POWER GENERATION
ENGINEERING CONSIDERATIONS FOR HOSPITAL STANDBY POWER With UK hospitals experiencing year on year growth in patients – up 21 per cent from 2009 to 2019 – and 2020 as a year like no other, healthcare operators are thinking hard about their back up power. Here Bradley Morrissey, Bid Manager at Finning UK & Ireland, the region’s exclusive distributor of Cat® energy and transportation systems, explains the engineering considerations when upgrading hospital backup generators.
H
ealthcare power is mission critical – a continuous power source is necessary to power everything from mechanical ventilators in intensive care, to medical imaging equipment and even the lighting and lifts needed for safe movement around the building. Diesel generators are a popular choice for hospitals due to the reliability they offer. However, there are several engineering considerations at play dictating what equipment is suitable for a specific healthcare facility.
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SIZE MATTERS Healthcare sites can consume over two million kWh of electricity a year, but this varies significantly from facility to facility. The first, and often most important, consideration is generator size – the backup generator must be able to provide enough power to keep all required equipment running. A genset package should be designed in line with the Health Technical Memoranda (HTM) regulations, which includes being correctly sized to meet performance requirements. There are also tools available to help with choosing the right genset size, including SpecSizer, a Caterpillar tool that allows the user to determine which generator best fits the performance requirements for the facility’s load. There are, however, multiple ways of achieving the same power output. In many facilities, a custom package is the best option, as healthcare operators can choose technology that achieves cost savings, is adapted to the available space and offers excellent performance. For example, if a facility is running multiple gensets, it could be more effective to run fewer at a different rating. A major factor in what size generator a facility can incorporate is the dimensions of the engine room, as many hospitals have limited space. There are ways of reducing the amount of
ENERGY MANAGER MAGAZINE • NOVEMBER/DECEMBER 2020
space a generator package takes, such as removing the radiators and putting them in a remote location. However, the most straightforward solution for hospitals with small engine rooms is to opt for a power dense engine. Power density is a measure of the size of a genset compared with its output and is the result of significant work by engine manufacturers. Standard hospital generators have increased from 2.5MVA to 3.0MVA, a considerable improvement. A specific example is the Cat 3516, which can now achieve over 3,000 kVA, compared with its previous 1,650 kVA, but from a similar footprint. Power dense solutions have an added benefit in that they require less ancillary equipment – they are cheaper to transport, install and maintain.
AIRFLOW Gensets are designed with two main cooling options – the most popular is a custom genset mounted radiator sized to suit the application and environment; the second is a remote radiator located separately, for example on the roof. However, the room must have enough ventilation to cool the engine down, to prevent overheating – maximum engine room temperature is around 50 degrees Celsius for a typical generator. Many hospitals have small plant rooms where air flow is a problem, making this an important consideration.
