We All Know Where
Data Center Demands
Are Heading – Up.
We also know what’s driving the demand: continual changes in rack density (heat and power) to keep pace with high-performance computing trends, including artificial intelligence and machine learning.
But there’s a problem. Traditional technologies like Rear Door Heat Exchanger (RDHx) and Liquid to Chip (LTC) are merely band-aids for legacy air cooling, and can only take heat rejection, power requirements and future flexibility so far.
Intel, NVIDIA, and AMD are producing chips running at 400, and soon to be 500, watts.
What’s the Answer? For CGG, It Was Single-Phase
Immersion Cooling
In 2010, global geosciences leader CGG dove into single-phase immersion cooling and hasn’t looked back. At the time, its aging 10,000-square-foot legacy data center in Houston, Texas had been mothballed due to obsolescence – suffering from a limited available power envelope and an extremely inefficient Power Usage Effectiveness (PUE) of >2.0. CGG’s goal was to retrofit the data center without any downtime to other systems or their network, minimize capital expenditures by deferring them over time, and limiting ongoing OPEX.
After careful analysis and consideration, CGG selected GRC’s patented immersion cooling solution, ICEraQ®, due to its unique ability to meet all its stated goals. The tailored solution included 4 x 42U racks with a 100 kW cooling capacity (25 kW/rack), all of which was installed within eight weeks of issuing the purchase order.
The Updated Environment: Calm, Cool and Quiet
After installation, even more benefits became apparent to CGG. Traditional air-cooled data centers often feel like cold, noisy wind tunnels – and require a lot of space. CGG’s upgraded data center is just the opposite. It’s half the size of a comparable kW air-cooled data center. It’s also nearly silent, maintained at a comfortable temperature, well-lit, and organized to view all the ICEraQ systems and CDUs at a glance.
In fact, the whole layout is more ergonomic, technician- and human-friendly overall. Cables are neatly stored in the back of the racks; and racks are spaced for convenient access, not temperature control.
The racks themselves are equally remarkable. Dip your hand in the ElectroSafe coolant, and it feels like a warm bath (and you can, because it’s completely safe.) No matter how hot the equipment runs, the coolant will keep all component temps consistent—within 3 degrees. Mission accomplished.
Simple Day-to-Day Operations
Of course, the adoption of immersion cooling also brought certain changes – but CGG was impressed with those, too. Some changes truly made things easier; others, just different.
Hear it Straight From CGG:
“Today there is not really much difference between managing this room and managing another traditional air based computer. Some of the differences as you can see because we’re right in the middle of this room, and it is producing as we speak, there’s no noise, almost no noise, the temperature is very reasonable, there’s no air draft, there’s none of the things you would normally associate with a very high density computer. So that makes for a much nicer environment overall.”
— Laurent Clerc, VP of Information Technology at CGG
“Today there is not really much difference between managing
this room and managing another traditional air based computer.
Some of the differences as you can see because we’re right in
the middle of this room, and it is producing as we speak,
there’s no noise, almost no noise, the temperature is very reasonable,
there’s no air draft, there’s none of the things you would normally
associate with a very high density computer. So that makes for a
much nicer environment overall.”
— Laurent Clerc, VP of Information Technology at CGG
Conclusion: It’s Hard to Argue with Silence.
According to CGG, immersion cooling is different, but a better different – simpler, quieter, plus a lot more cost-effective and space-saving than other cooling methods. Best yet, CGG was able to save on both CAPEX and OPEX costs.
Ready to Learn More?
Read our guide written by CGG: Operational Considerations for Single-Phase, Immersion-Cooled Data Centers — A Client’s Perspective or learn more about CGG’s successful transition to a single-phase immersion-cooled data center.
Concerns about global warming and environmental sustainability have moved to the forefront of boardroom and conference room conversations around the world. It has certainly become a hot topic in air travel and data centers.
Interestingly, while there’s widespread green shaming of the airlines for being prime polluters, data centers are now approaching the carbon footprint of our high-flying counterparts.
Carbon Copies:
Airlines and Data Centers Are Twin Energy Hogs
Globally, airlines contribute around 2% of all anthropogenic (human-caused) carbon pollution.1 Data centers are right up there with them, consuming about 3% of the global electric supply, and dumping hundreds of millions of tons of carbon into the atmosphere every year.2
This trend is sure to accelerate. In fact, several models suggest that data center energy usage could easily consume up to 10% of the global electricity supply in the next decade. It would be one thing if all those electrons were generated from wind or solar farms. But in reality, over 60% of the world’s electricity is still produced using fossil fuels.3
Digital Demands Are Soaring
This increasing dependency on everyday digital tools is likely to bring unintended consequences, and a not-insignificant environmental impact. The burgeoning internet of things, artificial intelligence, streaming entertainment, edge deployments, the launch of 5G mobile networks, along with the advent of more powerful (and power-hungry) CPUs and GPUs, are all destined to drive data center electrical usage significantly higher.
What’s more, according to the global marketing intelligence firm IDC, 152,000 new devices will be connecting to the Internet every minute by 2025, bringing the total to 80 billion worldwide.4 That’s a lot of data flying and flowing through data centers.
Reasons for Optimism
Fortunately, there are glimmers of hope in the quest to reduce global carbon pollution.
Where the airlines are concerned, 2020 became a game-changer of the highest order. If there’s a glimmer of positivity about the COVID-19 outbreak it could be this: the world is starting to recognize that a lot of air travel is unnecessary; that through the use of technology we can still stay connected, and get much of our work done without the environmental impact of jetting all over the globe.
Data centers also have the time and means to get ahead of the carbon curve through two main modes of attack: power-generation and powerconsumption.
On the power generation side, for example, more than 20 of the largest Internet companies – including Facebook, Google and Apple – have committed to powering their digital infrastructure with 100% renewable electricity. As a result, over 10 gigawatts of renewable energy has already been deployed worldwide.5
Where power consumption is concerned, there are many things operators can do, and are doing, to green up their data centers. Installing more energyefficient UPSs, servers and PDUs (power distribution units) is a good start. However, since upwards of 40% of a data center’s energy consumption goes into cooling alone, this is a much more productive focus for improvement.6
Immersion Cooling Can Clear the Air
Most recently, key technologies have matured that significantly reduce the amount of energy required to deliver a unit of compute, make an artificial intelligence decision, safeguard your home from porch pirates, or stream a scene from Game of Thrones.
For example, an oil services enterprise has realized a 40% energy savings over air cooling by implementing immersion cooling in their data center.
This breakthrough technology has also been endorsed by IT giants like Intel® and the NSA, and is at work within some of the world’s largest cloud, enterprise, education, government, high-frequency trading (HFT), and telecom organizations
Data Centers Can Lead the
Environmental Sustainability Charge
As more renewable energy sources come online, and technologies like immersion cooling become more broadly adopted, I believe the data center industry will continue expanding its commitment to a more sustainable planet. Raising awareness and urgency of this issue will help sustain the progress that’s being made.
Legislation that mandates energy efficiency goals, much like carbon reduction measures enforced in other industries, could further accelerate data centers toward a carbon-neutral state. Encouragingly, following the 2015 Paris Agreement, in countries around the world 99% of territorial greenhouse gas emissions are now covered under pledges known as “intended nationally determined contributions” or INDCs.
Nevertheless, at the risk of being pessimistic, it’s sobering to realize that global CO2 emissions from fossil fuels hit a record high in 2019.
A pioneer of single-phase immersion cooling since 2009, GRC (Green Revolution Cooling) has been an environmental evangelist as you see it engrained in our name and has been at the forefront of data center sustainability since our founding.
As a company we are totally committed to raising awareness and creating a sense of urgency around the issue of decarbonization. We encourage you to take a stand on this issue as well as, help flatten the carbon footprint curve, and not allow data centers’ environmental impact to “soar” nearly to the heights of the airlines.
Ready to Enhance Your Data Center Sustainability Efforts?
Send us an email at info@grcmain2025v2.wpenginepowered.com or call us at +1.512.692.8003. A GRC associate will reach out and talk details with you. Be sure to read our Guide to Sustainability Metrics with GRC’s ICEraQ™ — Going Beyond the Traditional Data Center.
At the end of every great action movie, hero and nemesis face each other for a final battle to prove that good triumphs over evil. At least that’s what we hope. Well, while we think single-phase immersion cooling is more than pretty good, we hardly believe air cooling is evil. (‘Aggravatingly exhausted’ might be a better term.)
In this installment of our comparison blog series we’ll stack these two diametrically different systems beside one another to show just how far data center cooling has advanced over the decades.
Matchup:
How These Competing Cooling Technologies Work
Air Cooling
The word “legacy” is often used to indicate an old technology fast moving toward obsolescence. That fairly accurately describes air cooling. Particularly so when you consider how long it has been around (nearly half a century), together with the inexorable threats to its effectiveness it now faces, which we’ll discuss later.
In its simplest form, a legacy air-cooled data center brings outside air in through intakes on air handlers. This air is chilled by a computer room air conditioning (CRAC) unit before it is forced beneath a raised floor up into the “cold aisle” of the server racks. This cold air moves through and cools the servers, then exits in the “hot aisle,” where it is contained and vented through a plenum that returns it to the air handlers. Cold-water chillers and cooling towers can also be used.
Single-Phase Cooling
Single-phase immersion cooling works on the principle that liquid is a much better conductor of heat than air. Here, servers are installed vertically in horizontally-oriented coolant bath of dielectric (electrically non-conductive) fluid. Coolant transfers heat through direct contact with server components. Heated coolant then exits the top of the rack, and is circulated between the racks and a cooling distribution unit (CDU) connected to a warm-water loop. This loop incorporates a cooling tower or a dry cooler on the other side as the final form of heat removal. In the end, cooled liquid is returned to the rack from a heat exchanger.
Air Cooling vs Single Phase immersion cooling
To help with your decision making we’ll now break down each of these technologies and see how they compare across four important categories.
| Category | Air Cooling | Single-Phase Immersion Cooling |
|---|---|---|
| Complexity & CAPEX | Complex infrastructure; higher upfront costs. | Simpler system; 50%+ lower CAPEX. |
| Energy Efficiency | Fans use 20% of server power; PUE: 1.35–1.69. | 90% less cooling energy, 50% less total energy; PUE: below 1.03. |
| Cooling Capacity | Inefficient above 15 kW/rack; some systems reach 30–35 kW/rack. | Up to 100 kW/rack, theoretically 200 kW with chilled water. |
| Maintenance | More equipment and maintenance requirements. | Fewer components and easier maintenance. |
| Reliability | Hot spots, humidity and airborne contaminants can damage hardware. | More uniform cooling and protection from outside contaminants. |
| Space & Flexibility | Requires more space and supporting infrastructure. | Compact setup; greater deployment flexibility. |
Complexity & Upfront Costs
Air Cooling
While air-cooled data centers have served the industry well for decades, they are arguably the most complex when compared to alternatives such as liquid-to-chip, rear-door heat exchangers (RDHx) and, especially, single-phase immersion cooling.
What might seem a simple server and rack-only system actually requires much more: some combination of raised floors, aisle containment strategies, chillers, air handlers, humidity controls, filtration systems and plenums. Furthermore, to support the above, air-cooled data centers must also operate a comparatively large ancillary infrastructure – notably backup generators, UPSs and batteries.
All this necessary complication equates to a relatively large capital expenditure (CAPEX).
Single-Phase Cooling
Since helping to pioneer the technology back in 2009, we’ve kept hammering away at perhaps the top value proposition for single-phase immersion cooling, which is its simplicity.
Considering it has just three moving parts – a coolant pump, water pump and a cooling tower/dry cooling fan, and the fact it requires no raised floors nor wasted space through aisle containment, single-phase immersion cooling can cut data center CAPEX by 50% or more.
What’s more, no CFD analysis of air flow is required with immersion because racks can be spaced closely together, and even placed on bare concrete floors. Electrical support systems can be downsized as well.
Before you assume that simplicity impacts performance, we should add that GRC ICEraQ™ systems can easily cool 100 kW/rack or more – far beyond the capabilities of even the best air-cooled operation.
Efficiency & Operating Expenses
Air Cooling
The plain fact is that air is a less effective conductor of heat than liquid – 1200X less effective. This not only makes air-cooled data centers intrinsically less efficient, but creates ripple effects that have a serious impact on operating expenses.
First off, fans account for 20% of server power consumption. To bolster air’s effectiveness, energy-sapping refrigeration components like chillers and air handlers are needed as well. Those in turn impact the size of power infrastructure.
Given all the above, basic air cooling requires the highest operating expenses of all major data center technologies while delivering a PUE of approximately 1.35 to 1.69.
Single-Phase Cooling
Again, with only three moving parts (GRC removes fans to optimize servers for immersion), zero refrigeration components, plus vastly reduced infrastructure requirements, single-phase immersion cooling delvers a 90% reduction in cooling energy and 50% cut in total data center energy usage over air cooling. As a result, operators can realize an immersion cooling PUE of <1.03.
By the way, the added infrastructure involved with air cooling not only increases costs from an electrical power perspective. That equipment can also come with expensive annual maintenance contracts. None of it is necessary with single-phase immersion cooling.
Plus, compared to two-phase systems, maintenance on GRC’s ICEraQ micro-modular, immersion cooling solutions is very easy. You just open the lid, lift out the server and set it on integrated service rails, which are placed at a convenient waist height. Problems solved.
Cooling Capacity & High-Density Performance
Air Cooling
It’s true that some air-cooled data centers are capable of cooling upwards of 30-35 kW/rack. But, in reality, air-cooled data centers become very inefficient above 15 kW/rack.
Industry trends are making the situation worse. Electricity-hogging GPUs are moving in to tackle HPC applications like IoT and AI. As another example, Intel’s® new Skylake release consumes a whopping 250 W of energy. Place two of those on a 1U server, add upwards of 200 W for other electronics, multiply that by 40 servers and you have 28 kW for a CPU-based system. Add co-processors and accelerators and you’re way beyond the limits of air cooling.
To keep up with demands, data center operators may be inclined to create mixed-density racks. Where air cooling is concerned, this inevitably leads to hot spots, which can lead to hardware failure.
In particular, this evolution in hardware will create a real moment of reckoning for operators of air-cooled data centers at their next hardware refresh.
Single-Phase Cooling
GRC ICEraQ™ and ICEtank™ systems are ideally engineered to break through the heat barrier and take data center computing into its next evolution—and beyond. Either solution can easily cool up to 100 kW per rack—theoretically up to 200 kW when used with a chilled-water system.
Read our Density Dilemma
White Paper >>
Reliability & Location Flexibility
Air Cooling
Any cooling technology that draws air from the outside is destined to create hardware reliability issues. Why? Because it exposes IT assets to potentially harmful airborne contaminants as well as the adverse effects of the air itself. By this we mean chiefly corrosion and oxidation.
That risk increases depending on the air quality and natural humidity levels of the unconditioned air itself. Clearly, locales with a high degree of humidity, air pollution or windblown particulates can wreak havoc on ill-equipped data centers. By the way, these concerns increase as the need for remote edge deployments increases.
Speaking of location flexibility, the inherent complexity and larger infrastructure requirements of air cooling present significant hurdles as to where computing power can be placed.
Finally, and as mentioned earlier, even with the best aisle arrangement approach, legacy air cooling creates hot spots which can lead to hardware failure.
Single-Phase Cooling
Three major factors give single-phase immersion cooling the highest possible marks in this category:
One, it is unquestionably the simplest practical form of cooling on the market. Thus, there are fewer things to go wrong: no chillers, air handlers, humidity controls, etc.; and no server fans to create vibrations that can (and do) increase MTBF (mean-time between failures).
Second, with immersion, critical IT assets are completely sealed off from the outside air, negating any environmental issues.
Finally, immersion cooling provides a more thermally consistent environment for the IT equipment, minimizing hot spots in the data center.
Now! Liquid cooling includes several approaches, and understanding single phase vs two phase immersion cooling can help clarify how different data center cooling systems manage heat.
Conclusion: Air Cooling Gets Blown Away
by Single Phase Immersion Cooling
Considering the fact that air cooling is an outmoded legacy system in the truest sense of the word, single-phase immersion cooling wins this battle in the Data Center Cold Wars. And it can be your hero, too.
Ready to Grow Your Data Center? Let’s Talk!
Send us an email at info@grcmain2025v2.wpenginepowered.com or call us at +1.512.692.8003. A GRC associate will reach out and talk details with you. In the meantime, be sure to read our other Data Center Cold Wars installments: Single-Phase Immersion Cooling Versus Two-Phase, Cold Plate, and Rear Door Heat Exchanger Cooling.
Things are really heating up out there. Even conventional computing operations are frequently pushing the 30 kW/rack barrier now. HPC apps like AI are becoming commonplace. And because IT is such an integral part of business growth, IT execs are under renewed pressure to have a fail-proof game plan for scaling up.
This fourth in our series of comparison blogs can help. By evaluating two popular data center cooling methods – single-phase immersion and rear door heat exchangers, we’ll give you insights on how best to “beat the heat” and master the trend.
Matchup:
How These Competing Cooling Technologies Work
Rear Door Heat Exchanger (RDHx)
Originally designed to make air-cooling more efficient, RDHx systems were an early solution for bringing the cooling effects of a liquid-to-gas phase change closer to the heat source. With RDHx, radiator-like doors are attached to the fronts or backs of server racks. Heat produced by IT equipment is removed by air blown into the exchangers via fans. That heated air travels a short distance before transferring to water or refrigerant running inside the radiators.
Heated liquid is then carried away from the server rack to a cooling distribution unit (CDU), which in turn is connected to an outside chilled water system.
Some RDHx systems have “active doors” with integrated fans, while others rely solely on server fans to eject the air.
Essentially, RDHx is just a better form of air-cooling. Although often mistakenly considered so, it is not a liquid-cooling solution.
Single-Phase Immersion Cooling
With single-phase immersion cooling, servers are installed vertically in coolant bath of dielectric (electrically non-conductive) fluid. Like its two-phase counterpart, the coolant transfers heat through direct contact with server components. Heated coolant then exits the top of the rack and is circulated through a CDU connected to a warm-water loop. This loop incorporates a cooling tower or dry cooler on the other side as the final form of heat removal. In the end, cooled liquid is returned to the rack from a heat exchanger.
Single-phase immersion cooling systems are noted for their simplicity, which translates into greater upfront affordability, easier operations and less maintenance.
What’s the difference between single- and two- phase immersion cooling?
Loads.
Compare, Contrast and Be Cool
Now let’s break down each of these technologies and see how they compare across eight important categories.
Complexity & Upfront Costs
RDHx
Absent the need for raised floors, air handlers and the like, RDHx is simpler than traditional air cooling. But since it still uses air as a medium of cooling, it requires compressor – or refrigerant-based cooling at the CDU level, or a chilled water loop. It also requires specialized building design and engineering such as CFD analysis to ensure appropriate layouts and cooling.
Further, environmental and humidity control systems are also needed. All these systems increase complexity and add costs. Although RDHx does not require raised floors, aisle containment, false ceilings, and plenums may still be needed.
On the plus side, operators will find it easy to add an RDHx to an air-cooled system, or to augment a liquid-to-chip solution attached solely to CPUs.
Single-Phase Immersion Cooling
In all fairness to competing systems, single-phase immersion cooling is arguably the simplest, most cost-effective way to cool a data center. For example, there are only three moving parts involved in GRC’s ICEraQ™ micro-modular immersion cooling solution.
As a result, we can confidently claim to reduce both data center CAPEX & OPEX by a full 50%, as we have for many of our customers.
Efficiency & Operating Expenses
RDHx
Again, because RDHx uses air – a bad conductor of heat, it requires a lot of air flow and a huge temperature delta between the incoming air and the heat source to maintain optimal core temperatures. The higher delta means that air must be cooled to temperatures that mandate the use of compressors or chiller plants to cool the air directly. Either way, when you consider the need for compressors plus the number of fans needed to create the required air flow, RDHx consumes significant amounts of energy
Plus, unlike immersion cooling, RDHx solutions still require server fans and do not reduce the server power consumption.
Given the combined electrical load of fans, chillers, CDUs and more,RDHx delivers a PUE of between 1.2 and 1.3.
It’s also important to note that, given tightening worldwide environmental regulations, many refrigerants are likely to get harder and costlier to acquire in the long run. This should definitely be considered when building a data center that requires compressor-based cooling.
Single-Phase Immersion Cooling
With single-phase immersion cooling systems, 100% of the heat is picked up by the coolant. In addition, the coolant’s comparatively higher density and superior thermal conductivity means that it can maintain optimal core temperatures with a much lower delta between the coolant and the heat source.. This eliminates the need for compressor-based cooling, and reduces the amount of mechanical work/electrical power needed to create flow and run chiller plants.
Add the disabling or removal of server fans and a 10-30% reduction of server power is possible.
Consider as well that single-phase immersion cooling does not require all the ancillary equipment (and corresponding energy draw) associated with RDHx. As a result, it delivers a remarkable PUE of about 1.03, despite the reduction in server power.
Cooling Capacity & High-Density Performance
RDHx
RDHx systems can run either water or refrigerant. The former comes with major safety and reliability caveats to be discussed later. Although RDHx can be cost-competitive for 25-30 kW rack densities, there are limits to those benefits. In fact, its advantages drop sharply as densities rise beyond 15 kW per rack. Given the ever-increasing density of chips and hardware, operators may soon start to hit the 30 kW-per-rack wall with hardware refreshes.
Single-Phase Immersion Cooling
GRC ICEraQ and ICEtank systems can easily cool up to 100 kW per rack – theoretically up to 200 kW when used with a chilled water system. And while the financial case for GRC’s immersion cooling makes sense at rack densities as low as 10 kW (less in some cases), the higher capacity future-proofs the infrastructure against rising hardware density and the ever-evolving technology landscape.
Immersion cooling is also ideal for creating a diverse density layout. This allows operators to run high-density racks right next to lower density ones without stratification or the mixing of hot and cold air
Reliability & Location Flexibility
RDHx
RDHx does not score well in this category, and here’s why:
Feeding the radiator-like doors of RDHx systems are fluid lines containing either water or refrigerant. Depending on which – and whether they’re routed above or below critical IT equipment, leaks can be a major problem. There have actually been cases when failures have sprayed conductive water onto servers and ruined them. So, clearly, using water is a concern.
Yet using refrigerant can be a problem, too, but for different reasons. Aside from high costs, RDHx refrigerants also have a global warming potential (GWP),putting them under the constant scrutiny of the EPA and EEA. In fact, some formulations are in the process of being banned, causing more than a few operators to be concerned about supply disruptions.
Two other factors impede RDHx’s reliability and location flexibility. One is the fact that these systems – much like any other air-cooling system – expose IT assets to airborne contaminants, moisture, and increased levels of vibrations. Thus, they require additional systems and equipment to protect them from harsher environments.
Next, RDHx still needs significant amounts of power and supporting infrastructure, which can limit location choices, especially for edge applications.
Single-Phase Immersion Cooling
In contrast to RDHx, single-phase immersion cooling scores an A+ when it comes to reliability and location flexibility. The reasons are simple. There are few moving parts (in other words, less things to go wrong). Also, servers are completely immersed, therefore shielded from any harmful environmental factors.
GRC ICEraQ and ICEtank™ systems are the epitome of simplicity, and can be placed virtually anywhere. In fact, our fully containerized ICEtanks can literally be deployed in a parking lot or loading dock.
Operators should also know that our ElectroSafe® coolant is non-conductive, totally inert, and planet-friendly. Most likely it will not need replacing over a typical data center lifecycle.
Conclusion: Single-Phase Immersion Cooling Finishes First
Because air-based systems are fast becoming an outmoded “legacy” method for cooling data centers – and since RDHx is essentially an enhanced form of air-cooling, it simply cannot match single-phase immersion cooling in the eight critical performance categories discussed here.
Ready to Grow Your Data Center? Let’s Talk!
Send us an email at info@grcmain2025v2.wpenginepowered.com or call us at +1.512.692.8003. A GRC associate will reach out and talk details with you. In the meantime, be sure to read Data Center Cold Wars — Part 1: Air-Based Cooling Versus Single-Phase Immersion Cooling and watch for the next installment.
Cooling a data center never used to be this hard. But IT and data center professionals have watched the thermal design power (TDP) of chips rise almost 50% in the last decade, generating more heat and using more power than ever before. Rack density has grown. And hot GPUs are becoming the weapon of choice for tackling high-performance computing (HPC) requirements.
This third in our series of blogs compares the two most emergent technologies designed to cool data centers: cold plate and single-phase liquid immersion cooling. Hopefully, these insights will help you understand the technological differences and choose the best solution for your operation.
Matchup:
How These Competing Cooling Technologies Work
Cold Plate Cooling
Basically, “touch,” “direct-to-chip”, or “liquid-to-chip” cold plate cooling replaces older, inefficient air-cooled metal-finned heat sinks with liquid-cooled heat sinks. As the name suggests, it attaches a metal plate atop a CPU or GPU, which transfers heat through a heat-spreading material (such as thermal paste) from the chip to the plate. The plate retains the ability to absorb this heat because it is cooled with liquid, which is a much better conductor of heat than air.
The heated liquid circulates from the plate through a coolant distribution unit (CDU) to the facility water loop. This may be connected to a chiller, or even cooling towers, then directed back to the plate. Since cold plate only cools the CPUs (which typically account for 60-70% of the total heat load), air-cooling is used to cool the remaining 30-40% heat load. This makes cold plate technology a hybrid solution that involves both liquid and fan-blown air cooling.
Cold plate is probably the most popular (and one of the oldest) forms of liquid cooling in the world of electronics and IT. Although most recognize the improved performance and efficiency it offers over air-cooling, the cost, complexity and potential risks involved have prevented large-scale adoption of liquid cooling.
Single-Phase Immersion Cooling
Single-phase immersion cooling offers the performance and efficiency benefits of cold plate without the added costs, complexity and risks. With single-phase immersion cooling, servers are installed vertically in a coolant bath of dielectric fluid. Like its two-phase counterpart, the coolant transfers heat through direct contact with server components. Heated coolant then exits the top of the rack and is circulated through a CDU connected to a warm-water loop. This loop incorporates a cooling tower or dry cooler on the other side as the final form of heat removal. In the end, cooled liquid is returned to the rack from a heat exchanger.
Many installations that have switched to single-phase immersion cooling have been impressed with its simplicity, which translates into greater upfront affordability, easier operations and less maintenance.
Compare, Contrast and Be Cool
Now let’s break down each of these technologies and see how they compare across eight important categories.
Complexity & Upfront Costs
Cold Plate Cooling
When comparing cold plate cooling to other technologies, you should know that its basic liquid-cooling architecture is only 60% to 70% effective at dissipating heat. Chiller-based air cooling is still required to complete the solution.
Because of this, data center infrastructure is a lot more complex with cold plate, often exceeding that of traditional air-cooling. What’s more, it often requires a chiller plus specialized engineering depending on the design of the servers. This all adds up to significantly greater upfront costs.
Further complicating things, each heat source (CPU/GPU) typically requires its own cold plate (custom heat sink) and the plumbing to go with it. This is because putting these in series would result in uneven cooling. The result is often a rat’s nest of custom heat sinks and plumbing crammed into a very limited space, requiring custom-made servers. As an extreme example, ASIC (application-specific integrated circuit) boards can have thousands of chips in each brick-sized chassis. Even today’s most basic enterprise server has two CPUs which require their own cold plates and plumbing. Add multiple GPUs to the mix and soon you have 10-20 hoses coming out of each server.
This fundamental complexity not only impacts upfront infrastructure and hardware costs. It also limits hardware choices and makes server refreshes (typically in three-to five-year cycles) much more involved and costly as well.
Single-Phase Immersion Cooling
One of the hallmarks of single-phase liquid immersion cooling is that it is arguably the most fundamental form of modern data center cooling around – one that absorbs 100% of the heat load. This simplicity serves as the basis of immersion’s main value propositions of reduced upfront and operating costs.
How simple is it? Data center systems using GRC’s ICEraQ™ micro-modular immersion cooling solutions have only three moving parts: a coolant pump; a water pump; and a cooling tower or dry-cooler fan. Unlike cold-plate-cooled operations, there’s no airflow engineering. And, GRC data centers have no need for expensive infrastructure, such as chillers, air handlers and raised floors.
But here’s the number that really matters: single-phase liquid immersion cooling can reduce data center CAPEX up to 30% over cold plate cooling.
Efficiency & Operating Expenses
Cold Plate Cooling
As explained earlier, liquid-to-chip technology will get you (at most) three quarters of the way to a fully cooled data center. Because it needs expensive and inefficient air conditioning to take you the rest of the way, it is intrinsically less efficient than single-phase immersion cooling. Along with server fans, it also requires chillers, air handlers and other air conditioning equipment, which demand more electricity and regular maintenance, thus kicking up operating expenses.
Most modern cold plate systems deliver a PUE somewhere in the neighborhood of 1.15.
Single-Phase Immersion Cooling
Single-phase liquid immersion cooling couldn’t be more efficient. Literally 100% of the heat is picked up by the coolant. That means there’s zero residual heat requiring less efficient air-cooling.
Simple in design, with few moving parts, systems like GRC’s ICEraQ and ICEtank single-phase liquid immersion cooling systems are 80% more energy-efficient than cold plate methods, delivering a PUE (PUE) of 1.03.2 That delta between cold plate and single-phase immersion pPUE is amplified by the 10-30% server power reduction immersion cooling enables through fan removal. The end result equates to a total data center energy cut of up to 35%.
Since immersion cooling eliminates the need for all air-cooling infrastructure and equipment – such as chillers, air handlers or humidity control systems, the annual maintenance cost associated with those is also eliminated.
Minimal consumables and vastly reduced electricity usage are what help single-phase immersion cooling deliver a 40% cut in OPEX for most data centers.
Cooling Capacity & High-Density Performance
Cold Plate Cooling
Unlike the dielectric coolant used in single-phase immersion cooling, direct-to-chip or liquid-to-chip methods typically employ water or a water/glycol mix. These offer higher thermal conductivity than dielectric coolants, but are good conductors of electricity, nevertheless. Higher conductivity theoretically helps support higher heat flux. Yet this has little to no impact on the power density cold plate can support on a per-server or per-rack basis.
Since the electrically conductive coolant needs to be contained within heat sinks and plumbed individually to chips, it is at times physically impossible to fit and plumb multiple cold plates to every CPU and GPU within a high-density server.
Even though cold plate solutions are great for cooling isolated and localized hot spots, they don’t do so well with multiple heat-producing chips within confined spaces. Plus, given the fact that there are multiple heat-producing chips within each server – and multiple servers in a rack, cold plate solutions can get very complicated at scale.
Immersion cooling, on the other hand, uses a dielectric coolant that is a good conductor of heat but not electricity. Therefore, the coolant can directly contact all components within a whole rack of servers to capture 100% of the heat and cool each chip effectively.
For these reasons – and the fact that plates do not contact all heat-producing components, cold plate can only chew up some 70% of a typical data center’s server heat. Air-cooling has to do the rest. What’s more, cold plate typically maxes out at about 50 to 60 kW in rack density, making it unsuitable for many next-gen apps. Again, the real constraint here is two-fold: a limitation on how many custom heat sinks you can plug into what becomes very crowded boards; and the air cooling required for the remaining 30-40% of the heat load.
Single-Phase Immersion Cooling
Although GRC’s ElectroSafe™ coolant does not have the heat-carrying capacity of water, it is still 1,000X more efficient than air. With 300+ gallons of coolant in a rack, plus the managed flow and convection at work, this allows us to easily and effectively cool over 100 kW per rack without compressor-based cooling (with warm water). Theoretically, we can range up to 200 kW with a chilled-water system.
So, while it’s possible that cold plate could support higher heat flux, the metric has no practical application, as no existing or anticipated chips have come close to the limitations of immersion cooling. Imagine buying headphones that support a wider frequency range, but one that can’t be heard by human ears. Yes, the spec is true. Yet is it useful and/or worth the higher cost and complexity?
Read our white paper on tackling the data center density dilemma>>
Reliability & Location Flexibility
Cold Plate Cooling
The complexity of cold plate solutions can present significant reliability issues. First, the sheer number of intricate parts and fittings creates numerous failure points. Furthermore, leaks can be catastrophic. Remember, we’re talking conductive water here: the enemy of electrical components.
Since server fans are still required, this introduces vibration and poses yet another point of failure. What’s more, IT assets are exposed to environmental assaults (e.g., moisture and airborne particulates), which can hasten deterioration and impact MTBF (Mean Time Between Failures).
As for location flexibility, two things work against cold plate when compared to immersion cooling. Cold plate is simply more complicated. It requires air conditioning infrastructure that is very energy-and cost-inefficient at a smaller scale. It magnifies capital, power and site constraints. Plus, the fact that components are exposed to air can make these systems a no-go for deployments in harsh environments.
Single-Phase Immersion Cooling
The cooling systems we’ve developed and perfected at GRC involve the total immersion of IT assets. This affords full protection from the heat, moisture, oxidation, and dust that can create real reliability problems. In addition, since no air flow is required, rooms or modular structures where the racks are enclosed can be completely sealed off if needed.
That’s how we give you the flexibility to locate your data center virtually anywhere on the planet, no matter how harsh the environment. Further, the 50% lower energy consumption and minimal site and space requirements allow you to maximize IT capacity within limited power and space envelopes.
Case in point: our ICEtank™ solutions sit inside an ISO container and are completely sealed off from the outside world. Not only can they be delivered in as little as 10 weeks, they can also go practically anywhere. Their simple, fully enclosed design makes them ideal for edge deployments.
CASE STUDY: See how our ICEtank solution helped the U.S. Air Force >>
We also offer a “plug-and-play” solution called the ICEraQ™ Micro – a 24U pre-configured rack that comes with an integrated CDU and pump. It lets you drop computing power in the most unlikely places with minimal site requirements. You just need power, water and a level floor.
Conclusion: Single-Phase Immersion Cooling Finishes First
Cold plate solutions have been around for some time. Although they can be a great spot-fix for isolated heating issues, their cost, complexity and risk have been obstacles to larger scale adoption. Single-phase immersion cooling not only overcomes all the limitations of cold plate. It delivers superior thermal performance and cooling of servers/components that wouldn’t be feasible with cold plate. And it features a modular form factor that is designed for scale and enterprise-grade data centers.
These factors together have made cold plate increasingly ineffective, and immersion an obvious solution for bringing data centers into the future. Conclusion: Single-Phase Immersion Cooling Finishes First
1 Based on a pPUE (partial PUE) of 1.03 vs. 1.15.
2 Based on a pPUE (partial PUE) of 1.03 vs. 1.15.
Ready to Grow Your Data Center? Let’s Talk!
Send an email to info@grcmain2025v2.wpenginepowered.com or call us at +1.512.692.8003. A GRC expert is looking forward to talking details with you.
In the meantime, be sure to read Data Center Cold Wars — Part 1: Air-Based Cooling Versus Single-Phase Immersion Cooling and be sure to watch for the next installment.
If you’ve already read Parts 1 & 2 of our “When Does Immersion Cooling Make Sense?” blog series, it’s hard not to conclude that single-phase immersion cooling technology solves most of the big-picture challenges facing data center operators today: issues relating to CAPEX and OPEX, energy efficiency, capacity. Expanding next-gen application platforms, and more.
As the final icing on the cake, here are three more cases illustrating when liquid immersion cooling makes a whole lot of sense.
Real-world “edge” deployments can easily become a genuine hurdle when you consider speed of deployment, lack of existing infrastructure and the often sub-ideal conditions awaiting them at the construction site.
The goal of edge computing is to reduce latency by situating sufficient computing power as close to transactions as possible. The challenge is that some of those places are “off the grid,” so to speak, amid significantly suboptimal conditions and environments. For sure, things like extreme ambient heat, high humidity, and airborne particulates cannot only unleash hell on IT assets. They can make edge computing an outright no-go.
Experience the Reality of
Immersion Cooling
To paraphrase one of my favorite movies, The Matrix, what if we told you there was a way to place easily expandable edge computing power practically anywhere on terra firma with the confidence you would be up and running in just 10 weeks? Moreover, with few, if any, worries about environmental issues.
What if all you needed to supply was water, electricity and an Internet connection and we could promise you as much as 800 kW of edge computing performance boxed up in one small, state-of-the-art package?1
Flying High for the USAF
That’s essentially what our ICEtank™ containerized solutions provide. And we have a very high-visibility client who can verify it. Given its ongoing need to deploy remotely controlled computing power in faraway, often forbidding locales – with minimum personnel and support, the U.S. Air Force went full throttle when they heard about our modular, containerized ICEtanks.
Ultimately, our work has helped them achieve 100% HPC uptime for three years and counting with a 93.1% reduction in cooling power for a 1.037 PUE.
Overcrowding can make city life stressful and can pose big problems for data center operators, too. The culprits? More shared compute time requests. That, plus the trend toward high-density computing spawned by apps like AI or IoT, machine – or deep learning and more. (15 kW racks may soon be ancient history.)
It’s a real dilemma with several possible solutions, the most radical of which is rebuilding a completely new high-performance-capable data center within your current footprint. The easiest? Moving operations to the cloud. Yet, the latter, while seductive in its simplicity, can present security and other issues your organization may not be able or willing to sidestep, like having to share time with other cloud users.
Embrace a Pack Mentality
Immersion cooling makes tackling the density dilemma surprisingly easy. Because of the great heat-carrying capacity of liquid (1,200X that of air), and the fact such systems require none of the big CRACs, CRAHs or raised floors conventional centers do, GRC solutions make it easy to deploy capacity quickly, incrementally, and cost-effectively. Want to go with mixed-density racks or rows? No problem. Or maybe you’d like to add a new dedicated on-premises HPC “pod” just for next-gen apps. Immersion cooling is a great solution in both cases.
GRC ICEraQ micro-modular, immersion cooling solutions can be placed in virtually any indoor location – even those with no supporting infrastructure. They can easily tie into most any existing infrastructure while delivering up to 200 kW of compute power per rack in a much smaller footprint.
But what if you’ve completely run out of space indoors? Well, our ICEtanks are convenient “data centers in a box.” These 20 or 40-foot ISO containers come with four or eight preconfigured, 42U, immersion-cooled racks, respectively, and can be placed anywhere outside. That includes harsh environments fraught with soaring temperatures and blowing sands or the relative tranquility of your parking lot. (Hint: the CEO’s spot is off limits.) All you need is water, electrical and networking.
For all their convenience, ICEraQ systems are hardly wimpy. Starting in 2009, the Texas Advanced Computing Center (TACC) enlisted GRC to help them build up computing power for what would ultimately yield one of the world’s fastest (and greenest) TOP500 supercomputers, Frontera. Our initial deployment involved an ICEraQ on their loading dock, and they effortlessly added racks over the years as their computing needs grew.
Blog Post: Super. Human. Computing — Immersion Cooled,
Frontera Supercomputer Helps Advance Science
Despite its attractions, some people have their head in the cloud when it comes to using that very same technology to overcome data center challenges. Yes, the cloud makes it easy to slough off scalability and maintenance concerns. Yes, it’s great for multi-location enterprises. But the cloud isn’t for everyone.
Security, shared time, downtime and other issues make the cloud unsuitable for some organizations. The U.S. military is one – and for good reason: increasingly, warfare is a data-driven undertaking. Distributed enterprises are another example of why the cloud is not a panacea, as many firms are reluctant o relinquish control of highly sensitive proprietary data and applications.
Hey, You, Stay Off of the Cloud
If you can’t go to the cloud, capacity planning becomes much more complicated as well. Lead time for IT development is often measured in years when design, approvals, and build-out are taken into consideration. This generally necessitates “guessing the future,” making it easy to over-plan, which misappropriates budget. But long-term projections can also cause you to err on the other side and underplan. That can truly hobble an organization, as corporate fortunes are increasingly tied to IT. Despite these burdens, there’s intense pressure on infrastructure and operations pros to “get it right.”
raQ Up Serious Benefits
GRC’s liquid immersion cooling solutions take the calculus, luck, psychic powers and crystal ball out of the capacity planning process. Our systems make it easy to deploy capacity quickly, cost-effectively and incrementally in accordance with computing demands.
Have a spare room, basement or a loading dock? Any space – even without a data center infrastructure – will support our ICEraQs. And, our completely self-contained ICEtanks can be placed anywhere outside, even in the harshest environments. These efficient, low-cost units enabled the U.S. Air Force to drop compliant computing power right outside their Hill AFB data center in Utah and save money by tapping into existing power, Internet and water resources. Both can tie into any existing warm or chilled water system.
Video: ICEtank Immersion-Cooled Modular Data Center Overview
1. Utilizing a chilled water system.
Does Liquid-Immersion Cooling Make Sense for YOUR Data Center?
We’d be surprised if it didn’t. Why not send us an email at info@grcooling.com and find out for certain? A GRC associate will reach out and run the numbers for you. Call 1.512.692.8003.
Be sure to read the other installments in this blog series:
When Does Liquid-Immersion Cooling Make Sense? – Part 1
When Does Liquid-Immersion Cooling Make Sense? – Part 2
Overcoming Tomorrow’s IT Barriers
We’ve said it before: corporate fortunes these days are increasingly tied to IT. So it follows that IT hurdles can easily hold businesses back. GRC & Dell Technologies make it easier for organizations to leap these hurdles and keep pushing ahead.
What are some of these hurdles to achieving success? Many Information and communication technology (ICT) professionals have spelled them out, notably Intel’s Senior Director of Infrastructure Systems Product Management, Steve Gillaspy. 1
Four of Gillaspy’s points we consider to be particularly strong:
- Hyper-growth and hyper-scaling epitomized by edge computing
- Hyper-density to increase efficiency while cutting CAPEX, and OPEX
- New workloads such as Big Data, AI/ML/DL, and IoT
- New hardware, notably FPGAs, GPUs, and ASICS
A formidable list for sure. And yes, you also need to make sure you can deploy assets quickly, while tempering energy consumption.
Clear the Hurdles with All-in-One Immersion Cooling
Server Systems
The solution is having agile, energy-efficient infrastructure that doesn’t place limits on cooling, growth, and location flexibility. This is precisely why we’re working with Dell Technologies: to help data center operators quickly procure, deploy and scale best-in-class server/immersion cooling combinations virtually anywhere — including the edge – with All-in-One Immersion Cooling Server Systems.
Through the seamless integration of powerful Dell EMC PowerEdge servers with our ICEraQ™ and ICEtank™ modular immersion cooling systems, IT leaders can now easily purchase an all-in-one high-performance cooling server solution through either GRC or Dell Technologies OEM | Embedded & Edge Solutions group.
In doing so, they can join the likes of the U.S. Air Force, the Department of Defense and the NSA, all of whom are currently using GRC ICEtanks and ICEraQs to achieve their IT objectives.
What Hurdles, Where?
So, how do our All-in-One Immersion Cooling Server Systems help operators tackle the fearsome foursome of IT hurdles mentioned earlier? Quite effectively.
- Dell EMC PowerEdge servers are ideally suited for new workloads like AI and IoT
- Fast procurement, deployment, installation, and configuration of these all-in-one immersion-cooling server systems speeds edge deployments, enabling hyper-growth and hyper-scaling
- The proven performance and reduced infrastructure of GRC’s cooling solutions increases efficiency while lowering CAPEX and OPEX
- The high rack densities we can achieve (up to 200 kW) “beat the heat” generated by GPUs, FPGAs and ASICS
What’s more, with these systems, customers can count on immediate energy savings, space consolidation and worry-free server reliability.
About Single-Phase Immersion Cooling
Single-phase immersion cooling is fast becoming the only viable solution for leaping over the hurdles Gillaspy and others have brought to light. Our systems immerse Dell EMC PowerEdge servers in racks filled with a non-conductive coolant called ElectroSafe™, which provides 1200X the heat capacity of air. Heat from the servers is easily absorbed by the coolant and quickly expelled from the rack. The result is a very energy-efficient system with a cooling capacity up to 200 kW/rack*.3
Notably, these systems have no need for raised floors, eliminate CRACs and CRAHs that add cost and complexity, which can severely limit location flexibility as well.
Fast-Forward Your Future
Learn What Makes Single-Phase
Immersion Cooling Superior.
The future is never certain. But certain challenges lay ahead for companies looking to leverage their IT assets to be successful. Offering breakthrough cooling, tremendous convenience, flexibility, and efficiency, GRC & Dell Technologies can help data center operators forge ahead with confidence.
1 Gillaspy, Steve. Why the Data Center Needs a New Architecture. DCD. February 01, 2018
2 Forrester Analytics. Global Business Technographics® Mobility Survey 2018
3 Utilizing chilled water
Ready to Take on Tomorrow?
Let’s Go There Together.
Data center challenges are mounting fast. These are fueled both by the rise of next-gen applications, super-hot, largely GPU-driven applications like AI, and the fact that business and IT growth must increasingly move in lockstep. Not surprisingly, as temperatures rise inside data centers, operators are scrambling to find workable, more power efficient alternatives to traditional air-cooling. In this second in a series of blogs comparing data center cooling technologies we’ll discuss arguably the most viable and practical of these – liquid immersion cooling, and contrast the two very different approaches of this seemingly similar method: two phase versus single-phase immersion cooling.
Our Goal: help you understand the differences and find the best cooling technology to grow and future-proof your data center.
Matchup: How These
Competing Cooling Technologies Work
The underlying principle behind both single – and two-phase immersion cooling is that liquid is a much better heat conductor than air. The other reason that makes both these immersion-based systems superior is the proximity of the liquid to the heat source. (Wet is about as close as you can get.) Furthermore, both options require no chillers, CRACs, CRAHs or raised floors. Apart from that there are significant differences in the two technologies.
Two-Phase Cooling
In a two-phase immersion cooled system, servers are sealed inside a bath of specially engineered fluorocarbon-based liquid. Because the fluid has a low boiling point (often below 50°C vs. 100°C for water), heat from the servers easily boils the surrounding fluid. The boiling of the liquid causes a phase change (from liquid to gas), which gives two-phase immersion cooling its name.
The vapor is then condensed back to the liquid form via water-cooled condenser coils, which are integrated into the top of the sealed racks. The condensed liquid drips back into the bath of fluid to be recycled through the system.
Single-Phase Cooling
With single-phase immersion cooling, servers are installed vertically in coolant bath of a hydrocarbon-based dielectric fluid that’s similar to mineral oil. Like its two-phase counterpart, heat is transferred to the coolant through direct contact with server components. But, unlike two-phase immersion cooling, the coolant does not boil off. Instead, it remains in the liquid phase (hence the name) and is cooled via a heat exchanger in a cooling distribution unit (CDU).
Many installations that have switched to single-phase immersion cooling have been impressed with its simplicity, which translates into greater upfront affordability, easier operations, and less maintenance.
Two-Phase vs Single-Phase Immersion Cooling
To help with your decision making we’ll now break down each of these technologies and see how they compare across important categories.
| Category | Two-Phase Cooling | Single-Phase Cooling |
|---|---|---|
| Complexity & Cost | Sealed racks; higher upfront costs. | Open-rack design; lower costs. |
| Coolant | Expensive; evaporates and requires replenishment. | Lower cost; lasts 15+ years. |
| Energy Efficiency (PUE) | 1.01–1.02 | 1.02–1.03 |
| Maintenance | Complex server access; potential coolant loss. | Easy server access; simpler maintenance. |
| Cooling Capacity | Claims up to 250 kW/rack. | Up to 200 kW/rack with chilled water. |
| Reliability & Safety | Potential vapor, leakage and seal-failure concerns. | Non-conductive, non-flammable and non-corrosive coolant. |
| Environmental Impact | Fluorocarbon coolants may have high GWP. | ElectroSafe has no direct GWP, according to the blog. |
| Location Flexibility | Requires less infrastructure than air cooling. | Compact infrastructure supports flexible deployment. |
Complexity & Upfront Costs
Two-Phase Cooling
Two-phase immersion cooling systems are a bit more complex in their engineering and present higher up-front costs. While pumps are not needed to circulate fluid around the servers, sealed racks with integrated condenser coils are required to make it all work.
The biggest cost difference between single – and two-phase relates to the coolant. Fluorocarbon-based two-phase coolants such as 3MTM NovecTM typically cost an order of magnitude more than hydrocarbon-based ones like ElectroSafe® from GRC. When you’re using over 300 gallons of the fluid in a single rack, those additional costs can be significant.
What’s more, the enclosure in which racks are immersed in the Novec must be completely sealed to avoid losing that extremely expensive coolant. Since servers often require maintenance, this can create annoying access issues and add operating costs related to topping up fluid that evaporates. In fact, a study by the Lawrence Berkeley National Lab (LBNL) found that the cost of replacing evaporated fluid negated any energy savings two-phase cooling offered.
Apart from the cost of evaporation, prolonged exposure to the vapor can cause health and environmental concerns. Fluorocarbon-based coolants often have extremely high GWP (Global Warming Potential) and are highly regulated.
Single-Phase Cooling
Although it requires a pump to keep the coolant circulating through the system, single-phase immersion cooling wins the complexity category. For example, GRC’s ICEraQ™ micro-modular immersion cooling solution features an open rack design allowing free access to servers. The synthetic hydrocarbon-based fluids, such as GRC’s ElectroSafe, in this process are clear, odorless, non-toxic, and widely used in domestic products such as cosmetics. They also have well-established material handling practices, minimal regulations, and no direct GWP (Global Warming Potential).
Efficiency & Operating Expenses
Two-Phase Cooling
Both single– and two-phase immersion cooling systems blow the doors off air-cooled data centers when it comes to cooling efficiency. But two-phase just squeezes by to claim first prize with a PUE of 1.01 to 1.02 versus 1.02 to 1.03 for single-phase.
However, unlike ElectroSafe™, fluorocarbon-based coolants must be regularly replenished – again at hundreds of dollars per gallon. That’s enough to raise overall operating expenses and offset any small power efficiency gains, to say nothing of total cost of ownership (TCO).
While two-phase systems are energy-efficient, pulling maintenance on them can be complicated. To access the servers, operators must unseal the enclosure while trying to minimize coolant loss and inhalation of vapor.
Single-Phase Cooling
At an impressive 1.02-1.03 PUE, single-phase utterly crushes the relative energy inefficiency of non-immersion-cooled systems which, according to the Uptime Institute, averages out to a 1.67 PUE.1
Where consumables are concerned, ElectroSafe is far less expensive upfront, does not evaporate, and will easily last 15 or more years. Regular lab tests are performed on the coolants to test for any variance in critical properties over time. Commercial deployments dating back to as early as 2010 have been running efficiently and reliably, with no degradation in the coolant’s performance.
Plus, compared to two-phase systems, server maintenance on GRC’s ICEraQ micro-modular immersion cooling solutions is very easy. You just open the lid, lift out the server and set it on integrated service rails, which are placed at a convenient workbench height.
Cooling Capacity & High-Density Performance
Two-Phase Cooling
Two-phase coolants can typically support extreme rack densities, with some providers claiming to support up to 250 kW in a single rack! While the claim sounds extremely impressive, it’s hard to find commercially available hardware that will get you to even 100 kW.
Single-Phase Cooling
By contrast, GRC’s ICEraQ is capable of handling 200 kW per rack when attached to a chilled water system. In fact, we’ve had a customer support over 130 kW within a 52U rack with cooling tower water. Given the anticipated long-term “heat trend” for incorporating next-gen applications like AI, IoT, facial recognition and others, that’s more than enough cooling performance for the foreseeable technology evolution.
Reliability & Location Flexibility
Two-Phase Cooling
Both single – and two-phase immersion cooling systems on the market today give information and communications technology (ICT) leaders tremendous flexibility in locating their data centers. This is due to the fact that neither requires the extensive infrastructure traditional air-cooled installations do.
However, studies have shown that fluorocarbon-based fluids used in two-phase immersion cooling present several safety and reliability issues GRC’s ElectroSafe doesn’t. For one, fluorocarbon-based fluids have a high Global Warming Potential (GWP). While the 2016 Lawrence Berkeley National Lab (LBNL) study found no harmful breathing zone concentrations during normal operations,2 some industry pundits have rightly expressed concerns about exposing data center personnel to this substance in any amounts.
That same study also found that “repeated logic board…failures were responsible for the high number of service requests.” Indeed, these amounted to 368% of the total cost of IT equipment energy consumption.3
Next, some experts have suggested that the boiling action on which two-phase cooling depends may harm IT assets over time through a process known as cavitation. Seals for the coolant bath can also fail. Plus, the expensive Novec evaporates quickly, leaving the rack empty and without cooling.
Finally, it should be noted that the condenser that’s placed directly over the servers in two-phase systems is water-cooled. While the two are unlikely to come in contact, there are widespread concerns about having a conductive liquid directly above the IT rack.
Single-Phase Cooling
Since pioneering single-phase immersion cooling back in 2009, GRC has made reliability one of the hallmarks of our ICEraQ and ICEtank solutions. Posing virtually no maintenance issues, both these systems can consistently cool 200 kW/rack using our dielectric coolant, ElectroSafe, which is totally inert, non-conductive, non-flammable, non-corrosive, and does not need replacement over the life of a typical data center.
Hardware reliability data for our systems show a significant increase in the Mean Time Between Failures (MTBF) over traditional air-cooled data centers. This increase, in part, is attributable to our close collaboration with key OEM partners such as Dell, Hewlett Packard Enterprise, 2CRSI, iXSystems, AMAX, and Supermicro.
Conclusion: Single-Phase Wins by Keeping its Cool
Without Boiling Away Costs
While it boasts some impressive theoretical performance metrics and considerable potential, two-phase immersion cooling is very complex, far too expensive and overly engineered for today’s data center cooling needs.
To that point, back in 2016 Lawrence Berkeley Laboratory concluded that two-phase immersion cooling was not viable, with liquid cost and IT equipment failures as primary obstacles.4 Since then, there have been no large-scale, public-enterprise deployments of the technology to disprove those findings.
Single-phase immersion, on the other hand, has been proven cost-effective and highly reliable by GRC over the course of a decade. Our ICEraQ and ICEtank solutions are now helping some of the world’s largest cloud, enterprise, government, education and telecom organizations grow while future-proofing their data centers.
1 Andy Lawrence, “Is PUE actually going UP?,” https://journal.uptimeinstitute.com, (May 2019)
2 Coles, Henry and Herrlin, Magnus. Immersion Cooling of Electronics in DoD Installations. Lawrence Berkeley National Laboratory. May 2016
3 Coles, Henry and Herrlin, Magnus. Immersion Cooling of Electronics in DoD Installations
4 Coles, Henry and Herrlin, Magnus. Immersion Cooling of Electronics in DoD Installations
Single-Minded About Growing Your Data Center? Let’s Talk!
Send us an email at info@grcmain2025v2.wpenginepowered.com or call us 1.512.692.8003. A GRC associate will reach out to talk details with you.
In the meantime, be sure to read Data Center Cold Wars — Part 1: Air-Based Cooling Versus Single-Phase Immersion Cooling and watch for the next installment.
Life is full of must-haves and just nice-to-haves. Brakes on a car? Gotta have ‘em. Seat warmers? Totally optional. Given the challenges data center operators face now and in the future, liquid immersion cooling is well on its way to becoming a must have to keep ICT (Information and Communications Technology) from overheating.
This second in our When Does Liquid Immersion Cooling Make Sense? series talks about situations when the answer verges on the obvious.
The growth in GPU-based applications is raising energy consumption and costs at an accelerating rate. Data centers are simply running out of available power. Arranging to have your utility bring in more power is both expensive and time-consuming.
Data Centers Are Energy Hogs
Data centers and cloud providers now devour 6% of global electricity. By 2025 that number could easily reach 20%! 1
While you’ve probably heard the adage “you can’t squeeze blood from a stone,” it is possible to squeeze a whole lot more compute from your existing power envelope. Data Center infrastructure & operations professionals can turn to liquid-immersion cooling, which can reduce energy costs by up to 50%.
Liquid immersion has an extremely low PUE. In particular, the power requirement for GRC immersion cooling systems is less than that needed for the removal of server fans. GRC’s patented immersion system power requirement amounts to a mere 3% of the “true” compute load versus an industry average of 70%.
We’ve had two notable success stories of extreme energy savings in parts of the world with infamously high energy costs: Australia and Japan. For DownUnder GeoSolutions (DUG), our ICEraQ™ micro-modular, immersion cooling solution cut cooling energy consumption by some 90%, and brought down total energy costs by about 35%.
And, our ICEraQ also delivered an incredibly low PUE of 1.02 for Tokyo Institute of Technology. The Green500 ranked their TSUBAME-KFC number one in the world in power efficiency – with a 24% lead over the second-ranked machine. This improved on the previous Green500 #1 record by over 40%, and gave Tokyo Tech their second Green500 win using GRC’s immersion cooling solutions.
What’s more, GRC’s solutions also have a wide operating range, and our clients often use a “warm water” loop, eliminating the need for chillers.
Analyst Report: The Immersion Cooled TSUBAME-KFC: The Greenest Supercomputer in the World >>
Data center infrastructure and density demands are changing dramatically, driven by the advance of next-generation application architectures in AI, IoT, AR, along with microservices. New high-performance, more densely packed processors and co-processors consume ever greater power and generate more heat than most existing data centers were designed to handle. Faced with significant time and money expenditures, many operators are struggling to keep up, much less stay ahead of the curve.
Liquid immersion shatters the typical limitations of legacy air cooling, raising the bar to support 200 kW/rack densities.2 Bottom line: this newfound cooling capacity flat-out solves the pervasive density dilemma.
Video: CGG’s Immersion-Cooled Data Center: Submerged Servers at Scale >>
Here again, GRC has helped many companies around the world find a cure for their density woes through liquid-immersion cooling; and in the process we’ve made energy costs a smaller, less bitter pill to swallow:
For Houston’s top geoscience company, CGG, we doubled the number of servers hosted in their facility (and the per-rack heat load capacity) while helping them achieve a 50% reduction in total data center energy usage. Negating the need to purchase new, capital-intensive cooling equipment, we built out the required cooling capacity in 100 kW increments, which eliminated any downtime.
We also delivered super results for the supercomputing facility DUG, mentioned earlier. They operate “Bruce,” which, at eight petaflops, is the Southern Hemisphere’s largest commercial supercomputer running one of the world’s largest deployments of Intel® Xeon Phi™ co-processors. With GRC’s help DUG was able to develop their impressive compute while vastly paring back costs along the way. We’re talking a 90% drop in cooling energy consumption and a 35% total energy cost reduction.
1 Andrae, Dr. Anders S.G. Total Consumer Power Consumption Forecast. October 25, 2017.
2 Utilizing a chilled water system.
Does Liquid-Immersion Cooling Make Sense for Your Data Center?
There’s a high probability. Why not send us an email at info@grcooling.com or call +1 512 692 8003 and know for sure? A GRC associate will reach out and run the numbers for you.
In the meantime, be sure to read the other installments in this blog series:
When Does Liquid-Immersion Cooling Make Sense? – Part 1
When Does Liquid-Immersion Cooling Make Sense? – Part 3
We here at GRC have cause to celebrate – and we think you do too! The reason? We’ve just signed an OEM Partnership with Hewlett Packard Enterprise (HPE), one of the most trusted names in servers!
Now, data center operators everywhere can get everything they’ve come to expect from HPE products – innovation, acceleration and exceptional reliability – protected by the most advanced and proven server cooling technology available today – all from a single source.
Cool Can Be the New
Normal – No Matter How
Hot Your Servers Run
We’ve said it before: high-performance computing is fast becoming the new norm, creating imposing heat and density barriers that are difficult to surmount with traditional cooling technology. With this new GRC-HPE alliance, IT leaders can now easily break through those barriers by purchasing an all-in-one data center solution direct from us — pairing any HPE server, like the Apollo 2000 HLF 2600, optimized for immersion cooling with any of our ICEraQ™ or ICEtank™ systems. It couldn’t be simpler.
Serving You Better – With Minimal Site Requirements
With immersion cooling from GRC, operations once limited by power, space or cooling can now seamlessly deploy HPE servers of any type virtually anywhere – with minimal infrastructure requirements.
Whether you’re building within existing white space, on the edge, or in a greenfield site, our new partnership makes it easy to create a high-density zone without the thermal constraints of air cooling.
As for kicking down those heat and density barriers, our ICEraQ One – can handle nearly 5,000 watts of heat load per unit of rack space*. Enough said.
Cool AND Confident
The trend toward high-density computing is unstoppable. The heat dilemma is inevitable. But, thanks to our new OEM partnership with HPE, you can be certain overcoming those challenges isn’t.
Will liquid-immersion cooling be your breakthrough?
With our new HPE alliance, the possibility is better than ever! Shoot us an email at info@grcmain2025v2.wpenginepowered.com or call +1.512.692.8003 to find out for sure.
A GRC associate will reach out and give you some great options.