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Biodiesel and its future in mining

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Diesel fuel is the life blood of the mining industry.

But as the government plans to cut back the fuel rebate scheme, miners are going to have to look at ways to not only save fuel, but also cut the costs of the fuel itself.

Bio-fuels can save company’s money and reduce emissions, but like any new technology, some adjustments need to be made when it comes to implementing the technology on mine sites. There are a number of both advantages and complications of using higher blended fuels.

The world’s future energy needs and how to best tackle the expected rise in the world’s population of nine billion people by 2050 was a key topic at Shell’s Technology Forum this year.

The company expects a dramatic rise in the consumption of energy to take place by 2050, estimating that energy needs will nearly double.

However, estimates by the gas giant suggest the levels of energy the world will need and what is able to be supplied will produce a gap dubbed the ‘zone of uncertainty’.

According to Catherine Ellis, Shell’s biofuels manager "that gap is the size of the energy industry in the year 2000 so it is enormous and none of us in the room quite know how that gap will be closed.

“Whatever we do it needs to be in the context of reducing Co2 emissions.

“So at the same time that we’re going to be almost doubling energy demand we need to halve the amount of C02 emissions.”

Pointing to a ‘mosiac’ of energy solutions which includes LNG,  Ellis said that for mining in particular, biodiesel is one way in which companies can reduce their green house gas emissions and reap financial incentive when it comes to their energy consumption.

Under current carbon pricing, biodiesel attracts a zero impost by the government.

Shell says this means when you compare buying 200 of mineral diesel pa to 200 of biodiesel pa, on average a company can expect to save $2.5 million dollars using B20.

Ellis pointed out that although these figures do not necessarily translate into the amount of money paid to the government, they do affect tax costs and so, impact on a company’s bottom line.

Ellis told Australian Mining that a "financial incentive around the carbon pricing scheme and environmental incentives" were "two key reasons we’d expect mining companies would be interested in this fuel."

However, she did concede that there were some ‘housekeeping’ issues to think about if you want to make the switch that “aren’t insurmountable but definitely worth thinking about”.

These issues surrounding biofuel includes how it acts with water or the potential for microbial growth, its coldflow properties, oxidisation and solvency.

Breaking down bio complications

Water

Managing water contamination is important when using bio-fuels and can help assist in extending the products life.

Higher blends can be hygroscopic and increase the solubility of water. If this happens, corrosion and microbial growth are both costly and complex issues to deal with as the removal of water from bio-fuel can be more difficult.

Solutions to mitigate these problems include routine cleaning of tanks, regular maintenance of tank filters and vents and keeping areas around fuel tanks clear of water.

Coldflow

Bio-diesel can exhibit reduced cold temperature performance, and often cold flow additives are used to improve its low temperature operability.

High bio blends can have a higher viscosity depending on the feedstock used - that is the specific type of oil, fat or grease used - and are mostly dependant on the level of saturated fat. For example palm and coconut oils have a higher level of saturated fat so have a higher cloud point.

Impacts of coldflow include crystallisation or waxing of fuel and also filter blockages.

Working with the company supplying the fuel and discussing operational needs all-year round will determine if higher bio blends are a suitable way forward.

Oxidisation Stability

Higher bio blends may have poorer oxidisation stability than conventional diesel, especially when using higher unsaturated compounds.

This means that if fuel is stored long-term problems around gumming and fuel blockages can occur.

It is recommended that stock not be stored for longer than six months so companies with a higher fuel turn over would benefit more from bio.

Keeping air space in tanks to a minimum is another way to mitigate the issue.

Solvency

Higher blends can act like a mild solvent in tanks and fuel systems and lead to blockage problems as the fuel mobilises particles in fuel systems.

Cleaning fuel tanks, maintenance of equipment, and monitoring flow rates are all ways to help reduce the impact of the fuel.

What’s best for your needs

Darren Barwick, Shell’s technical mining team leader, points out that choosing the right feedstock for biofuel is the key to ensuring it works for your business but admits there is "no perfect feedstock that fits every application".

Barwick said that although biodiesel can be used now on current infrastructure, things like poor quality feedstocks can create operational issues.

Because biodiesel is made from biological products it reacts differently to mineral diesel when put under different pressures and these are the most important things to keep in mind when making the decision to incorporate the product into operation systems.

However given its higher flashpoint, biodiesel is also less likely to ignite than conventional diesel providing an additional level of safety for underground mining application, as opposed to LNG or other such products where you have to invest in new infrastructure and technology.

He added biofuels held a distinct advantage for companies because they can use them ‘straight away’

Barwick says interest from mining companies who want to incorporate the fuel is strong.

“There is definitely interest in using bio fuels,” he told Australian Mining.

“They know it’s there but don’t know much about it or who may be a bit worried about using it because in the past there has been some poor quality bio fuels in the market place which has caused issues.”

Biofuels Association of Australia said adopting second generation technologies when they become viable will be a key way to sustain the mining, transport and infrastructure industries but says alternative feedstocks are needed, as well as additional infrastructure and more consistent access to markets.

B20 is available at commercially sized levels, with companies such as Australian Renewable Fuels currently having the capacity to produce sufficient biodiesel for 750 million litres of B20 annually, from its refineries in Western Australia, South Australia and Victoria.  

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Image: The Eco Alliance

 


 

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