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12 January, 2010
Page 27 

Industry experts say that forecourt operators are not taking the introduction of biofuels, and the problems associated with them, seriously enough.

John Davis, director at Cyrus Energy, comments: "Forecourt owners are under-estimating the amount of damage that can be done. Not just physical damage to tanks and pipework, but the financial implications of underground fuel tanks becoming contaminated. You only need the water course to leak or someone to lift the lid on the tank when it's raining for water to get in. It's as simple as that, and if it gets left untreated you get contamination and bacteria."

Cyrus Energy specialises in "delivering innovative products and solutions for maximising the performance and efficiency of fuel oil".

Its Eradicate fuel biocide has been developed, as its name suggests, to eradicate microbiological contamination found in fuel, storage tanks, bilges and fuel distribution systems. Davis says an application of Eradicate results in the immediate removal of "microbial manifestation" and can also be used on a preventative basis.

Nigel Plumb, director of DP Fuel Tank Services, agrees that forecourt owners are not taking the biofuel problem seriously enough and says good housekeeping is what's needed. "The best way to avoid problems is to thoroughly clean the tanks before introducing any fuel with a bio element and then have them regularly cleaned every few years. This is an operation that we find is much less expensive and takes a lot less time than most people think."

Edward Wheeler is managing director of Eurotank Environmental as well as a member of the Energy Institute's B5 User Group. He says: "The introduction of biodiesel also known as FAME (Fatty Acid Methyl Ester) into standard road diesel (EN 590) has resulted in an increase in the number of cases of microbial contamination issues at filling stations in the UK and other European countries."

He says that as well as providing an additional fuel source, FAME increases the amount of water droplets that are held in suspension within the fuel.

"Without getting too technical, the bottom line is that bugs like biodiesel. Water provides the essential environment for bugs to exist and FAME is a rich food source so they can grow. Bugs have always been present in diesel, and stopping them from growing within your storage system is the key to problem-free operations. Controlling water is critical to reducing microbial contamination.

"Since the introduction of biodiesel into parts of the UK network, the supply chain has done a lot of work in reducing the water content within EN 590. Up to 200 parts per million (ppm) is allowed within the standard, however, the vast majority of EN 590 is delivered with a water content of less than 80ppm.

"It is important for downstream retailers to focus on removing all free water from their storage systems as well as keeping the surfaces (tanks and pipelines) as clean as possible to reduce the risk of severe biofilm build up which leads to operational problems."

Wheeler reckons there is a lot of negative information going around the industry about the use of biocides. "It is a requirement of European law for products claiming to control or have an effect on microbial contamination to be registered as such with the European Union. This involves a significant investment from the manufacturer, which can run into millions of euros.

"Biocides that are used as additives in road transport diesel must be tested to ensure that there is no negative effect on vehicle engine performance this again is a significant cost. The important message for retailers is to carefully consider the type of biocide being used by their maintenance company. There are a small number of biocides on the market, which we have found to be very effective when combined with a thorough tank and pipeline cleaning procedure. Dumping biocide into a tank alone is unlikely to resolve any issues and will probably result in an increase in pump filter blockage as biofilm is released from the tank walls."

Wheeler says that obviously prevention is better than cure: "The problem is complex but the solution is simple keep your diesel tanks and pipelines clean and water free (as far as is reasonably practicable) and you are unlikely to suffer from microbial contamination problems."

E&S Environmental Services is Cyrus Energy's business partner. Andrew Clarke, director at E&S, says: "Microbial contamination of petroleum fuels is a growing and commercially sensitive problem faced by retailers and distribution companies. The constant need to clean clogged filters, pumps, purge fuel lines and de-contaminate tank bottoms is operationally disruptive and financially draining.

"But all fuel systems have the potential for contamination, and unprotected systems will continue to provide life support to the micro-organisms once they are introduced. Such organisms need water and food to survive. For biological contamination, the slimy rancid organisms only need a minute amount of water for survival and live and multiply at the fuel/water interface in the tank, using the hydrocarbons in the fuel as their food. As they grow, they form mats that are dark in colour and appear gel-like. Their waste produces water, sludge, acids and other harmful by-products.

"These organisms are either air or waterborne and contaminate fuel systems by entering through vents, standing water in sump bottoms, dissolved 'free water', sludges in tanks, or incurred during transport or delivery. They grow at incredible rates with some varieties having the ability to double in size every 20 minutes."

Clarke says they consume rubber gaskets, O-rings, hoses or tank linings and coatings for their mineral contents. "Microbes that produce slime therefore influence the onset of corrosion. Biological slimes are called biofilms. They have been shown to provide sanctuary for a variety of types of microbes that appear to work symbiotically, causing problems that no single microbe could achieve on its own. There is growing evidence to demonstrate that microbes, growing within the slime layers inside tanks, are responsible for a considerable amount of tank and pipeline damage. This is true for both steel and fibre-reinforced polymers."

He explains that bacteria are so small that you can't see a group of them until there are over a billion individual cells.

"Approximately 10 million cells will make a fluid slightly cloudy. Fuels, especially diesel, are organic compounds made up of hydrogen and carbon, and are a good food source for these microscopic organisms. Within a fuel tank they have all the elements for survival and growth water for germination, carbon for food, dissolved oxygen and sulphur for respiration, and trace elements for growth."

Clarke warns that low-level microbial contamination can be every bit as costly as a major infection. "Over 90% of the nutrients the microbes consume become by-products, such as slime, sludge and acids, which corrode and rust tanks. The rest become new colonies.

"Many companies are replacing old storage tanks with new ones so it makes sense to get as long a life out of these costly new installations as possible. It was thought that tanks lined with or made completely of resin materials, such as fibreglass or PVC, were immune from biodegradation. However recent studies in the US have found this is not true, and that microbes can attack the basic materials of the new tanks."

Apparently a common industry misconception is that fuel at a large volume throughput forecourt is cleaner than fuel at a smaller site. "From data taken in the US, it was found that the high-volume tanks tested were the ones with the most problems. Every time fuel is delivered, there is the potential to also get contaminants (sand, dust, water etc) which come with that load. The more fuel delivered, the greater the amount of contaminants. Some stations also get fuel from a variety of sources making them more susceptible to problems."

Of course, your customers can be affected by microbial contaminates in fuel. If micro-organisms reach engine fuel systems, they will plug filters, foul pumps and cause fuel starvation. They may cause caking around the injection nozzles, resulting in inefficient combustion and dark exhaust smoke.

"If problems occur with motorists, there is the potential for financial compensation to be paid to them," explains Clarke. "And the loss of customer confidence in your products also results in a severe setback to the supplying companies' reputation, with all the attendant unwelcome media attention." He says fuel life can be maximised through a well-managed water, sludge and microbial de-contamination programme.

"Keeping petroleum products dry and clean is essential to any well-maintained storage operation. The monitoring of water bottoms and removal of sludge and particulate matter is therefore vital. A monitoring and maintenance plan should be developed to avoid a critical problem. It is recommended that fuel be sampled every three months to monitor its condition and remedial action taken as necessary."

E&S has developed a mobile fuel polishing and filtration unit which it says is safe, reliable and efficient. Clarke explains: "Its primary function is to remove water and in-organic matter, with the use of our additive Fuel Treat, to eliminate bacterial growth and remove the debris. This unit cleans the tank at the same time (whetted part) and is far more cost effective than the conventional, time consuming, and expensive 'man entry' method."

Fuel Treat combines a biocide with a detergent and water dispersant agent. Microbes are killed (with the debris removed by the filtration unit) and the microscopic water particles held in suspension in the fuel and not allowed to settle out. This is said to drastically reduce the conditions that allow microbes to grow. It also reduces corrosion and ensures customers receive clean fuel.

Says Clarke: "Fuel Treat is a safe and environmentally-harmless product. It does not affect either the quality of the fuel, the efficient performance of the engine or catalytic converters. It is fully burnt in the combustion process and has no effect on exhaust emissions. It mixes easily and quickly with any hydrocarbon fuel and it is used as the final part of E&S' fuel maintenance programme."