POWER GENERATION
The future of standby power in hospitals
Chris Connors, head of Sales (South) at DTGen, discusses the future of standby power generation in hospitals and other healthcare facilities.
When I started out in standby generation, the specification for NHS installations was known as C44. I kept a well-thumbed copy in the office. It has long since been replaced with HTM 06. I can’t even find a copy of C44 on the internet any more, so if anyone can send me a copy ‘just for old times’ sake’, I would welcome it. HTM 06 is now my ‘go to’ for standby generation in hospitals, although I must confess to knowing the document inside out – to the extent that I could possibly go on Mastermind with it as my specialist subject.
Despite the years, there has been little movement away from the traditional standby solution of diesel prime movers. The likes of Perkins, Cummins, and MTU, are just three regular stalwart engine brands often seen in the darkest recesses of a genset plantroom. To be fair to HTM 06, mention is made of ‘alternative or supplementary electrical energy sources’ being considered as secondary power arrangements, but the direction of travel in 2021 still appears to be very much a diesel journey. Of course, many NHS sites have moved towards combined heat and power operating in parallel with the local grid, but this is not to be confused with the need for standby power when all else has failed. So, why are we reluctant to move away from the norm? Why is diesel still the ‘go to’? Well, it’s simple: autonomy. HTM 06 speaks of a 200-hour fuel autonomy required on site, and provided that diesel is being delivered to the generator set, then the FM engineer can sleep soundly in his / her bed knowing that the standby generator will operate in an emergency without relying upon the sun shining, the wind blowing, or battery banks being fully charged. Some of the aforementioned have been spoken of as alternatives to standby power generation, but have never achieved any traction.
Some ‘bad press’
Thanks to the automotive industry, diesel engines have received bad press in recent times. The Volkswagen Group scandal of 2015, when it was purported that the automotive manufacturer was tinkering with the electronics of its diesel engines to falsely represent the Nitrogen Oxide
Craning in a new generator at Huddersfield Royal Infirmary.
(NOx) emissions from vehicles, was a catalyst to anti-diesel rhetoric. That’s unfortunate, as modern automotive diesel engines have never been cleaner. They are designed to comply with stringent Euro VI emission limits; hence, long gone are the days of smoky diesel engines sitting at the traffic lights, unless it’s an old ice cream van of course. So, what of the world of diesel engines used in standby generation? Well, our industry is somewhat overlooked by the engine OEMs. Comparatively there is little volume, and the very nature of standby generators is that they will run only rarely in an emergency scenario. Hence there is little call from the market for low emission diesel engines in generators, and little will from the OEMs to deliver one.
Seeds of change
Notwithstanding this, there are seeds of change. A number of NHS Trusts are taking it upon themselves to specify engine after-treatment systems to clean up their diesel fumes, and, additionally, legislation is slowly creating change. The Medium Combustion Plant Directive (MCPD) specifies low NOx emission limits for standby generators. However, the aforementioned directive has a ‘get out’ clause; providing that the standby generator is only used in an emergency
mains failure scenario, then the emission limits set out in the directive can be ignored. As most generators are only used in an emergency, then the emission limits in the MCPD can be ignored, but these generators would still need a permit to operate.
You may wonder under what other circumstances a standby generator could be used that would mean it must comply with the MCPD. Some Trusts are engaging in revenue generation schemes utilising their standby generators in National Grid balancing schemes, which can pay handsomely to contributors. When sets are used in this mode, they could not be considered as being operated for emergency use only. Therefore, the MCPD would apply.
Let’s take a step back. A typical standby diesel generator engine used in a stationary application will be what we in the industry call ‘fuel optimised’ – a clever way of saying that the engine isn’t ‘emission optimised’. So, if the engine manufacturer is not producing a clean engine for standby generation, then the only method to reduce emissions is to add engine exhaust after-treatment – equipment provided by third-party manufacturers that bolts on to the exhaust stream, and, with the wonders of science, cleans the exhaust gases exiting the
September 2021 Health Estate Journal 73
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