Carbon Mitigation Plan Integrated Portfolios

There are multiple paths to achieve carbon neutrality for the UMA campus. The CMTF evaluated two different integrated portfolios that will meet campus electricity and thermal needs with 100% renewable energy with a combination of the carbon mitigation solutions described above. While both portfolios achieve carbon neutrality from a carbon accounting perspective, each portfolio used a fundamentally different strategic approach. Some carbon mitigation solutions were included in both portfolios, however their impacts may be different, as their carbon mitigation potential is relative to the centralized thermal distribution system proposed for each portfolio and how the campus electricity is supplied. For example, a solution focused on reducing building energy demands may appear to achieve higher carbon reductions if measured against a campus that uses steam and combustion turbines vs. a campus that uses lowtemperature hot water and renewable grid-purchased electricity. However, this is due to the inherent inefficiencies in the steam system, both in generation and distribution. Because of these types of interdependencies, the team tried to find a symbiotic set of solutions for each portfolio that produced the best aggregate outcomes.

Current System with Renewable Fuels & Offsets Portfolio

This portfolio focused on a strategy to maximize the useful life of current campus assets. The existing cogeneration equipment currently housed in the Central Heating Plant (CHP) was installed between 2009 and 2020. The primary supply equipment, assuming it is well maintained, could continue to operate into the 2040s. This portfolio assumes that UMA would continue to invest to maintain and/or replace distribution and supply assets at the end of their useful life. Fossil fuels would be replaced with renewable fuels such as renewable fuel oil (RFO), biodiesel and/or biomethane.

The combustion, production, and transportation of renewable fuels do result in carbon emissions. Current carbon accounting standards consider these renewable fuel emissions as biogenic and excludes them from Scope 1 emissions calculations. Using current carbon accounting standards this portfolio could technically allow UMA to claim a carbon-neutral campus powered by renewable energy by 2030. However, there is significant controversy about current carbon accounting standards since many biogenic emissions are carbon-neutral only if evaluated on a multi-decade timescale. The CMTF did review and consider this Portfolio, however, this strategic approach was ultimately dismissed as not adequately responding to the Chancellor’s Charge. The primary concerns were the significant uncertainty regarding GHG accounting methodologies and the availability of renewable fuel supplies as the scale required.

Solutions considered as part of this Portfolio are shown in Table 6 below.

#		Solutions Included
2	Image	Behavior Change
12	Image	Onsite Solar Photo-Voltaic (PV)
17	Image	Green Transport / Fleet Electrification
3	Image	Strategic Energy Management (SEM)
4	Image	Chilled Water Expansion and Optimization
13	Image	Renewable Fuel Oil Boiler
16	Image	Renewable Natural Gas (Pipeline Quality Biogas)
19	Image	Carbon Offsets
18	Image	Renewable Energy Credits

* Minor technical solution included in portfolio.

 

The carbon mitigation forecast showing GHG reduction by solution over time for this Portfolio is shown below in Figure 8.

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Key Insights – Current System with Renewable Fuels & Offsets Portfolio

• Strategic Energy Management could potentially provide a significant portion of the carbon mitigation required, since avoided energy demand would also avoid the significant losses inherent in the steam-based system. Avoided electricity demand could avoid additional on-site combustion of fossil fuels by avoiding the need to self-generate electricity.
   
• Despite the large, modeled impact of the Strategic Energy Management Solution, 60%-75% of emissions would require some form of combustible renewable fuel that could generate the temperatures required to make steam. This portfolio assumes the primary fuel would become Renewable Natural Gas (RNG) which could potentially be procured through the purchasing and retiring of RINs in equal quantity to natural gas consumption. Assuming an adequate supply of RNG could be procured, RNG would likely require UMA to pay a 200-300% price premium compared to fossil natural gas.
   
• This portfolio still requires between 7,000-9,000 MTCO2e of carbon offsets to mitigate emissions for fossil fuels other than Natural Gas.

 

 

Energy Transition Portfolio (Recommended)

The Energy Transition Portfolio seeks to change the underlying energy platform of the UMA campus. Rather than prolong the life of the current steam distribution and fossil fuel burning supply assets, the campus would transition to a system centered around the ideas of heat trading and electrification. At the end of this transition, UMA will no longer require fossil fuel combustion except in very limited cases for reliability and resiliency. The existing energy system would be maintained in the very near term to continue to provide the campus with reliable heating cooling and electricity. However, over the 12-year transition, major equipment and distribution capital investments would be redirected to the new energy platform. Legacy equipment could be retired or relegated to a backup role. This portfolio can be summarized by following 5 actions:

1. Transition Away from Steam – Replace the campus circulatory heating system. Move away from inefficient legacy steam. Move to a flexible, efficient low-temperature thermal distribution system.
    
2. Stop Burning Fossil Fuels – Move away from the combustion of fossil fuels which are the overwhelming source of UMA’s greenhouse gas emissions.
    
3. Accelerate Energy Efficiency – Upgrade and renovate buildings to lower energy demand and make them compatible with a low-temperature thermal distribution network.
    
4. Expand the Use of Renewable Energy – UMA has some room to expand onsite solar, but that will not be enough. Expand purchases of renewable electricity from the grid. More importantly, expand the use of renewable thermal technologies unlocked by the move away from steam.
    
5. Integrate the Transition into UMass Amherst Culture – Campus community support and mission alignment are critical. The energy transition presents a revolutionary opportunity for using the campus as a living lab for advancing sustainable education and research.

 

Solutions included in the Energy Transition Portfolio are listed in Table 7 and the following pages provide a summary of the key assumptions used in each solution.

2032 GHG Percent Reduction by Solution

#		Solutions Included	2032 Impact	%
		Business as Usual	124,594 MTCO2e	100%
1	Image		-5,260 MTCO2e	-4.2%
2	Image		-2,396 MTCO2e	-1.9%
3	Image		-6,518 MTCO2e	-5.2%
4	Image		*	*
6	Image		-35,766 MTCO2e	-28.7%
7	Image		-46,286 MTCO2e	-37.1%
8	Image		-4,734 MTCO2e	-3.8%
9	Image		1,578 MTCO2e	-1.3%
10	Image		-6,312 MTCO2e	-5.1%
11	Image		-3,631 MTCO2e	-2.9%
12	Image		-1,860 MTCO2e	-1.5%
13	Image		-3,205 MTCO2e	-2.6%
17	Image		-1,778 MTCO2e	-1.4%
18	Image		-1,309 MTCO2e	-1.1%
19	Image		-3,964 MTCO2e	-3.2%

* Combined with Solution 6

 

 

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Solution 1 – Green Building & Renovation Standards

This Solution assumes there would be avoided energy and related emissions savings as UMA pursues higher efficiency building standards than UMA default standards when constructing new or renovating existing buildings. This solution was modeled with Solution 3 (SEM) and 6 (LTHW) and informed by the GSF and programmatic use assumptions in the BAU Growth Forecast. Key assumptions include 27% reduction in thermal energy use intensity for new buildings and a 20% EUI reduction for renovated buildings over the study period relative to current campus averages. Any new or renovated buildings would be compatible with the proposed LTHW system. Capital cost premiums (relative to a theoretical code-compliant baseline) were not included in modeled results since these would not be considered energy system costs, but rather capital costs embedded in the building construction or renovation budget.

Solution 2 – Behavior Change

The Behavior Change solutions assumes UMA would hire staff to run a program that could achieve up to 2% energy demand savings in the buildings. Energy savings was proportionally split between the major CHP fuels and purchased electricity. The model assumed 1 FTE at $100,000 annually, growing at the rate of inflation. To achieve a sustained 2% campus-wide energy savings, the program would need to focus on high energy intensity buildings through a Green Labs program. The potential energy savings realized under this solution could pay for the additional costs 3-4x over.

Solution 3 – Strategic Energy Management

This solution was modeled as a group along with Solution 1 (Green Building and Renovation Standards) and Solution 6 (LTHW), Solution 7 (GHX). Solution 6 will dramatically change the campus energy supply and distribution system and will change the quantity, type and carbon-intensity of energy that could be avoided. For the purposes of this study, the team focused on near-term energy efficiency opportunities that would align with the LTHW conversion. Once the final stages of the LTHW system would be installed and operational, in order to avoid double counting the energy savings and the related carbon emission reductions, new SEM projects were modeled after 2030. It is likely UMA would continue this program, but

This solution proposes an early focus on “go-fast” thermal opportunities, like air-sealing, insulation and building heat-recovery projects, assuming $1 million dollars of projects deployed each year for 5 years. This program would also extend the recent Memorandum of Understanding (MOU) with Eversource which is largely focused on projects that avoid purchased electricity. This solution assumes 3 full cycles the Eversource MOU which would require about 1.2 million dollars for 9 years. Assumed electricity savings from future cycles were discounted with the assumption that savings would gradually become harder to achieve. Overall, this program would save roughly 5% of total campus energy relative to the BAU baseline.

Solution 4 – Chilled Water Expansion and Optimization

The Chilled Water Expansion and Optimization includes connecting the existing CHW districts and expanding the central cooling capacity to existing buildings. Interconnecting and expanding the existing CHW distribution network will require installation of approximately 22,000 feet of direct buried chilled water piping. New CHW utility piping will be installed over five phases starting in 2024 and ending in 2032. Phase 1 (2024) will connect the Mullins CHW district to a new central heat recovery chiller plant. Phase 2 (2026) will extend this CHW network to the Honors and Dubois CHW districts. Phase 3 (2028) will extend central CHW service to the Southwest residential area and connect the Whittemore CHW district. Phase 4 (2030) will interconnect the North and ISB CHW districts and Phase 4 (2032) will expand central CHW distribution to the North, Sylvan and Orchard Hill residential areas. Over this phasing period, the amount of air-conditioned space on campus will be increased from 5,600,000 GSF to approximately 10,000,000 GSF through building conversions that also convert heating systems from steam or high temperature hot water to LTHW. The added cooling capacity at the central plant will be provided through ground-source heating and cooling systems described later in this report. The chilled water piping phasing plan is included below in Figure 10.

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Solution 6 – Converting to Low-temperature Hot Water (LTHW)

Converting to LTHW will require the installation of a new campus wide LTHW distribution system and buildings conversions for all campus buildings currently served by central steam system. LTHW distribution piping will replace the existing steam distribution piping. The LTHW distribution piping will replace the approximately 141,600 feet of existing steam piping on campus. The steam piping will need to remain operational as the LTHW system is phased in. Once the LTHW system installation is complete, the new LTHW piping will be direct buried. New LTHW utility piping and building conversions will be installed over five phases starting in 2024 and ending in 2032, tracking with the CHW expansion phasing. The LTHW building conversion phasing plan is included below in Figure 11. Further cost breakdown of the building LTHW conversions is provided in Appendix K. The conversion to LTHW enables the trading of heat between buildings. For example, the heat rejected by a building in cooling mode, can be used by a building in heating mode. This simultaneous heating and cooling load represents approximately 36% of the total annual heating and cooling load for the campus.

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Solution 7 - Ground-Source Heating and Cooling (GHX)

Providing LTHW and expanded CHW service to the campus will require a new 8,750-ton heat recovery chiller central plant installed in a new mechanical plant building near the existing CHP facility. The heat recovery central plant will include seven 1,250-ton modular heat recovery chillers, distribution pumps for geothermal, LTHW and CHW and ancillary equipment. Geothermal heat exchangers would be installed at the athletic fields near the existing CHP facility. Installation could be phased to avoid disrupting all the fields at the same time. The geothermal heat exchanger system will require 2,490 bore holes, each 800 feet deep, spaced 20 feet on center. The geothermal heat exchanger layout, as indicated below Figure 12, requires 25 acres of existing athletic fields and parking lot. These areas will be returned to their current use after the geothermal heat exchangers are installed. A phased installation of the geothermal heat exchangers could allow for use of some athletic fields during construction, minimizing the impact on student activities. The geothermal heat exchanger installation can be completed in phases to match the phased installation of heat recovery chillers. The Ground source Heating and Cooling System, including the heat recovery chiller central plant and ground source heat exchangers, will cost approximately $96 million. Further cost breakdown is provided in Appendix L.

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Solution 8 - Wastewater Heat Recovery (HR)

The wastewater heat recovery system requires tapping into the sewage mains at or near the Town of Amherst Wastewater Treatment Plant. A new 12,000-gallon underground wastewater holding tank will be required and will collect wastewater near the treatment plant. A wastewater separator / filter temporarily removes solids from the wastewater before being passed through an application specific heat exchanger where thermal energy from the new heat recovery chiller central plant is extracted from or rejected to the wastewater, before being returned to the sewer mains.

A new mechanical building will be required at or near the wastewater treatment plant to house the new filtration system, heat exchangers and distribution pumps. The wastewater HR plant will be connected to the new heat recovery chiller central plant near the existing CHP facility via direct buried piping. The proposed wastewater HR layout is included below in Figure 13. The CMP assumes the wastewater HR system will be installed during the final implementation phase (2032), however this system can be installed any time after the new heat recovery chiller central plant is operational. The Wastewater HR systems will cost approximately $4.0M. Further cost breakdown is provided in Appendix M. The wastewater HR systems will reduce the geothermal heat exchanger size from 3600 to 3400 bore holes, reducing the ground source heating and cooling system initial capital costs by approximately $5.1M. The implementation of a wastewater HR system yields a net reduction of $1.1M over a ground source only system.

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Solution 9 - Air-Source Heating and Cooling

An array of air source heat pumps (ASHPs) installed outdoors, adjacent to the existing CHP facility will provide peak cooling and additional heating capacity for the campus. The ASHP array will consist of twelve 40-ton air to water heat pumps, capable of low ambient operation, providing approximately 2% of the 2030 heating load and 3% of the cooling load. The ASHPs will be connected to the new heat recovery central plant by direct buried piping. The proposed ASHP layout is included below in Figure 14. The Air Source Heating and Cooling System will cost approximately $2.6M. Further cost breakdown is provided in Appendix N.

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Solution 10 - Onsite Solar

This Solution shows the impact of a 3,000-kW onsite solar array procured through a Power Purchase Agreement (PPA). It was assumed 50% of the electricity displaces co-generation electricity demand while the other 50% displaces purchased electricity. The RECs generated by this project will be assigned to the local distribution company, which in turn will sell them in the market and reduce the overall cost of the program.

UMA already has about 5.8 MW of onsite solar installed. Since the project went operational in 2017 the developer retained ownership of the RECs, but starting in 2028, UMA can retire these RECs to help lower their Scope 2 emissions.

Solution 11 - Decentralized Modern Wood Thermal System

The modern wood thermal solution assumes providing individual biomass boiler plants for the Northeast, Orchard Hill, Southwest, and Sylvan Residential areas. Portions of the central steam distribution piping serving Sylvan, Northeast and Southwest are in fair to poor condition, according to a still in progress conditions assessment conducted by RMF. Under the BAU case, these steam lines would have to be replaced in the near term. These costs can be avoided by installing the decentralized modern wood thermal heating plants serving these building clusters. In the future, these biomass plants could be connected to the central LTHW distribution system to provide fuel diversity and system resiliency. This solution assumes biomass heating plant installations with the combined heating capacity of approximately 50,000 MBH at a cost of $12M with the potential to provide as much as 12% of the future campus heating load. Further cost breakdown is provided in Appendix O.

Solution 12 - Onsite Solar Thermal

A Solar Thermal Array will be installed at an existing lot, adjacent to the CHP facility. The solar thermal array will consist of 500 solar thermal collectors generating hot water year-round for campus heating. The solar thermal array will be connected to the new heat recovery chiller central plant. Considering the maximum output of the individual solar thermal collectors of 23.5 MBH, the proposed total installed maximum capacity of the solar thermal systems is 11,750 MBH. The solar thermal array is expected to produce approximately 7% of the 2030 campus heating load. The proposed solar thermal array layout is included below in Figure 15. The solar thermal systems will cost approximately $4M. Further cost breakdown is provided in Appendix P.

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Solution 13 – Renewable Fuel Oil (RFO) Boiler

UMA purchased and installed a packaged boiler in 2020 that is expected to be converted to allow it to burn renewable fuel oil in addition to natural gas and liquified natural gas. This solution assumes a $4.4M project for the necessary conversion and fuel storage in 2021. RFO could replace fossil fuels (largely LNG) for steam production during times of the year when the other boilers would normally be used. This solution assumes a capacity factor of about 28% in 2021 before the LTHW conversion is completed. After 2032, this boiler could be used as a thermal peaking asset, where the capacity factor would likely drop to as low as 15-20%. This solution makes two simplifying assumptions 1) the combustion of RFO would be considered biogenic and carbon-neutral on a short timescale and 2) the fuel would be considered renewable.

Solution 17 – Green Transportation / Fleet Electrification

This solution assumes a gradual shift of the fleet to plug-in battery electric, or other clean vehicles as the current fleet reaches the end of its life. Due to the de minimis scale of fleet emissions (just over 1% of total emissions), this Solution makes a simplifying assumption that this can be achieved at cost-parity by 2030.

Solution 18 – Renewable Energy Credits (RECs)

This solution assumes that UMA will procure enough RECs to achieve 100% renewable electricity starting in 2030. This will require a combination of retiring RECs from existing onsite solar and procuring RECs for grid purchases that are not already renewable through the Massachusetts renewable portfolio standard. This will require around 43,000 MWh of RECs in 2030 rising to a peak of approximately 49,000 MWh in 2032 as the proposed energy transition solutions come fully online. By 2050, this solution assumes that UMA will no longer need to purchase RECs since the grid will be 100% renewable. The price of RECs is assumed to be a $30/MWh premium. In practice, UMA is likely to procure a portfolio of renewable energy through one or more long-term power purchase agreements where the final cost to retain these RECs will be driven by the geographic location, technology, contract duration and scale and subject to market fundamentals. Further details on REC purchasing options are included in Appendix Q.

Solution 19 – Carbon Offsets

This solution assumes that starting in 2030, UMA will purchase carbon offsets for any remaining Scope 1 and 2 GHG emissions after all other solutions have been implemented. This would require UMA to purchase approximately 22,500 MTCO2e of offsets in 2030 and 2031. Once the final phase of energy transition projects come online in 2032, this amount will drop to 3,000-5,000 MTCO2e / year or less than 4% of UMAs 2019 emissions. The price of offsets is assumed to be $14 / MTCO2e in 2020 escalating at 5% / year which translates to a price of $22.80 in 2030 and $60.51 in 2050. This plan was created with a goal of eliminating the need for any carbon offsets, however, it is likely there will be some small quantity of hard-to-abate emissions even once the other solutions are fully deployed.

A Portfolio of Solutions

It is important to highlight that the Energy Transition Portfolio is more than a collection of individual solutions. Many of the technologies, if evaluated against the current UMA district energy system would not be financial or technical viable. As a group, these same Solutions have compounding benefits that can overcome these challenges. Conversely, some Solutions look very attractive in isolation, but when combined in a Portfolio they might erode the performance of other Solutions. The consulting team and CMTF members spent significant time during this process trying to understand where and how the various Solutions might interact most optimally. The following sections outline key insights learned by the team through modeling the aggregate interactions of multiple Solutions in the Energy Transition Portfolio.

Balancing Heating and Cooling Loads

The Energy Transition Portfolio seeks to improve the thermal balance of the campus to increase the amount of energy that can be met by renewable and carbon-free sources. Heat pump-based systems reach optimal performance when the system has a balance of heating and cooling energy demands. Heatrecovery chillers take advantage of simultaneous heating and cooling demands by moving heat between the chilled water and hot-water systems. GHX systems require an annual balance of heating and cooling to avoid degrading system efficiency by gradually heating up or cooling off the ground. UMA’s annual heating loads are currently much greater than the annual cooling loads. The following list summarizes the symbiotic technologies and operational tactics included in the Energy Transition Portfolio and how the different Solutions work together to improve this thermal balance.

• Building Policy (Solution 1) is designed to ensure that any new or renovated buildings are compatible with the LTHW system (Solution 6). More buildings connected to the centralized heating and cooling systems provide a greater diversity of load and help smooth system peaks and valleys.
   
• Energy Efficiency projects completed as part of the SEM program (Solution 3) include air-sealing and insulation which should help lower overall heating demands and improve system thermal balance.
   
• Chilled Water Expansion and Optimization (Solution 4) will help improve the balance by adding cooling demand. Adding energy demands to mitigate carbon emissions may seem counterintuitive but expanding the chilled water system will allow the overall system to capture more of the heat (Solution 6) that would have been rejected by traditional cooling towers and airconditioning systems. This heat can be redirected to other buildings using heat-recovery chillers or stored in the ground through the GHX system (Solution 7).
   
• A once very counter-intuitive concept discussed as part of the CMTF Energy Efficiency working group is to avoid “Free cooling.” “Free cooling” occurs when a building meets a cooling demand by pulling in outside air when outdoor temperatures are below the desired indoor temperature (e.g., an auditorium full of students during a crisp fall day). In the Energy Transition Portfolio, the system would benefit more (e.g., use less input energy) by using the chilled water system to “capture” this heat. The energy required to run a heat-recovery chiller (Solution 6) or the GHX heat pumps (Solution 7) is less than what is needed to generate this same heat through combustion.
   
• Onsite Solar Thermal (Solution 12) can meet a portion of the heating demand, pushing the campus closer to an annual thermal balance. · Wastewater Heat Recovery (Solution 8) and ASHPs (Solution 9) can meet a portion of both the heating and cooling demand. Neither technology requires a specific balance over the course of the year like GHX (Solution 7).
   
• During extreme cold weather, the decentralized modern wood thermal systems (Solution 11), if connected to the LTHW system, and/or central boilers using RFO (Solution 13), RNG or fossil fuels with carbon offsets (Solution 19) could help boost heating capacity when the relatively infrequent peak heating loads are not met by other Solutions.
   
• Finally, as average annual temperatures are expected to rise, UMA is expected experience more cooling demands and less heating demands on average which will also help lead towards an annual average balance of heating and cooling.

 

Implications for Energy Reliability

The Energy Transition Portfolio is essentially a form of campus “electrification” by phasing out the use of fossil fuel combustion as the primary fuel source and transitioning to technologies that are primarily powered by electricity. While this is a sound strategy from a carbon mitigation perspective, it does raise important system reliability questions. What happens if the grid goes down?

Currently, UMA has some ability to continue operating its CHP to deliver heating, cooling, and electricity to campus buildings during a short-term loss of electricity from the grid and/or during periods of natural gas curtailment. The scope of this plan did not specifically include evaluating UMA’s energy reliability. However, it was a topic of discussion that influenced the make-up of the Recommended Portfolio and related project phasing. The Energy Transition Portfolio expects that the current co-generation assets will continue operations, providing some self-generate electricity for at least the next 8-10 years and could conceivably remain longer in a back-up capacity. This is reflected in the near-term capital and operational cost assumptions (e.g., Energy Transition Portfolio includes the cost to keep core co-generation assets running for at least the next decade). Since this CMP is a long-range roadmap and not a detailed technical engineering study, the Energy Transition Portfolio does not include a detailed answer to what energy reliability would look like for UMA long term. That said, the following list highlight some key areas UMA should consider moving forward:

• How will UMAs reliability risks change? E.g.,
  • Power-outages vs. natural gas curtailment
  • Retirement of key staff vs. new (to UMA) technologies
     
• How can building system upgrades (for LTHW) also support the deployment of “smart campus” technologies to improve system intelligence and controls?
   
• Will or when will UMA need to increase its electricity import capacity?
   
• What is the role for expanding diurnal battery storage?
   
• Are there ways for grid assets to participate in wholesale power markets?
   
• How quickly will vehicle electrification and related charging infrastructure and electrical system occur?
   
• Is there opportunity to partner or contract with utilities and/or other third parties for energy reliability services?
   
• How can thermal energy storage help mitigate electrical peak demands?