Municipalities Generate Significant Savings Through
Reduced Utility Energy Consumption

A key benefit of public-private partnerships for municipal water and wastewater systems is cost savings. Such savings can be derived from a number of areas: chemicals, equipment, power, sludge, etc.

As an industry, partnerships have existed in the United States since Burlingame, California partnered with a private operator in 1972 – and so have these inherent cost savings. With more than three decades of operating, maintaining, servicing and managing water and wastewater utilities, private operators have the expertise to effectively utilize and maximize these facilities. With an estimated 11 percent of a water utility’s budget going to energy, reductions in consumption are one way private operators help municipalities generate savings.

Long viewed as a financial burden, power consumption is now considered a major environmental burden as well. Individuals and industry are both looking for ways to reduce their energy consumption as a result of the current “green” movement. While nothing new, private operators are approaching power consumption as more than a way to save clients money – reduction of greenhouse gases is playing a larger role in these operators’ corporate responsibility programs.

For instance, Severn Trent Services has documented energy reductions at projects for years. Beginning its partnership with Kingwood, Texas in 1974, the company trimmed electricity costs at the 0.378 MGD Montgomery County Municipal Utility District 48 wastewater treatment plant (WWTP) by $6,000 a month by installing soft-start contactor and timers for the blowers.

In Jackson, Miss., Severn Trent reduced energy costs by 30 percent at the outset of the partnership, which began in 1985. By retrofitting the 46 MGD Savanna WWTP’s aeration system from coarse bubble to fine bubble, power costs have been reduced, saving the City $650,000 per year.

In 2008, Severn Trent undertook a program to identify additional areas of energy reductions at major (flow >1 MGD) WWTPs the company operates in order to reduce greenhouse gases. Targeting five facilities geographically dispersed across the United States, the company rolled out its pilot Site Energy Management Program (SEMP). Process/plant optimization models were developed by Severn Trent’s Technical Services Group, with additional opportunities being identified by on-site personnel.

Following the plant optimization process, successful energy reductions were realized at all five facilities when year-over-year energy usage (kilowatt hours / million gallons) was compared:

• Lehigh Acres, Fla. achieved a 26 percent reduction by continuous improvement in process control allowing use of low horsepower blowers to reduce energy consumption.
• Genoa, Mich. achieved a 21 percent reduction by an improved utilization of sequencing batch reactors, upgrading to HVAC systems and a continuous improvement in process control to save power.
• Newbern, Tenn. achieved a 16 percent reduction by process optimization resulting in reduction on aeration and decreased levels in the oxidation ditch to lower amperage pull on motors and reduce energy use.
• Chandler, Ariz. achieved a 9 percent reduction by minimizing power usage through reductions in blower demand and optimization of recirculation pumps.
• Chickasha, Okla. achieved a 9 percent reduction by improved control of the sludge pasteurization system which requires 600 amps of 480 V electricity and reduction in the use of high horse power blowers.

Using the EPA’s Greenhouse Gas Equivalencies Calculator, the energy reductions above saved more than 806 tons of CO₂ – equivalent to CO₂ emissions from 83,012 gallons of gasoline consumed or the annual greenhouse gas emissions from 134 passenger vehicles.

In these economically and environmentally challenged times, municipalities can prove to be sustainable on both counts through a public-private partnership. Operating more than 415 municipal water and wastewater facilities with combined flows totaling more than 677 MGD, Severn Trent plans to implement its SEMP at additional facilities this year, calculating further reductions in greenhouse gases. Call it what you will – corporate responsibility, sustainability or going green – such reductions are a step in the right direction that began over three decades ago. As the environmental adage goes: “Think globally, act locally” – and don’t forget the cost savings to the client.

For more information, e-mail info@severntrentservices.com.