Diesels dominate in data

Data centres are where innovative state-of-the-art IT and the trusty diesel fuelled piston engine meet. High speed (>1000 rpm) diesels (in conjunction with a UPS, typically battery, flywheel or supercapacitor based) are the “perfect match” for data centre mission critical standby systems says Tobias Bertler of MTU Onsite Energy (part of Rolls-Royce). Among the attractions of diesel engines in this application are their outstanding transient response, reliability, and short start up time – which can be as little as about 10 seconds to reach full power and load acceptance.

They are also a proven technology and reassuringly familiar to data centre owners and users, who may be world leading innovators in their core business but are understandably conservative when it comes to data centre power supplies, where even the briefest power loss is unacceptable and close to 100% reliability is essential. That’s why they currently prefer diesel, explains Bertler.

Another consideration is fuel storage. Typically local health and safety regulations permit the on-site storage of diesel fuel for standby power installations, which is regarded as posing less risk than gas storage. Relatively large amounts of diesel can be stored, providing a relatively high degree of grid independence, without reliance on an off-site fuel supply such as a gas pipeline.

Looking to the future, there is of course interest in lowering emissions and moving to alternative fuels. Modified gas engines can, for example, match the flexibility and start up performance of diesels. But there remains the problem of having to put in place an infrastructure for gas. And this is a field in which most data centre operators seem to have no particular wish to be first. Power supply dependability is much more important to them.

So for now diesel engines remain dominant in the data centre business, and considerable efforts have been directed towards further improving the technology, in particular the availability of the engines. This has included such measures as preheating, redundant starting, automatic engine oil refill and redundant control systems.

A major market driver in Europe currently, says Bertler, is EU data protection legislation, leading US companies to install data centre capacity in Europe.

Another trend Bertler is seeing in the data centre market is the rise of co-location, where the servers of various enterprises are co-located in a common data centre, with shared digital connections and infrastructure, such as cooling, electricity supply and emergency power supplies. This requires a highly modular approach so that emergency power capacity can be built up in step with server installation, and the ability to deal with very short lead times.

MTU Onsite Energy has worked extensively with US-based co-locator EdgeConneX, supplying 80 gensets for data centres in the USA, as well as receiving recent orders for 12 x MTU 20V4000 DS gensets (total capacity 30 MW) for a data centre in Dublin, Ireland, and for 23 x MTU 20V4000 DS gensets (total capacity 57 MW) to be deployed at a data centre in Amsterdam.

The MTU Series 4000 diesel gensets for both of these latter projects can achieve full electrical output within 15 seconds of start- up. They are being supplied with 30 000 litre fuel tanks and can run for up to 48 hours in an emergency. The gensets are also being installed in containers to meet stringent noise control criteria.

Other recent MTU Onsite Energy data centre projects include the supply of 13 x MTU 4000 DS gensets (total capacity 26 MW) to SAP for its data centre at St Leon Rot, Germany, 34 x MTU 4000 DS gensets (88 MW in total) for another data centre in the Netherlands, 15 x MTU 4000 DS gensets for an Agricultural Bank of China data centre and 2 x MTU 2000 DS gensets (2 MW in total) for Bahnhof AB’s Pionen White Mountains data centre in Stockholm, Sweden.