SKF active magnetic bearings are key components in today’s energy transition and optimisation. Now they are finding applications in the technologies that will power a cleaner, more sustainable future.
As the world transitions from fossil fuels to zero-carbon alternatives, active magnetic bearings are finding new applications in emerging technologies in this energy efficiency revolution. An important area of future growth is likely to be in hydrogen production and transport.
While most of the hydrogen produced today is created from fossil fuels, gas can also be produced by electrolysis of water. If the energy for this process comes from renewable sources, the resulting “blue” hydrogen is a clean, carbon-free energy source. Hydrogen has potential advantages over other power generators in many applications. Its relatively high energy density could make it a suitable fuel for ships, aircraft and heavy trucks.
In addition, the combustion of hydrogen is a clean way to generate the very high temperatures necessary for steelmaking and other industrial and chemical processes. Hydrogen is a key ingredient for synthetic liquid fuels that could be a low-carbon replacement for fossil fuel-based alternatives.
While hydrogen gas needs to be liquefied for transport and storage, active magnetic bearings offer all the same advantages here as they do in hydrocarbon applications. Efficient and reliable turbo machines will be a critical element in many of the proposed models for green hydrogen production. These include the use of giant solar farms in desert locations such as the Middle East and Australia, and production located near wind farms.
More growth in storage
Another potential growth area for magnetic bearings is carbon capture, utilisation and storage (CCUS). This group of technologies is designed to keep greenhouse gas emissions out of the atmosphere by collecting CO2 at source and containing it in suitable storage locations such as exploited oil and gas deposits. Like hydrogen, many CCUS technologies rely on efficient, large-scale compressors.
“Blue” hydrogen technology is another area where extremely active development is underway. This approach combines conventional hydrogen production with CCUS, creating a way to make continuous use of conventional fossil fuel resources while mitigating their impact on climate change at the source. The blue hydrogen industry will need a lot of efficient turbo equipment to handle incoming gas, outgoing hydrogen and CO2 flows.
The transition from conventional fossil fuels to low and zero carbon alternatives is expected to be the most significant change in the global energy system in recent centuries. The transition will require fundamental changes from energy producers, energy consumers and society at large. You will also need a lot of clean and efficient rotary machines . Active magnetic bearings offer equipment manufacturers a proven, reliable and robust solution to some of the key technical challenges they face today.
Subsea gas compressors are a vital but hidden part of today’s global energy system, allowing for increased gas production from existing subsea wells. Installed on the seafloor below hundreds of meters of water, these powerful machines push natural gas from subsea wells through pipelines that deliver it to receiving facilities on land. They operate 24 hours a day, 365 days a year, with little opportunity for inspection, maintenance or repair.
Many subsea wells are running out because they are losing pressure. By using active magnetic bearings on platforms and in subsea applications, we have lessened the environmental impact from both a construction and operational point of view. This additional gas will allow for a smoother transition to greener energy.
Equipment operating in such extreme conditions requires highly specialised engineering. And bearings are among the most critical parts of subsea compressor design. Manufacturers need a bearing that can operate at high loads and speeds, can provide a life span of decades, and can function without the need for adjustment or lubrication after installation.
An attractive option
For many of the world’s leading producers of subsea equipment, the preferred solution for such applications is SKF’s active magnetic bearing technology. Active magnetic bearings are constructed similar to an electric motor. The bearing housing incorporates a stator, containing several copper coils. In use, an electric current runs through each of these coils, creating a magnetic field. This field attracts rotor components fixed to the machine shaft, removing it from contact with the housing.
As the shaft rotates, proprietary position detection technology tracks its precise location, and a high-speed signal processing system continuously adjusts the current flowing to the stator coils. This keeps the shaft floating inside the bearing, with a gap of 0.15 to 0.5 millimeters depending on the application.
As there is no contact between the rotating and stationary parts of the bearing, magnetic bearings are not subject to mechanical wear, and there is no need for a lubrication system. These are the right ingredients for a long, maintenance-free shelf life. SKF active magnetic bearings have been in continuous operation in subsea applications since 2015, and their typical design life is over 30 years. Some turbo machines built in the 1980s have magnetic bearings that are still in use today.
Cold, clean and robust
Active magnetic bearings offer many other advantages in addition to their long life. As they do not require lubrication , there is no risk of lubricant leaks that could contaminate process fluids or pollute the environment. And active magnetic bearings can operate at very low or very high temperatures, without the need for elaborate heating or cooling systems to protect the lubricant.
This can lead to significant energy savings. In the case of a 6 MW turbo expander used in a petrochemical process, conventional bearings consume 50 to 100 kW of power to operate the heating and cooling systems and the lubricating pumps. When the manufacturer switched to SKF active magnetic bearing turbo expander, the active magnetic bearing solution has an energy loss that is at least 10 times less than the lubricating film bearing solution.
The active control system in a magnetic bearing can also automatically compensate for process loads or imbalance in the machine. And the data collected by the bearing controller acts as an integrated condition monitoring system , providing operators with valuable vibration information that they can use to diagnose problems or predict potential failures.
Active magnetic bearings are used in many different industries today. They found a perfect fit wherever clean, quiet and reliable long-term operations are high priorities. Common applications for smaller bearings include high performance micromolecular vacuum pumps for semiconductor manufacturing, cooling applications and neutron cutters.
Huge in energy
For larger active magnetic bearings, the energy sector has become the most important market in the last 10 years. Much of the growth in demand has been driven by the evolution of the oil and gas market, especially with the exploration of subsea gas reserves in deeper waters and increasingly remote locations.
Magnetic bearing technology is also being used in a range of onshore power applications. Liquefied natural gas (LNG) has transformed energy markets in recent years as ships carrying LNG create a vital link between producers and customers in markets too far away to be served by a pipeline. Active magnetic bearings are now widely used in eliminating gas flaring and optimising LNG transport with advanced evaporation systems equipped with electric motors high speed in magnetic bearings. These SKF motors can rotate up to 60,000 r/min and have powers of up to 1 MW. Magnetic bearings are also found in turbo expanders used to increase energy efficiency as well as maximise productivity in hydrocarbon and other gas processing applications such as hydrogen, air separators and petrochemical applications.