Process & Control magazine is sponsoring the PPMA Show Learning Hub session ‘Energy efficient production: uncover the potential of waste’ being presented by Elliot Woolley, Lecturer in Sustainable Manufacturing – Loughborough University. The session takes place at 11:30am on Thursday 28th September. Here we ask Elliot some questions on the subject…
Manufacturing is responsible for about one third of global energy consumption and can represent a significant business cost. In this session, discover how waste heat energy can be recovered and re-used within a manufacturing environment and take a look into the future to see how new energy consumption models can change the way we manufacture products.
Q1. Please explain the different methods that can be used to recover waste heat energy.
There are four main methods used to recover waste heat energy. The most common uses a heat exchanger to improve the energy efficiency of a factory or plant by converting heat from one form to another. This is the most flexible method as it can be used by a wide range of applications thanks to the variety of heat exchangers available.
Manufacturers may also use a direct heat approach that recovers heat resulting from a process or product and reuses the ‘raw heat’; a thermodynamic cycle that uses a heat engine to effectively generate motion or electricity and finally; a thermoelectric method, which converts heat to electrical energy that can then be used for other processes within the manufacturing environment.
The variety of methods available means that there is a solution for almost any temperature range, ensuring that no matter the industry or sector – manufacturers can efficiently recover waste heat energy, monitor and control their environmental impacts from resource consumption and emissions in real time by using intelligent data collection, information processing and automated planning and control.
Q2. How easy is it to retrofit equipment used to recover waste heat energy, and what is the average ROI?
This widely depends on the application in question as some will lend themselves to heat recovery and some will present a more complex problem. When addressing which method to use, there are a wide range of factors to consider. Manufacturers need to assess how much heat is available, when it is available and when it would need to be reused. For example, can it be used at the same time it is recovered or will it need to be stored before it can be reused?
How heat is generated will also need to be assessed. For example, the medium of heat (e.g. a coolant fluid) may contain contaminants so, further steps may be required to ensure it can be recovered and reused within a plant or application.
Return on Investment (ROI) also largely depends on the same considerations. Typically, ROI can be seen within two years but this will vary on the application and industry. For example, the food industry usually operates at lower temperatures. While this might result in less efficient heat recovery, production is typically more consistent, which is a benefit. Each application will present different opportunities and challenges, so it is important to assess each site individually to determine the best method moving forward.
In my session at the PPMA Show, I will explore how we can assess different manufacturing environments to determine the most efficient ways to recover waste heat energy for reuse.
Q3. Please explain a little more about new energy consumption models. What are they and how easily can they be implemented?
First, manufacturers need to evaluate if they are recovering waste in the best way possible. One method recommended is the embedded product energy model. By assessing the energy used across different activities within a factory we can identify the hot spots for the most efficient and inefficient areas before suggesting a method for energy recovery. This not only allows us to address where energy is produced but review how it can be best repurposed for processing or used for back office or heating purposes.
In terms of implementation, this again widely depends on the application. Factors for consideration include the complexity of the factory, how many products and types of product it produces and whether these are in single batches of one product or is there a variety of different products and formats produced? We also address the existing metering available within the factory. By building a complete picture of the processes run, we can uncover the potential of waste at each site and deliver an energy management solution to ensure that the manufacturing industry moves towards a future of more energy efficient production.