Portlandzementwerk Wittekind Hugo Miebach outlines its experience of Orcan Energy's modular waste heat recovery units.
Global Cement (GC): How prevalent are cement-sector waste heat recovery (WHR) installations in 2023?
Markus Lintl, Orcan Energy (ML): There is enormous waste heat in the global cement sector, but very little recovery. The notable exception is China, where WHR installations became mandatory in the late 2000s. Orcan Energy estimates that there is the potential to generate more than 60TWh across the global cement sector every year via WHR, representing a multi-billion Euro market.
This is because the most mature solutions, steam Rankine cycle (SCR) and organic Rankine cycle (ORC), originally needed a fairly large and guaranteed quantity of heat - at high temperatures - to be fully effective and thus offer reasonable return on investment (ROI) periods. This has often made large WHR systems uneconomic, particularly in the past 10 - 15 years when capital expenditure has been so limited.
They are costly due to their scale, but also because they must be tailored to each plant. This has made systems inflexible in the face of process changes, for example expansions or the introduction of new fuels. Even in the EU, where there are high electricity prices and costs to emit CO2, the economic drivers have been lacking to date.
GC: How is WHR technology evolving?
ML: Orcan Energy, based in Munich, Germany, has simplified the engineering, installation and operation of WHR technology by developing a range of modular, ORC-based WHR units. They are deployed in the marine sector, in power applications and large industrial settings. Right now, we are branching into the cement sector. There are references at plants operated by Cemex, Buzzi, Portlandzementwerk Wittekind (PZW) and, just recently, Titan Group.
GC: Are all modules the same?
ML: Orcan mass produces the units in order to reduce costs and offer favourable terms to clients. This entails a degree of standardisation, albeit with some variations for different applications. A typical module that would be used at a cement plant is our eP150.200. It comes as a 40ft container and can handle up to 2.2MW of thermal energy input, producing 200kW of power net, when parasitic loads are accounted for.
GC: Are these the units used by PZW?
Lars Richter, PZW (LR): Yes. PZW uses six identical eP150.200 units at its cement plant in Erwitte to generate power from the clinker cooler exhaust. This provides 1.2MW of power at 100% load, equating to ~10% of the 100 million kWh that the plant uses each year. Each unit can be turned down to as low as 50% load, enabling the overall WHR system to be scaled appropriately at all times for maximum efficiency.
GC: Why did PZW choose Orcan Energy?
LR: PZW spoke to a range of ORC system suppliers but was ultimately convinced by Orcan's modular approach. This was due to the plant's substantial use of alternative fuels, which fluctuate in terms of energy output. This affects the amount of waste heat available from the clinker cooler exhaust, which must be actively cooled. The modular solution continuously adapts so that maximum efficiency can be maintained relative to the input energy.
GC: How was installation and commissioning?
ML: The order was placed in the middle of 2021. The first step was to build a new air-to-water heat exchanger to provide heat to the WHR units. This was quite challenging, as the plant remained in operation throughout.
The eP150.200 units arrived in February 2022. We then built the foundations, placed the units and installed the necessary ducting. We commissioned the system in November 2022. Each of the six units was commissioned and operated individually before they were switched on together.
The system now operates automatically, with only two control options for the operator - on or off! In the event of maintenance, an unlikely failure or too much heat being supplied to the air-to-water heat exchanger, the plant's previous air-to-air heat exchanger can be called upon as needed.
GC: What are the economics of this project?
LR: PZW calculated that it was most effective to buy the units outright. As a demonstration project, we received some funding from the government, which reduced the ROI period. CO2 emissions have fallen by 4000t/yr. In relation to the cost of Scope 1 CO2 permits now reaching Euro80 - 100/t within the EU Emissions Trading Scheme (ETS), the financial savings quickly become evident.
ML: At current electricity prices in Europe, the ROI of a similar installation would be 4 - 6 years, but that's not the only way we can deploy this technology. Various options are possible depending on local conditions, including a financed energy as a service (EaaS). This way, Orcan takes on the risk and the project is net cash flow positive from day one.
GC: Will PZW expand the system in the future?
LR: We are already looking at the next steps, with a project to filter the hot exhaust gas from the preheater gases. We will then be in a position to use more eP150.200 units for this heat source. Roll-out should be straightforward.
ML: I would add that, while PZW is a single-plant operator, other manufacturers routinely assess new technologies at one plant before spreading know-how around the group. Units can also be moved between plants.
GC: What would you like to see from national and regional governments to enhance WHR uptake?
ML: People are used to thinking that anything green costs money. While, in fact, energy efficiency always reduces cost and increases profitability. Thankfully, governments are now realising this. Germany passed its Energy Efficiency Act in September 2023, which states, among other things, that WHR must be used in industrial settings when available.
LR: More widely, we would encourage governments of all stripes to design their roadmaps and policies clearly and communicate them effectively. Private money will be crucial to the decarbonisation of the cement sector, other industries and society as a whole. However, it needs steady conditions in which to make sound investment decisions.
GC: Thank you for bringing this interesting project to our attention.
LR/ML: You are very welcome indeed!
Markus Lintl
Markus Lintl has worked at Orcan Energy since 2014, starting as Business Development Manager. He has been the Head of Industry & New Business, responsible for acquiring and implementing projects in a range of sectors, including cement production, since the end of 2016.
Lars Richter
Lars Richter joined Portlandzementwerk Wittekind Hugo Miebach, an independent family-owned cement producer, as a plant engineer in 2019. He was promoted to plant manager in February 2022. Lars earlier worked for VDZ, the German Cement Association.
