Why Hydroelectric Power Plants Should Stop Using Greased Bearings

According to the US Department of Energy's Office of Energy Efficiency & Renewable Energy, most hydroelectric power plants in the United States are more than 50 years old. Since building new hydroelectric power plants isn’t a realistically feasible option, the focus shifts towards modernizing these existing facilities to achieve operational efficiency, security, and cost-effectiveness.

Routine maintenance is essential for most hydroelectric power plants to ensure their continued operation. Nevertheless, eventual performance degradation or risk of failure is likely to occur. When it does, further spending in refurbishments and upgrades (R&U) is required – a reality representing a significant investment.

The Office of Energy Efficiency & Renewable Energy's US Hydropower Market Report, published in January 2021, states that at least $8 billion was invested in R&U of the US hydropower and pumped storage hydropower (PSH) fleet between 2021 and 2020. Moreover, much of that investment occurred more recently, with almost $2 billion worth of R&U projects initiated in 2017–2019. Given the significant costs associated with R&U, getting the best value for money is essential, which means using only the best parts available.

With advancements in technology and engineering, a main component of hydroelectric power plant modernization includes transitioning away from greased bronze bearings.

4 Reasons to Stop Using Greased Bronze Bearings at Hydroelectric Power Plants

1. Environmental Impact

First and foremost, greased bronze bearings are in constant contact with the surrounding water supply. While there isn’t an immediate, large-scale, visible effect like there would be with an oil spill, the lubricants in the grease seep out over time and contribute to water pollution.

The problem for hydroelectric power plants is they often find themselves in the crosshairs when it comes to water pollution. Non-profit organization, Columbia Riverkeeper, highlights that dam oil pollution is a real issue and monitors pollution from large hydroelectric dams. Through its work, Columbia Riverkeeper has forced the federal government to track the oil that leaks into the Columbia and Snake Rivers and begin switching to non-toxic lubricants.

2. Maintenance and Cost

To achieve optimum longevity and performance, greased bronze bearings require fresh lubricant on an ongoing and regular basis. This reality impacts an organization financially in two main ways. 

First, there is the actual lubricant that needs to be purchased. While environmentally-friendly lubricant options are on the market, they are typically more expensive than their traditional counterparts.

The second direct cost associated with lubricating hydro bearings is the manpower required to do so. Manual greasing takes time and effort. The time saved from not having to grease bearings can be spent on other value-add tasks within the hydroelectric power plant. 

3. Longevity

Traditional greased bearings have a higher coefficient of friction than more modern composite bearings. The higher coefficient of friction causes bearings to get hotter, wear faster, and need replacing sooner. As a result, the amount of downtime the hydroelectric power plant experiences increases and ultimately detracts from the bottom line.

Then there is the issue of corrosion, which is one of the reasons greased bronze bearings have been the gold standard in hydroelectric applications for decades; they don’t easily corrode. However, years of exposure to salt, alkalis, and acids take their toll, leading to even the highest quality bearings deteriorating.

Modern bearings made from composite materials don’t corrode after years of use. Many polymers are chemically inert, which actually makes them resistant to corrosion even in the harshest of conditions like those found in oil and gas applications.

4. Dampening

By their very nature, hydroelectric turbines experience severe levels of vibration while operating. Turbine failure is an enormous concern for hydroelectric power plant operators due to this vibration, and, unfortunately, turbine failures do occur.

Perhaps the most notable turbine failure in recent times was the one witnessed at the Sayano-Shushenskaya Dam on Russia’s Yenisei River. The largest power plant in Russia, the Sayano-Shushenskaya Dam, was the site of a catastrophic accident on August 17, 2009. A turbine at the hydroelectric power station failed, flooding the turbine hall and killing 75 people. Earlier that year, Sayano-Shushenskaya Dam underwent modernization works between January and March. An unbalanced turbine runner caused excessive vibrations, which wore down the turbine's mountings and bearings, resulting in its ultimate failure.

Hydroelectric turbines are now fitted with vibration monitoring devices to reduce the chances of such disastrous incidents happening. While this helps, there is nothing quite like actually reducing the amount of vibration the bearings experience. Modern composite materials, like Orkot®, are better at dampening vibrations than traditional bronze bearings.

Using Orkot® Instead of Greased Bronze Bearings

Hydro bearings have advanced significantly over the years. Bearings using Orkot® materials represent a superior alternative to the greased bronze bearings many hydroelectric power plants have used.

Orkot® bearings are self-lubricating and dry running, making them an excellent choice for hydroelectric power plant applications. Manufactured from a unique synthetic composite, Orkot® has been designed to have a lower coefficient of friction than greased bronze bearings, enabling them to achieve outstanding longevity (30+ years in most cases) without the need for maintenance.

Furthermore, Orkot® has a direct impact on an organization’s environmental efforts; they do not require any additional lubricants, Orkot® bearings mitigate the risk of grease leaking over time and contaminating the water, which is why Orkot® bearings are the smart choice for hydroelectric power plants that want to be at the forefront of environmental efforts.

Finally, Orkot® bearings exhibit virtually zero swell in water and offer high load and edge load capabilities, making them the bearing of choice for hydroelectric power plant applications, including:

• Wicket gate/Guide vane bearings
• Thrust rings
• Linkage bushings
• Headcover bushings
• Turbine guide bearings
• Runner blade hub bushings
• Operating rod bushings
• Operating shaft bushings
• Trash rake bearings and wear pads
• Fish screen bearings and wear pads
• Operating ring wear pads
• Servo cylinder rod eye bearings
• Servo cylinder seals
• Servo motor seals
• Spillway gate trunnion bearings
• Spillway gate thrust washers
• Hinge bushings
• Safety valve bearings
• Penstock valve bearings

Orkot® Bearings in Action

Replacing greased bronze bearings with advanced polymer materials is an essential step in hydroelectric plant modernization. Although the upgrade represents a larger investment than simply replacing your greased bearings with a like-for-like option, the longevity and other benefits of Orkot® justify the cost.

Testimony to Orkot® bearings’ superior performance is the fact that Carillon Power Station, the most powerful hydroelectric power station on the Ottawa River in Canada, has opted to use them as part of its turbine refurbishment works. CRC Distribution supplied Orkot® greaseless bearing materials for all six turbines, as well as two complete sets of spares.

If you’d like to discover how Orkot® can improve your hydroelectric power plant’s efficiency and uptime while reducing maintenance and associated costs, reach out to our Orkot® experts.