Water Online

January 2017

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

Issue link: https://wateronline.epubxp.com/i/773139

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electrical energy and nearly 100 percent of the thermal energy required to operate the facility. Utilizing this energy reduces the use of utility power and has displaced the emission of approximately 1,035 metric tons of CO 2 during 2015. This is the environmental equivalent of 150 houses off the electrical grid. The cogeneration system not only allowed SMRSA to reduce dependency on grid-based power, but it significantly curbed methane gas release into the atmosphere. On average, SMRSA is currently utilizing 99 percent of the digester gas produced by the treatment plant to fuel two on-site internal combustion engines. Approximately 1 percent is lost to the atmosphere through its flare as methane, as opposed to 70 percent prior to the installation of the cogeneration system. The implementation of the CHP program has had a five- year payback on its initial investment. "The resultant savings that are realized every year thereafter are being utilized as a revenue stream to fund additional climate change related incentives," says Michael Ruppel, executive director of SMRSA. During Superstorm Sandy, the treatment facility lost power supply for 14 consecutive days. During a power outage, SMSRA's cogeneration system must be shut down for the safety of the utility personnel repairing other portions of the power grid. Therefore, the authority was forced to rely on its diesel-fired standby auxiliary power systems to run the plant. While this allowed for reliable service from the treatment plant, access to diesel fuel was limited as other utilities in the region faced similar challenges. The lesson learned from the Sandy experience was that if the authority could increase the electrical and thermal energy production of the existing cogeneration system, it could provide continuous treatment capability during similar storms without relying on grid-based power or diesel fuel systems. To meet the full electrical demand of the treatment plant, the authority plans to install a third engine to expand the existing cogeneration system. A new dual-fuel 315 kW internal combustion engine and generator, operating on both natural gas and methane gas, will be installed. The two existing 140 kW internal combustion natural gas engines will be upgraded to 160 kW duel fuel engines (natural gas and biogas) and be operational only when there is a power outage or during periods when the 315 kW internal combustion engine is offline for maintenance or repair. During a power outage, the 160 kW internal combustion engines will be operated on natural gas only. The available methane gas that is generated by the treatment plant will fuel the 315 kW internal combustion engine. When methane gas is no longer generated by the treatment plant, natural gas will be used to fuel this engine. The combined operation of the three engines will supply enough power to operate the treatment plant, thus allowing the CHP system to operate in "island" mode, with zero reliance on a grid-based power system. Construction of the cogeneration system is anticipated to be completed in 2018. Adapting To Climate Change While mitigation strategies address one of the underlying causes of climate change, adaptation plans seek to prepare for and adjust to climate change challenges. SMRSA's pump stations are particularly vulnerable to the impacts of sea level rise and storm surge during wet weather events because of their low-lying and, in some cases, shoreline locations. To address this vulnerability, SMRSA has implemented the unique concept of a mobile enclosure that houses critical electrical equipment and can be removed from the pump station to a safe inland location in the event of a storm-related emergency. The mobile enclosure closely resembles a mobile home trailer and can be mobilized within an hour's notice. Diesel-powered portable pumps and/or a sacrificial generator render the pump station fully operational during a storm. Once the storm subsides, the enclosure can be moved back to the station and all electrical equipment is put back online. Electrical and control connections between the enclosure and the pump station and its equipment are made with cables and plugs that are opened to allow removal of the enclosure. An expendable portable generator and transfer switch will be transported to the site to operate the station if utility power is lost. Ryan Krause, authority engineer, noted, "This capability wateronline.com n Water Innovations 15 RESILIENCY SMRSA cogeneration system While mitigation strategies address one of the underlying causes of climate change, adaptation plans seek to prepare for and adjust to climate change challenges.

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