In a world where energy prices are rising and climate concerns continue to mount, manufacturers can no longer sit on the sidelines and hope the energy crisis will go away. It won’t anytime soon, and pressure is increasing for organizations that have pledged net-zero emissions to provide “real-zero” answers.
It’s clear we are moving quickly toward a cleaner, greener future and those who don’t act soon will be left behind. However, many companies have hesitated to act because of the false assumption that going green means “direct electric,” which is an expensive endeavor at this time. But decarbonizing does not have to be an either/or initiative, choosing between decarbonization or profitability.
There is a better way to net zero, one that can benefit an organization’s bottom line if done right. The U.S. Department of Energy (DoE) recently released its “Industrial Decarbonization Roadmap”—a comprehensive report identifying four key pathways to reduce industrial emissions in American manufacturing. The report singles out energy efficiency as “the most cost-effective option for near-term reductions of greenhouse gas emission,” highlighting the importance of software-driven, smart manufacturing systems and advanced data analytics that improve productivity related to energy use.
When people think of energy efficiency, they think about improving the efficiencies of existing utilities, steam loops (from steam generation to condensate return), and hot water loops. This approach can help reduce energy and emissions by five to 10 percent. But rarely is this being looked at from the process perspective. Seldom are organizations asking, “Why is this energy needed,” and “Where is it going?” Focusing on the process and on waste heat recovery can, on average, reduce CO2 emissions by 50 percent in light-manufacturing industries.
According to numerous studies conducted by our team at Armstrong International, between 50 and 80 percent of the primary energy input used in light manufacturing leaves the plant as waste heat. Just a small fraction of that fossil fuel-generated energy input is used for manufacturing the product, while the rest is released in the form of hot exhaust gases and radiating heat from hot equipment surfaces and heated products.
For example, let’s look at industrial air dryers. Such dryers are among the largest heating applications in light industry, each rejecting up to 90 percent of the energy produced into the atmosphere through stacks in the form of low temperature, humid air. This is also true for many other industrial applications, and it begs the question: Can light industry manufacturers recover that waste heat as energy and put it back to work in a circular approach? The answer is “yes,” and harnessing the power of this waste heat through a process Armstrong calls “circular thermal” could be the fastest and most cost-effective way to achieve net-zero emissions.
Understanding the flow of energy within a plant is a key aspect of defining a roadmap to decarbonization. Questions like “Where is the energy going?” and “How much energy is being rejected as waste heat?” must be answered before a net-zero plan can be put in place. As it stands in most of today’s light industry manufacturing facilities, the thermal utility systems were built decades ago and are not equipped for energy efficiency and waste heat recovery—even though a method to maximize the thermal efficiency of a plant has existed for more than 40 years. This method, known as Process Integration or Pinch, consists of mapping and overlapping heat sources and heat sinks in a plant to optimize heat recovery.
First, a trained thermal energy expert performs a walkthrough of a facility to evaluate the overall performance of its thermal utility system. This process includes establishing an initial baseline of the thermal utilities and identifying pain points within the utility infrastructure. Then, the engineer creates a thermal mapping of the process.
When making a product like powdered milk, for example, trained thermal energy experts will conduct analysis by following the raw material from when it enters the facility until it is shipped. They are looking at each step along the way where there is heat demand, known as a heatsink, and where there are cooling needs (heat sources). Once all these steps are identified, the team quantifies the current amount of energy needed to run each step in the process. From this point, an experienced thermal energy expert analyzes the data—using a set of digital tools and software to help frame the approach—and develops the best strategy for integrating all heat sources within the facility, to achieve the lowest amount of energy consumption.
Pinch requires an engineer to transform a theoretical solution into a practical solution that works for the plant and its process. The technique provides understanding of where energy can be recovered through heat exchangers and where other methods for heating and cooling need to be applied. For example, a variety of industrial processes generate waste heat that cannot be used efficiently because it is often available at lower temperatures than required. For that low-grade heat to be used rather than wasted, it needs to be upgraded with high-grade energy; and industrial heat pump systems are designed to do just that. With the use of high-temperature heat pumps, which produce two to three times more heat output than they consume in electricity input, manufacturers can process this energy to deliver a higher-grade heat for a specific use rather than letting it be wasted into the atmosphere.
Today’s process integration tools also allow for greater transparency, which is exactly what the public is asking for at a time when net-zero pledges need to start producing real-zero answers. Networks of applications—such as AI- and IoT-powered SaaS solutions and cloud services—provide engineers with more data than ever, allowing for more precise measurements, accurate reporting, and greater efficiencies.
As our world and the climate continue to demand cleaner, healthier energy solutions, it’s clear that optimizing facilities for energy efficiency through waste-heat recovery is a no-regret first step toward decarbonization. This method can reduce up to 50 percent of CO₂ emissions in light industry. But, until now, it had been largely ignored due to the affordability and abundance of fossil fuels and the lack of concern for CO₂ emissions. That has all changed. Now that energy is a business risk, recovering waste heat is not only vital for healthy profit margins, it is also the fastest and most economical method for achieving net-zero emissions with available technology.
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