According to a Power Engineering article from 2019, 60 gigawatts (GW) of coal-fired generation was expected to retire by this year, an amount it identified as far exceeding what was previously reported to the U.S. Energy Information Administration.
In this age of decommissioning, it’s no surprise that the topic of repowering — replacing older equipment with newer assets to increase capacity and/or efficiency — frequently enters the conversation. However, difficult questions and misconceptions still surround how to distinguish the right application for each individual situation.
Fortunately for plant owners, two viable options exist for repowering a coal-fired power plant to a natural gas combined-cycle plant:
Site Repowering: Demolishing the entire existing coal-fired plant and building new on the brownfield site. This repower option exceeds the benefits of greenfield building because plant owners can avoid the need for brand new permits and construction of new transmission lines.
Heat Recovery Repowering: Demolishing the coal boiler and replacing it with a gas-fired combustion turbine and a heat recovery steam generator (HRSG). If a plant’s equipment is in good working condition, this option offers the most significant capital cost savings opportunity because the plant can maintain and use its existing steam turbine — essentially eliminating a third of the cost of a brand-new build.
The overall success of a repower project hinges largely on the quality and condition of the equipment, facility and infrastructure. But the overwhelming potential benefits, from increasing generation capacity to enhancing speed to market capabilities by leveraging existing interconnections, make investigating these repowering options necessary.
Therefore, plant owners need to evaluate and understand the likelihood of its existing steam turbine, transmission lines and facility infrastructure to last for several more decades. Though this may seem like a risky decision to make versus simply starting from scratch, partnering with an experienced engineering and construction firm can help with the execution of a thorough survey and detailed repowering approach recommendation — offering the potential for a dramatic return on investment.
Learn how a cooperative in Mississippi is leveraging a heat recovery repower approach to triple its generation capacity, becoming the most efficient coal-to-gas repower project in the U.S.