Energy Focused Environmental Management Systems for Wastewater Treatment Facilities

Plan Do Check ActIn the State of Rhode Island wastewater is managed by nineteen individual wastewater treatment facilities (WWTF) capable of receiving and treating a collective 757 million liters per day (200 mgd) of municipal wastewater, along with some combined stormwater. These WWTFs are large energy users and (based on standardized WWTF energy consumption data) can consume as much as than 78,000 MWH of electricity annually at a cost of more than $9 million dollars per year.

The types of fuels used to generate electricity in the Unites States vary by region with the bulk of electrical energy produced in the Northeast Unites States being obtained from the burning of fossil fuels, primarily natural gas. This electrical energy production results in air pollution emissions including greenhouse gases: CO2, CH4, N2O and water-vapor. Based on the average New England power industry’s fuel mix every 1 MWH of electrical used results in the release of about 340 kg (750 lbs.) of CO2(e) . Thus a 5% reduction in electrical demand by Rhode Island WWTFs will result in a reduction of more than 1,300 metric tons (1,400 tons) of CO2(e) annually.

Electrical Energy Cost ComparisonThe cost of generating electricity also varies by region and as the provided graph clearly shows electricity costs in New England are much higher than the national average.

Recognizing the economic and environmental benefits of improving WWTF energy efficiency the Narragansett Bay Commission in cooperation with the Rhode Island Department of Environmental Management, EPA Region I, the University of Rhode Island, National Grid, and the Rhode Island Manufacturers Extension Services (the “Project Partners”) applied for and received $275,000 in grant funding from EPA’s 2008 State Innovation Grant Program to develop and implement a systematic low cost common-sense approach to reducing the energy demand of Rhode Island’s WWTFs.

Ensuring A Sustainable Future GuidebookThe Project Partners set as a goal for this project the development of an Energy Focused Environmental Management System (EF-EMS) for all of Rhode Island’s nineteen WWTFs, utilizing EPA’s energy efficiency guidance document “Ensuring a Sustainable Future: An Energy Management Guidebook for Wastewater and Water Utilities” (the “Guidebook”). To measure project outcomes, the energy performance of each participating WWTF is tracked using EPA’s Energy Star Portfolio Manager. The Guidebook, modeled on the ISO 14001 EMS “Plan-Do-Check-Act” (PDCA) process, is designed to help identify energy efficiency and conservation opportunities, and potential applications for the use of available renewable energy resource at WWTFs.

Working through the Rhode Island WWTF Energy Roundtable, a group made up of representatives of all 19 Rhode Island WWTF’s, NBC has established a partnership with National Grid to conduct Energy Efficiency Technical Assessments (EETAs) of all Rhode Island WWTF operations. An EETA consists of but is not limited to:

  • On –site spot power metering conducted by a licensed electrician,
  • A review of historic equipment power demands,
  • Quantification of renewable energy opportunities, and
  • Completion of a detailed cost benefits analysis report showing proposed energy and cost savings.

In May 2011 NBC received an $86,000 American Recovery and Reinvestment Act (ARRA) grant through the Rhode Island Office of Energy Resources (RIOER) to coordinate and oversee the performance of the EETAs. As part of the grant award National Grid has agreed to fund 50% of the cost of each EETA. NBC, using the ARRA grant funds, will pay for the other half.

At the completion of the EETA process each WWTF will receive a Report which can be used to help implement identified Energy Efficiency Measures (EEMs). EEMs are defined as improvements to a WWTF, including equipment and physical operating control systems which produce economically feasible reductions in energy use. EEMs include cost effective co-generation and use of renewable energy resources.

Each report summarizes the EEMs studied including a cost to install the measure and the energy savings in kilowatt hours or therms saved along with detailed engineering calculations and assumptions, cost breakdowns, and formulas showing where energy savings can be realized. The energy saving estimates and project cost information included in each report will allow each WWTF to apply for project funding through National Grid’s Energy Efficiency Incentives Program and/or grant funding offered through the RIOER. The combination of these two funding mechanisms will, in many cases, allow for total cost reimbursement for the EEM equipment and installation costs. The following is a list of just some EEM projects schedule as of June 2011:

ProjectScheduled Implementation DateEstimated Annual Energy Savings (kWh)Estimated Annual Renewable Energy Generation (kWh)
Electric Heater Efficiency Modifications March 2012 12,352  
VFDs for WWTF Water Pumps March 2012 387,617  
VFDs for WWTF Primary Sludge Pumps March 2012 55,112  
VFD and Controls for WWTF Primary Sludge Pump March 2012 38,546  
Heat Pump for WWTF Bi-Sulfite Storage Building March 2012 35,040  
VFD and Controls for WWTF Head-works Exhaust Fan March 2012 43,036  
High Efficiency Linear Mixer for WWTF Anaerobic Digester March 2012 100,499  
WWTF Lighting Upgrade March 2012 15,838  
WWTF Administrative Building Lighting Upgrade March 2012 99,895  
Wind Turbine Renewable Energy August 2012   7,000,000
Biogas Renewable Energy August 2012   5,000,000
Hydroelectric Renewable Energy March 2012   45,000
Total   787,935 12,045,000
% of Total Rhode Island WWTF Energy Use   1.4% 20.6%