By Dan Zhou, Josh Laverman, Kunyao Yu, Jingxian Tao

The Industrial Energy Efficiency in Automotive Manufacturing Project is comprised of three teams of students working in the area of energy management in this major US manufacturing sector.  Each team has been assigned a company and mentor from that company to define and implement a project around energy management that is directly relevant.  This is summary of the GM team’s project ideas and some individual student reflections on the fall semester.

GM TEAM PROJECT

As the manager at GM’s Energy & Carbon Optimization team, the GM company mentor, Mr. Johnson, is interested in achieving GM’s sustainable goal of reducing its energy intensity. In the long run, this reduction will have to come from the optimization of the plant design and a deeper understanding about the energy process in the paint shop especially.

Therefore, Mr. Johnson is interested in working with Duke’s team to design a bottom-up model that incorporates weather related loads. Specifically, the tool can extract weather information for different plant locations and time period detailed to at least daily level from some external website for data. With some formulas that take the information as input, and some specified parameters such as temperature and humidity setting, HVAC system capacity, the tool will give the user some energy usage numbers that can be pulled into another sheet and give the total energy usage numbers.

Personal reflections

“I am really grateful to have this fantastic opportunity to join the GM Industrial Paint Shop Energy Efficiency team this semester. We have learned so much about the engineering process for the automotive manufacture. I understood that vehicle manufacturing is extremely energy intensive (on average, ¼ annual electricity consumption per household and 1250 gallons of water will be used to produce one car). However, I was surprised by the fact the paint shop uses about 70% of assembly plant’s total energy consumption. Spraying, pumps, fans, air conditioning, and ovens in the paint shop consist of the large energy use. Knowing this important issue, we are conducted our analysis by improving Paint Shop Process Energy Model developed by GM experts.

For next semester, we are really excited for the on-site visit since we could communicate with the engineers and gather more valuable data. By integrating weather load data and associated formulas directly into the engineering model we now have, we could improve our analytical ability and data mining skills. I truly hope GM could use our more flexible model to meet its sustainable targets, which is reducing its energy intensity, measured as MWh per vehicle by 20%, from 2.3 in 2011 to 1.9 in 2019.”

–          Dan Zhou

“This semester has been extremely informative for me on energy use and efficiency in industry.  One very interesting thing I learned was how energy intensive the painting process is for an automobile.  70% of the total energy used in an automotive manufacturing process is solely in the paint booth, which is  a lot higher than I initially expected.  In addition, the size of paints booths is much larger than I initially anticipated.  The painting process involves pre-treatment, which is 200m long.  This process uses approximately 1 MW of horsepower.  The ELPO (Electro Deposition Primer system) is 300m long and 12 ft wide and requires 800 kw/hrs of energy.  Then the car reaches the oven, which is 320m long, and goes through several other stations until it finally reaches the inspection station.  Overall, the process is extremely energy and labor intensive and requires a lot of space, which means it is a key component to increasing energy efficiency.

A second major thing I learned about energy efficiency is that ultimately all companies are striving for the same goal, but they go about reaching that goal completely differently.  All companies want to use less energy without decreasing productivity to make their process more economically efficient.  But while one company might seek out clean energy and renewable sources directly to be more efficient, others may look internally to being more productive, thus decreasing energy use.  All of these tactics are very interesting to me, and ultimately serve the same common objective; increase efficiency and decrease cost.”

–          Josh Laverman

“Over the past semester, I have had the unique opportunity to learn about automotive paint shop processes from an experienced GM mentor. One of the most surprising things I discovered was the large impact of temperature control on paint shop energy use. While paint shops processes make up 70% of an assembly plant’s total energy use, 60% of the energy used in paint shops goes towards warming or cooling of outside air. As a result, the most effective past change in energy consumption was achieved through recirculation of air in the assembly zone. I learned that recirculating air can help control temperatures since air conditioning systems can be more effective when re-warming or re-cooling air that has already passed through the system a few times.  I was most surprised by the significant impact of this change- the amount of chilled water originally required to cool the air was reduced to a third of the original amount. This resulted in a reduction of thousands of tons of water and millions of dollars of savings.

I’ve also come to recognize the importance of a bottom-up approach in industrial energy management. Currently, EPA and other regulatory agencies seek to improve energy efficiency in different industries by focusing attention on plants with low performance scores. Wasteful facilities are analyzed and plausible improvements to already existing machinery/operating procedures are made. However, this approach is limited in the amount of improvement which can be made, due to high costs of manipulation of existing infrastructure. A bottom-up approach in facility design takes energy efficiency into account from the very beginning. By referencing an energy spreadsheet as projects are being developed, engineers may use energy/unit calculations to make the most environmentally friendly decisions. I look forward to developing this spreadsheet with my GM mentor, my Duke mentors, and my Bass Connection teammates this coming spring.

–          Kunyao Yu

“I really enjoy my BASS CONNECTION team project with GM’s industrial energy efficiency this semester. It surprised me that the automobile company has been taking energy consumption into consideration of their plant design. For so many years, companies and organizations have been using function or performance to evaluate energy consumption rather than efficiency. GM, as well as other automobile companies who are working with the team, are now considering energy usage as an important part of their cost and is dedicated to simulation of the energy process before new plant construction. I believe that this trend will spread over other manufacturing industries and push the economy’s efficiency and sustainability onto a higher level.

In addition to the rising awareness of improving energy efficiency, I didn’t expect that there are also so many companies outside who provide complicated software to assist the energy management process. However, the over-complicated algorithm deters the understanding process of the calculation behind the scene and the mentor company actually prefers a model where they can easily tune themselves. As much helpful as these software are, customization seems also be the rule for success in this case.”

–          Jingxian Tao