Don’t let the bugs bite

As ports search for ways to limit their impact on the environment, many are considering biofuel as an alternative because it promises to reduce both pollution and carbon footprint. But the issues are complex.

To start with the technical details, Clive Coker, a biofuel consultant, says that most engines, including port equipment, can switch over quite happily. “Biodiesel can be a ‘drop-in fuel’,” he explains. “As a liquid it can fit into existing fuel systems, with no large infrastructure changes – and, actually, you get up to 5% biodiesel at the pump in Europe, blended into the regular fuel.”

From an energy point of view, modern processing means biodiesel provides within 5% of the energy release or calorific value of petrodiesel. “It’s been shown that biodiesel can be competitive with fossil fuel if crude oil is $60 a barrel; at the moment it is around $80,” adds Mr Coker. His company is a partner in an EU-funded project focusing on non-food biofuel supply chains, with research centres in the UK, Italy, South Africa, Namibia and Ghana.

Given that other sources (like algae) are some way off yet, this project is particularly important. It aims to show that by allocating marginal or poor land with low rainfall to biodiesel production and by using non-food plants such as jatropha, the process does not impact on local food prices.

However, from the perspective of portside equipment operators, it gets more complicated. Firstly, some engine manufacturers have put a limit on what percentage of biodiesel can run through their engines without invalidating the warranty.

Clint Schroer of Cummins says that in the US: “Most industry people will agree on the B20 – 20% biodiesel – as a standard. However, biofuel specifications above B20 aren’t agreed upon, so many manufacturers consider this as the optimum percentage.” Even so, there are extra filter and oil changes to be taken into account if you transition to biofuel.

Other European industry sources have said that many manufacturers expect things to settle at around 20% biofuel blend in the medium term. Mark Neilson, of Cambridge Ethical Fuels, says that although this obviously doesn’t give the immediate and large ecological benefit of higher percentages of biodiesel, it’s worthwhile staying within the systems parameters as they stand.

“It makes sense – for while there could be a handful of enthusiasts using a pure 100% biodiesel mix, it’s much better to have a lot more people running at, say, a 20% blend and proving the technology, bringing it into the mainstream,” he says.

It is not necessarily hugely cheaper. “Getting biodiesel to adequate standards can push up the price,” says Mr Neilson, although with more development in specific high-yield biodiesel crops, the prices could come down, he adds.

Peter Klein of Gottwald says that although the company has not supplied mobile harbour cranes to be fuelled by biodiesel, depending on the engine brand it would be possible to use biodiesel admixings in the double percentage range or to apply 100% biodiesel on the mobile cranes with a few adjustments.

He says those using biodiesel would have a “low dependence on petroleum price fluctuations”. On the one hand, he says, biodiesel can be less expensive than diesel and is more ecological – but on the other, there is limited availability of good, standardised biodiesel in many countries and biodiesel is corrosive to non-ferrous metals (so users need to keep an eye on what it comes into contact with). In addition, the production of biodiesel still “raises some ethical questions”, he adds.

And although the engines may not immediately be able to tell the difference between “margarine and butter”, over the medium term there is actually a difference between the two.

Hugo Wall of Soltron explains that bacterial growth is a significant issue, especially for port operations. While diesel “bugs” are an existing problem for petrochemical fuels, the addition of a bio element and water lays on a banquet for them, he says.

“Fuel hygiene is a particular problem. Carbon is a food source for all forms of life, so a build-up of these bugs can interfere with a fuel’s combustion characteristics. Further, the bugs can block the filters, and lower the efficiency of the engine – raising emissions – and this negates the positives you have worked to achieve,” says Mr Wall.

His advice is that ports should make sure their fuel storage facility is free of water and that there are adequate drainage points, and have a regular round of inspections. “Fuel facilities have often been in place for a long time and miss out on being checked,” he adds.

Clint Schroer says that since water accelerates microbial growth, storage tanks must be equipped with a fuel water separator to make sure water is stripped out. Mark Neilson agrees, and adds that the addition of a proprietary biodiesel antioxidant/biocide additive at the time of manufacture, and installation of air dryers in storage facilities, is something that his company recommends.

Atmospheric changes due to rain or even just day and night air temperature differences enable moisture to form on the inside of fuel storage or tank walls. To minimise aspiration, keeping the fuel tanks full is a good idea.

Mr Schroer adds that, because biodiesel has lower oxidation stability compared to petrodiesel, users must also avoid storing equipment with biodiesel blends in the fuel system for more than three months. So, if biodiesel is used for intermittent applications, the fuel system must be purged before storage by running the engine on pure diesel fuel for a minimum of 30 minutes. Further, stored biofuel should be used up within six months of manufacture.

But not all is a joyous, leafy green, even with these precautions, because not all biodiesel is plant based. “Some have a proportion derived from animal fats,” says Hugo Wall, and further down the line this could cause both ecological and financial difficulties.

“A wider range of bacteria and fungi, yeast and moulds, are now found in distillate road fuels. The inclusion of fats from sources routinely treated with antibiotics will lead to mutation of both these organisms and the existing microbial contamination,” says Mr Wall. This would limit the effectiveness of the current (and narrow range) of effective fuel biocides.