Carbon Mitigation Solutions, Portfolios and Strategies

The term Carbon Mitigation Solution in this plan refers to a set of specific projects, policies, technologies, procurement decisions, and/or other operational and infrastructure changes that will help the UMA campus avoid, reduce, and offset greenhouse gas (GHG) emissions relative to the campus business-as-usual (BAU) actions. The term solution sometimes refers to a single technology (e.g., Solar Thermal), but more often will refer to multiple actions under a common theme (e.g., Strategic Energy Management). During the modeling and analysis phases of this planning effort, Solutions were not created in isolation, but rather modeled as a part of an integrated portfolio of solutions.

The term portfolio in this plan refers to a group of solutions that were evaluated together. Each portfolio includes a set of forecasted financial, energy and GHG impacts based on the aggregate impact of its solutions. For example, some solutions achieve carbon reductions by reducing fossil fuel consumption while increasing the need for grid electricity. Other solutions reduce emissions through energy efficiency efforts in the buildings, lowering the fuel required to run the central supply equipment. The portfolio approach allowed the modeling to account for these interactions and their implications for reaching carbon neutrality. For example, the portfolio calculations include adjusting the total requirement for clean electricity. It also calculates demand reduction before calculation of the emissions that could be avoided by switching to a renewable fuel.

The term portfolio and strategy are used somewhat interchangeably in this plan. Strategy refers to the overarching guiding approach and portfolio refers to the specific collection of solutions. During the planning process two macro level strategies were evaluated using the following portfolios:

Portfolio: Current System with Renewable Fuels & Offsets

This portfolio looked at solutions that could make incremental changes to the current campus steam-based district energy system. This portfolio focused on aggressive efficiency, fuel switching and offsets.

Portfolio: Energy Transition

This portfolio imagined a complete transformation of the UMA campus district energy system enabled by a transition from steam to a low-temperature hot-water system.

Upside down pyramid Avoid, Reduce, Replace, Offset
Carbon Management Hierarchy

The Solutions that were modeled as part of these two strategies were selected for their potential to reduce carbon emissions under the right circumstances. However, there is a logical order for how Solutions would be sequenced. For example, solutions that avoid or reduce the need for energy and the related greenhouse gas (GHG) emissions which often also save money, are prioritized ahead of solutions that offset emissions at a cost premium. This load-order, commonly known as the Carbon Management Hierarchy3, was used by the CMTF to help create a comprehensive and cost-effective long-term plan.

The following provides a high-level overview of the solutions considered as part of this planning effort.


Solution 1 - Green Building and Renovation Standards

High-Performance Buildings: Passive energy, Integrated Solar, Water Management

The Green Building and Renovation Standards solution uses policies for new buildings and major renovations to employ “green building”, net-zero and/or high-performance design criteria aimed at reducing building energy use. These measures include requirements that improve the quality of the building’s envelope, HVAC, lighting, and other mechanical systems to reduce its cooling, heating and electricity demands. These design elements are much more cost-effective to install or integrate during construction and can dramatically lower the operational costs for the lifetime of the building. These policies help ensure these features are not value-engineered out of the design. This solution was informed by the work of the CMTF sub-committee on Policy. Key elements of this solution include:

  • A requirement that new and renovated buildings are designed to be compatible with a future low-temperature hot water district energy system.
  • A Sustainable Development Policy including all development, redevelopment, and remodeling shall incorporate sustainable design principles that reduce the overall campus carbon emissions.
  • Establishing a Central Fund for Energy Efficiency to provide financial support energy efficiency measures.


Solution 2 - Behavior Change

The Behavior Change solution seeks to achieve energy savings and greenhouse gas emissions reductions by changing the actions of building occupants through campus policies, education, and outreach. This solution is based on the idea that a multitude of small changes in behavior, such as shutting off lights, eliminating “phantom” loads or closing laboratory fume hoods when not in use, can reduce energy demand one human decision at a time. This solution envisions an investment in staff to run communication and outreach programs to ramp up these efforts and monitor their success. Past examples of behavior change programs at UMA include Energy Dashboards, Green Games and Green Office programs.4 While UMA should continue these efforts, this plan recommends UMA focus on energy-intensive activities, especially in laboratory spaces which can use 4 to 5 times more energy per square foot than a typical office or classroom space. Green lab programs include ideas like procurement policies requiring high-efficiency or EnergyStar ultra-low temperature freezers, education initiatives like a “close the sash” campaign or a Green Labs Certification program.

Green Labs: Energy Management, Waste Management, Safe Chemicals


Solution 3 - Strategic Energy Management (SEM)

Strategic Energy Management (SEM) is a broad array of programs, policies and infrastructure improvements that can help a campus to reduce energy use and reduce operation and maintenance costs for existing buildings. SEM includes a variety of building retrofit projects; the development of supporting operations and maintenance procedures to maintain energy savings over time. The three legs of the SEM stool are 1) staff focused on project execution, 2) robust measurement and verification processes and 3) a reliable funding source. This solution expands on current energy efficiency efforts at UMA including the recent Memorandum of Understanding (MOU) and related financial incentives from the utility Eversource. This solution assumes dedicated staff and a continuous investment in cash-flow positive energy efficiency projects that can reduce building energy demand by at least 25%. SEM is often the most cost-effective solutions since saving energy saves money and avoids emissions. The scale of SEM’s carbon mitigation impact will decrease as UMA deploys more clean, renewable energy; however, SEM projects will continue to provide value through avoided energy (electricity) costs and other co-benefits such as thermal comfort and improved indoor air-quality.


Solution 4 - Chilled Water Expansion and Optimization

This solution assumes existing district chilled water systems and independent building cooling systems will be expanded and connected to form a larger centralized chilled water system for the campus. This will be accomplished through the installation of new chilled water utility distribution piping and expansion of existing chilled water plants. Higher efficiencies, better utilization of chilled water capacity and increased resiliency and redundancy are all direct impacts of transitioning to a centralized chilled water system. UMA is currently evaluating interconnecting chilled water districts as part of the Sustainable Thermal Energy Storage project. The centralized chilled water system, when coupled with the low temperature hot water system, will allow for the use of heat pumps and heat recovery chillers to provide simultaneous heating and cooling to the campus.


Solution 5 - Expand Cogeneration Capacity

When the CMP started, UMA had an empty bay in the Central Heating Plant that could be utilized to expand the electric generation (and/or steam production capacity). Proposals put forward in the 2015 Comprehensive Energy Plan proposed the installation of a new 8 MW Combustion Turbine Generator (CTG). The 8 MW CTG would also increase steam generation capacity. Such an expansion would also increase the need to combust additional natural gas, and other fossil fuels which would, in turn, increase greenhouse gas emissions and require additional air permitting. While this solution was considered, it was ruled out by the modeling team since this is no longer a viable carbon reduction strategy given that the carbon intensity of grid electricity is now lower than what could be achieved through this expansion. In addition, new central plant equipment has been installed in the expansion bay.


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

This solution transitions the current steam-based campus district heating system to a low-temperature hot water system. This phased transition would require numerous building-level equipment conversions, replacement of the central steam generating equipment and the installation of new hot-water distribution piping on campus. Low-temperature hot water systems operate between 120-140°F. They require less input energy and have lower heat losses in the distribution system relative to traditional steam-based systems. In a LTHW system, supply water is distributed via the piping network at temperatures much lower than steam. The LTHW supply temperature is closer to the temperature of the surrounding area (e.g. the ground) which reduces the heat loss in the distribution system. LTHW systems also enable the integration of high-efficiency equipment and renewable heating sources, such as heat pumps, heat recovery chillers, solar-thermal arrays, and ground-source heating wells, allowing the system to move and reuse heat instead of making it twice. This concept of simultaneous heating and cooling can also be described as “heat trading.”

Heat Trading - Trading heat instead of making it twice: Network of Buildings, Low-Temperature Hot Water, Simultaneous Heating and Cooling

The LTWH solution is the linchpin of the Energy Transition Portfolio and represents an operational paradigm shift for UMA, transitioning from fossil fuel produced steam to the electrified generation of LTHW. The CMP assumes a five-phase transition to LTHW beginning in 2024 with the final phase completed in 2032. This phased approach assumes the current cogeneration system would continue to operate at the current capacity in early phases. In later phases of the transition, cogeneration assets could remain for backup and resilience reasons, but the primary source of heating would come from heat recovery chillers and heat pumps. Electricity would come from renewable grid purchases. This solution assumes about 22% of the 2032 campus heating load and 35% of the campus cooling load could be met through simultaneous heating and cooling or “heat trading” enabled by this conversion. Additional information on the simultaneous heating and cooling system capacity can be found in the Energy Transition Portfolio section later in this report.


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

Geothermal Ground Source Heating and Cooling - using the ground as a heat source and heat sink - two major types: Vertical Deep bore holes or wells and Horizontal pipes bured 5+ feet under a field or open space

A ground-source heating and cooling system transfers heat to and from the ground. Ground source heat exchangers (GHX) use the relatively stable temperatures of the earth as a heat source in the winter and as a heat sink in the summer. A ground source heating and cooling system consists of water-to-water heat pumps and heat recovery chillers coupled with a geothermal bore field heat exchanger used for campus district heating and cooling. This technology is best suited for a low temperature hot water system rather than the current high-temperature steam system or high temperature hot water system since heat pumps and heat recovery chillers generate low-temperature hot water more efficiently.

A GHX system can displace the need for fossil fuel combustion and the associated emissions assuming the input electricity required for heat pump operation and distribution pumping comes from a carbon-free electricity source. The GHX solution in this plan assumes a system consisting of the following:

  1. A well field of ground-source heat exchangers installed in large open areas on campus such as athletic fields or parking lots.
  2. Distribution piping and pumps.
  3. Water-to-water heat pumps and heat recovery chillers located at the CHP and district chilled water plants. This solution assumes a GHX system that could provide UMA with about 20% of the 2032 heating load and 51% of the campus cooling load. Additional information on the GHX system capacity can be found in the Energy Transition Portfolio section later in this report. The remaining heating and cooling for the campus would be provided by the additional solutions described below.


Solution 8 - Wastewater Heat Recovery (HR)

A wastewater Heat Recovery (HR) system can extract heat from or reject heat to a municipal sewer system. This solution will operate in tandem with the ground source heat exchange system and will utilize the nearby Town of Amherst Wastewater Treatment Plant as an energy source / sink for the water-to-water heat pumps in lieu of the ground. This solution will reduce the size of the geothermal bore field and, because wastewater HR systems are less capital intensive than ground source heat exchange systems, will reduce the overall capital investment for the project. The reduced geothermal heat exchanger will also require less space on campus to install. The wastewater HR solution will result in a 6% smaller ground source heat exchanger and yield a net cost reduction of over 1 million dollars.

Wastewater heat recovery systems require coordination with the municipal sewer system to ensure that the incoming wastewater flow rates and temperatures to the treatment facility are maintained so that water treatment is not negatively impacted. The Town of Amherst Wastewater Treatment plant can establish a rate structure based on the annual or monthly amount of energy transferred between the UMA wastewater HR system and the sewer.


Solution 9 - Air-Source Heating and Cooling

An Air Source Heat Pump (ASHP) is a heating and cooling system that transfers heat to and from the outdoor air using a compressor and a refrigerant in a closed loop system. This solution assumes a series of ASHPs could provide UMA with about 2% of the 2030 heating load and 3% of the cooling load. While ASHP are not as efficient as GHX systems, it would provide a more capital-efficient capacity alternative to a GHX system sized to meet system peaks which occur during limited hours of the year.


Solution 10 - Onsite Solar Thermal

This solution envisions one or more solar hot water panel arrays that would produce hot water to be distributed to the campus for heating. Solar hot water panels can be installed on roofs, parking structures and can also be surface mounted on grade. In addition to the solar hot water panels new distribution pumps and piping will be required to connect the panels to the campus hot water distribution systems (Solution 6). The solar thermal system would reduce the need for fossil fuel combustion. This solution assumes a solar thermal system with capacity to provide about 7% of the 2030 campus heating demand.


Solution 11 - Decentralized Modern Wood Thermal System

Decentralized biomass boiler plants would be installed to provide heating hot water to single buildings and clusters of buildings on the perimeter of campus. A modern wood-thermal system can use locally resourced pellets or semi-dried wood chips as a fuel-source which can be stored in onsite storage silos outside the building. Modern wood-thermal systems can be fully automated and have sophisticated emissions controls, including particulate and ash removal. These decentralized plants could be connected to the LTHW system to boost to system capacity or temperature during periods of peak demand, providing an important diversification of energy sources. This solution would produce emissions so UMA would need to source fuel from a source that could be considered carbon-neutral on a short time scale. For purposes of this study biomass was treated as a renewable fuel that would produce biogenic emissions which would be excluded from Scope 1 emissions. This solution considered providing biomass boiler plants for the Northeast, Orchard Hill, Southwest and Sylvan Residential areas.


Solution 12 - Onsite Solar Photo-Voltaic (PV)

Solar Photovoltaics: Rooftop solar, ground solar, parking lot canopy solar

An onsite solar PV array works by absorbing sunlight and converting the useful energy into an electrical charge, providing local generation. The electricity generated from the solar PV array will directly reduce the amount of electricity that would otherwise be purchased from the grid or provided from onsite generation. The campus currently has 5.5 MW operational and another 3 MW of onsite solar PV in negotiations and design.


Solution 13 - Renewable Fuel Oil (RFO) Boiler

In the fall of 2020, UMA installed Boiler 500 in the CHP. This packaged boiler has the capacity to burn natural gas and or ULSD to produce steam. This boiler is scheduled to be modified to allow the boiler to burn Renewable Fuel Oil (RFO). RFO is a cellulosic biofuel produced through refining wood waste collected from commercial forestry operations. The prioritization of boilers within the CHP could be revised, to displace fossil fuel use in other boilers, reducing non-biogenic GHG emissions. Federal and state incentives will provide financial support for RFO when used for heating, however the incentive is not available for systems that also produce electricity. With the incentives, RFO is a cost-competitive alternative to LNG. Based on the capacity of this boiler and the limitation of the incentives, this solution assumes RFO will displace a modest 5% to 7% of campus stationary fossil fuel use. There are open questions about the carbon accounting of all biofuels. For purposes of this study RFO was treated as a renewable fuel that would produce biogenic emissions which are excluded from Scope 1 emissions.


Solution 14 - Thermal Energy Storage (TES)

UMA is currently studying the installation of a diurnal Thermal Energy Storage (TES) system as part of the North / LRGC chilled water district. This system would allow UMA to produce chilled water at night when outside-air temperatures are cooler, and electricity is less expensive. Stored chilled water could then be used during the peak times of the day, expanding the chilled water system capacity without adding additional chillers. TES also would allow UMA staff more operational flexibility to optimize use of existing chillers. This plan does not specifically model any carbon impacts from diurnal TES since it is not inherently a carbon mitigation strategy. However, assuming a TES system is installed, it would provide additional flexibility for the energy system envisioned for the Energy Transition Portfolio.

The CMTF did explore the concept of seasonal thermal energy storage, which captures heat energy in the summer to be used in the winter. At UMA there are areas with a 100 ft deep layer of saturated clay, with minimal ground water movement and high soil conductivity which all contribute to a favorable geological condition for a Borehole Thermal Energy Storage (BTES) system. A BTES would be comprised of a heat exchanger, similar to a geothermal heat exchanger, that would charge the clay with hot water in summer and later extract this heat in the winter for use in the LTHW distribution system. The BTES has the potential for significant carbon emission reductions assuming the energy used to charge the clay was produced by a renewable thermal energy source (e.g., solar thermal panels).

There are limited examples of this technology in production and there are currently no known installations at the scale of the UMA campus; therefore, seasonal TES has not been included in our recommended portfolio nor modeled for carbon emissions reductions. The CMTF does recommend additional research into this promising technology, which could provide UMA with an additional carbon-free thermal energy that is compatible with the proposed LTHW system.


Solution 15 - Anaerobic Digester (AD)

Anaerobic digestion is a process used to breakdown organic materials such as animal waste and other biogenic source to produce biogas. This process takes place in a sealed tank called an Anaerobic Digestor. Biogas is a form of gas composed of hydrocarbons, typically a mixture of mostly methane and carbon dioxide. Biogas forms as a natural breakdown process of organic waste through bacteria. Sources of biogas include organic wastes such as food scraps, yard waste, and animal manure, though it can also be found in landfills and wastewater treatment plants. Pipeline Quality Biogas is biogas that has been processed to remove water and impurities so it can be directly injected into a natural gas pipeline.

UMA has previously studied the viability of installing an Anaerobic Digester to process organic waste from the campus and generate electricity with the biogas produced. However due to the large industrial nature of such a project, the physical space requirements, flood zone issues, and unfavorable electricity pricing these efforts have not advance beyond the initial studies. There are still opportunities for UMA to partner with existing anaerobic digestor facilities in the region to process campus biogenic waste streams. It is not clear that such a partnership would yield a direct carbon reduction to UMA since the renewable attributes of the biogas produced would likely be sold by the partner to fund the venture. The CMTF and consulting team did review these previous studies and modeled the potential impacts of an Anaerobic Digester. Ultimately this solution was not included in the recommended portfolio due to the uncertainties mentioned above.


Solution 16 - Pipeline Quality Biogas

Pipeline Quality Biogas waste sytsems transferred to an anaerobic digestor

The Current System with Renewable Fuels and Offsets Portfolio does include a solution to purchase Renewable Natural Gas in the place traditional natural gas starting in 2030 and beyond. This solution does not assume UMA would make any physical changes to the CHP. Instead, UMA would purchase and retire Renewable Identification Numbers (RINs)5 from a pipeline quality biogas project to offset the emissions associated with natural gas combustion. This would likely require UMA to pay a significant premium above the natural gas commodity and delivery charges. There are open debates regarding the scalability and carbon-neutrality of biogas. This solution was evaluated to understand the potential costs, benefits, and challenges as part of a renewable fuel strategy. However, neither the Current System with Renewable Fuels and Offsets Portfolio nor Renewable Natural Gas are being recommended given the uncertainties mentioned above.


Solution 17 - Green Transport / Fleet Electrification

This solution proposes replacing the existing diesel and gasoline fleet vehicles with electric vehicles (EVs) as fleet vehicles reach the end of their useful life or as additional vehicles are being procured. UMA has an opportunity to lower the life-cycle costs of the campus fleet by electrifying passenger vehicles, vans, and light-duty trucks. This solution assumes that the additional electricity required to charge vehicles would come from a renewable source.


Solution 18 - Renewable Energy Credits

Renewable Energy Credits from various sources sent back to the powergrid

According to the GHG accounting protocols, UMA is responsible for the emissions associated with purchased electricity, also known as Scope 2 emissions. To eliminate Scope 2 emissions, UMA must acquire and retire enough Renewable Energy Credits (RECs) to match total electricity purchases. A REC represents the renewable attributes of 1 MWh of electricity. This plan assumes UMA will purchase enough RECs to match total purchased electricity by 2030 and beyond.

UMA’s options to acquire and retire RECs are as follows – (1) UMA can purchase RECs from existing generators through spot purchases or under short-term contracts, (2) UMA can retire RECs for onsite solar PV arrays which they have ownership of, or (3) UMA can purchase RECs from new generation projects under one or more long-term agreements. These options have varying cost, additionality, geographic, and contracting characteristics that will need careful consideration by UMA.


Solution 19 - Carbon Offsets

Carbon Offsets putting money back into offset projects

Carbon offsets, also referred to as Verified Emissions Reductions (VERs), represent a unit of carbon dioxide-equivalent that is reduced, avoided, or sequestered and claimed to mitigate increases in global greenhouse gas emissions by offsetting Scope 1 and/or Scope 3 emissions being generated elsewhere. The concept of carbon offsets is based on the notion that reducing greenhouse gas emissions by financially supporting an offset project has an equivalent global emissions outcome as reducing an entity’s own emissions footprint through direct changes in operations and energy consumption.

Entities purchase carbon offsets to be able to claim carbon neutrality, which implies the purchased offsets’ avoided emissions equal to the purchaser’s own Scope 1 and Scope 3 emissions, plus REC purchases to offset Scope 2 emissions, for a defined period, typically by year. Carbon offset projects span a broad variety of actions that can be taken to avoid or sequester carbon emissions, including landfill gas capture and destruction, organic waste composting, coal methane capture, agricultural methane capture, ozone depleting substance capture, and tree planting.


Solution 20 - Carbon Capture and Storage (CCS)

Carbon Capture and Sequestration is a process that uses a series of technologies to extract carbon dioxide (CO2) from industrial processes or directly from the atmosphere. The captured CO2 is compressed, transported, and injected into underground geological sites for permanent storage (sequestration). In theory, CCS holds the promise to reduce CO2 emission 80-90%6 from the combustion of coal, natural gas, or other fossil fuels. However, this technology is not yet commercially deployed outside of the oil industry where injected CO2 is used to boost oil production, a process known as enhanced-oil recovery. The CMTF discussed this technology but ruled it out as a nonviable option for UMA at this time.