Vegetable oil production is among the most energy-intensive sectors in the food industry, ranking in Europe just behind sugar production and animal feed. In our first article, we examined the processing of oilseeds such as sunflower and rapeseed, focusing on crushing and pressing powered by Kraftblock’s thermal storage system. This article now looks at the even more energy-demanding refining stage and how thermal batteries can replace fossil fuels in these processes.

After crude oil is extracted, it undergoes several refining steps — degumming, neutralization, bleaching, and deodorization — to remove impurities and enhance quality and safety. These processes require high operating temperatures, typically between 150 °C and over 400 °C, depending on the stage and equipment. Heat is usually supplied through thermal oil or steam as the transfer medium.

Process Heat with Steam Can Be Transitioned Easily Using Thermal Batteries

Refining consists of several stages, each targeting specific contaminants and requiring distinct processing conditions, particularly in terms of temperature and heat input. There are two main refining methods — chemical refining and physical refining — each with unique process steps and thermal demands. Throughout the refining process, heat is typically supplied by steam or thermal oil systems to maintain precise operating conditions.

Among all steps, deodorization is the most energy-intensive due to its high temperature requirements. In most large-scale refineries, steam networks are powered by fossil-fuel boilers, making them a major source of Scope 1 emissions. Kraftblock replaces these fossil systems with renewable electricity — sourced specifically at times of low-cost availability — which is efficiently stored as heat and later used in a waste heat steam generator to deliver the large volumes of process heat required for vegetable oil refining.

Refining begins with degumming, which removes seed residues, phosphatides, proteins, carbohydrates, and metals that impair oil quality. Water degumming operates at around 65 °C, while dry degumming reaches up to 140 °C for more efficient treatment. Physical refining typically uses higher temperatures at this stage since no alkalis are added.²

In chemical refining, the next step is alkali neutralization, where sodium hydroxide at 55–90 °C is used to remove free fatty acids (FFAs) and oxidation products. This step alone consumes 20–25% of the refinery’s total energy demand. In contrast, physical refining skips neutralization, with FFAs instead removed later during deodorization.³

The bleaching stage removes pigments, soaps, and trace impurities using activated clay or silica under vacuum at around 100 °C. Both refining methods employ bleaching, though physical refining may require greater amounts of adsorbents to compensate for the absence of alkali treatment.³^,⁴

Finally, deodorization eliminates residual FFAs, odors, and volatile compounds through steam distillation under deep vacuum. In chemical refining, deodorization operates at 180–230 °C and <5 mbar. Physical refining, however, incorporates a high-temperature stripping step (240–260 °C) under even deeper vacuum (<2 mbar) before final deodorization.¹

Electrification and Thermal Energy Storage with Kraftblock 

Electrified heat combined with thermal battery storage offers significant advantages for vegetable oil producers. Many of the industry’s energy-intensive processes, traditionally supplied by thermal oil or steam, can be transitioned to a carbon-neutral, reliable, and flexible heat supply system.

With Kraftblock’s thermal storage, electrification becomes far more cost-effective: electricity is stored when market prices are low and released later, avoiding expensive peak periods. More details on this economic potential can be found in our whitepaper on flexible electrification.

A compelling example comes from the Volt project, where Kraftblock, together with Eneco and PepsiCo, is replacing natural gas in the frying of potato chips at 300 °C at PepsiCo’s production site in Broek op Langedijk, Netherlands. The same approach can be applied in vegetable oil refining, where steam — and in some cases thermal oil — can be supplied efficiently through Kraftblock’s thermal battery system.³

Thermal energy remains essential in vegetable oil processing, where different heating systems are in use. A typical thermal oil plant features a gas-fired heater with a 2,000 kW capacity and a control range of 1:10. It maintains over 90% efficiency even at operating temperatures up to 375 °C, achieved through preheating of combustion air to 210 °C and precise oxygen control during combustion. The system typically includes the heater, air preheater, pumps, chimney, and an expansion and collection tank.⁵

Steam heating is also widely used in edible oil refining, particularly for deodorization. One example is the Garioni Naval GMT/HP800 boiler, which operates at up to 110 bar and is fired with gas or liquid fuels. Steam systems generally run at lower temperatures (150–250 °C) and achieve efficiencies of 70–85%, but are subject to energy losses through condensation and venting.⁶

‍Energy Efficiency in Vegetable Oil Production

Energy efficiency measures demonstrate the substantial potential of heat recovery in vegetable oil production. For example, one rapeseed oil plant redirected excess heat from oil cooling into factory heating and hot water. A 14 m³ storage tank balances heat supply and demand, supported by high-performance heat exchangers and automated control systems. The installation delivers 470 kW of thermal output, saving approximately 3,500 MWh per year and cutting CO₂ emissions by 707 tons annually.⁷

When combined with efficient electrical solutions and the flexible use of power grids and electricity markets, these measures show how one of the world’s largest food industries can successfully transition from fossil fuels to renewable energy with the help of thermal storage. A first-of-its-kind example is the Volt project with PepsiCo in Broek op Langedijk, Netherlands, where Kraftblock’s thermal battery is being deployed to decarbonize industrial frying processes.

This project is supported by the German Federal Ministry for Economic Affairs and Energy as part of the Renewable Energy Solutions Programme of the German Energy Solutions Initiative.

References

1. FEDIOL (2020): Code of Practice on vegetable oil and fat refining for food purposes Online: https://www.fediol.eu/data/FEDIOL%20Code%20of%20Practice%20on%20Oil%20Refining%20-%20revision%209%20March%202020.pdf
2. The Scientific World Journal (2022): Refining Vegetable Oils: Chemical and Physical Refining. Online: https://pmc.ncbi.nlm.nih.gov/articles/PMC8767382/ 
3. The Bleaching process, TINYTECH Online: https://www.oil-refinery.com/process-solutions/bleaching-process/?utm_source
4. Jorge Bello (2021): BLEACHING EARTH: A variety of practical steps can be taken to optimise the process. Online: https://www.ofimagazine.com/content-images/news/Bleaching-earth-optimisation.pdf?utm_source
5. Heat11.com (2015): Application fields of thermal oil plants: Chemical industry. Online: https://www.heat11.com/application-fields-of-thermal-oil-plants-chemical-industry/?lang=en#:~:text=The%20high%20demands%20for%20the,up%20to%20380%20%C2%B0C.&text=According%20to%20the%20strict%20H&R,two%20years%20following%20successful%20commissioning 
6. Garioni Naval: Steam generator for edible oils treatment plant Boiler realized by Garioni Naval for the South East Asian market Garioni Naval GMT/HP model. Online : https://www.garioninaval.com/en/realizations/steam-generator-for-edible-oils-treatment-plant/?utm_source 
7. Filter (2024): Waste heat recovery project in rapeseed oil processing plant Estonia 2024 Online: https://filter.eu/reference/waste-heat-recovery-project-in-rapeseed-oil-processing-plant/