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Wastewater Treatment Facilities Still Have Needs and Concerns When it Comes to Energy Savings


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Like water supply systems, waste water systems use a great deal of electricity used for pumping, air compressors and various support systems.  In addition to being able to host solar and wind systems for onsite generation, waste water systems can also be configured to produce bio-methane which is an excellent source of energy for boilers or cogeneration systems.  Unfortunately, when a waste water utility invests in anaerobic digesters and generation equipment, the resulting electric power earns Class 1 Renewable Energy Credits (RECs) which have been valued around $2/MWh. This compares to Solar Renewable Energy Credits which have recently been earning $100-150/MWh.

New Jersey also has to develop acceptable in state resources for sewage sludge disposal.  The current paradigm of landfilling this material in state or shipping it hundreds of miles out of state is not a sustainable or responsible solution.  The BPU and DEP should jointly develop policies and spearhead efforts to find in state uses including use as energy resource or other sustainable solutions. If sewage sludge is incinerated this should only be done with technologies which can assure that the emissions will meet NJ clean air standards and that will to the maximum extent feasible recover the energy so that the use of fossil fuels can be reduced.

In addition to the desire to use treated effluent safely to reduce pressure on potable water resources, effluent can also be an energy source.  The use of advanced heat pumps to extract heat from or reject heat to water prior to discharge is an accepted and encouraged use in Europe.  NJ regulators and energy programs should seek ways to support innovative technologies such as this to become commercially accepted. Industrial facilities also can use bio-treatment on their waste water discharge to minimize their biological oxygen demand (BOD) and help manage their water treatment cost.  A focused program to promote these technologies as well as anaerobic digesters to fairly value these onsite resources would save energy and provide justifications for the necessary investments.

If allowed, regulatory flexibility with waste water treatment processes can be interrupted or curtailed as part of a demand response program, however this is not often possible due to the environmental regulations.  Efforts in this area need to revisit the processes used for water treatment and to recognize that short term interruptions have little or no impact on the efficacy of the process, but can save thousands of dollars.  This would not ask or expect any relaxation of the final discharge permits which are in place to provide protection of our streams and rivers.  Some flexibility and cooperation in seeking the most cost effective solutions that do not compromise the environment is the mutually desired goal.

Contributor: Joseph Sullivan
Date: November, 2014

 

 
 
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