Growing interest in glycerol in hydropower

Interest in glycerol as a lubricant in hydropower is growing. The lubricants in hydropower plants have so far been mostly fossil-based. Researchers at Luleå University of Technology are working to develop glycerol oils so that they can be adapted to the needs of hydropower plants. Yijun Shi, professor at LTU, is passionate about the development of glycerol and has both started companies and received awards for his glycerol research.

Environmental adaptation of hydropower does not always have to be about fish migration and flows, but can also be about what is inside the station.
An important piece of the puzzle to reduce the negative environmental impact of hydropower is to replace fossil mineral oils with glycerol-based oils.

Yijun Shi is a professor of machine elements at Luleå University and one of those working on developing the glycerol to meet the standard requirements for machine operation in the hydropower industry.

– When we started working on glycerol, we only had two facts to go on, we knew that glycerol has low friction and is durable.
Through research we quickly found potential applications in industry.
It started with oils for forestry and we were able to work with forestry companies to test and further develop the innovation.
Now we have come a long way with glycerol oils for the hydropower industry.
We have done several field tests and we are well on our way.
Hydropower must become more environmentally friendly!

Glycerol is safe to use, it is so healthy that you can eat it.
It is a by-product of biodiesel (RME) production and has been around for 7-8 years,” says Yijun Shi:

– I find the hydropower industry to be a relatively conservative industry, but now we see that Uniper and Fortum are using glycerol on a trial basis and that Vattenfall is about to start tests.
Glycerol is a little more expensive than mineral oil, but think how much better it is for the environment!
If a spill of glycerol were to occur, this type of oil is not in the least harmful to either animals or humans.

At LTU, researchers are now working on the viscosity of glycerol to make it less temperature sensitive.

– We are also working on adapting the glycerol to different hydropower plants, they all have different conditions and requirements for how the oil should work.

The energy transition is contributing to tougher demands on hydropower with more starts and stops, and the escalation of frequency regulation has contributed to an increased number of load cycles on critical components such as bearings in hydropower turbines.

– It is therefore crucial that we can develop a variant of glycerol that can work in many of our hydropower plants,” says Yijun Shi.

Yijun Shi is also co-founder of the start-up Sustainalube, which develops and markets environmentally friendly lubricants and hydraulic fluids without ecotoxicity.
The company has been nominated for several awards, including in SEB Bank’s Next Awards competition, which recognizes sustainable business and new ideas that contribute to a better future.
The prize is funds, advice and exposure within the bank’s network.
Yijun Shi also recently won the Venture Cup’s best business idea competition for this type of non-toxic, degradable lubricant.

– I am passionate about developing these lubricants.
I have seen figures that the world uses more than 37 million tons of lubricants per year.
98% of lubricants are made from crude oil.
This is really a big problem in a sustainable society.
It’s time for industry to switch to glycerol-based lubricants now!

Hydrual oil is an important component of a hydropower plant.
It is used, for example, in the control of turbine blades and guide rails.
Virtually all hydropower oils are fossil-based mineral oils or synthetic oils.
However, there are now fossil-free glycerol-based oils, which are made from biofuel residues.

For the past year and a half, Uniper has been testing glycerol-based oils at five small hydropower plants in Sweden.
Lars Svensson at Uniper says that Uniper has a policy that says that when hydropower plants are rebuilt, fossil products must be evaluated to see if they can be replaced with more environmentally friendly products:

– The glycerol is very interesting for us, especially as it can be used with existing hydraulic systems.
We would find it much more difficult to justify replacing the mineral oil we have if it would mean the installation of new and special equipment in the form of pumps and valves.

Uniper is testing the glycerol in hydraulic systems, exhaust valves and in the hubs of Kaplan turbines.

– What matters to us is functionality, longevity and durability.
We need to see that it works and that there are no failures.
Glycerol is slightly more expensive than mineral oil, but it is a negligible part of the operating cost of a hydropower plant.

It has been shown that glycerol works very well as a lubricant.
Lars Svensson can’t see any disadvantages, but it’s a little more complicated to use in the spillways:

– In the hydraulic systems needed for the operation of the air vents, we can see that the glycerol is sensitive to different temperatures, so it is important to find a fluid that can work in both summer and winter.
The glycerol turned out to be very sluggish in winter.
We have a good collaboration with the research team at Luleå University of Technology.
They have now developed glycerol with different viscosities, so we can test.

“Mineral oil is not as sensitive to temperature,” says Lars Svensson, “but it has been tested for many years.

– I definitely think that glycerol will be able to develop and work as well as mineral oil, but it might take a few years.

In the 1980s, a water-based oil was developed with certain additives to prevent corrosion.
The idea was to reduce the risk of mineral oils leaking into waterways.
But according to Lars Svensson, the water-based oils have not worked so well.

– If glycerol works well, we can use glycerol as a lubricant in our kaplan units as well.
It can then replace the mineral oil used today.

Glycerol oil was initially developed for forestry machinery.
One difference with forestry is that there the machines are usually used daily or at least at frequent intervals.
Compared to, for example, the spillways in hydropower, there is a big difference, as a spillway can stand still for several weeks.

– We have seen that the glycerol does not perform well over time and that it does not keep its shape and viscosity if it is not in motion.
We need to continue to evaluate how the glycerol evolves in systems with normally few operating hours per year.

Do you have any advice for others in the industry who haven’t dared to try glycerol yet?

– You have to dare, and you don’t have to test on the most sensitive component and in the largest plants.
We have tested in southern Sweden on smaller plants to gain operating experience, and on the whole it has worked very well.
It will probably take a couple of years before we can implement glycerol on a large scale in our hydropower plants.
We need to bring it up in our management teams and tell them how useful glycerol is,” concludes Lars Svensson.