Batteries are of central importance for the energy transition. They can help to cushion the fluctuating feed-in of renewable energy. To this end, many solutions are already being worked on in engineering and network technology.
Help is now coming from an unexpected source: data centres. They store and process huge amounts of data, but to date they have only been considered large consumers of electricity. To be on the safe side, however, they have uninterruptible power supply (UPS) systems and emergency power generators available around the clock. These systems are rarely used.
Thanks to the Master+ solution developed by RWE Supply & Trading and Riello Power Systems, data centres can now contribute to the energy transition: their UPS battery systems help to stabilise the grid. Master+ features a premium battery with increased storage capacity and an integrated battery monitoring system. The system can automatically draw power from the grid or supply power to the grid in the event of grid imbalances. In addition, RWE has developed a service with which the emergency power generators can significantly relieve the load on the power grid by means of a few targeted operations. Both the UPS batteries and the emergency power generator are marketed with the support of RWE.
Coping with intermittent supply
Electricity generation in the UK is in the process of a huge transformation, with old-style plants powered by fossil fuels on the way out. In May 2019, Britain actually went coal-free for more than a fortnight, with renewables such as solar, wind, and tidal playing an increasingly important role.
While this shift to low carbon delivers significant environmental benefits, it does pose a problem as these green sources are a lot more unpredictable. This, in turn, makes it more difficult for National Grid to balance supply with demand and ensure a stable frequency.
The obvious solution to this challenge is a move away from the traditional centralised method of power generation, transmission, and distribution to a dynamic, decentralised network driven by smart grids, onsite generation, and battery storage, where energy users can also be producers. Until now, the majority of data centre operators have been slow to embrace this change. Risk-averse by their very nature, they often simply refuse to compromise on their chief priorities of uptime and availability. Using batteries for anything other than emergency backup is seen as an unnecessary risk.
The partnership between Riello UPS and RWE promises to end this uncertainty by offering a route into demand side response while at the same time strengthening – rather than undermining – system resilience.
Delivering a virtual power plant
The collaboration focuses on a smart grid-ready UPS that in effect transforms the data centre into a ‘virtual power plant’. It is based on a modified version of the Master HE power supply fitted with a special rectifier that enables the bi-directional flow of electricity both from and to the grid. Alongside this modern, efficient, high-performing UPS is premium battery blocks equipped with RWE’s intuitive monitoring and communications systems that enable real-time interaction with the grid and quickly detect any potential issues with the batteries.
These batteries are divided into two elements with very defined roles. The first section’s job is purely to provide back up electricity in the event of a power failure. The second commercial element stores electricity that can be fed back into the grid via DSR mechanisms such as Firm Frequency Response or used as a substitute to more expensive, peak-demand power.
If there is a power failure, any remaining energy stored in the commercial battery cells is activated to complement the main backup, a potentially significant increase to overall autonomy.
The concept has been successfully piloted since September 2018 at RWE’s global headquarters in Essen, Germany. Based on a site with a 100-kW secured load, the project has already received international recognition having been a finalist in the ‘Data Centre for Smart City’ category of the international Datacloud Global Awards.
The benefits for data centres
Obviously, premium lead-acid or lithium-ion cells are more expensive than traditional UPS batteries. RWE covers part of the cost of the batteries, significantly reducing the capital cost of buying a new UPS system.
Another advantage compared to a UPS using standard lead-acid is the mandatory monitoring of the Master+ model. Without an expensive battery monitoring system, it is difficult to know for sure whether lead-acid cells will work when called upon. However, the advanced monitoring of the premium batteries means operators are certain their batteries will kick-in when required – if the analysis highlights any cell weaknesses or issues, the offending batteries can be replaced before they become a problem, greatly enhancing system reliability.
In addition, RWE – rather than the data centre – takes on any risk associated with trading on the energy market. This sees the UPS system tap into the DSR mechanism known as dynamic Firm Frequency Response (FFR). This pays companies that either quickly reduce their consumption or feed back into the network to ensure a grid frequency of 1% within 50Hz.
Head start for Germany
In Essen, Germany, The Kraftwerks-Simulator-Gesellschaft (KSG) has become the first customer worldwide to use RWE’s UPS battery solution and is also providing its emergency power generator for network services. “With Master+ and the marketing of our emergency power generator, we can benefit from the energy market,” Dr Burkhard Holl, head of engineering and operations, at KSG, said. “We have a higher storage capacity and our battery storage is monitored around the clock. This means greater security of supply while at the same time generating additional revenues – a solution that is both profitable and resource-efficient for us.”
Another advantage is that the emergency power generator is not used much more frequently than usual, even with RWE´s remote control system. “Put simply, we cycle the test runs of the emergency power generators, which take place anyway, in exactly the same way so that the networks are relieved,” Claudius Beermann, the responsible product manager at RWE, said. “In this way, we replace wear-promoting test runs at low load with targeted operations under high load.“
Due to its high degree of innovation, the system was awarded the German Data Center Prize in the Energy Technology category in 2018 and the eco award category at the Datacenter Infrastructure awards in 2019.
The expansion of KSG’s data centre is now being gradually expanded: in the first stage of expansion, which has already been implemented, two UPS battery solutions, each with 250kW Master+ type power, and a 1,100 kW emergency power generator to secure the emergency power supply were installed. The next step is to increase the UPS output to two MW and to add a second emergency power generator.
The certification of the KSG computer centre based on the TSI.STANDARD including the DIN EN 50600 specific extensions will be carried out by TÜViT. The overall concept of the site is currently undergoing conformity testing for Level 3, which stands for a universally available data centre. The catalogue of criteria also defines requirements for the planning of the building construction, energy supply and security systems trades and specifies criteria for the operation of computer centres.
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