The issue of refrigerants and Global Warming Potential has been at the forefront of climate regulation targeting cooling applications.
The discussion saw a major milestone in the Kigali Amendment which, in 2016, saw 197 countries agree to cut down on hydrofluorocarbons (HFCs) by more than 80% in the next three decades. An ambitious measure that, if successful, would mean avoiding +80 billion metric tons of carbon dioxide equivalent emissions (or up to 0.5° Celsius warming by the end of the century), according to EPA figures.
Meanwhile, rising cooling demand means the phasing out of any refrigerant with ozone depletion potential or GWP must necessarily be accompanied with alternatives for more sustainable refrigerants.
In this quest, companies are required to navigate evolving regulations targeting refrigerants used in chillers, while also looking for the right alternative to achieve compliant, sustainable cooling that is also cost-efficient.
Understanding the current context of refrigerants with Global Warming Potential and the low-emission alternatives thus represents a crucial first step towards building cooling systems that align with present and future environmental concerns.
Understanding Global Warming Potential (GWP)
What does GWP measure?
The term Global Warming Potential measures how much heat is trapped in the atmosphere by greenhouse gases when compared to CO₂ over a specific period of time. For the sake of compliance with most regulations, this time period is established at 100 years.
In other words, GWP aims at finding out how harmful substances are when it comes to atmospheric warming compared to CO₂. It also includes a time-specific framework so that “the GWP represents the combined effect of the differing times these gases remain in the atmosphere and their relative effectiveness in absorbing outgoing thermal infrared radiation.” (IPCC, 2007: Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change)
CO₂ acts as the baseline in GWP: this means it has a GWP of 1. From there, other gases can be assessed.
GWP applied to refrigerants
When it comes to refrigerants, Global Warming Potential is at the heart of discerning which substances have the greatest impact on climate change, thus identifying which refrigerants to avoid and which ones should be adopted moving forward.
GWP allows for an objective comparison of refrigerants with CO₂ and thus provides a measure of their potential for climatic harm. For instance, refrigerant R-410A has a GWP of 1,923.50 (AR5), meaning it’s almost 2,000 times more potent than CO₂ at warming the Earth over 100 years.
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How refrigerants contribute to climate change
Many substances used as refrigerants exhibit high GWP values, acting as powerful greenhouse gases capable of trapping more heat in the atmosphere than CO₂.
While refrigerants are employed in contained systems, their leak or accidental release across their lifecycle (from manufacturing, to installation, operation and beyond) is a main source of their negative climate impact. In fact, the CARB calculates “many of these [refrigeration systems] leak at the rate of 20% or even more per year –sometimes much more”.
Asides from leaks, improper management of the end cycle for refrigerants is also credited as a major source of environmental harm. In fact, according to figures by the COPA alliance, improper management and disposal of refrigerants translates into the release of approximately 1.5 Gt CO2-eq each year, which “corresponds to the annual greenhouse gas emissions of 441 coal-fired power plants.” Figures that lead the COPA to state that “reducing leakage and recovering refrigerants for future reuse has a far greater impact on our climate than the adoption of lower GWP refrigerants alone.”
As a result, designing protocols and systems where the occurrence of leaks and accidental release is minimized to the fullest represents a key movement in building the cooling systems of the future.
Other environmental concerns: lifecycle emissions
In order to understand the total climate footprint of a refrigerant, measures around Global Warming Potential should be accompanied by a look at a system’s lifecycle emissions.
Categorized as an indirect impact of cooling systems, lifecycle emissions refer to the CO₂ emissions originating from the equipment use.
Largely dependent on system efficiency and electricity source, the move away from fossil fuels towards more environmentally friendly cooling systems such as seawater cooling represents a promising transition.
High-GWP refrigerants: what are they and examples
High-GWP refrigerants are defined by the California Air Resources Board (CARB) as “all ozone-depleting substances and any refrigerant with a GWP of 150 or higher”, according to the IPCC's fourth Assessment Report (AR4).
High-GWP refrigerants have been targeted by environmental regulations such as the ones by the EPA and CARB, as well as the Kigali Amendment.
The list of high-GWP refrigerants evolves as new approaches to measure GWP emerge, taking into consideration the evolution of the IPCCs assessments. However, the CARB provides a publicly-available list of some of the most common high-GWP refrigerants, including:
- R-22: one of the most common high-GWP refrigerants, it exhibits a GWP of 1,760.00 (AR5), so that, according to CARB, “just one pound of R-22 is nearly as potent as a ton of carbon dioxide.” Asides from the GWP, the negative impact of R-22 is also due to its Ozone Depletion Potential (ODP), which means the production of R-22 has been targeted since the Montreal protocol. According to EPA documentation, R-22 can no longer be produced or imported to the US from 2020, and manufacture of new equipment for this refrigerant is banned.
- R-404A: a common replacement for R-22, this substance is “more than twice as potent a greenhouse gas than R-22”, so that “one small canister of R-404A is as potent as annual fuel for 8 cars”, according to the CARB.
- R-410A: a blend of HFC refrigerants, it has also been employed as an alternative to R-22. With a GWP of 1,923.50 (AR5), it also stands among high-GWP refrigerants.
- R-507A: another common replacement for R-22, the CARB warns “it has been identified by both California and the U.S. EPA for future restrictions because of their high GWP value.”
Regulatory efforts surrounding refrigerants and Global Warming Potential
The Kigali Amendment
An international agreement that amended the Montreal Protocol with the aim of phasing down the production and consumption of hydrofluorocarbons (HFCs).
The Montreal protocol originally focused on phasing out CFCs and HCFCs for their Ozone Depleting Potential. With the Kigali Amendment, the targets were HFCs: the gases developed as alternatives to substances covered in the Montreal Protocol and which later were acknowledged for their Global Warming Potential.
As part of the Kigali Amendment, countries agreed on a timeline for gradually minimizing HFCs, with the aim of achieving a reduction between 80-85% by the late 2040s. However, different timelines were acknowledged for developing countries, so that the freeze for HFCs in some countries could start in 2028.
IPCC
The Intergovernmental Panel on Climate Change doesn’t develop regulations regarding refrigerants used in chillers, but has been and continues to be instrumental in defining GWP values.
At the time of writing this article, the most updated GWP values were those related to the IPCC’s Sixth Assessment Report (AR6). However, for compliance and reporting purposes, AR4 and AR5 might still apply.
The US Environmental Protection Agency (EPA)
The US Environmental Protection Agency has set different norms that apply to refrigerants.
The Clean Air Act introduced important measures such as the SNAP (Significant New Alternatives Policy) Program, which determines acceptable and unacceptable refrigerants as well as a timeline for phasing out high-GWP refrigerants.
The American Innovation and Manufacturing (AIM) Act is also crucial as part of regulation phasing out HFCs, and mandates a 85% phasedown of their production and consumption by 2035.
California Air Resources Board (CARB)
The Refrigerant Management Program was established as part of the California Global Warming Solutions Act of 2006, and determines a series of requirements for reducing emissions related to high-GWP refrigerants.
According to official sources, this regulation establishes “a more rapid reduction in HFC use is required than specified in the Kigali Amendment”, with Senate Bill 1383 2016 requiring a 40% reduction in statewide HFC emissions below 2013 levels by 2030.
Acceptable refrigerants as per EPA and CARB
Both the US Environmental Protection Agency and the California Air Resources Board have provided resources for understanding what are the alternatives for phased out refrigerants.
- The EPA offers different lists for acceptable refrigerants depending on the application. Some of the available sources include refrigerants for motor vehicle air conditioning, substitutes for industrial process refrigeration, and substitutes in refrigeration and air conditioning.
- Rather than a list of alternatives, in 2024, the CARB published the following list of phased out refrigerants:
- HFC-blends
- R-410A
- R-404A
- R-134A
- R-407C
- R-22
It has also introduced several GWP limitations for certain contexts. Generally speaking, from 2024, the use of refrigerants with a GWP greater than or equal to 2,200 is prohibited, but the article linked above includes a detailed look at particular cases.
Moving forward: what are the available low-GWP alternatives today?
Role of HFOs and natural refrigerants
HFOs and natural refrigerants stand out as the two key alternatives moving forward to comply with environmental regulations and move away from high-GWP substances.
On the one hand, HFOs (hydrofluoroolefins) represent a new type of synthetic refrigerants that have been presented as low-GWP alternatives. As such, their GWP values typically are less than 10 and most have Ozone Depleting Potential values of 0 or nearly 0. Examples of HFOs include R-1234yf, R-1234ze(E) and R1233zd. One of their significant advantages is that HFOs can often be employed without requiring a full system redesign.
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At the same time, it’s worth noting the CARB mentions “unresolved environmental concerns regarding HFO refrigerants such as regarding trifluoroacetic acid (TFA) buildup in water bodies.” As such, HFOs are understood as a bridge solution between earlier, more polluting refrigerants and the implementation of cooling solutions where natural refrigerants take the lead.
Natural refrigerants, on their part, are naturally occurring substances that offer low or zero GWP, as well as good energy efficiency and growing regulatory support. Some of these include carbon dioxide, ammonia, water and hydrocarbons like propane and isobutane.
These substances are thus offering promising pathways to reduce greenhouse gas emissions and comply with environmental regulations.
Challenges for adoption
The transition towards low-GWP refrigerants involves a series of challenges related to the transformation of cooling systems to adapt to these substances.
When looking at these challenges, it’s important to note each alternative presents its own opportunities, limitations and requirements. However, the following list includes some of the common issues that can arise during the transition:
- Requirements for specialized equipment and specific system design. Such is the case of operation of CO₂, which must take place at high pressures and which requires equipment changes and may be incompatible with certain cooling systems.
- Specific safety measures. For instance, hydrocarbons and certain HFOs are flammable, requiring specific safety protocols, while the toxicity of ammonia also calls for strict handling procedures.
- Applicable compliance regulations. Certain substances acting as alternatives to high-GWP refrigerants might be subject to their own regulatory compliance requirements. Such is the case of ammonia and hydrocarbons, which are bound by safety standards.
These aspects involve initial investment costs for transforming cooling systems, which emerge as a challenge of their own even with the prospect of long-term savings due to some alternatives’ energy efficiencies. In this regard, it’s essential to explore potential incentives and grants for retrofitting cooling systems to determine their applicability in each project.
Other technologies and trends helping in the transition to sustainable cooling
As mentioned above, the transition towards more sustainable cooling must necessarily incorporate measures that go beyond simply replacing one refrigerant with another.
Strategies must target refrigerants, but also understand the key role of designing cooling systems that are more energy efficient, thus also targeting the lifecycle emissions related to cooling.
As such, the following technologies are emerging as key allies in making cooling more sustainable and compliant with environmental regulations:
- Industrial heat pumps: this piece of equipment’s basic working principle is to transfer heat from a source to a sink following a refrigeration cycle. Hailed for their outstanding energy efficiency, they can be employed both for heating and cooling and incorporate renewable energies for large-scale projects such as district cooling. A number of heat pump grants are available to support their implementation.
- District cooling: these systems rely on a centralized plant to distribute cooling energy to a network of buildings or consumers. Paired with low-emission energy sources, this centralized approach to cooling offers increased efficiency and lower operational costs.
- Thermal Energy Storage (TES): a technology that aims at storing thermal energy produced during off-peak hours for providing cooling during peak demand. This approach offers key efficiency improvements and cost reductions.
The future of refrigerants and climate responsibility for cooling systems
Increasing environmental regulations and major shifts in consumer environmental sensibilities mean that companies today must aim at achieving sustainability across all aspects of their business.
Regulations are driving rapid changes when it comes to refrigerants and Global Warming Potential, a context that means natural refrigerants are experiencing increasing traction.
As seen above, their implementation requires an analysis that incorporates notions around technical feasibility, costs and compliance, a step that will engage many operators now and in the foreseeable future. In the meantime, hybrid approaches that incorporate HFOs or reclaimed and natural refrigerants are expected to provide a bridge solution.
But optimizing cooling systems for top sustainability goes beyond that. Leak detection and control protocols are also becoming increasingly important, and so are the key cooling technologies mentioned above, capable of pushing energy efficiency to new levels.
In this quest, ARANER stands out as a key ally for operators looking to comply with environmental regulation and build cooling systems that are both sustainable, safe and cost-efficient.
Through our thermal engineering expertise and a close collaboration with developers and planners, we create tailored district energy solutions that fit each project’s needs. As such, we play a role in helping operators navigate current regulatory requirements and make the right strategic decisions for their cooling needs.
Want to learn more? Discover some of our key cooling projects around the world and get in touch with us to speak to our team about how we can help you.
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