Clearly there are big challenges facing all sectors today. Ensuring continuity of power is of critical importance at this challenging time. Gary Hickey, Specialist Fuel Divisions Director at Adler and Allan, explains the issues of microbial contamination in back-up generator tanks operating in the facilities management sector, and how a focus on testing and storage integrity is critical.
As a result of heightened regulatory measures to decrease greenhouse gas emissions and reduce reliance on fossil fuels, the composition of the fuels we use has changed dramatically in recent years.
Traditionally when straight hydrocarbon fuels were used, you could have a back-up generator tank that was 50 years old and never been cleaned out, and as long as that suction point – the point where the fuel leaves the tank – was above where the water and sludge was sitting, there would be no issues at all. This means that in the event of a power cut, it would take over and generate power for as long as the fuel lasted. But when biofuels were introduced about 11 years ago, all those tanks started to fail.
The reason was, when these biofuels came into contact with water, they created a microbial contamination in the tank – microbes such as bacteria and fungi that live in the interface between the water and fuel cause havoc to both the performance of the tank and the fuel itself.
Microbial contamination of diesel fuel occurs when water finds its way into a tank as a result of condensation, rainwater penetration or from the air.
Modern biodiesel is especially hydroscopic, attracting and holding water molecules from the surrounding environment.
The presence of water encourages microbial growth which either occurs at the interface between the oil and water or on the tank walls.
This kind of contamination not only accelerates tank corrosion, it can block lines and filters and significantly reduce the performance of the fuel itself.
Biodiesel is made by reacting vegetable oil with other common chemicals. The bugs love vegetable oil, they feed off it and multiply very quickly, and this can be a particular issue to tanks that have little use such as back-up generators for example.
Because biodiesel absorbs a lot more water than diesels of old, it can lead to significant degradation in fuel performance and usability if not managed properly.
Subsequently, as diesel is commonly used for emergency power generation, the potential for microbial growth exposes companies to considerable operational and reputation risk.
If there is a power cut, many companies have the facility to switch over to oil. A full tank of diesel fuel can maintain power for an entire company for about eight hours. But if that fuel has been sat there for years vegetating in the tank, the second it is put it into use, it will break down.
Once microbial contamination starts it can grow very quickly. From one year to the next you can have a clean bill of health to heavily contaminated fuel.
There was a site in Suffolk that would run their generators once a month for half an hour to make sure they were running well, but actually, when they had a power cut and they started putting it on full load, within about three hours the system broke down because the fuel wasn’t fit for purpose.
With even small amounts of water in a tank system, reformulated fuels can create a maintenance nightmare such as biological activity, increased corrosion, blocked filters and lower pump flow rates. Testing has therefore evolved from a best practice discipline to a critical part of the tank maintenance process.
Investing in remedial work should now be essential to your operations, especially when you consider microbial induced corrosion can accelerate tank corrosion by as much as 1mm per year, meaning a new steel tank could fail in less than seven years.
The key to all of this is how seriously you look after your storage tank. Biodiesel is a breeding ground for micro-organisms that will affect the oil and damage the tank.
Every time you put a new load of fuel through a tank, it’s adding another contaminant, but all of this can be avoided if you’re checking your fuel regularly and making sure it is water free.
More importantly, it’s not just the tank that’s going to be an issue, it’s the fuel above it too, which is a very expensive commodity. If you’ve got 50,000 litres of diesel in a tank, that’s £25k of fuel at risk of contamination, and that’s without considering the fact it might not work in the event of a power outage when you need it most.
If microbial contamination has occurred, experts can uplift the fuel, remove the residue from the tank and polish the fuel before returning it so that the generator will provide power when required.
However, with increased demand on capacity at this challenging time, the best course of action is prevention. Experts like Adler and Allan provide regular tank testing and maintenance, because an absolute focus on storage integrity has never been more critical for today’s facilities management sector back-up generator.
For more information visit www.adlerandallan.co.uk
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