Looking Ahead at Dry Cooling Alternatives in Power Plants
Dry cooling has become a popular process in power plants to reduce water usage, but this operation is still energy-intensive. Researchers are considering alternatives to reduce water and carbon intensities.
There are more than 7,300 power plants in the United States. Many power plants, especially traditional thermal power plants, require large amounts of water for cooling. Water is used directly in cooling towers (wet cooling) or indirectly through cooling loops (dry cooling). Cooling is necessary to maintain the efficiency and safe operation of the internal equipment.
Power plant. Image used courtesy of Adobe Stock
To help mitigate the intense water usage, dry cooling has become more popular than wet cooling because it is considered more environmentally friendly. However, dry cooling systems are generally less efficient than wet cooling systems and cause potentially higher energy consumption. The challenge becomes finding a balance between reducing water use and maintaining plant efficiency.
Researchers from Stony Brook University and Peking University have been assessing this challenging balance and considering other solutions to both reduce water usage and carbon emissions. The insights from their study have been published in the journal Nature Water.
Ongoing Water-Carbon Research
A collective effort of researchers has yielded a global analysis of power plant information. This analysis showcases a comprehensive strategy for managing the water-carbon relationship, effectively connecting various water and carbon mitigation technologies with complementary approaches.
Worldwide CO2 increases due to dry cooling processes. Image used courtesy of Stony Brook University
Thermal electric power production depends on significant volumes of freshwater, primarily for the cooling of power plants, which accounts for around 40-50 percent of total water withdrawals in the U.S. Subsequently, power generation is responsible for a significant portion of carbon dioxide emissions, notably 36 percent of energy-related emissions globally in 2019.
The authors note that these resource-intensive processes have critical implications for energy security in light of climate change.
The research group developed a worldwide unit-level structure to evaluate the effects of dry cooling in conjunction with alternate water-sourcing methods and carbon capture and storage (CCS) across various scenarios.
Dry Cooling Research Findings
The data gathered from individual power plant units – including types of fuel and engines used, installed capacities, and cooling methods ‒ allowed the research team to estimate carbon emissions and water withdrawal based on the unit variables.
Researchers observed that the CO2 emissions and energy efficiency reduction caused by dry cooling units varied based on location and climate conditions, spanning from 1 to 15 percent of power plant output. They observed notable declines in efficiency in scenarios involving shifts in climate.
Possible Solutions to Water Scarcity Mitigation
The research team identified potential encouraging solutions to mitigate water scarcity near power plants. These include enhancing the utilization of wastewater and brine water, which can serve as viable substitutes for dry cooling, effectively reducing energy and carbon-related challenges.
Additionally, the authors found that CCS may be a valuable mechanism to offset the carbon emissions linked to dry cooling. This is especially true when alternative water sourcing alone falls short in specific regions with power plants. However, the authors stress that the exact balance of using CCS and alternative water sources is largely region-specific, depending on available resources.
With mounting water-related challenges, the authors are concerned that dry cooling might be a strategy for mitigating freshwater issues in some economies, especially in tandem with the transition to renewable energy.
This research emphasizes the immediate need for integrated planning within the power sector, given the concurrent challenges of water and carbon, including the significance of incorporating climate-specific variables and interlinked systems to attain viable and enduring energy solutions.