Energy use and savings at our Mason Farm Wastewater Treatment Plant

July 28, 2015

The Mason Farm Wastewater Treatment Plant (WWTP) in southeast Chapel Hill is our facility with the highest amount of energy use, so the WWTP has been a priority for energy efficiency improvements.

In September 2014, we completed $10.4 million of improvements to reduce electricity use, further reduce off-site odor releases, improve plant performance, and help meet future standards for treated wastewater quality.

  • Electricity use from July 2014 through June 2015 (FY 2015) totaled 8.368 million kilowatt hours (kWh), which is 4.975 million kWh or 37% less than in FY 2012
  • To put that savings into perspective, it is almost equivalent to the total amount of electricity we used in calendar year (CY) 2014 for (1) drinking water treatment, (2) pumping and distribution of treated drinking water and (3) pumping wastewater combined.
  • It is useful to look at energy use in light of the amount of wastewater treated. The WWTP’s electricity use is now about 2.85 kWh per 1,000 gallons treated, or about 40% less than in FY 12, and 28% less than in FY 14.

  • Our FY 15 Duke Energy cost for the WWTP totaled about $464,000. That is 37% lower than our FY 12 costs of $741,000 and 33% lower than our FY 14 costs of $697,000. Part of the savings is due to the lower "contract demand" charge we now pay to Duke Energy. (Contract demand refers to the maximum demand that Duke Energy is expected to deliver to our facility at any time.  The contract demand portion of a bill is designed to cover Duke Energy's costs to have capacity available to meet the WWTP's needs.)