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Coolbrook: Harnessing electricity for cement production – Global Cement

Coolbrook, a manufacturer of electrically-powered thermal processing equipment, has made a number of high-profile announcements in 2022. Here, Global Cement speaks with Joonas Rauramo, CEO of Coolbrook, about how its technology could revolutionise our sector.
Global Cement (GC): Please could you introduce Coolbrook and what it does?
Joonas Rauramo (JR): Coolbrook is a Finnish company that was founded in 2012 by our Chairman Ilpo Kouakonen. It develops technologies to revolutionise how large processing industries, such as cement, operate.
Over the past 10 years, the company has developed the Roto Dynamic Reactor (RDR) and Roto Dynamic Heater (RDH). Both of these efficiently convert electrical power into thermal energy, in the form of high-temperature gas. This means that energy-intensive industrial processes, such as cement production, could be completely electrified. If an RDR or RDH is powered using renewable power, this would eliminate the CO2 emissions from using thermal fuels. The RDH is the technology that will be most applicable to cement production.
This technology has benefitted from a collaboration with ABB, which supplies the high-speed motors and variable speed drives used, as well as analytics and optimisation expertise. Of course, ABB is also very well connected to the main players in the sectors that we are looking to develop into.
GC: How do the RDR and RDH units work?
JR: Both technologies are based on a rapidly-rotating shaft connected to a series of rotor blades, similar to those used in gas turbines. As the blades rotate, the gas in the reactor is mixed and accelerated to very high velocities. It is then slowed down in a diffuser. Doing this heats up the gas in two ways. Firstly, there is heating due to friction from the intense turbulence. Secondly, the acceleration of the gas to supersonic velocities, followed by a return to subsonic velocities, creates a shockwave that heats it up.
After the first blade / diffuser stage, there’s a second, third, fourth and so on, with up to 20 stages, depending on the inlet and outlet temperatures, gas volumes and other parameters. Each step imparts more energy to the gas, increasing its temperature, up to as high as 1700°C.
So, instead of a hot gas turning a turbine to produce electricity, we have an electrical motor turning a blade to generate a hot gas, be it air, nitrogen, CO2, hydrogen or another gas, a reverse gas turbine if you will. While this is a novel approach to heating large volumes of gas, there is a lot of expertise in this area and we apply all the same laws of physics.
GC: Where has the technology currently reached in its development curve?
JR: At the moment we are setting up a 0.8MW pilot plant operating in the Netherlands. We will ramp it up to temperatures beyond 1000°C first, with an eventual target to hit 1700°C in 2024 – 2025. Its motor will have an electrical-to-heat conversion efficiency of around 90%, which we aim to increase towards 95% in due course. The shaft in the pilot plant will rotate faster than 20,000rpm, but the speed will be significantly lower in the full scale units.
GC: A 0.8MW motor that heats gas to 1700°C… that’s very compact…
JR: Yes, this is a major advantage compared to traditional electrical heating technologies. It is because we are not heating something, for example a heating element, that then heats the gas. The gas itself is the heat transfer agent. This means that the process avoids the heat losses inevitably seen in other electrical heating processes.
Additionally, it takes just milliseconds to heat the gas in each step, so the volumes heated can be very high. When we scale up, we should be able to treat hundreds of thousands of Nm3, making it suitable for cement production.
GC: Is this approach only for greenfield plants or could existing plants be retrofitted?
JR: Its small footprint will make the RDH very applicable for retrofitting to existing cement plants, where space is often scarce. The industrial scale version will be just a few metres in length. To fully convert an existing plant would take two to four RDH units, if it were to run exclusively on electrical power.
We believe, from our research, that this will be the first technology that will be able to run a conventional cement plant entirely using just electricity. Coolbrook is at the forefront of decarbonisation.
GC: How will cement plants have to be altered to accommodate RDH units?
JR: Each cement plant is unique and has been designed to operate in a certain way, using certain fuels and energy flows. Many have been altered and optimised over time to accommodate changing trends, with many retrofits and adaptations.
We see the switch to electrical heating as a continuation of this development. There will be several options for cement plants, most likely a hybrid approach at first. For example, a plant might decide to install an RDH for use with its preheater / precalciner, while retaining its main burner for the time being. Another option is to use an RDH instead of the main burner, or even to generate the hot air and split it to different locations, depending on the process requirements.
Overall, there is a lot of flexibility. The plant doesn’t have to commit to just using electrical power right from the start. Of course, should it have a sufficient and reliable enough source of renewable power, full electrification will be possible. Indeed, it is the goal of this technology. This is still a fairly long way off, but we can see the steps towards it.
Eventually, the RDH unit will allow users to remove almost all equipment involved in the burning of fuels, conventional or otherwise. This will include fuel reception, sorting and storage areas, feeding systems and burners. This will reduce the space needed for these activities, lead to an increase in reliability and also simplify the acquisition of energy. It will also reduce NOx emissions in addition to CO2.
GC: An obvious question: Is there enough renewable power to do this?
JR: Right now, there is not sufficient renewable power to fully electrify the global cement industry. However, by 2030 most electricity will be CO2-free. I am a firm believer in this trend, as solar and wind are already very cost effective. The projected growth of this technology will follow the development of renewable energy.
At the end of the day, moving to renewable electrical production makes sense sooner rather than later. There is no solution to decarbonisation that doesn’t require energy and, for all the benefits of hydrogen, electricity is going to play a major part. Indeed the IPCC advises users to ‘electrify where possible.’ It may be that you start out with a mixture of fossil-derived power and renewable power, but this will inevitably trend towards renewable in the coming years.
GC: What new operation and maintenance challenges will this technology present?
JR: We do not anticipate that they will present cement producers with significant new operation or maintenance issues. The RDH will be as reliable as a gas turbine, with availabilities in excess of 95%. You would need to conduct an endoscopic inspection on an annual basis, with the potential for larger revisions every 4 – 5 years. This is something that can easily be accommodated within a cement plant’s annual shutdown and will not present a bottleneck on the maintenance side. In any case, Coolbrook will retain contact with the client throughout its lifetime, both to maintain and develop the technology.
GC: How will the economics of the RDH work?
JR: We expect the RDH to be among the most competitive alternatives to traditional cement production technology. The relative attractiveness of that ‘price point’ will, of course, depend on the environment that the individual plant finds itself within.
If there is an Emissions Trading Scheme (ETS), such as in the EU, the drivers towards RDH will be stronger than in places without an ETS. In sunnier climates, this may not be necessary, given the falling cost of solar power. We already see this in India, the Middle East and North Africa and in Central / South America. The same is true in windier places, for example in Northern Europe. So, the environment around the plant will be key to the approach taken, how much it costs the plant and how rapidly the technology is adopted.
Overall, Coolbrook wants to have a global impact with this technology and already has two major cement sector partnerships. One is with the Mexican multinational Cemex, which has cement plants in various locations. The other is with UltraTech, the biggest player in the world’s second-largest cement market, India. We have further partnerships in development that will be announced in due course.
GC: What is the biggest barrier to the roll-out of this technology?
JR: We are talking about fundamentally transforming the cement sector, which has traditionally been resistant to change. I would argue that’s not the case now, as there is the desire to decarbonise.
However, Coolbrook understands that it is still a big leap to switch to a new technology. We have to demonstrate to the sector as a whole that the RDH technology works, that it is reliable and that it is scaleable. In other words, we have to show that it is the correct investment for the future. Within Coolbrook, we are very confident that this process will work on the largest scales, but many potential users would like to see it operating – at someone else’s plant – before they will have the confidence to do it themselves.
That said, we will see this technology applied commercially to different parts of the cement process over the next two years. This, plus the ever-pressing need to decarbonise, which is now – finally – being realised by heavy industries, will hopefully shorten the time it takes Coolbrook to penetrate the market. The need for decarbonisation and energy independence has never been more urgent. Coolbrook looks forward to being part of that transition.
GC: Thank you today Joonas for a very interesting discussion.
JR: You are very welcome. It was great to talk!
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