Turning "Carbon" into Treasure: a Giant Green Power Bank in a Cement Plant

Carbon dioxide compression energy storage is an innovative long-term and large-scale energy storage technology, which realizes energy storage and release through the "gas-liquid mutual conversion" of carbon dioxide. How about its working principle, system composition, realization path and specific application in cement enterprises? Ccement. Com/news/2510/richtext/IMG/vlf9pukv2791761450230581.

Energy storage (charging) process: During periods of low demand for electricity or when there is a surplus of renewable energy generation, the system uses the surplus electricity to drive the compressor. Carbon dioxide gas at normal temperature and normal pressure is compressed into high-pressure liquid state. This process generates a large amount of compression heat, which is stored by the system through a heat storage device for subsequent use. Energy

release (discharge) process: During peak electricity demand, the system releases the stored compression heat, which is used to heat high-pressure liquid carbon dioxide, vaporize it and convert it into high-temperature and high-pressure gaseous carbon dioxide. These high-pressure gases are then expanded through a turbine (turboexpander) to do work, drive a generator to generate electricity, and send the electricity back to the grid.

It is worth noting that the unique advantage of cement enterprises is that their production process and waste heat power generation will also produce a large amount of low temperature waste heat of 90 ° C-110 ° C. The system can skillfully use the low-grade waste heat to further enhance the heating effect and improve the evaporation efficiency of carbon dioxide, thereby significantly improving the overall energy conversion efficiency of the system.

2 Main components

of the system a complete 10MW/80MWh completely describes the scale of the energy storage system: it is a "giant power bank" with strong power (10MW) and long endurance (8 hours), and it is an advanced technical equipment for the cement industry to achieve energy saving and cost reduction and participate in grid regulation. Cement plant CO2 energy storage systems typically include the following key subsystems:

3. Firstly, the power load characteristics of the enterprise should be evaluated. The quality (temperature, flow) and stability of waste heat resources, as well as the site conditions for the construction of energy storage.

System capacity planning: determine the power (MW) and capacity (MWh) of energy storage according to the enterprise's peak shaving demand, waste heat utilization target and economic benefit analysis. 10 MW/80 MWh means that the system can be discharged for 8 hours at 10 MW.

Technology and partner selection: Conch Group has chosen to carry out joint technology research and development and tackle key problems with Baiyi New Energy and Xi'an Jiaotong University, combining the advantages of industry, scientific research and equipment manufacturing.

3.

Wide load adaptive equipment: develop compressor and turbine equipment that can adapt to the fluctuation of cement production and the demand of power grid dispatching. Long-term

energy storage and thermal management: solve the problem of heat loss control under long-term energy storage, and ensure the efficiency and stability of the thermal storage system.

Safety and control: ensure the safety of high-pressure carbon dioxide storage and operation, and establish an intelligent control system with rapid response.

3.

Equipment installation and integration: install compressor, storage tank, turbine, heat storage device and heat exchange pipeline connecting cement kiln flue.

System joint commissioning and grid connection: After the single commissioning of the equipment is completed, the joint commissioning of the whole system is carried out to simulate the charging and discharging process, and finally the grid-connected power generation is realized. The Conch Project was successfully commissioned and connected to the grid in December 2023.

3.

Efficiency evaluation and optimization: continuously monitor the actual operation data of the system (such as electricity efficiency, waste heat utilization rate, emission reduction), and continuously optimize the control strategy and equipment.

Experience replication and promotion: Summarize the experience of the demonstration project, optimize the system design and cost, and can be extended to other cement enterprises and even high energy-consuming industries such as steel and chemical industry in the future.

4 Technical advantages and challenges

4.1 Significant advantages

Good economy: Cost per kilowatt-hour (LCOS) can be as low as 0.

Utilization of industrial waste heat: Creatively combine the carbon neutralization challenge (industrial emissions) with the solution of energy problems (waste heat utilization) to greatly improve the overall energy efficiency. Save standard coal for enterprises (Conch Project saves about 3130 tons of standard coal annually).

Safety and environmental protection: carbon dioxide itself is non-toxic and non-flammable, the operating pressure and temperature level of the system is relatively low, there is no risk of deflagration, and there is no new emission during operation.

Grid-friendly: flexible charging and discharging time (up to more than 8 hours), can provide moment of inertia and peak regulation and frequency modulation services for the power grid, and enhance the stability of the power grid. Less

geographical constraints: less dependent on geographical conditions than pumped storage and flexible deployment in industrial parks.

4.

The complexity of system integration is high: the industrial process and energy system are deeply coupled, and the design, construction and commissioning are difficult. Dependence on

policy and market mechanism: its economic benefits are highly dependent on the maturity of policy environment such as peak-valley electricity price difference, ancillary service market and carbon trading market.

Technology maturity and talents: As an emerging technology, professional design, construction and operation talents still need to be trained and strengthened.

5 Quantitative analysis

of CO2 life cycle The main flow paths and life cycle stages of CO2 in the cement production and energy storage synergistic system are shown in the following figure:

Based on the illustrated path, Refer to the following table to summarize the key quantitative indicators related to the Wuhu Conch case:

:

Direct Storage: Large-scale, Thousands of tons of CO are fixed for a long time.

Indirect emission reduction: indirectly reduce fossil energy consumption and carbon emissions by improving waste heat utilization efficiency and participating in grid peak shaving to promote renewable energy consumption. Extension of the

industrial chain: The CO CO captured by the cement plant is not only used for energy storage, but also for the production of industrial and food-grade CO CO products, dry ice, and even for smart agriculture (gas fertilizer), forming a diversified way of carbon utilization and enhancing the risk resistance and profitability of enterprises.

6 Summary and Outlook

Wuhu

For cement enterprises, this system is like a huge "green power bank". On the one hand, it uses valley electricity or green electricity to charge, on the other hand, it eats waste heat, and then spits out stable and reliable electricity when needed. It not only reduces production costs, but also enhances the regulation capacity of the power grid, and reduces carbon emissions.

In the future, with the progress of carbon capture (CCUS) technology and the reduction of cost, the carbon dioxide energy storage system can even form a closed-loop linkage with the carbon capture device of cement plant, temporarily store the captured carbon dioxide in the energy storage system and recycle it, further deepen its emission reduction value, and finally realize the carbon dioxide emission reduction. It provides crucial technical support for deep decarbonization in industries such as cement enterprises, which are difficult to reduce emissions.