First step for decarbonization : Switching from coal to gas

Jan 30, 2024

Case study

Industry: Industrial plant owners with coal-fired power generation systems

A well-established industrial plant owner utilizes coal-firing facilities for supplying heat and power to its own factory. While the facility has been economical in the past, the manufacturer is now faced with a dilemma. It is imperative to deal with decarbonization, since they have made a commitment to reducing CO₂ in line with the government and stakeholder expectations and increasing burden of carbon taxes, while still maintaining a financial perspective.Considering the above-mentioned context, it is not their choice to renew coal-fired facilities or continue operating existing ones.Switching the fuel from coal to other low carbon one is inevitable. Currently natural gas is available as commodity that can be counted on for steady operation. The owner is considering natural gas-powered cogeneration facilities in order to balance CO₂ reduction with stable plant operations. One option is converting the existing coal fired boiler and steam facility to natural gas firing. The other option is gas turbine and exhaust heat recovery steam generator that is more energy efficient. However, the owner does not have experience with owning a gas turbine or any knowledge of operational and maintenance requirements.The owner also needs to consider future action to achieve carbon net zero further while switching to gas-fired that enables them to go low-carbon as a first step.

Gas turbine is a rotating machine that operates with turbine inlet temperature at above 1000 degree Celsius. Its exhaust gas temperature can be above 500 degree Celsius that would be high enough to generate steam to run steam turbine or to supply pressurized heat to manufacturing processes. Advanced technologies are applied to gas turbine while efforts are being made by OEMs to prove safe and reliable operation. In 2021, the number of gas turbine selected for industrial cogeneration application fueled by natural gas were three time more than steam turbine*. (*source: McCoy Report)

Gas turbine cogeneration plants use electricity from a gas turbine and steam from a heat recovery steam generator (HRSG) and have low energy loss. These plants have higher overall energy efficiency of 80% or higher compared to conventional boiler-steam turbine with condenser and are ideal for cogeneration. Its standardized package enables less complicated local installation work in limited area as well as well-developed human-machine interface helps simplified operation. Similarly, they are also suited for distributed power sources and district heating.Replacing coal-fired cogeneration to gas-fired reduces CO₂ and with gas turbine the reduction of CO₂ will be greater, expected to be 69%.

Mitsubishi Power maintains proven basic design and conducts long-running verification tests when developing new technology in order to eliminate troubles occurring at product introduction. This approach of validation of the first unit at one's own manufacturing location is unique to Mitsubishi and is the key to high reliability of its gas turbine.

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