A possible lack of awareness among wind farm developers about the impact of lubricants on the efficiency of wind turbines could lead to inadequate planning for project costs, according to Robert Pears, Renewable Energy Lubricants Business Development Manager at ExxonMobil.
Pears estimates that parallel to this, the company has harnessed more than 20% of the global wind industry, which adds up to exceeding 200,000 turbines installed around the planet. ExxonMobil is a leading pioneer of specialised lubricants for wind turbine gear boxes. With ExxonMobil’s recent announcement that its advanced high performance gear oil lubricant is used in approximately 40,000 wind turbines, it is easy to see why this industry is continually growing and awareness of the business needs to be of a top, high level standard.
Without proper lubrication a wind turbine wouldn’t be able to run smoothly, this is why critical lubrication is essential for wind turbines. The viscosity of the oil provides the fundamental task of separating the gear teeth, preventing wear and tear and faults that could impact the productivity of a wind farm - a wind farm developer’s worst nightmare.
"If you don't have the right viscosity in there, you don't get the right separation and you get metal to metal contact in the gear teeth and it starts to wear very quickly," said Pears. "Replacing a 500-tonne gear box up a wind turbine isn't cheap."
Lubricant research is a science that is continually developing, ExxonMobil’s team of researchers are aware that the lubrication of a piece of equipment as large as a wind turbine or indeed any piece of machinery, is the single most important thing in the whole process of industry. If you have a piece of machinery, the chances are it needs a lubricant to help it along its way. No lubricant, no business. It’s that simple.
The viscosity needed for a generator lubricant is ten times as thick as that needed in a car system, and the viscosity needed for oil in a gear box is more than three times thicker than required in a generator. The faster the application, the thinner the oil needs to be.
A field trial of a new lubricant will take approximately up to two years. However, before field trials can even begin, a lengthy development period of around 7 years is required to research, test and hone the product before it even leaves the lab. This being said, a new wind turbine product is released every 2-3 years - good news for wind developers.
ExxonMobil tend to work specifically with original equipment manufacturers that provide specifications for gear box and other vital lubricants.
Industry lubricants or indeed any Mobil product, needs to be rigorously tested and must meet a high industry standard. In addition to even tighter specific standards set by OEMs. These criteria are centred on balance formulation and focus on rust performance, micro-fitting gear and bearing protection, oxidative stability, risk metrics, how the oil operates at low temperatures, filterability, water tolerance, foam and air release. Everything you can think of is tested and pulled apart to make sure that all aspects of the product are 100% perfect.
Rather than formulating oils to meet only certain specifications, ExxonMobil chooses to develop an all-round high performance lubricant that fulfils a range of different performance criteria.
"The main thing we look to in terms of formulation of a product is balanced formulation," said Pears. "Because the chemistry is so complex, we took the view that there is no point in formulating one area, if another is going to suffer."
The durability of the oil's life is of particular important to the reliable functioning of the turbine, as the longer the oil lasts, the less manpower is needed to maintain the performance of the gear box. - Which of course saves money.
"There's a certain amount of risk associated with climbing wind turbines to change lubricants," Pears said. "If you can reduce that maintenance period, that means people go up the turbines much less, which means we can improve the safety performance and the financial performance of a wind farm as well. If the turbine is having additional down time it is not producing energy or money."
The offshore market presents new challenges for Mobil lubricants. The products need to withstand the harsh effects at operating efficiently at sea. An even greater challenge for the ExxonMobil scientists.
"It is quite a challenge developing oils for the offshore market - is it is quite an extreme application used in variations in temperature," said Pears. "The nature of the wind turbine means that at different wind speeds there are different loads on the components. It's start up, shut down, and it's constantly changing. From a lubricant point of view it's very, very challenging to formulate a lubricant to work in that environment."
If for example a turbine is constantly running at a high temperature, it can disrupt the performance of a gear box significantly. This is why Mobil synthetic lubricants, which use crude oil as a base, but are then produced through polymerisation, making them easily specifiable, are preferable to mineral oils as lubricants. Oils made from a synthetic base stock are much more stable and resistant to oxidisation.
"If oils are operating at higher temperature, they get thinner, which means they are not providing the right equipment protection," Pears said. "With a synthetic lubricant such as Mobil SSE our gearbox has got 50% stronger film strength than with the mineral oils, which means you have that separation of the gear teeth, they're getting less wear, and that means that you get less downtime associated with failures and greater equipment protection."
"Wind farm operators often don't know there is lubricant inside the turbines," added Rainer
Some wind farm developers aren’t even aware that there is a lubricant inside the wind turbines, this lack of awareness could be detrimental to the economics of a wind project, not only this but there are no spare parts available if a gear box should fail. Lead time is from 12 - 18 months which is an incredibly long time and can crush a business from lack of profit and economic calculations will break down.
With developers, involvement depends on warrantees and probabilities, it is important that the knowledge be passed on and digested, otherwise one simple wrong decision can make or break a gearbox inside a wind turbine, and this can shatter a business beyond repair.
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Notes For Editors
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