Energy optimization
The food industry has traditionally used gas in its thermal processing and yet electricity is versatile and can increasingly be generated sustainably. Energy optimization technologies are changing this over-dependency on gas as innovative new ways of turning electricity into heat at competitive prices while cutting greenhouse gas emissions are being discovered.
Stuart Spear, November 2024
Successful businesses have always optimized resources. For food businesses, this means sourcing raw materials and the energy to process them at the best prices. That often involves a thermal process. Before reaching the point of sale, our food has typically undergone heating, whether drying, roasting, steaming, conditioning, baking, kilning, or cooking.
This is why Bühler is currently focusing on thermal technologies as part of its energy optimization program. Put simply, energy optimization is about reducing how much energy is used to produce each tonne of end product to the desired quality.
Depending on where you are located, gas has traditionally been the fuel of choice for heating processes in food manufacturing. But the climate change crisis and advances in energy optimization technologies are changing this energy profile. Electricity is becoming a more attractive alternative in terms of cost and the environmental benefits from wind, solar, and hydroelectricity.
As part of its environmental commitment, Bühler has set a target to have solutions ready to multiply by 2025 that reduce energy, waste, and water by 50 percent in customer value chains. Bühler estimates that across its portfolio of solutions sold over a 10-year cycle, thermal technologies account for between 30 percent to 50 percent of total emissions. James Maari, Bühler Lead Project Manager Resource Efficiency, has been tasked with optimizing energy used for these thermal processes to help reach that 50 percent energy reduction target.
“My focus at the moment is specifically what we do with thermal processing because that’s where right now we are burning the most fossil fuel to generate thermal energy,” says Maari. “As green electricity becomes more available, this means not always burning gas but finding better alternatives, examining energy systems around machines, and ensuring these solutions work well with our processes, cut costs, and reduce emissions.”
The International Energy Agency (IEA) strongly warns that achieving our global sustainability targets will require a trebling of renewable energy sources to power our industrial processes by 2030 compared to 2022. In its World Energy Outlook report for 2023, the IEA estimates that global renewable power capacity needs to rise from the 2022 figure of 3,629 GW per annum to a substantial 11,008 GW per annum by 2030.
+ understand the current energy use in your plant;
+ determine the potential for energy recovery and key technologies to integrate to achieve energy reduction;
+ evaluate the financial and CO₂e impact of the implementation of the various available solutions.
The same IEA report also warns that industrial processes need to become more efficient. The agency estimates that by 2030 improvements in the energy efficiency of technologies need to achieve a 4 percent annual decrease in energy intensity compared to the 2 percent annual drop reached in 2022. Most of these efficiency savings in technological advances will need to come from renewably sourced electricity.
Bühler is reframing its approach to its thermal technologies to enable its customers to take advantage of these global trends. The sustainability argument is compelling. A recent environmental audit shows that heat treatments involved in food processing can account for as much as 75 percent of the greenhouse gas emissions of customers’ Scopes 1 and 2 emissions. “Switching thermal technologies from gas to renewable electricity could potentially cut up to 10 million tonnes of these CO2e emissions over a 10-year period,” says Maari.
The financial benefits for customers are also starting to look attractive. In recent years, new energy optimization technologies have evolved for use by industry. For thermal processes, these include heat pumps, thermal batteries, induction techniques, and electric batteries. These advances are making electrical solutions much more cost-effective.
Maari uses the example of heat pumps to explain how these new technologies are changing the energy landscape. “The heat pump is one of the biggest levers we can pull when it comes to optimization. If you have an 80°C heat stream emitting from your dryer and you need 120°C for your process, the heat pump uses electricity to boost the temperature from 80 to 120°C,” explains Maari.
The beauty of the heat pump is that the electrical power input to raise the temperature is less than the thermal power made available for recovery in the exhaust stream. “You are basically achieving your energy savings by leveraging the wasted energy that was being emitted from your dryer to drive a new process,” Maari says. “It means that you achieve a net gain, you use one unit of electricity, and you pull out of the environment two or maybe three units of heat.”
The heat pump is one of the biggest levers we can pull when it comes to optimization. You are basically achieving your energy savings by leveraging wasted energy.
James Maari,
Lead Project Manager Resource Efficiency at Bühler
Another way of creating energy savings is by using battery and thermal storage technologies that enable a business to store power when it is cheap or when there may be an intermittent wind or solar supply. Different methods of thermal battery storage are appearing on the market as ways to leverage electricity prices or store energy from different manufacturing processes within a plant for later use.
It is when this approach to energy optimization is applied to a business’s whole manufacturing process that significant cost cuts are achievable. “You can’t just consider a machine in isolation, you have to look at all the energy streams within a plant and consider them as potential sources of energy recovery,” explains Maari. “If you have hot water coming out of one process, instead of chucking it out it can be used elsewhere; you can even expand beyond your plant. If you are operating near a town with a district heating system, for example, you could consider selling your excess energy. It is important to take a systemic approach when it comes to energy optimization.”
To find out whether these optimization technologies are right for your business, the process starts with Maari and his team carrying out an energy system assessment. This shows how much energy can be potentially reclaimed and whether it is sufficient to be used to drive other processes. The “pinch analysis” methodology used for the audit originated in the 1970s, when the energy-intensive chemical industry realized it could save money by not wasting energy by heating some compounds and cooling others.
The audit starts with a performance assessment workshop to establish if each food manufacturing process is operating at maximum efficiency. Next comes an energy audit of the whole food process, looking at temperatures, mass throughput, humidity levels, and mechanical heat generation, and establishing how much energy can be potentially recovered. A Coefficient of Performance (COP) is then calculated for heat pumps. This shows how much electricity is needed to leverage the excess heat being dissipated from factory processes and how much energy can be recovered. This figure is then compared to the current cost to the customer of continuing to use gas as the energy source.
“Once we have all this information, we get a clear picture. For example, if the payback time for the investment is 5 years, it makes sense, or it may be that the benefits just don’t stack up,” explains Maari. “We might also start to strategize, looking at the potential volatility of existing fuel prices or whether thermal storage might make it cost-effective.”
Next comes the pre-engineering phase. Specialists look at the plant to see how the technology can be best engineered into the existing manufacturing process, what piping is needed, where heat exchangers can be installed, the positioning of heat pumps, and the insulation required. The rule of thumb is the greater the spare space available within the plant, the easier the installation.
Would you like to learn more about an energy system assessment and whether it is a suitable solution for your plant? Let’s talk!
However, heat pumps may not always be the most appropriate solution as they do come with their technological constraints. The first is temperature. For now, the heat pump is the right way to go if you are using a thermal process up to 130°C, which includes drying and kilning processes. “We are looking at the next generation of technologies which might provide benefits up to 160°C or 180°C, but they are not market-ready yet,” says Maari. “There will eventually be a temperature ceiling for heat pump optimization that will be difficult to break through, such as in the field of die casting.”
The other constraint is the comparative cost of gas and electricity. In some regions it is so great that it will never be a competitive proposition to switch to a renewable electricity supply, regardless of how many energy optimization technologies are used. In other regions including Scandinavia and much of Europe, the price difference makes converting to electricity much more attractive.
“If we are going to keep global warming below 2°C, we have to make sure our customers can transition to more sustainable energy sources that are cost beneficial. The use of energy optimization technologies – that will only become more efficient in the future – is making that transition from gas to electricity much more attractive for a growing number of businesses,” says Maari.
The use of renewable electricity sources combined with the installation of these energy saving technologies is not a silver bullet. But as these technologies advance and renewable electricity sources become cheaper and more available, the number of businesses that find transitioning financially attractive while also cutting their environmental footprint will rise.
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