1,400 SCR systems worldwide, supporting plants in meeting stringent international environmental standards.

The NOx abatement principle of SCR is described as follows: ammonia (NH3) is injected into the flue gas, and under the action of the catalyst, NOx reacts with ammonia and oxygen to form nitrogen (N2) and water (H2O)—two substances described as harmless to the environment.

Expected benefits for emissions and efficiency

The SCR catalyst, described as the core of the system, is intended to enable high NOx reduction, reliable operation, low pressure drop, and flexibility to apply to various fuels (coal, oil, natural gas) and plant sizes from hundreds of MW to over 1,000 MW.

According to Mitsubishi Power, the fuel switching at O Mon I is expected to reduce operating costs versus DO, increase electricity generation efficiency, and significantly reduce greenhouse gas emissions. The company links these outcomes to supporting the Lô B gas-electric chain and helping realize Vietnam’s sustainable energy development strategy.

Industry perspective

In 2025, Nguyen Van Hung, CEO of LILAMA, said: “With world-leading technology from Mitsubishi Heavy Industries (MHI) and the EPC experience of LILAMA and EVNGENCO3, I believe O Mon I will become a model project for Vietnam's energy transition.”