The synergy between power plant flue gas de-whitening and carbon neutrality is essentially derived from their common pursuit of clean energy utilization and ecological environment governance. Power plant flue gas de-whitening eliminates the "white plume" phenomenon at the chimney outlet, solving the visual pollution and potential environmental problems caused by the combination of water vapor and pollutants emitted by heat sources such as traditional coal-fired power plants; while carbon neutrality focuses on achieving net zero greenhouse gas emissions through energy structure adjustment, carbon capture, utilization and storage (CCUS) and other means. Although the two tasks seem to belong to different governance fields, they are actually deeply coupled in terms of technical paths, system optimization and resource circulation, and jointly serve the overall goal of green transformation in the power industry.
From the perspective of improving energy utilization efficiency, power plant flue gas de-whitening technology can indirectly help carbon neutrality by recovering flue gas waste heat. The high-temperature flue gas (usually above 120°C) emitted by traditional coal-fired power plants contains a large amount of sensible heat. Direct emission not only causes energy waste, but the "white smoke" formed by condensation of water vapor may also aggravate local haze. The condensation phase change technology in the de-whitening process condenses water vapor into liquid water and releases latent heat by reducing the flue gas temperature to below the dew point (such as 50℃-70℃). This part of the recovered heat can be transferred to the boiler feed water or heating system through the heat exchanger to improve the overall thermal efficiency of the unit. Taking a 600MW coal-fired unit as an example, flue gas waste heat recovery can reduce the power supply coal consumption by about 2-3g/kWh. Based on the annual power generation of 3 billion kWh, it can reduce the standard coal consumption by 6,000-9,000 tons per year, and correspondingly reduce carbon dioxide emissions by 15,000-23,000 tons. This positive cycle of "energy saving and carbon reduction" makes de-whitening an important means for power plants to improve energy efficiency and reduce carbon emission intensity.
Under the framework of carbon capture and pollutant coordinated governance, power plant flue gas de-whitening creates favorable conditions for large-scale capture of carbon dioxide. About 15%-18% of the flue gas in coal-fired power plants is carbon dioxide, but its concentration (volume fraction) is low and the water content is high, so the cost of direct capture is high. The de-whitening process removes most of the water in the flue gas by condensation, which relatively increases the concentration of carbon dioxide and reduces the load of subsequent capture processes such as amine absorption (water will increase the energy consumption of solution regeneration). For example, a power plant reduces the humidity of flue gas from 12% to below 5% after de-whitening, and then uses chemical absorption to capture carbon dioxide, which reduces the system energy consumption by about 12% and the capture cost by 8%-10%. In addition, pollutants such as particulate matter and sulfur dioxide removed in the de-whitening process can reduce the risk of corrosion and blockage of carbon capture equipment and extend the service life of the equipment. This technical combination of "de-whitening first and carbon capture later" achieves the synergistic effect of pollutant control and carbon emission reduction, and promotes the transformation of power plants from simple "environmental protection facilities" to "carbon resource hubs".
At the system integration optimization level, power plant flue gas de-whitening and low-carbon energy systems can build a more complementary coupling model. In the scenario where coal-fired power plants are mixed with renewable energy (such as biomass and hydrogen), the de-whitening technology needs to adapt to the fluctuations in flue gas composition caused by fuel changes (such as biomass combustion produces more water vapor and alkali metals), and the flexibly adjusted de-whitening system can provide a guarantee for the increase in the mixing ratio. For example, after a power plant mixed with 20% biomass fuel, it optimized the condensation parameters and anti-corrosion process to keep the de-whitening efficiency above 95%. At the same time, the biomass carbon ratio of carbon dioxide in the flue gas increased, reducing the carbon intensity of the whole life cycle. In addition, in the integrated energy system of "coal-fired power plant + carbon capture + heating", the condensed water recovered by de-whitening can be reused as high-quality industrial water to reduce the amount of fresh water, and the captured carbon dioxide can be used to improve the transportation efficiency of the heating network (such as injecting supercritical carbon dioxide into the network), further improving the overall carbon utilization rate of the system.
The coordinated design of policies and market mechanisms is the key driving force for the deep integration of the two tasks. At present, my country's carbon emission trading market has included the power industry in the first batch of emission control scope, and power plant flue gas de-whitening, as a mature environmental protection technology, can bring energy-saving and carbon reduction benefits that can be converted into economic benefits through the carbon market. For example, the power plant can reduce the carbon emission intensity through de-whitening, reduce the purchase of carbon quotas or obtain additional income through the sale of CCER (national certified voluntary emission reduction). At the same time, when formulating the "coal power zero" timetable, local governments can retain units with de-whitening and carbon capture capabilities as transitional infrastructure, and strive for a time window for the maturity of renewable energy consumption and energy storage technology by extending their service life and strengthening carbon management. This dual incentive of "environmental compliance" and "carbon asset appreciation" will guide enterprises to actively increase investment in technology upgrades and form a benign interaction between policy goals and market mechanisms.
The cross-integration of technological innovation is giving rise to a new paradigm of synergy between power plant flue gas de-whitening and carbon neutrality. For example, the membrane separation-based de-whitening technology and membrane carbon capture technology share core materials (such as selective permeable membranes), and the development of composite membrane materials with both water separation and carbon dioxide enrichment functions can simplify the process and reduce investment costs. For another example, the condensed water generated during the de-whitening process is used for photocatalytic hydrogen production, and the waste heat of the power plant is used to drive the hydrogen production reaction, forming a "de-whitening-hydrogen production-carbon storage" cycle chain: hydrogen can be used as a fuel to replace part of the coal combustion and reduce carbon emissions; the generated carbon dioxide can be combined with hydrogen production by-products (such as oxygen) to synthesize chemicals such as methanol through electrochemical reduction. This cross-domain technology integration transforms the power plant from a single power production unit to a "low-carbon technology test platform", providing a new path for achieving "negative carbon electricity".
However, the coordinated promotion of the two still faces challenges in technical economy and system compatibility. On the one hand, the combined investment of deep de-whitening and carbon capture is high (for example, a new 3 million tons/year carbon capture device requires an investment of about 1.5 billion yuan), and the market value of recovered heat (such as heating prices) has not yet fully reflected its carbon reduction benefits, affecting the enthusiasm of enterprises; on the other hand, parameter matching and energy flow optimization of different technical routes (such as condensation de-whitening and dry decarbonization) require more refined system design to avoid efficiency loss due to process conflicts. In the future, it is necessary to focus on key technologies through scientific research mechanisms such as "unveiling the list and taking charge", and at the same time explore the income distribution model of "green certificate + carbon certificate" linkage, quantitatively couple the environmental benefits of de-whitening with the economic benefits of carbon neutrality, and build a more vital collaborative development ecology.
From the macro perspective of industry change, the synergy between power plant flue gas de-whitening and carbon neutrality goals is essentially a microcosm of the transformation of the power industry from "end-of-pipe governance" to "source carbon reduction + process optimization + recycling". When de-whitening is no longer limited to eliminating visual pollution, but becomes a key node in energy cascade utilization and carbon resource management, its technical value goes beyond the scope of environmental protection and becomes a basic unit for building a new power system. This change in thinking will promote the upgrading of more traditional environmental protection technologies to "low-carbon enabling" technologies, and provide a practical example for my country to establish its technical discourse power in global energy governance.
