The Nuts and Bolts of Coal Plant Conversion
What if we told you that your plant could experience a 94% increase in capacity? If you think that’s impossible, think again – it’s exactly what happened for owners of more than 15 U.S. plants between 2011 and 2019. Their secret? Repurposing and modernizing aging coal plants to run on natural gas, reducing emissions and cutting costs in the process.
The ideal candidate for a coal-to-gas conversion is a unit that’s more than 50 years old, less than 300 megawatts in capacity and typically, an early generation sub-critical utility boiler (i.e., the least efficient and most expensive to operate with the lowest overall capacity). If this doesn’t describe your equipment, it’s time to consider what’s best for your operation, decommissioning and shutting down or adding additional equipment to keep your plant viable.
Unlike typical grass root combined cycle projects, where all equipment is new, these projects occur onsite at existing coal-fired power facilities. The options are either to convert a boiler’s fuel stream to natural gas or completely replace a boiler with a combined cycle steam generator (i.e., gas turbine + HRSG) to feed an existing (often rebuilt) steam turbine.
In short, the sooner, the better. MATS compliance is forcing producers to take a look at the older coal plants on their roster and figure out whether additional emissions control equipment is the best option to bring those plants into compliance. The former alternative was shutting those plants down and replacing them with plants that use alternative fuels. Now, the option of conversion exists – and is growing in popularity rapidly.
Most units that are prime candidates for repurposing are located in the eastern U.S because their limited-to-no air quality control systems make the cost of adding an AQCS steep. Plants west of the Mississippi River aren’t as viable because they’re often larger, more efficient and burn a cost-effective fuel with a more favorable emission profile than many eastern plants.
The initial drivers for plants to switch from coal to natural gas were stricter emissions standards, low natural gas prices and more efficient new gas turbine technology. Arguably the biggest benefit to repurposing existing plants is to avoid those old units becoming stranded assets long term. This means energy producers can continue providing generation that complies with emissions regulations and remain competitive in the market. Need a few more reasons? Think about high investment returns, significant fleet-life extensions, lower operating, capital and carbon costs and the elimination of complex mining operations.
Complexities increase when using existing equipment because systems are configured differently for connecting new equipment and systems to existing boilers. These projects require an experienced team to design an effective cleaning program, which can extend beyond an EPC’s experience level. Luckily, that’s where B&W can help. We’re proud to have been recognized as one of the most active vendors assisting with the currently high volume of coal to gas conversions.
Right now, our work includes supporting a project for Cooperative Energy’s Plant Morrow. Their aging coal units entered service in 1978 and weren’t providing competitive MISO. As coal costs rose and gas-fired generation costs decreased, the need to repower the facility became eminent. Upon completion, the plant will be equipped with a Siemens HL gas turbine plus Nooter Eriksen HRSG and re-use of an existing steam turbine. The plant is scheduled to achieve its first fire this summer and be fully commercial by March of next year. In addition to this project, B&W supported some of the conversions Alabama Power did in the mid-2010s.
If you’ve decided repurposing is the best option for your plant, contact B&W for more information today!
