Facilities managers and organisations storing gas oil in bulk are being warned to be extra vigilant against contamination by "bugs" as UK supplies are supplemented with biofuel for the first time.

Gas oil, widely known as "red diesel" is now following the same path as fuel for road use which has been manufactured using a minimum of five per cent content from renewable sources – biofuel- since Spring 2009.

Now it’s the turn of gas oil, which can have up to seven per cent biofuel content, and is already being on stream as suppliers strive to meet new European directives.

"This opens up a whole new area for concern," states Barry Jenner, Managing Director of UK commercial fuelling solutions specialist Cameron Forecourt. "It is proven that under certain conditions any fuel supplies with a biofuel content can grow bugs, which if allowed to proliferate, can contaminate the whole system, clogging up tanks, filters, pipework and equipment."

He adds: "Where supplies of fuel are regularly used, then replenished it can still be an issue, but where the use of bulk stored fuel is infrequent or irregular, the potential for problems is that much greater."

He believes the type of installations most under threat include premises such as hospitals where supplies are stockpiled to power emergency generators, schools and commercial premises where heating systems are closed down for part of the year and other situations, such as call centre, where gas oil is used mainly for powering "failsafe" stand-by systems.

Fuel bugs exist at low levels in all systems storing supplies with a biofuel content. The microbiologial bacteria are hygroscopic and, under certain conditions, thrive on the higher water content of fuel with a "bio" content, developing into a thick acidic sludge that contaminates the fuel and clogs up the system.

"It’s a bit like cholesterol in humans, too much of it unchecked and you can have serious problems," adds Barry Jenner. "The worst case scenario could be that, at a crucial time, the equipment that relies on the fuel will not be able to start up and do its job."

Although there is no "golden bullet" for the problem, there are measures that can be taken to negate the threat of fuel bugs. Cameron Forecourt believes regular testing of stored fuel for contamination is the minimum safeguard. It recommends sampling and testing at least every six months.

Periodic changing of filters and, where necessary, adding biocides and de-watering agents should be a part of scheduled tank maintenance.

More advanced solutions include specialist equipment such as magnetic equipment which depolarises any bio microbes, stopping them latching on to water molecules and making it impossible for them to thrive.

In larger tanks where supplies are static for long periods, regular rotation of the stock is also required, using a pumping system to recirculate the fuel in the tank.

"It’s early days, but feedback from the field where we look after 100’s of commercial fuelling installations indicates that there is a problem that needs to be addressed. Where fuel supplies are going to be relatively static for extended periods, there is obviously a need for greater vigilance from the outset," concluded Barry Jenner.