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Making data centre power pay

Danel Türk

Danel Türk

Global Data Centre Segment Leader from ABB
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High energy prices are creating a challenge for data centre operators: how to cut their own energy consumption while also taking the opportunity to earn income by supplying excess power to the grid.

The technologies of medium voltage (MV) uninterruptible power supply (UPS) and fuel cells can help data centres become cleaner and greener while protecting availability and providing power to the grid.  

Why do data centre operators want to become greener?

Operators in Europe are coming under increased legislation to meet environmental targets. At the same time, we’ve been experiencing record high energy prices due to a combination of factors including a supply crunch at the same time as high demand.

The result is that energy-intensive businesses like data centres see a need to take more control over their energy. This will primarily help them to meet incoming legislation but also protect power continuity and earn income from energy markets.

The latest UPS and fuel cell technologies can maintain power continuity and also provide power to the grid. This enables the data centre to support the integration of renewable energy while also earning income from participating in demand response or frequency response schemes.

And while a financial return is essential, switching to low-carbon and sustainable technologies can also highlight an operator’s green credentials, helping them to stand out in the market to attract customers and potential employees.

Why should a data centre operator consider a UPS system at medium-voltage level?

Data centre UPS systems have traditionally operated alongside servers and HVAC equipment at the low-voltage level. However, medium-voltage systems offer the two main benefits of increased reliability and reduced costs, as well as providing additional advantages.

Working up to 24 kV improves reliability as it uses robust equipment in smaller numbers than at low-voltage. This reduces downtime as it is more straightforward to install, operate and maintain as individual modules rather than multiple low-voltage systems spread around the facility – after all, the more equipment that is installed, the more can go wrong.

Meanwhile, the medium-voltage approach also saves energy as currents and electrical losses are lower. The latest systems have reached efficiency of up to 98% thanks to using power conversion equipment that supports power quality continuously without needing to draw on batteries. Compared with a rotary UPS, this level of efficiency can represent up to 4.2 GWh, or 1,245 tonnes of CO2 emissions over a 15-year life for a large site. It also reduces HVAC loads as less energy is lost to heat.

Additional benefits are possible by using a modular MV UPS that is scalable. As an example, you could deploy up to 10 MV UPS modules of 2,250 kVA in parallel to provide up to 22.5 MVA power. In addition, when used in an N+1 configuration, one system can be taken offline while the others remain in service.

Because it operates at medium-voltage level at the point of the grid connection, the MV UPS can be used flexibly to support any data centre loads. This protects service continuity and reliability of servers across the estate by overcoming short outages and power quality issues. This contrasts with the potential for stranded capacity and additional CAPEX required for UPS capacity at low-voltage, when individual systems are connected to specific local loads and cannot be easily reassigned.

Working at the MV level also saves on CAPEX as the UPS can be located in an electrical room or substation, rather than on the high-value real-estate of the server room. This also makes it ideally located to feed power back into the grid if needed.

What is the potential for using fuel cells?

There’s a current trend for major operators to reduce reliance on diesel generators. For example, in 2020, Google announced a commitment to use large batteries instead of diesel gensets at a site in Belgium and Microsoft committed to eliminating diesel fuel by 2030 and has started testing fuel cells as an alternative.

Fuel cells have potential to provide backup power as well as injecting power into the grid at times of peak demand. This approach combines fuel cell technology with automation, and protection and control systems, requiring engineers with knowledge of both. 

Fuel cells are already providing power for systems rated at up to 200 kW for electric vehicle charging stations where grid power is not available. In addition, there are examples of fuel cells providing power for telecoms sites or as emergency backup in microgrids, where operators can combine different generation and storage technologies to operate off-grid in island mode or as a prosumer.

However, systems need to be more sophisticated at the multi-megawatt level, requiring additional development at the interfaces between fuel cells, energy storage systems, electrical switchgear and control infrastructure, as well as extensive testing. The most practical approach is to deploy these in modules of around 1-3 MW that can be combined to deliver the required power – and being standardised, these are faster to deliver and deploy on site.

What are the prospects for using backup capacity to earn income?

Energy prices have been hitting record high levels in recent months and this is giving data centre operators extra incentive to optimise their own energy consumption by using efficient systems. However, operators can also earn additional income and offset their costs by providing electricity to the grid at times of peak demand.

This might take the form of demand response schemes or using a battery energy storage system to support the integration of renewables by injecting and absorbing energy to overcome the natural intermittency of wind and solar.

The top priority has to be the data centre’s own loads – systems must have very high reliability and be able to fully support servers and HVAC systems at a moment’s notice. Only then can spare capacity be used to support the grid.

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