An ammonia-based approach to chilling for pharmaceutical manufacturing

Cooling technology is a critical component of pharmaceutical manufacturing, as it aids in controlling process temperatures, keeping equipment in good working order, and maintaining environmental conditions on-site. While a number of substances and technologies have been utilised in cooling over the years, ammonia has seen a recent resurgence because of its relative efficiency and minimal environmental impact.

As part of its efforts towards achieving complete carbon neutrality, Sterling partnered with KGM Refrigeration to pilot ultra-low charge ammonia chilling technology at its Cramlington, UK manufacturing site. The technology relies on much lower volumes of ammonia than traditional ammonia-based cooling methods, resulting in greater energy efficiency and lower costs. This partnership has enabled KGM to validate the chiller’s results, while providing Sterling large energy savings and supporting its sustainability objectives.

In this whitepaper, we’ll compare ammonia-based chilling to other standard methods, explore how this new solution differs from other ammonia-based cooling technologies, and discuss some of the results Sterling and KGM have experienced.

Comparing ammonia-based chilling to other methods

Ammonia has been utilised in cooling for nearly two centuries, but increased environmental urgency has been a key contributor to its recent resurgence. In particular, synthetic-based cooling methods were previously widely adopted, but regulations have phased them out because of their ozonedepleting potential (ODP). Let’s take a closer look at some alternative cooling methods and how they compare to ammonia.

CFCs and HCFCs are known to be excellent refrigerants that are chemically stable, and non-flammable. However, these substances have been phased out in the last several decades as a result of their impact on the ozone layer, and CFCs are now known to be acutely toxic. In the US, for example, CFCs have already been phased out, while all HCFCs will be phased out by 2030 due to their ozone-depleting potential. In the UK, both CFCs and HCFCs are banned. This has required individuals and organisations to transition to refrigerants that are less harmful to the environment.

Like CFCs and HCFCs, HFCs are efficient and stable refrigerants with high heat capacity. While they do not pose the same risk to the ozone layer, they are greenhouse gases that demonstrate high global warming potential (GWP). Consequently, actions have been taken to reduce dependency on HFCs in many regions.

Carbon dioxide R744 has seen increased use in refrigeration because it is non-toxic, easy to obtain and has low ozone-depleting and global warming potential. However, it requires high pressures for effective cooling, resulting in lower energy efficiency, and it is an asphyxiant gas.

As a natural refrigerant, ammonia is known for its heat transfer properties, efficiency and sustainability. It has no global warming or ozone-depleting potential. It also comes with low operating costs compared to other refrigeration methods and operates under moderate pressure. In addition, leaks are much easier to detect than other refrigerants like CO₂. However, ammonia can present safety risks when handling large concentrations, and is flammable under certain conditions. As a result, cooling techniques that use limited amounts of ammonia are ideal.

An innovative, safe and sustainable approach to ammonia-based chilling

Ammonia’s inherent drawbacks as a chilling mechanism are its levels of toxicity and flammability. However, by reducing ammonia charges and implementing additional controls, organisations can realise the advantages of ammonia-based cooling while mitigating the safety risks involved.

As part of its focus on environmental sustainability, Sterling partnered with KGM Refrigeration to pilot its 150kW ultralow charge ammonia chilling technology at its Cramlington, UK site. As the chillers are compact and lightweight, they can be mounted on a production plant roof, avoiding the need for additional risk mitigation measures that come with using ammonia-based cooling indoors. ... Read more

The results

Since Sterling began using the technology in August 2022, it has run for over 5,000 hours while operating as designed. Sterling has saved over 65% on electrical energy costs compared to other chillers, demonstrating significant financial and environmental advantages.

After a successful pilot programme, Sterling is now planning to roll out the use of these chillers across its network. In addition to enhancing energy efficiency and mitigating environmental impact, these chillers will aid Sterling in futureproofing against the phase-out of other common refrigerants.

An unwavering commitment to sustainability and innovation

The installation of the ultra-low charge ammonia chiller, in partnership with KGM Refrigeration, has allowed Sterling to reduce costs while increasing energy efficiency. It represents just one initiative in Sterling’s work towards achieving complete carbon neutrality.

At Sterling, innovation and environmental sustainability go hand-in-hand. We continue to adopt new technologies that aid in measurably reducing emissions and explore new ways to reduce our carbon footprint. ... Read more

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