Previously, we looked at how liquid immersion cooling and smart environmental monitoring can make data centers more sustainable. Let&#;s now look at another option that&#;s currently available, Battery Energy Storage Systems (BESS), and why it can replace diesel generators, which are estimated to provide over 20 gigawatts of backup power globally in the data center industry today.

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A possible game changer, BESS are fast, reliable and virtually maintenance-free; they require no fuel storage, are quiet, environmentally friendly, and can last for more than 20 years. Diesel generators, in contrast, struggle with increasingly regulated emissions, noise and fuel storage, and they need regular testing and frequent maintenance to ensure reliability.

Alternatives to diesel generators: promoting the use of BESS

In September , during the Critical Facilities Summit in Dallas, I shared my insights about the benefits of replacing diesel generators with BESS in a presentation I co-presented titled &#;Backup Power: New Approaches via UPS, Energy Storage & EV Technologies&#;.

We discussed how diesel generators, despite their well-documented long-term negative impacts on the environment, have been providing backup power to critical facilities for decades. Thankfully, improvements in the cost and performance of rectifiers and chargers, inverters, high-speed power switching, control systems and, more specifically, new battery technologies mean we now have viable alternatives to these fossil fuel-powered machines.

Dealing with power outages

Data centers and other critical facilities require long-term backup power, sometimes for days at a time, so if we&#;re to have BESS as viable alternatives to diesel generators, then we must ensure their longevity. Currently, the typical designs of BESS limit their ability to provide backup power for no more than four hours unless combined with more traditional backup systems.

Fortunately, most non-major event outages are less than two hours. The average US electricity customer experienced just over eight hours of power interruptions in . Moreover, the best states average between 44 and 101 minutes for individual outages, while the worst ones average considerably more, ranging from 29 hours to a whopping 60 hours.

By anticipating an outage that lasts for more than two hours, we can engage a hybrid configuration. We can use the more traditional diesel or natural gas generators early enough to allow us to recharge the BESS. We could then extend the four-hour window to perhaps eight hours or more, covering an even greater percentage of annual outages.

Supposing an outage lasted more than eight hours, as might be the case in a major natural disaster, we could implement load shedding protocols to extend the eight hours even further or use remote backup facilities. This way, by using a hybrid configuration, we can substantially reduce greenhouse gas emissions in our environment.

This may not always be the case, though, as rapid breakthroughs in battery technology are extending the duration of BESS, and this may phase out hybrid configurations. An example is California Community Power&#;s first eight-hour, long-duration lithium-ion battery energy storage resource project, which will have a 69 MW output and 552 MWh capacity (8 hours) operational by .

Liquid metal batteries for future energy storage

While lithium-ion batteries dominate the BESS industry, their pros and cons have been discussed and debated repeatedly. They&#;re expensive, don&#;t like being fully charged or discharged, are extremely sensitive to high temperatures and are inherently flammable.

Liquid metal battery systems are promising and may soon replace lithium-ion in larger-scale BESS installations. Antimony and calcium alloy are combined with a solid salt electrolyte inside a sealed, insulated and positively polarized stainless-steel case with a negative terminal at the top.

The contents are then heated to 932 ˚F (500 ˚C), at which point the metals and electrolyte become molten. The discharge process generates its own heat, eliminating the need for an external heat source. With an efficiency of 80% and the ability to undergo tens of thousands of charge and discharge cycles with little to no degradation or drop in efficiency, liquid metal batteries easily outperform their lithium-ion counterparts.

Unlike lithium-ion batteries, liquid metal batteries&#; high operating temperature does not require cooling, making them suitable for any climate. As far as safety goes, liquid metal batteries have no issues compared to those plaguing lithium-ion batteries.

American startup company Ambri is a major player in the spread of this technology and has the potential to revolutionize BESS and the transition to a more sustainable energy system. Massachusetts Institute of Technology professor of materials chemistry Donald Sadowa established the company, which has Microsoft founder Bill Gates as a major supporter and investor through his Breakthrough Energy Ventures fund. Other investors include Khosla Ventures and TotalEnergies.

In May , Ambri teamed up with data center provider Terrascale to provide 250 MWh of renewable energy battery storage for the latter&#;s Energos Reno project. And in September , Microsoft announced it had installed Ambri-manufactured high-temperature liquid metal batteries for backing up one of their data centers, but the capacity and location were not disclosed.

Goto Voltgent to know more.

Green data center: pushing for sustainability

Changes can be made so that the data center industry will be able to drive meaningful change on global warming and climate change issues. In fact, some of the biggest technology firms have already made moves to make their data centers more sustainable.

In July , Microsoft announced that it would eliminate its reliance on diesel fuel by the year . In December of that same year, Google announced that it would be using large BESS to replace the diesel generators at one of its data centers in Belgium. Meta also announced in September the formation of a consortium to measure the emissions benefits of using large BESS.

As we continue moving toward achieving our sustainability goals, liquid immersion cooling, smart environmental monitoring and BESS are just a few environmentally friendly data center trends to keep an eye on as we shift toward green data centers. 

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A diesel-powered generator. Image by Mehmet Demirli via Pixabay

Sunjoo Hwang

Diesel Generators are the Next Frontier in Curbing Carbon Emissions

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California again claimed to be a vanguard in emissions reduction initiatives across the globe by approving a ban on the sale of new diesel trucks by . Once approved by the federal government, the rule will enable California to execute the most stringent practices in curbing tailpipe emissions. Both supporters and critics keep their eyes on the impact of this rule to be implemented by California, the world&#;s fourth largest economy, which would regulate diesel fuel consumption that accounts for about 26% of the U.S. total transportation sector CO2 emissions. Transportation, one of the largest contributors to U.S. greenhouse gas emissions, is usually the first thing that comes to people&#;s mind as far as diesel emissions are concerned. Meanwhile, in contrast to its strong policy against diesel trucks, California increasingly burns diesel to operate backup generators for electricity.

Since severe weather conditions induced by climate change adversely affect the U.S. grid infrastructure, concerns about the reliability of grid electricity have led to a surge in public and private demands for backup options such as diesel generators. As one of the most commonly used types of backup generators, more than 7 million diesel generators are currently in use in the United States. Although they are often preferred as a convenient option to address power outages, diesel generators have risks and limitations. First, burning diesel fuels emits greenhouse gases, which would exacerbate climate change and extreme weather events, one of the leading causes of power outages. Air pollutants in diesel emissions negatively affect human health, and diesel particulate matter accounts for about 70% of the air toxins that increase the risk of cancer. Because diesel generators are often placed close to where people breathe, the impact of their emissions is as significant as those from tailpipes.

In addition, diesel generators bear a financial risk because of volatile fuel prices, as evidenced by the all-time high diesel price due to Russia&#;s invasion of Ukraine. Diesel generators also require high maintenance costs as the level of maintenance determines the reliability of diesel generators. Aside from the equipment itself, diesel fuel requires attentive maintenance in order to prevent fuel degradation or mishaps such as spills.

Furthermore, another challenge to successfully operating diesel generators is securing uninterrupted fuel supply in an emergency. As diesel fuel is usually transported by trucks, its availability is vulnerable to extreme weather events that damage roads and render other transportation infrastructure inoperable. Emergency situations can also impede fuel supply. For example, during Hurricane Katrina, commercial generator owners were not given diesel fuel as it was redirected to support rescue work. Additionally, disruptions in fuel supply present even more serious problems to the military or defense industry since military actions such as attacks on logistics convoys and transportation infrastructure can lead to causalities and impair the success of an operation.

However, diesel generators are not the only option. For example, microgrids can be a resilient alternative negating the need for a generator. A microgrid is a network of distributed energy resources within defined boundaries, with capabilities to connect and disconnect from the grid. Microgrids can incorporate diverse energy resources such as solar and wind, and they can take various forms from portables to utility-scale systems. In the case of a power outage due to infrastructure damage, the smaller, firewalled nature of microgrids can help reduce the likelihood that localized damage will impact a wide area. While the lower installation cost makes diesel generators favorable in the short term, recent federal legislation such as the Inflation Reduction Act provides financial incentives to install microgrids. Given that the diesel generator operation is often restricted to emergency use only, their investment cost is rarely recouped in the short durations they are used. Alternatively, microgrids with solar and storage resources better help customers save energy bills which ultimately helps to recoup their initial installation costs. In this regard, the cumulative cost of diesel generators (with their minimal use) outweighs that of microgrids over a longer period.

Meanwhile, the Centers for Medicare and Medicaid Services has recently issued a waiver to allow microgrids to be used as health care facilities&#; backup power, whereas the federal agency had previously reimbursed costs only for fossil-fueled generators. Given that backup power is particularly important for critical facilities such as hospitals, transportation, communication, and national defense installations, this remarkable change demonstrates the potential of microgrids as resilient energy systems.

Despite viable alternatives, the world expects that additional 3 million diesel generators will be installed annually by . It is imperative to take actions to protect U.S citizens and troops at home and abroad from toxic diesel emissions, while securing energy security and resilience. Diesel generators are not the only option to secure energy during an emergency. Though it would be challenging to entirely phase out of fossil fuel generators in the short term, a transition to clean and sustainable electricity systems such as solar-plus-storage should be implemented at a much faster pace in the light of the drawbacks of diesel generators. Just as the sale of diesel trucks is being targeted for regulation, similar efforts could regulate the future sale of diesel generators. It will enhance the resilience of energy supply and the sustainability of energy sources while reducing the risks to the environment, national security, and human health.

If you want to learn more, please visit our website Mitsubishi Diesel Generator.