Industrial separations are an essential contributor to global energy consumption and carbon emissions. Today they account for a significant portion of global energy consumption, making them a focus area for those looking to decarbonize the industrial sector.
But what exactly are industrial separations, and why do they matter in the context of decarbonization? In this article, we’ll break down the role of industrial separations in global energy consumption, explore the industries that rely most heavily on these processes, and examine the pathways to reducing their energy footprint.
Industrial separations refer to processes used to separate mixtures into their individual components. These are energy-intensive activities that span a wide range of industries, from chemical production to petroleum refining and paper manufacturing.
Remarkably, up to 50% of the energy used in industrial operations (or 15% of total global energy consumption) is devoted to separations. This energy use translates to approximately 4.9 gigatons of annual carbon dioxide emissions.
Reducing emissions from industrial separations is not easy, as it requires addressing the unique energy demands of different industries and processes. To effectively tackle this challenge, we must consider multiple approaches to decarbonization. From my vantage point, there are four main pathways.
Using the most energy intensive industries in America as proxy, we collected data on plant-level energy use, and the energy consumed across various separation processes.
Here, we can see that separation plays a major role in plant-level energy consumption across three key industries: petroleum refining, chemical production, and paper manufacturing.
Petroleum refining is one of the largest consumers of energy for industrial separations. Here, distillation is employed to separate crude oil into various fractions like gasoline, diesel, and jet fuel based on their boiling points. While petroleum distillation is effective, it is also highly energy-intensive, responsible for around 1 gigaton of CO2 emissions per year.
The challenge here is that refining companies, such as Shell and ExxonMobil, rely on distillation to produce multiple valuable products from a single process stream. Alternative separation technologies, on the other hand, are highly specific, designed to extract one component based on chemical or physical interactions with the given process stream (path 1). Even if we developed a new way of producing one fraction (path 3), big oil companies are unlikely to shut down their refining operations and lose out on other valuable products. In fact, since all fractions originate from the same process stream, displacing one fraction may just result in the increased production of similarly weighted other. This creates a challenging situation, in order to make a dent in process emissions, we need to find a way to decarbonize the entire distillation column. For these reasons, the most viable approach to decarbonize distillation is to decarbonize the heat energy used (path 2). By doing so, we can reduce emissions across all fractions simultaneously.
The chemicals industry is another major energy consumer, with 50% of all separations energy in this sector used for distillation. Chemical processes like the production and purification of ethylene, caustic soda, and ammonia all rely heavily on distillation to separate chemical mixtures. In fact, the chemical sector emits approximately 1.2 gigatons of CO2 annually from distillation alone.
Unlike petroleum refining, the chemical industry is fragmented, with a variety of stakeholders operating different production processes. This fragmentation makes it difficult to implement a single alternative separation technique across the board (path 1). That being said, specific chemicals like ethylene, which are produced at significant scale and rely on large amounts of energy for separation, offer potential for impactful and targeted intervention. These improvements could come via replacing current production methods (path 3), or by introducing alternative separation technologies. The challenge with the latter is overcoming the often corrosive nature of chemical production environments and addressing the inherent fragility of lower-energy, physical separation technologies. Nonetheless, if one wants to decarbonize chemical separations as a whole, targeting process heat once again presents as the most effective pathway to address emissions on the gigaton scale (path 2).
The paper and pulp industry is responsible for 0.4 gigatons of CO2 emissions annually, primarily due to its energy intensive evaporation and drying processes. Mills use drying techniques to remove water from paper pulp and evaporation to concentrate and recycle the chemicals used for pulping.
Unlike the chemical and petroleum sectors, the paper and pulp industry is more centralized, making it easier to implement widespread changes. In addition, separation energy use accounts for 8% of the total operating costs of a paper mill — the largest variable cost after fiber and personnel. Given this, there are a few possible options for non-thermal separation techniques; however, challenges lie in the ability to withstand the high levels of alkalinity and match the throughput of existing mills (path 1). In that regard, perhaps the most promising pathway involves eliminating water use altogether, and thereby reducing energy consumption, and emissions, by up to 90% (path 3). We are yet to see a company in this space, however, research into non-thermal drying processes is ongoing at the university level. At this point in time, perhaps the simplest, and most efficient way to decarbonize separations, once again lies in decarbonizing the industrial process heat (path 2).
While the potential to reduce emissions through alternative separation techniques is exciting, the most effective and scalable approach to decarbonizing industrial separations lies in addressing the energy source itself. By focusing on decarbonizing industrial heat — particularly in industries reliant on thermal processes like distillation and drying — we can make significant strides in reducing the carbon footprint of industrial separations.
As we continue to explore the decarbonization of industrial separations, there’s potential for further research into medium- to low-grade industrial heat. Investments in this area could help accelerate the transition to cleaner industrial processes across multiple sectors, ultimately helping to reduce global emissions on a larger scale.
What do you think? Is this a challenge worth tackling? Let’s keep the conversation going as we look for ways to decarbonize industrial separations and make a meaningful impact on global energy use and emissions.
