Tier One Automotive Supplier

Overview

In early 2016, Bay Controls worked with a Tier One automotive supplier who was concerned that their compressed air system was not operating as efficiently as it could be. Bay Controls coordinated with the supplier to conduct a site visit and metered compressed air system assessment to generate a representative data sample that accurately captured the supplier’s compressed air needs during typical production and non-production periods.

Using the data collected during the assessment, Bay Controls was able to recommend a control system upgrade that would enable the supplier to significantly reduce their energy costs by providing improved pressure control and automatically shutting air compressors off during periods of low demand. Based on the supplier’s production profile and electricity costs, Bay Controls was able to show that a controls upgrade would generate annual savings of $61,000. When combined with incentive payments from the local utility, the project would have a simple payback of 12 months.

Site Visit

After speaking with the supplier’s facilities manager on the phone, Bay personnel arranged to visit the supplier’s facility to conduct an initial site survey. The site survey is an important initial step in the Bay Controls project timeline because it is an opportunity for Bay personnel to learn about the customer’s production process and compressed air needs and also verify the equipment on site. In the case of this Tier One automotive supplier, their equipment consisted of the following:

• (1) 550 HP Cooper (TA28) 3-stage centrifugal compressor
• (1) 350 HP Cooper (TA2000) 3-stage centrifugal compressor
• (1) 300 HP Cooper (TA2000) 3-stage centrifugal compressor

Through conversations with the facilities manager and plant operators, Bay Personnel determined that the supplier’s production schedule consisted of three weekday shifts and two weekend shifts. While the plant operators believed all three compressors ran almost fully loaded during most weekday production shifts, there was a question about how often the compressors ran during the weekend shifts.

To fully understand the plant’s needs and generate accurate data for compressed air demand and compressor performance, Bay Controls proposed a metered site assessment as a next step.

Metered Compressed Air System Assessment

To fully understand the plant compressed air demand during different production periods and identify potential savings opportunities, Bay Controls proposed a metered assessment of the plant compressed air system. The supplier agreed to proceed with a metered assessment, and Bay Controls engineers installed a short-term metering solution to capture the following key performance indicators (KPIs) over a two-week period:

• Compressor Motor Power (kW)
• Compressor Energy (kWh)
• System Pressure (psi)
• Compressor “blow-off” (% of loaded hours)

After a data collection period of two weeks, Bay Controls used these KPIs to calculate the supplier’s compressed air needs and energy usage as shown in the following tables.

Weekly Compressed Air System KPIs (Entire Compressed Air System)

Weekly Compressed Air System Energy Usage

As the data captured during the assessment shows, the supplier was fully utilizing their air compressors during the weekday shifts, but was running them unloaded for long periods of time during the weekend shifts (as shown in the highlighted cells above), and the compressors were venting air (blowing off) during the weekend shifts. In addition, the plant air pressure was actually higher during the Sunday shift than the weekday shifts (108 psi vs. 105-106.5 psi).

System Analysis and Proposal

Using the data captured during the assessment, Bay Controls built an accurate model of the supplier’s compressed air usage and needs and shared it with the facilities manager. Until this discussion, the facilities manager had never seen his compressed air system data measured and modeled for the weekday and weekend shifts. When he saw the discrepancies in loaded and unloaded operation between the weekday and weekend shifts, he immediately noted that although the system was operating at 106 and 108 psi on the weekends, the plant only needed 82 psi on the weekends. He also said that the plant only needed 102 psi during the week (instead of the 105-106.5 psi the compressed air system was supplying), but that the compressors could not consistently maintain that pressure without being set to a higher set point (105-106.5 psi).

After our discussion with the facilities manager, the Bay Controls team used the assessment data and the facilities manager’s feedback to identify three ways in which the supplier could significantly reduce compressed air energy use:

• Network the compressors to enable more precise pressure control
• Reduce system operating pressure to match plant needs during different periods
• Reduce unloaded compressor operation during periods of little or no demand
• Reduce air venting (blow off)

Using the assessment data, Bay Controls estimated the savings from each of these actions. The savings estimated for pressure reduction, unloaded operation reduction, and air venting reduction are shown in the following tables.

Pressure Reduction Savings (Weekly)

Unloaded Operating Hours Reduction Savings

Air Venting (Blow-Off) Reduction Savings

The total weekly, monthly, and annual savings from implementing all three strategies are shown below. The table also includes the energy cost reduction the supplier could expect given their electric cost of $0.085/kWh.

Total Savings Potential

To achieve these savings, Bay Controls proposed that the supplier upgrade their air compressor controls with the Bay Compressor Controller and the BayView Scheduler. Upgrading to a current generation control system like the Bay Compressor Controller would accomplish three primary goals for the customer:

1. Enable system pressure reduction during both weekday and weekend production through precision pressure control and compressor networking
2. Reduce unloaded compressor run time with auto start-stop capability
3. Reduce air venting with improved throttling range

In addition, BayView Server would enable the supplier to remotely control (within the plant) and schedule the compressed air system operation to easily respond to changes in plant demands and/or schedules.

Project ROI

Given the project cost and estimated energy savings, Bay Controls estimated a simple payback of 23 months if the project were paid for up front in cash without any added incentives or rebates. However, the local electric utility was offering an incentive payment of $0.08 for every kWh in project saving. Using the project’s estimated annual saving of 726,633 kWh, the utility incentive would work out to $58,130.64.

After factoring in the available utility incentive, the simple payback period was reduced to 12 months.