Busch, Lindsey, Busch

Busch, Lindsey

Lindsey is the manager of Carollos Great Lakes region. She is both a proud Badger and Jayhawk, having received her undergraduate degree in Civil Engineering from the University of Wisconsin at Madison, and her graduate degree in Environmental Engineering from the University of Kansas. She is currently active in CSWEA, volunteering as the conference planning chair for the regional conference, and is chair of the WI Section Energy and Resource Recovery Committee. In her free time, Lindsey enjoys spending time with her husband, kids, and fostering rescue dogs.

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Description: A Holistic Look At Infrastructure Replacement: The Madison Metropolitan Sewerage...

A Holistic Look At Infrastructure Replacement: The Madison Metropolitan Sewerage District's Energy Management Master Plan

Abstract

Relevance
Energy efficiency and sustainability are becoming top priorities for utility operations as evidenced by the growing number of energy management and renewable energy projects across the country. Utilities are combating rising energy costs and making good on their promise to be responsible environmental stewards while maintaining compliance with stringent discharge limits. This talk will walk through the development of and findings from the Madison Metropolitan Sewerage District's (District) 2020 Energy Management Master Plan (Plan), a comprehensive document that recommends targeted improvements to the Wisconsin-based utility's energy infrastructure and energy-management approaches over the next two decades.
Energy Planning Drivers, Goals and Approach
The Plan was born out of the District's need to upgrade or replace aging energy-producing and -consuming infrastructure at the Nine Springs Wastewater Treatment Plant (NSWTP), an effort that was estimated to cost approximately $88 million to$93 million without any process or energy optimization. To make strategic use of their resources and funding, the District decided to pursue improvements that would not only rehabilitate the NSWTP's energy infrastructure but also reduce its energy footprint by decreasing overall energy demands and increasing the generation and use of renewable energy. To this end, the Plan began with seven energy goals, which were influenced by the EnvisionTM scoring system: 1. Reduce fossil-fuel-based greenhouse gas (GHG) emissions by at least 10 percent within 10 years. 2. Reduce the cost of peak electricity demand by at least 5 percent within 10 years. 3. Reduce operational energy consumption by at least 10 percent within 10 years. 4. Use renewable energy to meet 50 percent of energy demands within 10 years. 5. Reduce the Class B biosolids processing and reuse program's energy demand or produce higher-value biosolids without significantly increasing energy demand. 6. Improve the resiliency and reliability of energy supply sources. 7. Improve the reliability of energy-using and -consuming infrastructure. In collaboration with the District and an industry-wide energy expert panel, the project team identified 'the universe of technology and energy options' that were grouped into the following major categories: co-digestion, biosolids, biogas, thermal, renewable energy, and effluent pumping as shown in Figure 1. Using a systematic screening process, the project team and the District then pared down 133 unique concepts into 26 strategic and feasible alternatives that were evaluated against criteria relevant to the District, including energy efficiency, resilience, reliability, cost, and operation and maintenance. This process generated 11 alternatives, which were merged into four synergistic combinations called 'scenarios.'
Analysis of Synergistic Alternative Combinations
The project team identified the following combinations of energy alternatives:
- Enhanced Baseline (Alternative 1a): Upgrades the plant's heat and power systems and partners with Madison Gas and Electric (MGE) to procure solar energy through their Renewable Energy Rider (RER) program.
- Maximize Renewable Energy Production (Alternative 2): Contains the same components as the Enhanced Baseline and includes new processes to capture and beneficially use additional waste heat energy.
- Energy Grid Resilience (Alternative 3): Upgrades heat systems and expands on-site power generation by using both biogas and natural gas in large co-generation systems, thus operating the plant 'off-grid.'
- Reduce Infrastructure Complexity (Alternative 4a): Simplifies infrastructure by upgrading heat systems, partnering with MGE through the RER program, and exporting renewable natural gas (RNG) to the renewable fuels market instead of using it for onsite power production.
To reduce the labor and transportation fuel needed for biosolids distribution, all four scenarios also included reconfigurations to the NSWTP's biosolids treatment processes and a new dewatering facility with expanded biosolids storage. After thorough alternatives evaluations and sensitivity analyses, the project team recommended that the Enhanced Baseline and Reduce Infrastructure Complexity alternatives be considered further. As shown in Table 1, both alternative combinations offer significant benefits over the baseline (i.e., continuing to rehabilitate and maintain existing infrastructure) with little to no drawbacks and at similar or even lower lifecycle costs.
Both alternatives have relatively similar capital costs, though the Reduce Infrastructure Complexity scenario has the potential for higher revenue production depending on the value of renewable identification numbers (RINs) in the U.S. Environmental Protection Agency's (EPA) Renewable Fuel Standard (RFS) program. In fact, revenues from the sale of RNG are projected to offset this scenario's increased costs in peak energy demand. In either case, Figure 2 shows that both recommended alternatives have considerably lower capital and 20-year net present value (NPV) costs compared to the other alternatives.
Energy Goals Achieved
The Enhanced Baseline scenario maintains the District's current operational philosophy (i.e., cogeneration and renewable electricity production) and meets all seven of the Plan's energy goals. The Reduce Infrastructure Complexity scenario offers a lower lifecycle cost potential, simplified infrastructure and lower operational complexity but does not meet the goal of reduced peak demand costs since it converts biogas to RNG rather than on-site electricity. With that being said, this scenario has the potential for high revenue production depending on the value of renewable identification numbers in the EPA's Renewable Fuel Standard program. In fact, revenues from RNG sales are projected to offset this scenario's increased costs in peak energy demand. Insights Gained (Lessons Learned)
During the 20-month development process of the Plan, the project team gained insights, both expected and unexpected, that will serve as valuable knowledge on future projects.
What does 'net-zero' really mean?
Although the Plan's focus wasn't on achieving 'net-zero,' grid independence was considered to help guide future policy decisions. A key lesson learned in this endeavor was that capturing all available energy on site (e.g., thermal, solar, carbon), especially with the goal of 'net-zero,' is not always cost-effective or practical.
The consequence here is to always question: What does 'net-zero' mean for the project at hand? Is it net-zero electricity use? Net-zero carbon? Thermal? For facilities like the NSWTP where net-zero electricity use may be impractical, net-zero carbon is a realistic goal that may become even more feasible over time as various electric utilities source greener energy.
Community energy partnerships can achieve multiple goals
The Plan was crucial in showing the District that, by establishing partnerships with the local electric utility or other entities, they can advance their goals to increase generation and use of renewable energy without having to bear the sole burden of owning and operating renewable energy infrastructure.
What's Next?
In their future facility planning efforts, the District will further evaluate the options recommended in the Plan to determine a path forward. In the process, the District will engage stakeholders and community partners to earn their support in developing effective, responsible, and transparent projects that bring value to the community.

Energy efficiency and sustainability are becoming top priorities for utility operations as evidenced by the growing number of energy management and renewable energy projects across the country. This talk will walk through the development of and findings from the Madison Metropolitan Sewerage District's Energy Management Master Plan, a comprehensive document that recommends targeted improvements to the utility's energy infrastructure and energy-management approaches over the next two decades.

SpeakerBusch, Lindsey

Presentation time

15:30:00

15:55:00

Session time

15:30:00

17:00:00

TopicIntermediate Level, Energy Production, Conservation, and Management, Facility Operations and Maintenance, Sustainability and Climate Change

Author(s)

Busch, Lindsey

Author(s)Lindsey I. Busch1; Becky J. Luna2; Tanja Rauch-Williams2

Author affiliation(s)Carollo Engineers, Madison, WI1; 2Carollo Engineers, Broomfield, CO

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158681

Volume / Issue

Content sourceWEFTEC

Word count16

Converting HPO to Nitrogen Removal: Closing the Oxygen Gap Through Electrolysis

Abstract

APPLICABILITY Major US water recovery facilities (WRRFs) operate as High Purity Oxygen Activated Sludge (HPOAS) systems, originally built for BOD removal. Stringent nutrient limits now require lowering effluent nutrients, leading HPOAS facilities to consider expanding or upgrading for nitrification/denitrification processes (NDN). Upgrading presents challenges, including the need for extra oxygen to nitrify ammonia, requiring expansion of the existing oxygen supply system. In parallel, there has been global recognition of green hydrogen as a way to decarbonize hard-to-electrify sectors , with several facilities commissioned in the US. This study explores co-locating electrolytic green hydrogen generation at HPOAS facilities, producing green hydrogen and co-valorizing byproduct oxygen to increase oxygenation capacity. This strategy interfaces with two trends: expanding oxygen capacities of large HPOAS transitioning to NDN and decarbonizing hard-to-electrify industries through green hydrogen. Converting HPO Facilities to Nitrogen Removal and Its Implications Adapting Large High Purity Oxygen Activated Sludge (HPOAS) systems for nitrogen removal is gaining attention (Pitt et al. 2023). Coastal facilities, traditionally exempt from strict nitrogen regulations, are anticipated to upgrade their system to nutrient removal due water reuse and ocean discharge requirements. Retrofitting for nitrogen removal poses challenges in meeting increased oxygen demands, potentially surpassing existing oxygen demand by over 60%. Thorough evaluation of the oxygenation system is crucial for HPOAS upgrades to an NDN process, considering both immediate and future oxygen requirements. Energy Transition and Green Hydrogen An emerging solution for decarbonizing hard-to-electrify industries is green hydrogen production, which enables the storage of renewable energy in hydrogen form, addressing reliability issues during low renewable energy periods. Green hydrogen benefits energy storage and aids in decarbonizing sectors like long-distance transportation, industrial chemical synthesis, and various fuel applications (Davis et al., 2018; Saeedmanesh et al., 2018). The Case for Green Oxygen Recovery at HPO Plants Green hydrogen generation yields a valuable by-product: pure oxygen. In the context of Water Resource Recovery Facilities (WRRFs), this by-product oxygen, holds the potential for beneficial re-use in the bio-reactors. Given WRRFs' frequent co-location with industries (i.e., airports, ports, chemical industries, etc.) there is an opportunity to integrate renewable hydrogen generation systems at WRRFs. This enables the supply of green hydrogen for local industry decarbonization while recovering pure green oxygen for aeration. Since HPOAS systems operate at high purity oxygen levels (greater than 95%) the oxygen produced by the electrolyzer can be easily blended into the pure oxygen line of the plant. The ability to leverage the existing oxygen equipment allows to minimize the need for modification to the existing oxygenation system. Figure 1 illustrates a process schematic of an HPOAS system incorporating green oxygen from electrolysis. Case Study: City of Cedar Rapids The Cedar Rapids Water Pollution Control Facility (CRWPCF) shows the application of this approach. Operating on a UNOX configuration (45 MGD), with an oxygen generation capacity of 80-ton/day. Available renewable energy sources (RES) were assessed when developing hydrogen production curves. Figure 2 shows the specific solar power generation for the geographic coordinates of the CRWPCF (PVWatts, NREL). Various electrolyzer sizes are considered to project dynamic green oxygen generation curves. These are compared with the estimated oxygen demand from the hetero- and auto-trophic process and to assess oxygen storage needs. Overall, to supply the near-term oxygen needs of the CRWPCF approximately 35MW are required. As part of the ongoing work, this study will further explore different RES blends and assess the costs/performance/constructability/ implications of retrofitting the existing UNOX equipment to receive electrolytic oxygen. Conclusions This case study explores integrating green hydrogen production at HPOAS facilities at WRRFs. Co-valorizing oxygen enables concurrent green hydrogen production, supporting the acceleration of global decarbonization. Re-using by-product oxygen for nitrification meets NDN transition needs of HPOAS systems, expanding capacity and generating renewable fuel. This approach allows to leverage ongoing decarbonization funding opportunities, offsetting costs, and expanding oxygen supply operations at HPOAS. The City of Cedar Rapids provides practical insights on infrastructure, power, and equipment considerations, offering a sustainable solution for wastewater utilities. RELEVANCE TO AUDIENCE This research introduces an innovative approach for HPOAS plants aiming for NDN and sustainability. Valuable insights for plant operators, engineers, and decision-makers for upgrading HPOAS systems will be addressed. The study also highlights the potential synergy between wastewater treatment and green hydrogen production. The proposed co-location of electrolytic green hydrogen generation and HPOAS facilities not only addresses environmental concerns but also creates economic opportunities for nearby industrial users. This research contributes to a holistic understanding of sustainable practices at WRRF.

This study assesses the financial opportunities and barriers of co-valorizing the oxygen by-product of a renewable-powered green hydrogen facility at a High Purity Oxygen Activated Sludge (HPOAS) plant, with the intent of expand the oxygenation capacity of HPOAS transitioning to nitrification/denitrification (NDN).

SpeakerReifsnyder, Samuel

Presentation time

14:30:00

14:50:00

Session time

13:30:00

15:00:00

SessionBuilding a Hydrogen Future

Session number206

Session locationRoom 244

TopicEnergy Production, Conservation, and Management, Intermediate Level, Research and Innovation

Author(s)