I. ALABBAS, W. ALBLAIES, K. AL-SHEHRI and B. FAQEER, Saudi Aramco, Dhahran, Saudi Arabia; D. RANA, Fluor Corp., Houston, Texas (U.S.); M. O’SULLIVAN, Lummus Technology, Houston, Texas (U.S.); and D. MCKENZIE, Lummus Technology, West Orange, New Jersey (U.S.)
Saudi Aramco’s SASREF+ project includes the integration of a large-scale steam cracker and polymer units with the existing SASREF refinery located in Jubail, Saudi Arabia. This project aims to enhance SASREF's refining and petrochemical capabilities that utilize the well-developed infrastructure of Jubail and its strategic geographical location.1 SASREF+—in the pre-front-end engineering design (pre-FEED) stage at the time of this publication—has a set of clear objectives that includes boosting production capacity to meet the growing demand for petrochemical products and promoting international collaboration and investment, while aligning with Saudi Arabia’s Vision 2030. During this early design phase of the project, the focus is to reduce carbon dioxide (CO2) emissions and optimize energy efficiency while incorporating circularity by design.
The SASREF+ project and objectives. The energy industry is experiencing a paradigm shift guided by the principles of managing carbon footprint, efficient resource utilization, leveraging technologies for lower carbon production and mitigating the climate impact via energy transition. Saudi Aramco has the ambition to achieve net-zero Scope 1 and Scope 2 greenhouse gas (GHG) emissions across its wholly owned and operated assets by 2050.2
The Saudi Green Initiative (SGI) is a national effort aimed at combating climate change, improving quality of life and protecting the environment for future generations. SGI aims to reduce carbon emissions by 278 MMtpy by 2030, reaching net-zero by 2060.2 The SASREF+ project is aligned completely with the United Nations (UN) Sustainability Development Goals3 (SDG) as follows:
Affordable and clean energy, UN SDG 7: The project incorporates energy-efficient technologies, low-carbon fuels and renewable energy, along with advanced refining and petrochemical processes to reduce emissions.
Industry, innovation and infrastructure, UN SDG 9: The project promotes sustainable industrialization through the modernization of the SASREF refinery’s infrastructure via the integration of petrochemical technologies.
Responsible consumption and production, UN SDG 12: The project implements a carbon circular economy (reduce, reuse, recycle and remove), promotes responsible consumption, increases recycling rates and reduces industrial waste.
Climate action, UN SDG 13: The project supports carbon reduction through various initiatives such as carbon capture, blue/green hydrogen (H2), electrification, carbon offsets and energy efficiency, among others, for net-zero decarbonization.
Life below water, UN SDG 14: The project protects biodiversity through designated biodiversity protection areas, permaculture, etc., and targets a net-positive impact on ecosystems.
Life on land, UN SDG 15: Protects biodiversity through tree plantation and permaculture and aims for a net positive impact on ecosystems.
Partnerships for the goals, UN SDG 17: Strengthens international cooperation through joint ventures, aligning with global sustainability frameworks.
Achieving net-zero emissions by 2050 is a critical objective for the global energy sector, requiring a phased and strategic approach to decarbonization. The SASREF+ project exemplifies this commitment through a structured roadmap that integrates short-, medium- and long-term initiatives. These initiatives are designed to balance technical feasibility, economic viability and environmental impact. Early-stage pre-investments (e.g., H2-ready infrastructure, digital optimization, carbon capture provisions) enable future flexibility while minimizing retrofit complexity and cost.
As the availability of low-carbon fuels and advanced technologies improves, the project transitions toward deeper decarbonization through fuel switching, electrification and carbon capture. This article outlines the technical considerations, design strategies and infrastructure readiness measures that position SASREF+ as a scalable model for industrial decarbonization, aligned with evolving regulatory and market conditions.
Technical framework. The SASREF+ expansion project includes an ethane cracker and polymer derivatives that convert ethane into various grades of polyethylene (PE). The project includes supporting utilities, offsites, pipelines and marine terminal facilities. The technical framework of the SASREF+ project is shown in FIG. 1.
Decarbonization case study. For the purposes of this case study, only the ethane cracker inside battery limits (ISBL) were considered. The decarbonization case study considers four cases for decarbonization:
Case 1: Base carbon capture
Case 2: No H2 export
Case 3: Blue H2
Case 4: Hybrid.
The assumed basis for utility costs is:
Gray H2: $1.65/kg
Blue H2: $2.54/kg
Fuel gas: $2.50/MMBtu
Electricity: $55/MWh.
Case 1: Base carbon capture. In this case, all H2 generated by the ethane cracker is exported as a product, while methane offgas, pressure swing absorption (PSA) offgas and imported natural gas are utilized as fuel sources. The PSA offgas stream is 6 wt% H2 and 91 wt% methane. A schematic representation of this case is shown in FIG. 2.
Case 2: No H2 export. This option considered the raw H2 offgas produced in the cracker to be used as fuel, along with the methane offgas and natural gas import. The H2 compressor and PSA capacity may be reduced significantly to only account for the H2 needed for the ISBL hydrogenation reactors. Alternately, this equipment may be eliminated altogether, and low-carbon H2 imports may be used for these units in addition to the polymer units [high-density PE (HDPE), linear low-density PE (LLDPE)]. A schematic representation of this case is shown in FIG. 3.
Case 3: Full H2 (blue) firing. This option considered that all purified H2 is used as fuel, with H2 imports. Methane offgas and PSA offgas are exported. Carbon capture is not required for the ethane cracker heaters in the full H2 case. A schematic representation of this case is shown in FIG. 4.
Case 4: Hybrid. This configuration considered fuel gas segregation. The purified H2 product will be used as fuel for three heaters, with a small amount of H2 for export. These three heaters will not require carbon capture. Methane offgas, PSA offgas and natural gas imports will be used as fuel for the remaining heaters and will include carbon capture. A schematic representation of this case is shown in FIG. 5.
RESULTS AND DISCUSSION
Case 1: Base carbon capture. Base carbon capture does not require any modifications to the current ethylene plant layout, particularly the fuel gas system and H2 processing infrastructure. Moreover, it preserves the full H2 export revenue potential while making the most efficient use of existing equipment. This configuration is suitable for regions with an established offtake for low-carbon H2.
Since the base carbon capture configuration exports all H2 generated by the cracker, it produces a flue gas with a higher CO2 concentration that more closely resembles that of a naphtha cracker. This results in a lower specific energy for the carbon capture unit. Therefore, this configuration will result in the lowest CO2 emissions reduction and the lowest amount of avoided CO2 (TABLES 1 and 2), leading to be the largest carbon capture facility in terms of capacity and capital investment.
Case 2: No H2 export. When H2 is utilized as fuel, high-purity PSA-grade H2 is not required because lower-purity H2 can achieve comparable carbon reduction objectives while requiring less capital investment for its production. The "no H2 export" configuration may decrease the required PSA capacity and H2 compressor capacity.
This configuration generates flue gas with a lower CO2 partial pressure, which increases the specific energy consumption compared to Case 1. However, it also generates less CO2 compared to Case 1, reducing costs associated with CO2 disposal. This case eliminates H2 as a revenue-generating product.
Case 3: Blue H2. H2 firing offers the primary benefit of eliminating the need for carbon capture within the ethylene plant, thereby avoiding substantial capital investment in decarbonization infrastructure, assuming blue H2 is purchased and brought over the fence line rather than produced onsite. Additionally, the cracker’s fuel gas comprised of methane and PSA offgas can be exported and potentially sold as feedstock for the H2 production unit. H2 pricing and market dynamics will play a critical role in determining the economic feasibility of this case.
H2 firing may present a viable alternative in a scenario where carbon capture implementation becomes impractical (such as a retrofit), where there is insufficient plot space for carbon capture near heaters. However, since this assessment is being conducted during the pre-construction phase, it is not an issue for the SASREF+ project.
Case 4: Hybrid. The hybrid configuration integrates key elements of both the H2 firing and base configurations through selective fuel gas allocation. Onsite H2 production is sufficient to supply three heaters with high-purity H2, while also allowing for limited H2 exports. The remaining heaters operate on a combination of methane-rich offgas, PSA offgas and imported natural gas, with carbon capture applied.
This setup reduces the carbon capture unit feed by > 40% compared to the base configuration, while maintaining a relatively high CO2 concentration in the flue gas beneficial for capture efficiency. As carbon capture is only implemented on select heaters, it can be optimized for locations with favorable spatial conditions, reducing complexity and cost.
Economically, this configuration offers the lowest capital expenditure (CAPEX) per ton of CO2 avoided among the evaluated carbon capture options (TABLES 1 and 2). This case also reduces risk from the key challenge in the underdeveloped H2 market, which limits the potential for revenue generation from H2 sales and adds uncertainty to the overall economic outlook.
Decarbonization roadmap strategy.There are numerous ways to reach decarbonization goals. Decarbonization initiatives can be grouped into short-, medium- and long-term. Each category addresses different stages of the transition to net-zero. These decarbonization initiatives can be combined in various ways, as shown in TABLE 3. The balanced mix depends on project goals, economic factors and changing market conditions. The ultimate objective is to achieve net-zero emissions by 2050.
Phase 1: Short-term initiatives (2025–2030). This phase includes pre-investing for future CO2 reductions, such as:
Plot space and tie-ins for a future CO2 capture unit
H2 firing-ready design with up to 80% H2 firing capacity
Digitalization to track and minimize energy losses and improve process optimization
Reduced firing in heaters via combustion air preheating.
Pre-investing at the early design phase of the SASREF+ project has a low- to medium-investment level. At this stage, conceptual feasibility to evaluate process electrification could set the stage for reaching net-zero by 2050.
Phase 2: Mid-term initiatives (2030–2040). This phase includes fuel switching (blue) H2 and infrastructure changes. Currently, SASREF+ is ready to switch to up to 80 mol% H2 blending without any modifications in burners or other components. Therefore, as soon as blue H2 becomes commercially available, the project will initiate H2 blending to achieve up to a 50% lower carbon footprint.
Phase 3: Long-term initiatives (2040–2050). This phase includes full carbon capture, blue H2 and carbon offsets via nature-based solutions and carbon credits. At this stage, one obstacle is the price availability of blue H2. It is believed that by 2050, the price and availability of blue H2 will make the units commercially feasible. The CO2 reduction potential of these long-term actions is 95%–100%, leading to net-zero.
SASREF+ innovations for net-zero decarbonization. The following are some of the innovations included in the SASREF+ project to achieve decarbonization goals.
Carbon capture-ready infrastructure. Post-combustion carbon capture pre-investments involve key structural and spatial provisions:
Plot space allocation: Adequate space is reserved near the heaters for large equipment such as the direct contact cooler and absorber towers, which process low-pressure flue gas.
Equipment layout optimization: The regenerator, which handles pumped liquid streams, can be located further from the heaters, although co-locating all major capture and compression equipment minimizes cost and complexity.
Induced-draft fan considerations: Provisions are made for future induced fan upgrades or replacements to meet higher pressure head requirements, potentially avoiding the need for additional blowers and plot space.
Utility system sizing: Steam generation systems, such as auxiliary boilers, are evaluated for future capacity needs to support carbon capture, reducing the complexity and cost of future retrofits.
Pre-investments for carbon capture focus on low-cost planning activities with minimal capital requirements. These measures have little impact on total plant investment. However, obviating them can significantly hinder future carbon capture deployment. Without early planning, retrofitting may require extended shutdowns and complex modifications. Although exact cost impacts are difficult to quantify, estimates indicate that implementation without pre-investment could be up to 50% more expensive. This increase is primarily due to construction constraints and the need for rework.
H2 (blue)-ready infrastructure. Select elements of the cracking heater have been pre-designed to support full H2 firing. However, due to uncertainties in the implementation timeline, it is recommended that modifications to other components be deferred to a later phase. The following design features have been integrated into the heater configuration:
H2-ready fuel gas piping: All fuel gas piping will be pre-designed to accommodate 100% H2 firing, enabling a seamless transition to H2 fuel in the future without requiring major piping modifications.
Instrumentation strategy: Flow control instruments will initially be configured for current plant fuel gas to ensure optimal turndown. For future 100% H2 operation, these instruments will need to be replaced or supplemented with a parallel set to support dual-fuel flexibility.
Burner compatibility and modifications: Hearth burners are currently designed to handle high-H2 fuel gases (up to ~80 vol%) and are expected to accommodate 100% H2 with minor modifications, such as burner tip replacement. In contrast, side-wall burners will likely require a significant revamp or replacement for full H2 operation.
Emissions and regulatory compliance: Nitrogen oxide (NOx) emissions are anticipated to remain at or above current levels with 100% H2 firing, potentially exceeding future regulatory limits. Mitigation options include installing a DeNOx unit in the convection section or upgrading burners to advanced low-NOx designs under development.
Performance considerations: Transitioning to 100% H2 may impact heat flux distribution and increase combustion noise slightly [though expected to remain below 85 dB(A) at 1 m]. These factors should be addressed during future burner upgrades to ensure optimal performance and compliance.
Future-ready design for nitrogen oxide (NOx) reduction systems: The convection section of the cracking heater has been designed to include reserved space for a future DeNOx system and ammonia injection grid, strategically located where flue gas temperatures are optimal for NOx reduction performance.
Takeaways. The SASREF+ project demonstrates a comprehensive, phased approach to achieving net-zero emissions by 2050 through strategic pre-investments and infrastructure readiness. By categorizing decarbonization efforts into short-, medium- and long-term initiatives, the project ensures flexibility and adaptability to evolving technologies and market conditions. Early-stage actions—such as a H2-ready heater design, digitalization and carbon capture readiness—lay a strong foundation for future transitions. Mid-term strategies focus on fuel switching to blue H2 and leveraging existing design capabilities to reduce emissions with minimal modifications. Long-term initiatives, including full carbon capture and nature-based offsets, are expected to deliver a net-zero ethane cracker design. The integration of future-ready systems, such as NOx control provisions and dual-fuel instrumentation, minimizes retrofit complexity and cost. Collectively, these efforts position SASREF+ as a forward-looking model for industrial decarbonization, balancing technical feasibility, economic viability and environmental responsibility. HP
NOTE
The content of this publication has not been approved by the UN and does not reflect the views of the UN nor its officials or Member States.
LITERATURE CITED
Aramco Life, “Aramco, Rongsheng Petrochemical Co. sign agreement to expand SASREF,” November 19, 2024, online: https://www.aramcolife.com/en/publications/the-arabian-sun/articles/2024/week-47/aramco-sasref-expansion-framework-agreement
Kingdom of Saudi Arabia Vision 2030, “Saudi Green Initiative,” online: https://www.vision2030.gov.sa/en/explore/projects/saudi-green-initiative
UN, “United Nations Sustainability Development Goals,” Department of Economic and Social Affairs, Sustainable Development, online: https://sdgs.un.org/goals
Ibrahim Alabbas is a chemical engineer with more 8 yrs of experience at Saudi Aramco, specializing in petroleum refining with a focus on hydroprocessing units. He earned a BS degree in chemical engineering from King Fahd University of Petroleum & Minerals (KFUPM). Throughout his career, he has played a key role in major industrial initiatives and is currently contributing to one of the largest liquids-to-chemicals projects in the Middle East (the SASREF+ program). Alabbas has also led multiple corporate-wide decarbonization initiatives, where he jointly developed an innovative in-house solution known as the Emissions Management System (EMS), a tool designed to monitor and abate carbon emissions across operations at more than 100 facilities.
Wael Al-Blaies has been with Saudi Aramco for 19 yrs, working on multiple engineering and project management initiatives. He earned a chemical engineering degree from Heriot Watt University in 2006, as well as an MS degree in risk management and process safety. He is specialized in areas related to flare and relief systems and graduated from Saudi Aramco’s Specialist Development Program in 2018. Al-Blaies has assumed several leadership positions in the company since 2016, including Supervisor of the flare, gas processing and flow assurance group; Division Manager of downstream process engineering and H2 systems engineering divisions; and the Fourth Industrial Revolution Center. He is currently the Manager of the LTC Program Technical Support Division.
Khaled Alshehri is a seasoned technical expert with more than a decade of experience in the oil and gas industry. He currently works at Saudi Aramco. Alshehri earned an MS degree in chemical engineering from King Abdullah University of Science & Technology (KAUST), and an MBA from the Swiss Business School. With a strong background in central engineering, he has provided critical support to refinery operations and projects, leveraging his technical expertise to drive business growth and optimization. Notably, he has played a key role in the pre-commissioning, commissioning and startup of major refineries, including the YASREF and Jazan refineries. Currently, he is leading as a Supervisor Project Engineer at the Liquid-to-Chemical Program Technical Support, where he is applying his technical and business acumen to deliver project excellence with a unique blend of technical expertise and business savvy.
Bader Al Faqeer is a specialist in refinery and petrochemical planning. He has 9 yrs of experience. Al Faqeer has led and supported the development of major capital projects from initiation through pre-FEED, supporting the full front-end planning cycle. His experience spans a range of corporate business initiatives, and the shaping of downstream master plans to support long-term strategic goals.
Diwakar Rana is a Principal Process Engineer at Fluor Corp. He has more than 20 yrs of experience within the energy industry. As Fluor's Process Lead for Sustainability, he assists clients in developing a decarbonization roadmap strategy for net-zero and advancing the circular economy. Before joining Fluor, Dr. Rana served as a Consulting Manager at Accenture and a Technology Development Manager at DuPont. He holds three U.S. patents in process and reactor designs and catalysis, which help oil refiners reduce both CAPEX and OPEX while minimizing their environmental footprint. He has authored several books and industrial papers within the energy industry, covering topics such as sustainable fuels and energy security. He earned a BE degree (Honors) in chemical engineering from Deenbandhu Chottu Ram University of Science and Technology in India, an MS degree in chemical engineering from the Illinois Institute of Technology (U.S.) and a PhD in chemical engineering from Washington State University (U.S.). Dr. Rana has been a Licensed Professional Engineer for the State of Texas since 2008. He also holds Certified Energy Manager credentials from the Association of Energy Engineers.
Melanie O’Sullivan is the Technology Manager for Carbon Capture and Energy Storage within Lummus Technology’s Green Circle business group. She has been with Lummus for more than 12 yrs and has worked extensively in the ethylene industry, contributing to and leading major projects. O’Sullivan works extensively in developing decarbonization solutions across the Lummus portfolio. She earned a BE degree in chemical engineering, with a minor in literature, as well as an MS degree in materials engineering from Stevens Institute of Technology.
Daniel McKenzie is a Technology Manager at Lummus Technology, specializing in ethylene and other olefins production technologies. With > 17 yrs of experience in process engineering design, he has led major projects worldwide, contributing to advancements in sustainable petrochemical production. McKenzie plays a key role in Lummus’ decarbonization initiatives, focusing on reducing CO2 emissions in steam crackers. He has authored and presented numerous technical papers on sustainable solutions for steam crackers and is a contributing author to the Handbook of Petrochemical Production Processes. He earned a BS degree in chemical engineering from the University of South Carolina, and has been with Lummus since 2011.