Transforming data centers

Transforming data centers

Did you know large data centers consume power equivalent to the power consumption of an average-sized town? But a solution, in the form of modern gas-fired engines, holds the potential of providing affordable and reliable power and also generating additional profits.

Text: Adam Rajewski Photo: Adobe Stock, Viking Line, Wärtsilä

The phenomenal use of information technology has made data centers an indispensable part of modern day business needs, as they store an enormous volume of data that is generated on a daily basis. Every data center, thus, needs an extremely reliable and affordable power supply to ensure uninterrupted functioning, 24/7. 

The traditional mode of power supply, which involves a combination of grid electricity and diesel generators, has its own drawbacks in the form of unstable power prices and high local emissions. 

But what if these emergency power generation facilities helped in revenue generation? Can a back-up power supply facility become the primary source of power supply? And can this be achieved using cleaner forms of energy? The answer to all of these is a big YES. Our white paper – Smart Power Generation for data centers – substantiates that the solution lies in modern gas-fired engines. 

 

The modern approach 

The need for a smarter solution for emergency power supply has led to the advent of modern gas-fired engines that are cleaner than diesel engines and work faster. 

To understand how gas-fired engines are changing the dynamics of emergency power back-up mechanism for data centers, one needs to understand the functional requirements of an emergency back-up system. They are:

  • Very rapid automatic start-up: Data centers use Uninterruptible Power Supply (UPS) systems based on electrochemical batteries. They are typically dimensioned to last a couple of minutes and are very expensive.
  • Modularity of capacity: A good emergency power supply system needs spare capacity in a separate independent generator set, sufficient to cover the capacity lost due to maintenance or isolated failure. 
  • Ability to run on locally stored fuel: The facility needs some locally stored fuel to ensure an uninterrupted supply for a certain amount of time until the external power supply can be restored.
  • Technological maturity: Finally, the requirement of maturity is natural for a system where reliability is of fundamental importance.

An internal combustion engine still remains to be the only solution capable of meeting the above mentioned functional requirements. But such an engine does not have to run on diesel fuel anymore – especially, when there is a cleaner and more economically effective alternative: natural gas. Compared with other fuel-based technologies used in large-scale commercial power industry, gas engines meet all the features of a smart power backup system. It is fast to start, cheap to build, and extremely flexible.

An internal combustion engine still remains to be the only solution capable of meeting the above mentioned functional requirements. But such an engine does not have to run on diesel fuel anymore – especially, when there is a cleaner and more economically effective alternative: natural gas. Compared with other fuel-based technologies used in large-scale commercial power industry, gas engines meet all the features of a smart power backup system. It is fast to start, cheap to build, and extremely flexible.

Transforming data centers1
Fig. 1 - Start-up curves of a modern medium-speed gas engine. These are direct screenshots from engine control systems and were made during tests of a rapid start-up of a medium-speed gas engine operating in island mode. The top diagram shows a case of linear loading, while the bottom one involved pre-programmed load steps. In both cases start-up duration (40 and 41 seconds respectively) is measured from the start command until full output. Testing was performed in island mode. 

   

  
Gas engines, come of age

But not long ago, gas-fired engines suffered a major drawback in terms of very delayed start-up timing – at times as high as 10 minutes. But recent years have seen huge progress on this front. Now these state-of-the-art gas engines can be started and brought to full power in considerably less than one minute of the starting order, ushering them into the world of emergency power supply. 

In Figure 1, there are some exemplary and representative start-up sequences obtained during actual engine tests performed by Wärtsilä.

Gas engines have also taken care of the issue of fuel storage. Recent years have seen emergence of small-scale affordable gas storage technologies, especially in the form of liquefied natural gas (LNG). As a matter of fact, small-scale LNG storage and regasification plants are so reliable and safe that they are currently being installed on passenger ships. (Figure 2)

Clearly, modern gas engines hold enough power to become a potent alternative to diesel generators. However, gas engines go far beyond merely providing an equivalent solution. Restricting carbon emissions is very important amid growing environmental concerns. And adopting gas engines is the need of the hour as natural gas is the cleanest of all fossil fuels. Using gas means less CO2, which in turn means corporations can reduce their carbon footprint besides reducing costs. (Figure 3)

This means operating the generating sets continuously instead of relying on electricity grids would have a positive effect on the carbon footprint of the data center. 

Transforming data centers2
Fig. 2 - MS Viking Grace, a cruise ferry powered by
liquefied natural gas, has been safely carrying
passengers since January 2013.

   

Transforming data centers3
Fig. 3 - Carbon footprint of different sources of electricity.
Note that generating power with on-site natural gas power
plant has lower footprint than the grid electricity.
  
  

             
The real power 

That modern gas engines are the future of emergency power back up systems, has been established beyond doubt. But gas engines are not merely futuristic alternatives to diesel generators. In fact, gas engines are the game changers – because they can go beyond emergency. 

Once an emergency power generation system is built using a solution that is neither legally nor technically restricted from operating beyond emergencies, there are two essential ways of using this capability: 

  • Self-generation 
  • Merchant operation

  
    

Self-generation model

This model shifts the source of primary power from the electricity grid to the emergency power generation facility. If a data center has a power-generation facility that can be operated continuously on an inexpensive fuel with very low emission footprint, then it may very well be used as a primary source of power. 

This would make the local power plant the primary source of electricity, while the grid functions as a backup. This approach protects the data center operator from higher power costs and reduces carbon footprints too. 

Data center operators can generate additional revenue as data centers do not operate on full design load. That time can be used to generate additional power & sell it to the electricity market along with the spare and redundant capacity of power plant. (Figure 4)

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Fig. 4 - The self-generation model for a gas-fired
data center power plant.

   
   
Merchant plant concept

Unlike the self-generation model, in this case the gas-fired power plant can be used only as an emergency back-up power source while operating independently as a merchant generating station co-existing with data center and selling its production to external customers. In the event of any disruptions in the grid power supply, it would automatically switch to the emergency power supply mode. This might be a preferred approach for markets with high electricity cost. (Figure 5)

With the phenomenal advancement in gas engine technology and the advent of LNG solutions, there is no denying that the future of gas-fired engines, in data centers, holds immense potential. 

Transforming data centers5
Fig. 5 - Merchant plant model for the gas-fired data
center power plant.
    

Author: Adam Rajewski, Manager, Data Center Technology, Wärtsilä Enery Solutions,
mail: adam.rajewski@wartsila.com

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