Wärtsilä partners with Schneider and advocates gas engines for data centres

15 May 2018

Wärtsilä and Schneider Electric have signed a global co-operation agreement to bring together their individual products and services, along with those of third parties, for the purpose of co-operating on data centre projects. The co-operation focuses on “hyperscale” data centre projects with at least a 10 MW electrical load.

Wärtsilä and Schneider Electric have signed a global co-operation agreement to bring together their individual products and services, along with those of third parties, for the purpose of co-operating on data centre projects. The co-operation focuses on “hyperscale” data centre projects with at least a 10 MW electrical load.

Wärtsilä and Schneider signed the co-operation agreement in Helsinki in December 2017. The objective of the co-operation is “to work together to open markets for innovative data centre energy optimisation solutions”, the partners say. Wärtsilä’s responsibility is to provide the power generation plant, while Schneider’s focus is on “energy distribution optimisation.”

Wärtsilä says its medium speed gas fuelled reciprocating engines “offer highly efficient, sustainable and cost-effective power compared to traditional back up diesel generators.” It suggests redundant engine capacity can be used to sell electricity to the grid, opening up “a new business model for data centre operators.” Thanks to the efficiency of gas engines, “they provide power to the data centre at a lower price than grid electricity, “while “switching to natural gas can also significantly reduce the carbon footprint of a data centre”.

Gas engines for data centres

A recent white paper from Wärtsilä, Smart power generation for data centers (by Adam Rajewski, manager, data center technology, Wärtsilä Energy Solutions) sets out the case for employing gas (piston) engines in this mission critical application.

Traditionally, data centre power has been provided by a combination of grid electricity, ensuring affordability, and emergency diesel generators, guaranteeing reliability. Unfortunately this has certain drawbacks, Wärtsilä says, “from dependency on increasingly unstable power prices to high local emissions from diesel generators, which sometimes might even lead to problems obtaining environmental permits.”

The white paper argues that “state-of- the-art gas engines are capable of starting up just as fast as diesel engines, but unlike those, they are able to competitively generate power not only in emergencies, thus recouping their costs and even generating additional profits.”

Data centres predominantly employ battery based UPS (uninterruptible power supply) systems to provide power in the event of grid failure just long enough for the emergency power supply system to start up. The UPS systems are “typically dimensioned to last for a couple of minutes and are very expensive”, says the white paper, which effectively means that the emergency power generation technology should be able to ramp up as quickly as possible, “ensuring that the battery system is only as big as absolutely necessary.”

Despite the technical advancements in many power generation technologies, “a reciprocating engine still remains the only solution capable of meeting emergency power supply requirements”, argues the white paper, “but such an engine does not have to run on diesel fuel anymore – now there is a cleaner and more economically effective alternative: natural gas.”

However, until quite recently, the white paper notes, “gas engines had a major flaw compared to diesels: the starting time.” While “ten minutes – the state of the art just a few years ago – is very impressive in the world of commercial power generation and faster than any other technology except diesel or hydro, for an emergency power generation system this would be way too slow,’ the white paper says. “In fact, this is more than ten times slower than any decent emergency diesel generator.”

However, during recent years, huge progress has been made, the white paper points out: “In general, the increasingly volatile electricity markets have forced equipment vendors to improve the flexibility of all power generation technologies, but in the case of the gas engines the progress has been perhaps the most impressive. Over just a few years, standard series-built medium-speed gas engines had their start-up times reduced from ten minutes to just two. This was still longer than diesel, but the difference was no longer an order of magnitude. And even this has been further reduced. Recent development and testing has conclusively demonstrated that state-of-the-art gas engines may be started and brought to full power in considerably less than one minute of the starting order, which brings them within the world of emergency power supply.”

The white paper includes two “exemplary and representative” gas engine start-up curves obtained during actual engine tests performed by Wärtsilä. These were obtained from tests during start-up of a medium-speed gas engine operating in island mode and indicate start up times of around 40 seconds, measured from the start command until full output (see diagram, left).

“Of course, this still leaves the issue of fuel storage”, the white paper notes, but “recent progress has also been significant here”, in particular with the emergence of small-scale affordable gas storage technologies, especially in the form of liquefied natural gas (LNG). “LNG systems have been adopted in various applications, notably on some ships, where gas is getting increasingly popular as an environment-friendly alternative to fuel oils. Small-scale LNG storage and regasification plants are so reliable and safe that they are currently being installed on passenger ships.”

Therefore, argues the white paper, there is now an alternative to diesel engines as a source of backup power for data centres. However, “adopting gas goes far beyond just providing a different equivalent solution.” First, using gas means less carbon dioxide. This is an inherent feature of natural gas as a fuel. The higher hydrogen-to-carbon ratio in its constituent compounds means that the exhaust gas contains less carbon dioxide and more climate-neutral water vapour. When combined with high efficiency of modern industrial gas engines (which is “among the highest of all power generation technologies and higher than the diesel engines currently used for emergency power generation”), this means that using electricity generated by gas engines has a considerably lower carbon footprint than using diesel-generated power. In fact, “the carbon footprint is much lower than that of grid electricity in most countries”, the white paper says. This means, “operating the generating sets continuously instead of relying on the grid would have a positive effect on the carbon footprint of the data centre” and “once an emergency power generation system is built using a solution that is neither legally nor technically restricted from operating beyond emergencies” this new capability can be used for self-generation and even merchant operation.

In either case, the white paper suggests, the power plant could be owned and operated by the data centre owner or a third party, which would then conclude a long-term agreement with the data centre owner. 

Wartsila Example of a start-up curve for a state-of the-art Wärtsilä gas engine (screenshots from engine control system). The start-up duration, 40 seconds, is measured from the start command to full output

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