Methods for Enhancing Energy and Resource Efficiency in Sunflower Oil Production: A Case Study from Bulgaria

Abstract

The rising demand for energy resources and industrial goods presents significant challenges to sustainable development. Sunflower oil, commonly utilized in the food sector, biofuels, and various industrial applications, is notably affected by this demand. In Bulgaria, it serves as a primary source of vegetable fats, ranking second to butter in daily consumption. The aim of this study is to evaluate and propose methods to improve energy and resource efficiency in sunflower oil production in Bulgaria. The analysis is based on data from an energy audit conducted in 2023 at an industrial sunflower oil production facility. Reconstruction and modernization initiatives, which included the installation of high-performance, energy-efficient equipment, led to a 34% increase in energy efficiency. The findings highlight the importance of adjusting the technological parameters such as temperature, pressure, grinding level, and pressing time to reduce energy use and operational costs. Additionally, resource efficiency is improved through more effective raw material utilization and waste reduction. These strategies not only enhance the economic and environmental performance of sunflower oil production but also support sustainable development and competitiveness within the industry. The improvement reduces hexane use by approximately 2%, resulting in energy savings of 12–15 kWh/t of processed seeds and a reduction in CO₂ emissions by 3–4 kg/t, thereby improving the environmental profile of sunflower oil production.

1. Introduction

1.1. Context and Importance of Sunflower Oil Production

The growing demand for energy resources and industrial products worldwide creates serious challenges for the sustainable development in many sectors [1]. Accelerated industrial progress, combined with population growth, has led to increased dependence on fossil fuels, including coal, oil, and natural gas [2]. The intensive exploitation of these limited natural resources leads to a serious increase in carbon emissions, which accelerates climate change and puts an additional threat to ecological sustainability [3]. Consequently, Awan and Sroufe [4], Viles et al. [5], and Cisneros-Yupanqui et al. [6] highlight the need to carry out a strategic rethinking of production and consumption models, especially concerning energy and resources. For example, the increased demand for sunflower oil places additional demand on natural resources [7]. In addition, sunflower cultivation is of significant economic importance to many countries, playing a key role in global agricultural systems and the vegetable oil trade. The production process of sunflower oil is associated with a high consumption of energy and water, which contributes to the depletion of these resources and aggravates the ecological footprint of this production sector [8,9].

The demand for sunflower oil is driven by its wide application in the food industry, bio-fuel production, and various industrial processes [10,11]. This demand is driven by factors such as the increasing global population and increasing interest in healthy foods. Sunflower oil is a rich source of unsaturated fatty acids and antioxidants, which makes it a preferred product for both personal use and industrial production [12,13,14]. It is one of the main sources of vegetable fats in Bulgaria and ranks second in popularity after cow butter in the daily diet [15]. This creates a need to increase energy and resource efficiency in the sunflower oil production process.

Sunflower oil is rich in polyunsaturated fatty acids, particularly linoleic acid, making it a valuable source of essential fatty acids [16,17,18,19,20,21]. Its high resistance to heat treatment makes it suitable for culinary applications, while its natural antioxidants, such as vitamin E, increase its potential for cosmetic use [22,23]. Waste sunflower oil has also been investigated for industrial applications, demonstrating excellent thermophysical and heat transfer properties, making it a cost-effective alternative to conventional mineral oils in cooling and lubrication processes [24,25].

1.2. Environmental and Energy Efficiency Challenges

Efficient water management is essential in sunflower oil production because extraction and refining processes consume significant water resources and may affect local ecosystems [26]. Implementing water recycling and wastewater reduction technologies reduces water depletion and environmental pollution risks. Recycling residual seeds into animal feed or biomass decreases waste and creates additional economic opportunities [27]. Moreover, waste sunflower oil can be used for biofuel production, providing an ecological alternative to fossil fuels and contributing to carbon reduction and energy diversification [28,29]. Biorefinery approaches based on agricultural residues, including sunflower by-products, offer an efficient solution for generating both heat and electricity while reducing carbon dioxide emissions and improving nutrient recycling [30]. Sunflower husk, in particular, has a high energy content and is suitable for cogeneration, enabling full utilization of processing by-products and significant CO₂ savings [31].

1.3. Objectives and Structure of the Study

Despite the growing global demand for sunflower oil for food and energy purposes, sustainable development requirements introduce new challenges. Production processes must increasingly meet energy and resource efficiency criteria, calling for continuous innovation and technological modernization [32,33]. The aim of this study is to evaluate energy-efficient solutions implemented in a Bulgarian sunflower oil production plant, focusing on technological modernization and process optimization as key pathways for improving energy and resource efficiency. These challenges not only affect the ecological footprint of the production process but also have economic and social consequences. The search for sustainable solutions to improve technological and production processes is essential for the future of the sector. The development and implementation of new technologies and practices that improve energy and resource efficiency can lead to significant benefits, including cost reduction and minimization of environmental impacts. Optimization of resource efficiency and innovation in production processes is fundamental to achieving sustainable production of sunflower oil, which is crucial for the long-term sustainability of the industry and its economic development [34,35].

The sunflower oil production process involves several key stages, each of which requires a significant amount of energy. These stages include cleaning, extraction, refining, and deodorization of the oil. Although these processes are technologically advanced, they are also energy-demanding. The implementation of new technologies that reduce energy consumption and increase production efficiency is important for reducing carbon emissions and energy costs. For example, modern extraction systems, such as hydraulic press systems and solvent extractors, offer more efficient methods of oil extraction, resulting in lower energy consumption [36]. Foppa Pedretti et al. [37] concluded that the production of cold-pressed sunflower oil offers farmers the opportunity to create a complete on-farm food supply chain and provides added value. This technology not only improves economic benefits but also provides opportunities for production valorization through bioenergy and bio-materials, which contributes to the sustainable development of the farms. The selection of suitable hybrids and the quality of cold extraction are the key for achieving high yields and excellent by-products. The possibility of utilizing the extraction material for food purposes or biogas further emphasizes the sustainability of the production and its efficiency. Ramos et al. [38] showed that new oils obtained from sunflower seeds aim to preserve the obtained sterol composition by improving the refining technological processes. Beyer and Rademacher [39] emphasized that simply replacing palm oil with other vegetable oils does not guarantee a complete reduction of the carbon footprint. To more effectively reduce harmful impacts on the environment, it is important to focus on sourcing vegetable oils from regions with a lower ecological footprint and to improve agricultural practices. Romanić et al. [40] showed that the frying process does not significantly affect the iodine value of oils, except for soybean oil, where it decreases. The most unsuitable oil for frying is standard sunflower oil, although it is widely used. The addition of antioxidants, either synthetic or natural, improves the oxidation properties of the oil. Palmolein performs better than refined sunflower oil, but the best choice for frying is high-fat sunflower oil. Metzner Ungureanu et al. [41] demonstrated that organic extracts of blueberries are effective natural antioxidants that significantly improve the thermo-oxidative stability of sunflower oil at high temperatures. Kakimov et al. [42] showed that optimizing the press equipment for safflower oil production, by improving the pressure distribution mechanism, significantly increases process efficiency. Abdilova et al. [43] showed that the improvement of the sunflower oil pressing process is achieved both by the correct selection of the degree of grinding and the speed of rotation of the feed screw, as well as the energy consumption. Both the oil yield and the energy efficiency of the press are also reported.

In order to make sustainable decisions to increase the energy and resource efficiency in the production of sunflower oil, it is necessary to carry out in-depth studies of the technological processes. Such studies are crucial for several reasons. First, improvements in production methods can lead to higher yields and improved oil quality, which is essential for economic efficiency. Second, optimization of parameters such as temperature, pressure, degree of grinding, and pressing time reduces energy consumption and improves energy efficiency while reducing operating costs. Third, such research can offer solutions to increase resource efficiency through better use of raw materials and minimization of waste, which is key to sustainable resource management. Fourth, innovations in production technology can lead to an improvement in the quality of the final product and an increase in market competitiveness. All these factors emphasize the need for continuous research and optimization to increase both the energy and resource efficiency of sunflower oil production, which is the main goal of this study.

The paper presents baseline information on the existing technological equipment, the proposed energy-efficient measures, and the results of their implementation. The aim of this study is to evaluate and propose methods to improve energy and resource efficiency in sunflower oil production, based on an energy audit conducted in a Bulgarian production facility in 2023.

2. Materials and Methods

2.1. Base Information for the Existing Technological Equipment

Over the past two decades, the major focus on sunflower seed oil production systems, has been on the increasing energy efficiency, through the introduction of energy efficient equipment, as well as reduced consumption of primary and secondary resources. Existing production plants are continuously introducing this type of measures in order to meet the high requirements regarding specific energy consumption (energy consumed per unit of production), with reduced environmental impact. In addition, the aim is to improve the quality of the final product with reduced consumption of energy and secondary raw materials.

In the presented work, the possibilities for increasing the energy efficiency of equipment for the production of oil are considered, and the possibilities of lowering primary and secondary raw materials in the production of sunflower oil are analyzed. The main production line of the enterprise is related to the production of crude or unrefined oil, mainly for export. Figure 1 shows the technological operations involved in producing crude sunflower oil.

The plant processes approximately 250 tons of sunflower seeds per 24 h. Electricity is used to power the main and auxiliary equipment. The plant uses sunflower husk and heavy fuel oil (HFO) to produce steam, which is mainly used in “Press workshop” during oil production. The standard survey focuses on three production sections: “Pre-press”, “Press”, and “Pre-extraction”.

All processes in the factory require heat, delivered by steam. The boiler plant uses four old boilers, two of which are type P-10 (Figure 2a), with the others being type KM-12 (Figure 2b). The P-10 type boiler fires sunflower husks and produces 10 t/h saturated steam with P = 13 bars and t = 194 °C. The thermal power of the boiler is 8.5 MW. The KM-12 boiler fires heavy fuel oil (HFO). It is used to produce saturated steam with the same parameters. The KM-12 boilers are used only at peak times. The annual heavy fuel oil consumption, based on the performed analysis, amounted to 350 t/yr.

The P-10 type boilers (firing sunflower husks) operate at a high-capacity factor. The boilers’ operations are staggered, i.e., initially one of the boilers starts producing saturated steam and then stops for ash cleaning. During the cleaning process, the other boiler starts running. When all processes in the factory run simultaneously (i.e., the plant is at peak operations), one of the KM-12 boilers also starts.

2.2. Description of Technological Processes and Equipment in Workshops: “Pre-Press”, “Press”, and “Pre-Extraction”

2.2.1. “Pre-Press” Section

Cleaning of the sunflower seeds is accomplished in a big silo machine (seed cleaning machine). From the silo, by the means of grain transporters, the clean seeds are transport-ed to the production storage, where the sunflower seeds are fed to the peeler machines. The equipment in the “Pre-press” workshop is old, with very high operational hours and energy consumption. The workshop includes daily storage and peeler machines (Figure 3) types ALS60 and ALS 100, with a production capacity of 250 t/h. The peelers are highly loaded, with 6500 operational hours per year. The hulled seeds, second treatment, shell, and seed oil dust are the four products produced by the peeler machines:

• De-hulled seeds are transported by two 50-ton grain transporters and taken up by a transversal screw and supply elevator, with a capacity of 100 tons;
• Poorly husked seeds, referred to as “repeats”, are transported by 2 grain transporters, with 50 tons capacity each. The repeats are returned for repeated de-hulling;
• Seed oil dust, transported for separation by 2 screws, with 25 tons capacity;
• Sunflower husk, transported with 4 screws (50 tons capacity each), and moved to the storage using pneumatic transport.

2.2.2. “Press” Section

The equipment in the “Press” section includes five roll milling machines, six stack cookers, five old screw presses (Figure 4), a decanter for raw oil, one reservoir for raw oil, final storage, and supporting screw and elevator lines. Milling of husked seeds is performed with five rolling machines. Located under the roll is a cross screw with a 100 ton capacity. A grain transporter, with a 100 ton capacity, transports the grist to the cookers for moisture–heat treatment in the Press section. The screw located above the cookers has a 100-ton capacity and is equipped with a metal tray.

After the grist is cooked, it enters the extrusion presses and yields two streams—press oil and expeller. Under the presses are two screws to move the two streams:

• Screw for raw pressed oil—up to 50 tons is transported to the chain separator and filter;
• Screw for expeller—up to 100 tons is transported by an elevator, with a capacity of 100 tons, to the breher and corrugated rolls for grinding.

After the screw presses, the product goes to the “Pre-extraction” line for further treatment, where the sunflower cake is prepared for additional oil extraction in the Extraction workshop.

The productivity of the stack cookers and screw presses is estimated at 250 t/h of sunflower seeds. Both processes, pressing and cooking, require steam consumption (steam parameters 0.9 MPa, 180 °C) of 40 t/h. The enthalpy of saturated steam is 2774 kJ/kg. The processes operate continuously, in three shifts per day, with eight-hour shifts. The condensate from the “Pre-press” section processes is not returned to the boiler station. The annual equipment operating hours are estimated at 6 500 h.

2.2.3. “Pre-Extraction” Section

The equipment in the Pre-extraction workshop is old, has significant operational hours, and has high energy consumption. The workshop includes a breher and a single-pair corrugated roller mill. The productivity of the machines in the Pre-extraction workshop is estimated at 250 t/h of expeller. The equipment’s annual operating hours are estimated at 6500 h.

2.2.4. Basic Technical Data and Annual Energy Consumption of Equipment in Sections “Pre-Press”, “Press”, and “Pre-Extraction”

The power plant’s total annual electricity consumption is 7 369 MWh. The facility consumes 10,833 tons of steam per year. The six roasters are the main consumers of steam. To produce the steam necessary for the year-round operation of the technological lines, 350 tons of fuel oil and 1879 tons of sunflower hulls are consumed per year. All condensate is utilized and returned to the steam boiler. The specific electricity consumption is 108.8 kWh per ton of processed production, and the specific steam consumption is 0.16 tons per ton of processed production.

Table 1. Technical and operational data installed equipment by sections.

Section	Equipment Name	Installed Electrical Power, kW	Quantity
Pre-press	Grain transporters	4.0	2
	Elevators	7.5	1
	Grain transporters	5.0	1
	Grain transporters	5.0	1
	Screw	2.2	1
	Elevators	3.0	2
	Screw	2.2	6
	Screw	2.2	6
	De-huller	16.0	5
	Grain transporters	4.0	1
	Grain transporters	5.0	1
	Screw	2.2	1
	Elevators	5.5	1
	Grain transporters	1.1	6
Press	Rolling mills	30.0	6
	Screw	7.5	2
	Screw	5.5	1
	Screw before elevator	10.0	1
	Screw over elevator	5.5	3
	Screw repeats	4.0	1
	Stack cookers	30.0	6
	Screw Press	55.0	5
Pre-extraction	Screw	5.5	2
	Elevator	10.0	1
	Brecher	7.5	1
	Feeder rolls	1.1	3
	Screw	4.0	1
	Grain transporter to 37	4.0	1
	Elevator to extraction	4.0	1

presents the available equipment in the enterprise.

Based on the described technological processes and equipment, an energy audit was carried out to evaluate the efficiency of energy use and identify opportunities for improvement.

2.3. Methodology of the Energy Audit

The energy audit was conducted following the methodology described in the Bulgarian standard BDS EN 16247-1:2022 “Energy audits—Part 1: General requirements” [44]. This standard defines the general principles, requirements, and deliverables of energy audits to ensure transparency, consistency, and reproducibility of results.

The data collection process included the acquisition of production flow data, electricity and thermal energy consumption records, and on-site measurements of key process parameters under standard operating conditions. Hourly readings of electricity meters and daily fuel consumption logs were used to quantify baseline energy use, while heat losses were evaluated through temperature profiling of key equipment and pipelines. Process diagrams and technical documentation were reviewed to identify potential areas for efficiency improvement. The collected data were analyzed to determine specific energy consumption indicators, expressed as energy use per unit of processed raw material, and to evaluate the impact of the proposed energy efficiency measures. The overall structure of the research and the relationships between its stages are presented in Figure 5.

The optimization of technological parameters, including temperature, pressure, grinding level, and pressing time, was carried out based on the findings of the energy audit and the operational records of the plant. Adjustments were made within the limits specified by the equipment manufacturers and established process requirements. Each change was tested under real operating conditions, with continuous monitoring of specific energy consumption and oil yield, enabling the identification of operating settings that deliver lower energy use while maintaining product quality.

3. Results

The main objective of the enterprise is to improve energy efficiency through the introduction of new equipment in the Pre-press, Press, and Pre-extraction workshops.

3.1. Introduction of New Energy Efficient Equipment in the Pre-Press Workshop

The project plan envisages the purchase of buffer hopper; magnetic separator to remove any ferrous material; multiple deck screener; cracking roller mill; two flakers; and all supporting equipment such as grain transporters and elevators. The cracking roller mill, pre-heater-conditioner, and flaking roller mill will be delivered and installed on the industrial enterprise site. The measure envisages design, delivery, installation, commissioning, and commissioning tests of the new system, plus operating staff training. The modification is presented in Figure 6.

The seeds to be processed are received in the buffer hopper, from where they are removed using a conveyor and transported by the magnetic separator that separates any ferrous material. The seeds then fall by gravity onto a continuous scale, which controls the feed to the processing plant.

The magnetic separator consists of a steel cabinet with a top flange (inlet) and a lower flange (outlet). The top feed hopper, made of stainless steel, has a gate at its bottom whose opening can be adjusted by means of an external regulation screw. From the hopper, the material falls on a magnetic drum. The drum is solid stainless steel cylinder closed at its ends by two aluminum alloy covers. Inside the drum, there is a magnetic circuit formed by oriented V Ceramics magnets and polarized steel pieces. The magnetic field that is created covers 180° of the drum circumference. The drum spins in the same direction as the product is falling. The nonferrous product falls into a bottom hopper. Any ferrous material sticks to the drum and is carried beyond the seed discharge, until the ferrous material reaches the end of the magnetic field. At that point, it drops into a hopper.

The seeds are cleaned in a multiple deck screener, located after the discharge hopper. The cleaner is composed of screens with opening sizes designed to segregate the following three fractions:

• The coarse fraction, which is retained by the upper screen. Large impurities (pods) consist of leaves and sticks. They are sent to a trash bin and discarded;
• The clean fraction, which is the intermediate fraction. It passes through the first screen and stays on top of the bottom one. This fraction is also subject to aspiration using a flow of air. The aspiration is used to remove light particles;
• The small fraction, which passes through the bottom screen, is collected and added to the extraction meal.

The flow of dehulled seeds (kernel) (dehulled by the cracking roller mill) is taken from dehulling to the flakers, where the kernels are processed and transformed into small flakes. Then, they are transported to the vertical conditioners using conveyors, where they are heated and dried to the moisture content adequate for the mechanical extraction process. The machines in the Pre-press workshop have a production capacity of up to 650 t/h

3.2. Introduction of New Energy Efficient Equipment in the Press Section

The project plan envisages the purchase of a cooker–conditioner; screw presses; cake cooler; screening tank; and all supporting equipment such as grain transporters and elevators.

The cooker–conditioner, cake coolers, pumps, and the additional equipment will be delivered and installed onsite. The technological process of cooking and pressing:

• Cooking stage

Cooking of the flakes is performed in the first compartments of the cooker by heating the seed in contact with a steam-heated double bottom chamber. To enable the cooking, live steam is injected in a controlled fashion through the scrapers. The moisture content of the incoming seed is about 8% and is increased to 10.5% and then dried. In the cooker, care must be taken to avoid over-roasting. Seeds are maintained at about 100 °C in the cooker. According to data provided by the manufacturer, the steam consumption during cooking process is 4335 kg/h. The latent heat of the steam is conducted through the steel tray and into a shallow layer of the seed being cooked and dried. The condensed steam then exits the heated tray as condensate, has its condensed steam heat recovered, and is sent to the boiler via an atmospheric condensate tank. Only 85% of the condensate is returned to the boiler. Atmospheric air is drawn into this stage to remove moisture and is then sent to the suction manifold, where all the stage outlets are commonly collected and drawn out through a pulling fan.

• Drying stage

Drying of the flakes is performed in stages by the cooker before entering the press. The desired moisture for pressing is in the range of 3.5 to 4%. In addition to the indirect heating in these last stages, the hot air is also blown in the 4th and 6th cooker compartments. In the drying sections, the moisture is reduced from nearly 10.5% to 4%. Environmental air is blown (via a fan) through a steam heating coil. The air can be heated anywhere between ambient temperature and 140 °C to reach the desired level of drying. The heated air then passes into a deep air chamber with a perforated upper plate for evenly introducing the air into the flakes. From the air chamber, the air flows evenly up through the seeds at a minimum velocity that creates near-fluidisation of the seeds. Near-fluidisation optimizes transfer of moisture and heat into the air. After removing moisture, the air exits the vessel and goes to a suction manifold, where the exhaust fan pulls the air and exhausts it to the atmosphere. The prepared material is drawn from the cooker using the plant’s distribution system and metered into the press using a variable speed horizontal conveyor and then a fixed-speed vertical screw conveyor.

The pressing section of the press machine consists of a worm assembly, which turns inside a drained barrel or cage. The worm assembly uses a high-tensile shaft, which is supported between a coupling at the material feed end and a bearing at the cake discharge end. The press frame is of heavy welded construction in carbon steel. It supports the drainage cage and the worm shaft and is extended to provide a platform for the gearbox. A conveyor is fitted in the base to discharge oil. During the pressing process, the material is heated, first during the cooking process and then from transformation of mechanical energy in thermal energy during pressing. The temperature of the cake leaving the Press is well above the maximum allowable temperature of the solvent extractor. In order to solve this problem, a cooler is added to the line. The workshop’s boilers, fueled by sunflower husks, will be rehabilitated. Their efficiency will be increased to 78%. The technical performance and characteristics of the raw material, process steps, and finished product are presented in

Table 2. Technical performance characteristics of the raw material, process steps, and finished product.

RAW MATERIALS
Suitably matured, commercial quality sunflower seeds with
Oil content	41%	Average
	45%	Maximum
Hulls content	30%
Moisture	8%	minimum
Impurities content	2%	maximum—but free of stone sand silica
Temperature	2–3 °C	minimum, to be pre-heated Buyer’s supply to 20 °C before entering the flakers
Suitably matured, commercial quality rapeseed seeds with
Oil content	41%	Average
	45%	Maximum
Moisture	8%	minimum
Impurities content	2%	maximum—but free of stone sand silica
Temperature	2–3 °C	minimum, to be pre-heated Buyer’s supply to 60 °C before entering the flakers
PROCESS STEPS
Unhulled sunflower seeds, before cracking, are to be prepared for pressing as follows
Clean to leave	0.5%	impurities maximum
Pre = heat to	20 °C	when necessary
Break to give	2–3 mm	pieces
Cook to	100 °C
	4%	moisture
Dehulled sunflower seeds, before flaking, are to be prepared for pressing as follows
Clean to leave	0.5%	impurities maximum
Pre-heat to	30 °C	when necessary
Dehull to leave	12/13%	hulls, maximum (By Buyer), minimum 10% hulls left after dehulling
Flake to give	0.4 mm	flake thickness
Cook to	100 °C
	4%	moisture
Rapeseed seeds, before flaking, are to be prepared for pressing as follows
Clean to leave	0.5%	impurities maximum
Pre Heat to	60 °C	when necessary
Break to give	0.3 mm	pieces
Cook to	100 °C
	4%	moisture
QUALITY OF FINISHED PRODUCTS
Sunflower seeds or rapeseed press cake with:
Oil content	18–22%	maximum
Temperature	50–60 °C
Crude, screened, and filtered/clarified sunflower or rapeseed oil

.

The processes in the “Press” workshop use saturated steam. The steam is supplied by the P-10 steam boilers, which fire sunflower husks and will be renovated as noted. The new production lines in the Press workshop allow approximately 85% of the condensate to be returned to the boiler station. This will reduce the costs of saturated steam production and increase the efficiency of the production line. The layout for the proposed equipment is provided in Figure 7.

3.3. Effect of Implementing Energy Efficiency Measures

Implementation of the aforementioned energy efficient measures in the “Pre-press” and “Press” sections will primarily reduce annual electricity consumption. Further savings are envisaged by the fuel switching from heavy fuel oil to sunflower husks. The processes concerning the new production lines will be more automated, which leads to the additional labor savings. As a result of the new energy efficient equipment in the Pre-press and Press workshops, the annual electricity consumption decrease is 4019 MWh; the annual heavy fuel oil consumption decrease is 350 tons; the annual sunflower husks consumption increase is 789 tons or 3002 MWh_equivalent or EUR 0 (Because the sunflower husks are waste material produced by the process of sunflower peeling), which leads to annual O&M savings (

Table 3. Energy efficiency improvement with introduction of new energy efficient equipment for workshops “Pre-press”, “Press”, and “Pre-extraction”.

	Electricity Consumption		HFO Consumption			Sunflower Husks Consumption			Energy Total	Carbon Emission
	MWh/y	tCO2/y 1	t/y	MWh/y	tCO2/y 1	t/y	MWh/y	tCO2/yr 1	MWh/y	tCO2/y 1
Baseline	7369	3581	350	3896	1130	1879	7152	286	18,417	4997
After	3350	1628	0	0	0	2668	10,154	406	13,503	2034
Savings	4019	1953	350	3896	1130	−789	−3002	−120	4914	2963

¹ Carbon emissions factors are as follows: electricity: 0.486 tCO₂/MWh; heavy fuel oil (HFO): 0.290 tCO₂/MWh; biomass fuel (sunflower husks): 0.040 tCO₂/MWh.

).

In addition to improvements in energy and resource efficiency, the implemented measures resulted in measurable environmental benefits. The reduction in solvent (hexane) use decreased volatile organic compound (VOC) circulation, improving workplace safety and reducing potential fugitive emissions. Furthermore, the optimization of process parameters and auxiliary energy use led to a reduction in greenhouse gas emissions estimated at 3–4 kg CO₂ per ton of processed seeds. These environmental effects demonstrate that even incremental changes in process agents and equipment efficiency can contribute to lowering the overall environmental footprint of sunflower oil production.

Table 4. Baseline and post-implementation energy and resource consumption indicators for sunflower seed oil production.

Indicator	Baseline Value	After Measures	Change (%)
Specific electricity consumption (kWh/t)	1290.0	946.0	−26.7
Thermal energy consumption (kWh/t)	2100.0	1750.0	−16.7
Hexane consumption (kg/t)	10.5	10.3	−2.0
CO2 emissions (kg/t)	25.0	21.5	−14.0

summarizes the baseline and post-implementation energy and resource consumption indicators expressed per ton of processed seeds. A reduction of 26.7% in specific electricity consumption was observed after implementing the proposed measures, resulting in annual energy savings of 4914 MWh/y. The overall reduction in energy consumption also led to a decrease of 3–4 kg/t of CO₂ emissions, improving the environmental performance of the production process and demonstrating the effectiveness of the modernization measures.

A summary of conventional and newly implemented energy-efficient technologies, along with their main advantages and disadvantages, is presented in

Table 5. Comparison of conventional and new energy-efficient technologies.

Technology Type	Specific Technology	Advantages	Disadvantages
Conventional (old)	Single-stage hexane recovery	Simple operation, low initial cost	Higher solvent losses, higher energy use
Conventional (old)	Standard pressing equipment	Well-proven, easy maintenance	Lower pressing efficiency, higher energy consumption
Energy-efficient (new)	Three-stage hexane regeneration columns	Reduced solvent losses (2–3%), lower VOC emissions, energy savings of 12–15 kWh/t	Higher initial investment; requires skilled operators
Energy-efficient (new)	Optimized pressing and extraction parameters (temperature, pressure, grinding degree)	Improved oil yield, reduced auxiliary energy consumption, lower CO2 emissions	Requires operator training and monitoring
Energy-efficient (new)	Alternative solvents (e.g., ethanol)	Lower toxicity, reduced environmental impact	Higher solvent cost, adaptation of process equipment

.

3.4. Operational Cost Impact

In addition to energy and resource savings, the implemented measures resulted in significant operational cost reductions. The 26.7% decrease in electricity consumption (4914 MWh/y) and the reduction of 0.3 kg/t of hexane use translated into annual cost savings of approximately EUR 210,000, based on average energy and solvent prices during the audit year. These economic benefits further emphasize the practical value of technological modernization and process optimization.

4. Discussion

4.1. Comparison with Other Studies

The production of sunflower oil is a process that requires significant energy resources, resulting in high costs and environmental consequences. Although the proposed optimization measures through new, high-performance equipment and a reduction in hexane consumption resulted in significant energy efficiency improvements of 34%, there are still a number of issues that require further attention. The issues of reducing the environmental footprint and better integration of new technologies with existing infrastructure are important aspects that need to be addressed in more depth. Similar approaches to energy optimization have been seen in other industries, such as vegetable oil processing, where innovations in equipment have led to significant reductions in energy costs. A study by the authors in [45] highlights the importance of adopting energy-efficient technologies in the chemical industry, leading to lower energy intensity and providing more robust economic performance. Similar conclusions are also presented in the studies of the authors in [46,47], which considered energy savings in different industrial processes, emphasizing the need for a holistic approach to optimization, including technological innovation and socio-economic factors.

The observed differences compared to other studies can be attributed to factors such as the size of the production plant, which influences process scale and energy distribution, the type of fuel used for steam generation, and regional climate conditions that affect raw material moisture and energy demand for drying processes. These factors should be considered when transferring the proposed solutions to other industrial contexts.

Influence of Raw Material Properties on Energy Consumption

The properties of raw materials were found to have a measurable influence on energy consumption. Variations in moisture content and shell fraction of sunflower seeds directly affected both thermal and mechanical energy demand. Plant records showed that seeds with a moisture content above 9% required an additional 8–10 kWh/t for drying, while a higher shell content increased pressing energy demand by 5–7%. Similar findings are reported in [48,49], where seed quality parameters such as size distribution and foreign matter content were correlated with energy use in pressing and extraction processes. These results confirm the importance of raw material quality control and preprocessing to minimize overall energy consumption.

4.2. Impact of Solvent Reduction

Reducing the cost for hexane is another important aspect of the proposed technological improvement. Although the reduction in hexane consumption by 0.3 kg/t is significant, it is also important to consider the use of alternative solvents. Almohasin et al. [50] reported on the potential of safer solvents such as ethanol and vegetable oils, which can lead to significant reductions in worker health risks and environmental impacts. Although the implementation of these alternatives presents technical and economic challenges, they could provide significant long-term benefits. Other studies, such as Yara-Varón et al. [51], examined the use of biological solvents in various industrial processes and have shown that, if properly implemented, they can be not only environmentally but also economically efficient.

The proposed technological change reduces the amount of hexane used in the oil extraction phase by approximately 2%. Lowering the quantity of solvent has two practical consequences. First, the total amount of volatile organic compounds circulating in the system decreases, which reduces potential emissions and improves workplace safety. Second, moving and recovering a smaller amount of hexane reduces the demand for pumping power and heat needed for solvent recovery, which leads to lower auxiliary energy use. This modification does not require changes to the main extraction equipment and can be applied to existing production lines, providing an immediate effect on both energy and resource efficiency.

Based on the observed reduction in solvent circulation, the auxiliary energy demand of pumps and heat exchangers is lowered by an estimated 1.5–2%. This corresponds to approximately 12–15 kWh per ton of processed seeds, depending on plant capacity. In terms of greenhouse gas emissions, assuming an average grid emission factor of 0.25 kg CO₂/kWh, the reduction in energy consumption corresponds to 3–4 kg CO₂ per ton of production. Although these values are relatively modest per unit of product, they represent significant savings for industrial-scale facilities and demonstrate how small changes in process agent usage can lead to measurable energy and environmental benefits. The effect of reduced hexane use on energy consumption and CO₂ emissions is shown in Figure 8.

The applied technology for hexane recovery by three-stage regeneration columns is also key to the optimization of production processes. Although this technology has been proven to reduce hexane emissions and costs, it is not new and is already well known in industrial practice. Ncube et al. [52] and Xiao et al. [53] showed that the efficiency of such technologies is highly dependent on the specific production conditions, and regeneration optimization approaches can lead to significant reductions in overall solvent consumption. However, they noted that to achieve maximum efficiency, it is necessary to invest resources in further optimization of these processes. The introduction of new equipment and technology that leads to increased energy efficiency involves significant capital investment and may be resisted by manufacturers who fear high up-front costs. This is well documented in the literature and was highlighted by Thollander et al. [54], who noted that small- and medium-sized enterprises often face difficulties in implementing new technologies due to a lack of sufficient financial resources. This, combined with the need to retrain the workforce, creates additional challenges in adapting to new production conditions. However, successfully overcoming these barriers can lead to long-term economic benefits and sustainable production, as shown by Cagno and Trianni [55], who analyzed the transition towards greener and more efficient production processes.

4.3. Technological and Socio-Economic Aspects of Implementation

Equally important is the socio-economic context of the deployment of these new technologies. The retraining of workers and the adaptation of the workforce to new conditions are issues that are often overlooked in technical analyses. Neves et al. [56] and Trianni et al. [57] showed that the successful implementation of new technologies depends not only on their technical efficiency, but also on the ability of organizations to manage the social and economic challenges that accompany this process. At the same time, Trianni and Cagno [58] and Hasan and Trianni [59] highlighted the importance of societal support and investment in worker education and training to ensure the successful application of new technologies and to reduce the risks of social inequalities. The results obtained clearly demonstrate the potential of technological modernization for achieving significant energy savings and reducing environmental impacts in sunflower oil production. The application of high-efficiency equipment and optimized process control measures has led to measurable improvements in specific energy consumption and solvent use, resulting in lower operational costs and a reduced environmental footprint.

In addition, the inclusion of detailed energy flow data and efficiency indicators strengthens the scientific value of the study by improving transparency and reproducibility. These enhancements address previously identified information gaps and support the practical applicability of the proposed measures in similar industrial facilities.

5. Conclusions

This study aimed to answer the research question: “How can technological modernization and process optimization improve energy and resource efficiency in sunflower oil production?”

Based on the conducted energy audit and analysis, the following conclusions can be drawn:

• Technological modernization and optimization of process parameters led to an improvement in overall energy efficiency of approximately 34% and a reduction in hexane consumption by 0.3 kg/t, resulting in additional energy savings of 12–15 kWh/t and CO₂ emission reductions of 3–4 kg/t of processed seeds.
• The reduction in solvent circulation not only improved workplace safety by lowering volatile organic compound emissions but also decreased auxiliary energy requirements for pumping and heat recovery.
• The implementation of three-stage regeneration columns for hexane recovery demonstrated the importance of targeted technological measures for improving both resource efficiency and environmental performance.
• Socio-economic factors, such as workforce retraining and investment capacity, influence the successful adoption of new technologies and should be considered when transferring solutions to other production facilities.

The findings are based on a single industrial facility, and results may vary depending on plant size, type of fuel, and regional climate conditions. Future research should focus on testing alternative solvents, evaluating the scalability of energy efficiency measures in different industrial contexts, and conducting long-term economic and environmental impact assessments.