CASE STUDY

TSMC Successfully Developed Industry's First Chilled Water System Optimization, Energy-Saving Control Program

Using Big Data to Study Energy Conservation in Chilled Water System while Improving Overall Energy Efficiency
Aga Chuang
2018/4/20

Greenhouse gas emissions lead to climate change and global warming, which impacts the environment. Now, we have to rely on all mankind to find solutions to problems, such as how to reduce greenhouse gas emissions by carrying out energy conservation and carbon reduction. For TSMC, finding the best technology to reduce the greenhouse gas emissions has been most imperative.

Through the in-depth analysis of power consumption in the factory, it was found that . In order to improve energy efficiency, TSMC applied big data analysis to successfully develop the industry's first chilled water system optimization energy-saving control program while greatly improving overall equipment operating efficiency.

Pie chart of power consumption in a wafer fabrication plant (taking TSMC 12" plant as an example)

Interrelationship between Chilled Water System and Energy Consumption

The chilled water system is composed of a chiller, chilled water pump, cooling water pump, cooling tower and other ancillary equipment. The energy consumption of each device is related to temperature changes. Currently, the industry's method to improve energy efficiency of chilled water systems focuses mainly on upgrading single pieces of equipment alone (for example: upgrading the energy efficiency of cooling towers). However, relevant studies show that upgrading only a single device improves the and may lead to increasing the energy consumption of other devices, causing the whole chilled water system operate inefficiently.

General Control Mode is limited to a single equipment item to improve energy efficiency

  • Single energy saving improvement: Energy saving improvement of Cooling Tower fan a ➞ b
  • Factors not considered: Chiller power consumption A ➞ B
  • Comprehensive benefit: Chiller + Cooling Tower fan power consumption 1 ➞ 2 Energy saving benefit 3~5% (not operating at the optimal energy saving point)

Table on the Correlation Between the Various Temperature Changes and
the Energy Consumption of the Chilled Water System Equipment
Temperature/Chilled Water System Equipment Power Consumption Power Consumption of Chiller (kW) Power Consumption of Chilled Water Pump (kW) Power Consumption of Cooling Water Pump (kW) Power Consumption of Cooling Tower (kW)
①Temperature change of chilled water supply Inversely proportional Directly proportional to the power of 3 NA NA
②Temperature differences change of cooling water in and out of chiller Directly proportional NA Inversely proportional to the power of 3 NA
③Temperature change of cooling water Directly proportional NA NA Inversely proportional to the power of 3

Applying Big Data to Determine Optimum Energy Efficiency for Entire Chilled Water System

TSMC applied big data analysis to collect 500,000 operational data instances related to external air, air conditioning, process cooling water and heat dissipation, and exhaust. This data was combined with the Mollier curve of the chiller and the performance curve of the chilled water pump, the cooling water pump and the cooling tower. Then we made use of regression analysis to develop the industry's .

The chart of each equipment's power consumption and the automatic optimization control program of the chilled water system at different temperatures

The energy-saving control program will automatically calculate the total power consumption according to the different chilled water temperature, cooling range, cooling water temperature, and under different external conditions the on-site load changes will immediately correct and reset the optimum temperature at any time. At this optimum temperature, the chiller and ancillary equipment are set to run at the optimum energy-saving control point and the energy-saving benefit can reach 8% to 17%, which when compared with the general control mode of the industry, the energy-saving efficiency is successfully improved by 5% to 12%.

Comparison between General Control Mode and TSMC Invention Energy Saving Mode

In addition to allowing the chilled water system to operate automatically at the optimum energy saving point, TSMC also leads the industry in successfully developing methods to automatically change the temperature of the chiller to ascertain the correlative equlization of the chiller and the chilled water pump. In 2017, the chilled water system optimization of energy-saving control program has been successfully implemented to all of TSMC's 12" wafer fabrication plants, and each fabrication plant area's instrumentation certification has been completed. The annual power savings reach 120 million units, that is 9% in terms of energy-saving and is equivalent to1.8% of the whole plant's power consumption.