STORY Power Generation

What will future mission-critical power solutions look like?

Posted on February 18, 2021 by Silke Rockenstein, Images by Rolls-Royce Power Systems, Robert Hack

Are we on the way to a climate-neutral data center? Interview with Tobias Bertler, Senior Manager Direct Sales at Rolls-Royce Power Systems

How concerned about sustainability are data center operators when it comes to back up power?
Data center operators are very interested in sustainable backup power solutions. This is partly because the entire data center market is dominated by the large technology companies, which are very much in the public eye and feel a social responsibility to reduce their carbon footprint. This has also moved data center emergency power systems into the fore. Although they have only a few operating hours, gigantic capacities with a very high available power are being built for these mission-critical data centers. 

Is there still a big demand for diesel gensets from data center operators?
Definitely. Today every mission-critical data center has backup power systems built into it that typically run on diesel fuel. Last year's exceptional situation caused by the COVID-19 pandemic showed once again how important it is to ensure an uninterrupted power supply for sensitive and critical infrastructures such as global continuous Internet traffic. This was also demonstrated in our diesel emergency power systems business. We have also further expanded our range of power supply systems for mission-critical applications with the acquisition of Kinolt as a leading company for dynamic UPS systems. 

Diesel gensets currently offer the highest safety and most coherent technical characteristics for mission-critical energy systems.

Tobias Bertler, Senior Manager Direct Sales at Rolls-Royce Power Systems

How do you reduce emissions from your diesel generators?
We have different ways of reducing emissions from diesel gensets: we continue to work on reducing exhaust emissions through internal engine measures and we offer exhaust gas aftertreatment systems. We provide different, flexible and project-specific solutions for the very heterogeneous market, where there are different directives and legislation depending on the region.

What alternatives for backup power supply for data centers do you see on the way to climate neutrality?
We see it as important to expand renewable energies and Power-to-X technologies, make alternative fuels available, prepare combustion engines for alternative fuels, and develop alternative energy and propulsion systems. We see great potential in hydrogen as a fuel. The numerous initiatives by various countries to further expand the infrastructure are also encouraging. In addition to hydrogen, we are working on other fuels produced from renewable energies such as e-diesel, e-methanol and e-methane. Accordingly, we are expanding our portfolio to include fuel cells and are currently testing hydrogen engines for energy supply.

The first fuel cell module is currently being tested on the test bench at Rolls-Royce Power Systems. Based on these fuel cell modules from automotive production, a demonstrator is being developed that will contribute to the stationary energy supply of Rolls-Royce Power Systems at its headquarters in Friedrichshafen.

Strong arguments for using and promoting the fuel cell technology for data center are high reliability, scalability and the ability to reduce both pollutant and climate-damaging gas emissions to zero.

In what ways can fuel cells be used for data centers? 
Strong arguments for using and promoting the fuel cell technology for data center are high reliability, scalability and the ability to reduce both pollutant and climate-damaging gas emissions to zero. With their modular design, fuel cell systems are easily adaptable to match output with demand, and their low maintenance requirements and low running costs also make them attractive. The greatest plus point arises when the fuel used is regeneratively produced hydrogen because it allows both pollutant and climate-damaging gas emissions to be reduced to zero. Fuel cell systems can also be easily integrated at a later date and grow with it when a data center expands. This makes fuel cell systems a long-term and future-proof investment.

Fuel cells can play a central role for CO2-free data centers (see graphic). In the future, the basic power requirements of a data center could be covered by solar and wind power plants instead of from the public power grid, as has been the case to date. If sufficient "green" electricity is available, hydrogen can be produced from water by electrolysis and stored on site. In addition, the hydrogen demand can be covered by a supply network that will be available in the future and used to operate the fuel cell: It would immediately take over the supply of the data center to maintain the infrastructure in the event of a power failure. Rolls-Royce, Daimler Truck AG and Volvo are planning to cooperate on a CO2-neutral emergency power supply for mission-critical facilities such as data centers using stationary fuel cell generators. 

For a CO2-neutral power supply, Rolls-Royce Power Systems aims to offer an integrated complete emergency power solution in the future. This includes the fuel cell system, a UPS system, the batteries and the hydrogen infrastructure.

Is the use of synthetic fuels approved in accordance with EN 15940 for driving mtu generators?
For the synthetic fuels according to EN 15940, we have run extensive tests on the test bench and also in the field in recent years and released GtL and HVO now for our Series 4000 G03/04 powergen engines. The synthetic EN 15940 fuels GtL (Gas-to-Liquid) and HVO (Hydrotreated Vegetable Oil), which are produced using the Fischer-Tropsch process are very similar to diesel in terms of their properties. They also offer some advantages, such as storage stability, which is much better compared to conventional diesel (especially with increased bio content). HVO is largely made from biological feedstocks and can be produced in a CO2-neutral manner.

What about biodiesel – is it a viable fuel given the sporadic use of gensets that are only used at back-up power?
Biodiesel has a higher bio and water content and thus has a poorer storage capability than regular diesel. Biodiesel is more susceptible to aging due to microorganisms in the fuel and can even tip over. This is referred to as the "diesel plague", where a bio-sludge forms in the fuel that can cause equipment malfunction and damage. Since fuel is often stored for long periods in emergency power systems, we view this fuel rather critically for this area. We consider other alternative fuels, such as the synthetic EN 15940 and e-fuels, to be more suitable for this purpose. Nevertheless, we have approved an admixture of 7 % biodiesel, as is common today in fuels according to EN590, without any further measures. For blending up to 20% biodiesel, we recommend various accompanying measures such as additives, a tank maintenance system or engine flushing.

Is it possible to connect emergency generators in data centers to the grid for control reserve and thus support the expansion of renewable energies?
Absolutely! Emergency gensets offer excellent conditions for feeding control reserve into the power grid and thus compensating for fluctuations in the grid (frequency and voltage) caused by the increased integration of renewable energies. The gensets can thus play a significant role in supporting the energy transition (and integration of renewables). To this end, there are various capacity markets in different countries in which to participate and create another source of income. For many years, Rolls-Royce Power Systems has had cooperative agreements with various national and international companies that enable our gensets to be integrated into the respective capacity markets. 

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