Powering data centers: On-site electricity generation for digital infrastructure 

With highly efficient gas turbine technology, data center operators have a forward-looking option for autonomous, uninterrupted power supply that helps to reduce their operating costs while maintaining maximum reliability and sustainability.

By Christopher Findlay

Data centers are the factories of digital societies, indispensable nodes on the information superhighway whose operators’ primary objective is to ensure maximum availability and uptime for digital services. However, in an energy system marked by volatility due to stochastic in-feed of renewables, electrical power from the grid can no longer be fully relied upon to ensure uninterrupted, high-quality electricity and cooling power – not if data center operators aim to achieve industry benchmarks of up to 99.994 percent availability or even higher. One way of reaching this level of uptime is through on-site power generation with highly efficient gas-turbine technology that keeps the hardware running reliably and stable and ensures the data center remains operational under all conditions.

As netizens and users of digital services, we tend to think of data as intangible and ephemeral, as the term “cloud computing” suggests. But the business of data storage and communication is a very physical one that requires not only real estate but also, crucially, increasing amounts of energy. Several often-cited, yet simplistic analyses claim that the energy used by the world's data centers has doubled over the past decade and their energy use will triple or even quadruple within the next decade. For every watt of power consumed by computing equipment, another 0.5 to 1 watt is required for cooling. Overall, data centers will be a crucial part of efforts to decarbonize power supply and mitigate climate change.

Efficient gas turbines provide that high-quality power in a way that ensures constant availability from second to second – the main concern of data center operators. But with a reduced CO₂ footprint compared to power from the grid they are also the ideal choice for future-proof energy supply in data centers over the middle term. Not only can on-site gas turbines bring down costs along the entire power chain, from generation and backup to uninterruptible power supply (UPS); their scalable modular concept makes them suited for expansion to cope with the constant increase in the volume of data stored and transmitted – by a rapidly growing and increasingly urban global population, which means increasing numbers of connected devices. 

Finally, with high power density and high-quality electricity, gas turbine-driven on-site power generation can help facilitate the continuing integration of renewable power into a distributed, bidirectional energy system without instabilities in frequency and voltage, making them future-ready in more ways than one. Already today, they offer forward-looking fuel flexibility and can use a high share of hydrogen. They provide operational flexibility to generate residual load as required, and by providing real inertia for frequency stabilization, the design and operation of the UPS system can be cost-optimized compared to a grid-supplied solution. That flexible design opens up new business models for data center operators, who can strike the ideal balance between their own power needs and opportunities to sell surplus capacities to the grid.

With turbine packages, data center operators can customize the configurations of their decentralized power supply to fit local conditions and requirements, including maintenance intervals. Simple-cycle turbine packages can provide high power density in combination with modularity and redundancy in case of failure or scheduled maintenance, with fuel utilization and electricity efficiency rates in the range of 33–43 percent. In a combined cycle (CC) package, a heat recovery steam generator and steam turbine can raise these figures to ranges from 48 up to over 60 percent, ensuring maximum electric efficiency and lower operational expenditures (OPEX) through better fuel utilization. A combined heat and power (CHP) configuration that harnesses process steam can even boost fuel utilization to 75–85 percent and more, again bringing down OPEX and lowering emissions into the bargain. Finally, combining a CC array with process steam (CC-CHP) gives operators top marks for efficiency, OPEX, and performance, as well as optimal fuel utilization.

On-site power generation solutions may be delivered as a basic power package, a power island, or a turnkey power plant. This versatility and autonomy is a hallmark of gas-turbine technology that makes them a suitable option for data centers and other businesses, but also, for example, for industrial operators that are facing similar challenges and planning for the transition into a carbon-free and decentralized economy. 

Natural gas-fired power generation already emits less carbon and other emissions than the grid average of most nations. A further reduction of the footprint can be achieved in combined cycle operation and by using biofuels or green hydrogen in combustion.  

In the long run, gas turbines are designed for the transition to 100 percent e-fuels, with the capability to run on synthetic combustibles such as e-methane or e-hydrogen. E-fuels are produced using excess renewable energy, enabling carbon-neutral or even carbon-free generation of power and heat.

If the growing energy demand for the supply of data centers could be met by intelligent sector coupling, this would also be a sustainable solution for other applications like renewable power-driven chillers for cooling or thermal storage. It would correspond optimally with the requirements of operators in terms of future viability, availability, and operation and maintenance as well as their specific business model and carbon footprint targets. As a reliable, future-oriented and efficient decentralized energy source, on-site power generation based on gas turbine packages ensure that data centers remain stable hubs and provide highly available, stable data for industry players and consumers on the threshold of the digital age.

Apr 22, 2020

Christopher Findlay is a freelance journalist based in Zurich, Switzerland.

Combined picture credits: Siemens Energy