A new way of cooling continuity
Mon 1 Jan 2018 | Tim Mitchell
Chiller battery innovation offers resilience and load-shifting potential for critical data centre cooling, says Tim Mitchell, sales director at Klima-Therm
Cooling for data centres is always mission critical. The traditional approach is based on an uninterruptable power supply (UPS), typically provided either by standby generators, a conventional lead-acid battery array, or both.
This is expensive and adds significant capital costs, with the additional ongoing operating cost of maintenance to ensure the backup system is always ready to kick in at a moment’s notice. A new approach offers a more reliable and cost-effective safety-net solution for data centres, based on a highly compact reserve power module for chillers.
The Teslamiser backup system for chillers uses lithium battery technology, like that used in the Tesla car. It is coupled with a smart control system, which constantly monitors and controls electrical power supply to the chiller.
It not only provides backup power in the event of electrical failure, but actively manages ongoing power usage to optimise efficiency, reducing chiller running costs. Although designed primarily for use with Turbocor compressor-based chillers, because of their superior part-load performance, the system can be applied to any chiller or HVAC system.
How it works
On a similar principle to a night storage heater making use of off-peak electricity, the chiller batteries can be charged at night
Teslamiser automatically optimises energy flows into, within and out of the chiller. This includes managing the respective power inputs from the mains electrical supply and any renewable sources, such as photovoltaic (PV) panels and wind energy, according to pre-set criteria.
This enables the system to harness the preferred energy source at any given time to power the chiller, with the battery pack providing the buffer. Power source selection can be based on lowest cost, lowest carbon, even the most profitable, with some energy providers now paying customers to consume energy at certain times.
On a similar principle to a night storage heater making use of off-peak electricity, the chiller batteries can be charged at night, when tariffs are lowest or the greenest electricity is available, and the accumulated charge used during the day, avoiding peak electricity costs.
This delivers significant savings in itself, given the typical reductions in night-time energy costs. However, there are further savings to be made through limiting peak power demand on a site, using the batteries to augment mains supply and renewable inputs to keep peak power within a set limit.
Demand side response
This approach, known as peak lopping or demand side response, is likely to become increasingly attractive for two reasons: first, the closure of older, more polluting power stations to comply with European carbon reduction and clean air targets is putting pressure on peak time energy supply availability; second, the continuing roll-out of so-called smart metering will see costs for peak power being driven higher, very much more than costs for off-peak power are reduced.
A further advantage of Teslamiser is that it can operate as a UPS, maintaining chiller operation in the event of a power cut for long enough to restore normal operating conditions.
In critical applications such as data centres, this is not just nice to have, it’s a must-have capability. With this new approach, UPS comes as standard rather than an expensive add-on, providing a high level of resilience that for many installations may previously have been out of reach.
In the event of a power cut or reduction in supply (sometimes referred to as a brown-out), it connects the Teslamiser batteries into the circuit to replace or augment the lost mains supply. In terms of demand side response, it opens up a potentially transformational range of new possibilities for powering and controlling HVACR plant.
Total energy approach
The key is to take a total energy approach, which combines and integrates advanced battery technology with multiple renewable energy sources and mains power, to optimise plant performance and efficiency resulting in lower running costs, reduced environmental impact and more comfortable and sustainable buildings.
The ability to time-shift electrical demand has a double advantage, as it not only reduces running costs but also enables end users to manage a site’s demand profile in order to reduce peak electrical draw. As mentioned, this reduces exposure to punitive peak demand energy tariffs.
When a renewable energy source, such as a photovoltaic supply, is available, Teslamiser can be set to charge and store energy when supply is free in the day and release it when supply is reduced or unavailable, at night.
Teslamiser adds extra capabilities to the already efficient Turbomiser chiller. Its ability to time-shift electrical demand, so reducing running costs, coupled with its role as a UPS, gives end users an additional level of reassurance by significantly improving resilience.
It is a particularly attractive option on Turbomiser chillers because the compressors on these chillers have a very low starting current (5A), and from then on the current draw is smooth and steady up to full load operation. We believe this combination will be useful in many situations, particularly for critical applications such as data centres, where continuity of cooling is vital.
There are exciting possibilities for extending the capabilities of Teslamiser to include intelligent energy recovery directly from the chiller to charge the batteries. This would create a genuine total energy system that optimises power from all sources for even greater efficiency and savings.
This post originated at Data Centre Management magazine, from the same publisher as The Stack. Click here to find out more about the UK’s most important industry publication for the data centre space.