Update date: Jul 08, 2026 | 299 Pages | Report ID: SFC-005024
Renewable Urea Market
DMA IntelligenceRenewable Urea Market Growth Drivers & Forecast 2033
Segments: Source (Biomass-based, Electrochemical, Enzymatic, Others), Application (Agriculture, Industrial, Chemical, Automotive, Others), Form (Granular, Prilled, Liquid), End-User (Fertilizer Manufacturers, Chemical Industry, Automotive Industry, Others), By Region, And Segment Forecasts
$10.5B
Market Size, 2025
$11.0B
Market Estimate, 2026
$15.8B
Market Forecast, 2033
5.2%
CAGR, 2026–2033
Renewable Urea Market Size, Share & Key Insights
The Renewable Urea Market size was valued at USD 10.50 Billion in 2025, and the market is projected to grow from USD 11.05 Billion in 2026 to USD 15.75 Billion by 2033, growing at a CAGR of 5.2% during the forecast period 2026–2033. The market saw distributed global demand in 2025.
Study Overview
 Study Period | 2021 - 2033 |
 Base Year | 2025 |
 Estimated Year | 2026 |
 Forecast Period | 2026-2033 |
 Historical Range | 2021-2025 |
| Units | USD Billion |
 Coverage | Global | North America, Europe, Asia-Pacific, Latin America, Middle East & Africa |
 Deliverables | PDF + Excel Data Pack |
Major Market Players
Key Insights
- The Renewable Urea market is poised for significant expansion, projected to grow from USD 10.50 Billion in 2025 to USD 15.79 Billion by 2033, demonstrating a robust CAGR of 5.20% over the forecast period, driven by increasing environmental mandates and sustainable agriculture practices.
- North America currently holds the largest market share in 2025, accounting for USD 3.50 Billion, while the Asia Pacific region is anticipated to be the fastest-growing market with a CAGR of 6.50%, attributed to rapid industrialization and agricultural demand.
- The market is moderately consolidated, with key players focusing on strategic partnerships and technological innovation to enhance production efficiency and broaden their renewable feedstock portfolio, indicating a trend towards sustainable and circular economy models in fertilizer production.
Market Definition and Strategic Context
The Renewable Urea Market refers to the global industry engaged in the production, distribution, and consumption of urea derived from sustainable and renewable feedstocks, primarily biomass, rather than conventional fossil fuels like natural gas or coal. This market is a critical component of the broader push towards decarbonization and sustainable agriculture, offering a greener alternative to traditional urea fertilizers which are energy-intensive to produce and contribute significantly to greenhouse gas emissions. Renewable urea leverages processes such as gasification of biomass, followed by the synthesis of ammonia and subsequently urea, utilizing renewable energy sources to minimize its carbon footprint. The market's relevance is growing due to increasing environmental regulations, corporate sustainability goals, and consumer demand for eco-friendly agricultural products. It plays a pivotal role in reducing the environmental impact of nitrogen fertilizer production, fostering circular economy principles, and enhancing food security through sustainable means. The Renewable Urea market size was valued at USD 10.50 Billion in 2025 and is projected for substantial growth outlook, driven by technological advancements in biomass conversion, supportive government policies promoting green fertilizers, and the rising adoption of sustainable farming practices globally. This market forecast anticipates continued industry expansion as more agricultural stakeholders seek to minimize their carbon footprint and adhere to stringent environmental standards. The long-term growth is underpinned by the essential role of nitrogen in crop nutrition and the imperative to produce it in an environmentally responsible manner. The market's trajectory is also influenced by volatile fossil fuel prices, which make renewable alternatives increasingly competitive.
| Report Attribute | Details |
|---|---|
| Market size value in 2025 | USD 10.50 Billion |
| Revenue forecast in 2033 | USD 15.75 Billion |
| Growth rate | CAGR of 5.2% from 2025 to 2033 |
| Actual data | 2021 - 2024 |
| Forecast period | 2025 - 2033 |
| Quantitative units | Revenue in USD Billion and CAGR from 2025 to 2033 |
| Report coverage | Revenue forecast, company share, competitive landscape, growth factors, and trends |
| Segments covered | Source, Application, Form, End-User |
| Regional scope | North America; Europe; APAC; Latin America; MEA |
| Country scope | All; All; All; All; All |
| Key companies profiled | Yara International; Nutrien Ltd.; CF Industries Holdings, Inc.; OCI N.V.; EuroChem Group AG; Koch Fertilizer, LLC; SABIC (Saudi Basic Industries Corporation); Acron Group; Indian Farmers Fertiliser Cooperative Limited (IFFCO); Coromandel International Limited; TogliattiAzot; Qatar Fertiliser Company (QAFCO); Borealis AG; Haifa Group; China National Chemical Corporation (ChemChina); Shandong Hualu-Hengsheng Chemical Co., Ltd.; Hubei Yihua Chemical Industry Co., Ltd.; Agrium Inc.; Sinofert Holdings Limited; Grupa Azoty S.A. |
| Customization scope | Free report customization (equivalent to 8 analysts working days) with purchase. Addition or alteration to country, regional & segment scope. |
| Pricing and purchase options | Avail customized purchase options to meet your exact research needs. Explore purchase options |
Growth Catalysts & Market Constraints
The Renewable Urea market is shaped by a confluence of factors that both propel its expansion and present significant hurdles. The imperative for sustainable agriculture and stringent environmental regulations are primary drivers, pushing demand for eco-friendly fertilizers. Concurrently, the market faces challenges related to the high capital expenditure required for establishing biomass-to-urea plants and the variability of feedstock availability. Understanding these dynamics is crucial for stakeholders to navigate the Renewable Urea market size and growth forecast effectively, ensuring strategic investments and operational resilience. The industry's trajectory is also influenced by global energy price fluctuations, which can impact the cost competitiveness of renewable alternatives against conventional urea production methods. Adapting to these evolving conditions will be key to unlocking the full potential of the Renewable Urea market.
Growth Drivers
- Growing global emphasis on sustainable agriculture practices and environmental protection acts as a significant driver for the Renewable Urea market. Governments and international bodies are implementing stricter regulations on greenhouse gas emissions and chemical fertilizer runoff, compelling agricultural industries to adopt greener alternatives like renewable urea, thereby boosting its demand and market penetration significantly.
- Advancements in biomass conversion technologies, coupled with increasing investments in renewable energy infrastructure, are enhancing the feasibility and cost-effectiveness of renewable urea production. These technological innovations improve efficiency, reduce operational costs, and expand the range of viable feedstocks, making renewable urea a more attractive and scalable option for fertilizer manufacturers and end-users.
Restraints
- The high initial capital investment required for establishing dedicated biomass-to-urea production facilities poses a substantial restraint on market growth. The complex infrastructure and specialized equipment needed for biomass gasification, ammonia synthesis, and urea production demand significant financial outlay, making it challenging for new entrants and small-scale players to compete effectively.
- Variability and seasonality of biomass feedstock availability, alongside logistical challenges in sourcing and transporting large quantities of renewable raw materials, can impede consistent and cost-effective production of renewable urea. This inconsistency can lead to supply chain disruptions and higher operating costs, thereby affecting the overall market competitiveness of renewable urea.
Opportunities
- Strategic collaborations and partnerships between technology providers, fertilizer manufacturers, and agricultural cooperatives present a significant opportunity for market expansion. Such alliances can facilitate knowledge transfer, shared investment in R&D, and streamlined market access, accelerating the commercialization and adoption of renewable urea solutions across diverse agricultural landscapes.
- The development of integrated biorefineries that produce renewable urea alongside other valuable bio-products, such as biofuels and biochemicals, offers an opportunity to enhance economic viability and resource utilization. This approach can diversify revenue streams, optimize feedstock use, and improve the overall sustainability profile of renewable urea production, attracting further investment.
Challenges
- Ensuring the consistent quality and performance of renewable urea, particularly when derived from diverse and variable biomass feedstocks, presents an operational challenge. Maintaining product specifications that meet agricultural standards and farmer expectations requires rigorous process control and quality assurance, which can add complexity and cost to production.
- The lack of standardized certification and regulatory frameworks for renewable urea can hinder its widespread market acceptance and create confusion among consumers and producers. Developing clear, internationally recognized standards for renewable content, carbon footprint reduction, and sustainability claims is crucial to build trust and facilitate market growth.
Market Level Breakdown
The Renewable Urea market is segmented by Source, Application, Form, and End-User, each contributing distinctively to the overall market dynamics. The segmentation by Source highlights the different feedstocks used, such as natural gas, coal, naphtha, and biomass. Biomass-based renewable urea is gaining traction due to its lower carbon footprint, aligning with global sustainability goals. This segment is crucial for understanding the supply chain and environmental impact of urea production, influencing strategic investments in green technologies and resource management. The shift towards biomass as a primary source is a key trend in the Renewable Urea market segmentation, reflecting the industry's commitment to decarbonization.
The Application segment categorizes renewable urea's usage across agriculture, industrial, and animal feed sectors. Agriculture represents the largest application, primarily for fertilizers, driven by global food demand and the need for sustainable farming practices. Industrial applications include the production of resins, adhesives, and other chemicals, while animal feed utilizes urea as a protein supplement. Understanding these diverse applications is vital for market players to tailor their product offerings and marketing strategies, ensuring that renewable urea meets specific industry requirements and contributes to the overall market size.
Segmentation by Form distinguishes between prilled, granular, and liquid urea. Prilled and granular forms are widely used in agriculture due to their ease of handling, storage, and controlled release properties. Liquid urea formulations are gaining popularity for precision agriculture and foliar application. The choice of form often depends on end-user preferences, application methods, and logistical considerations, directly impacting distribution channels and product development efforts within the Renewable Urea market. Innovations in form factor can unlock new market opportunities and enhance product efficacy.
The End-User segment differentiates between farmers, manufacturers, and research institutions. Farmers are the primary end-users, utilizing renewable urea for crop fertilization. Manufacturers incorporate urea into various industrial products, while research institutions explore new applications and production methods. This segmentation provides insights into the demand side of the Renewable Urea market, helping producers understand their target audience and develop specialized products and services to meet their specific needs, thereby driving market growth and adoption.
Renewable Urea Segmentation Breakdown
- Source
- Biomass-based
- Electrochemical
- Enzymatic
- Others
- Application
- Agriculture
- Industrial
- Chemical
- Automotive
- Others
- Form
- Granular
- Prilled
- Liquid
- End-User
- Fertilizer Manufacturers
- Chemical Industry
- Automotive Industry
- Others
Geographic Performance & Regional Trends
Geographically, the Renewable Urea market demonstrates varied performance and growth trajectories across key regions. North America emerged as the largest market in 2025, primarily due to advanced agricultural practices, strong regulatory support for sustainable fertilizers, and significant investments in green technologies. Conversely, Asia Pacific is projected to be the fastest-growing region, driven by its vast agricultural land, increasing population, and government initiatives promoting eco-friendly farming to combat environmental degradation. The region's rapid industrialization and growing awareness of sustainable practices are fueling the adoption of renewable urea, indicating robust Renewable Urea market growth in the coming years. These regional dynamics are critical for understanding global market shifts and strategic investment opportunities.
Regional Growth Drivers
- North America: The region's stringent environmental regulations and robust agricultural sector drive demand for renewable urea. Government incentives for sustainable farming, coupled with significant R&D investments in biomass conversion technologies, particularly in the United States and Canada, accelerate adoption and market expansion. This focus on decarbonization and soil health underpins regional growth.
- Europe: Strong policy support for the circular economy and ambitious decarbonization targets across the European Union are key drivers. Countries like Germany, France, and the Netherlands are leading in sustainable agriculture and investing heavily in green fertilizer production, enhancing renewable urea's market penetration and fostering innovation in biorefineries.
- Asia Pacific: Rapid population growth and increasing food demand necessitate efficient and sustainable agricultural practices. Governments in countries such as China, India, and Japan are actively promoting green fertilizers and providing subsidies, which, combined with abundant biomass resources, position the region for the fastest Renewable Urea market growth.
- Latin America: The expansion of agricultural land and increasing awareness of environmental sustainability among farmers are boosting demand. Countries like Brazil and Argentina, major agricultural exporters, are exploring renewable urea to enhance crop yields sustainably and meet international environmental standards, driving regional market modernization.
- Middle East & Africa: Diversification strategies away from fossil fuels and growing efforts to enhance food security are influencing market adoption. Investments in sustainable agriculture technologies, particularly in countries like Saudi Arabia and South Africa, are creating new opportunities for renewable urea, supported by government initiatives to green their economies.
The regional forecast indicates a dynamic landscape where mature markets in North America and Europe will continue to innovate and refine their renewable urea production and application methods. Emerging economies in Asia Pacific and Latin America are expected to experience accelerated growth, fueled by increasing agricultural intensity and environmental imperatives. This divergence creates strategic implications for suppliers, who must adapt their market entry and expansion strategies to cater to varying regulatory environments, technological readiness, and agricultural practices across these diverse regions. Investment in localized production and distribution networks will be crucial for capturing growth opportunities.
Competitive Insights & Leading Companies
The Renewable Urea competitive landscape is characterized by a moderately consolidated structure, featuring a mix of large multinational chemical and fertilizer companies alongside specialized bio-based solution providers. Key players such as Yara International, Nutrien Ltd., and CF Industries Holdings, Inc. leverage their extensive global distribution networks, established customer bases, and significant R&D capabilities to maintain a competitive edge. These industry giants often integrate renewable urea into their broader portfolio of sustainable agricultural solutions. The market also includes emerging players focused on innovative biomass conversion technologies and niche applications. Competitive intensity is driven by factors such as pricing strategies, the efficiency of biomass sourcing and processing, product innovation to enhance nutrient use efficiency, and the ability to secure regulatory approvals and certifications for renewable claims. Strategic partnerships and collaborations with technology developers and agricultural cooperatives are crucial for market penetration and scaling up production. The global versus regional player mix sees large companies operating on a global scale, while smaller, more agile firms often focus on regional markets with abundant biomass resources or specific regulatory incentives, contributing to the evolving Renewable Urea competitive landscape.
Companies in the Renewable Urea market are employing diverse strategies to gain a competitive advantage. Many are engaging in strategic mergers and acquisitions to consolidate their position and expand their technological capabilities or geographical reach. Product launches of advanced renewable urea formulations, often with enhanced efficiency or lower environmental impact, are common. Expansion into new markets, particularly in regions with high agricultural demand and supportive policies, is also a key strategy. Significant investments in R&D are directed towards improving biomass conversion efficiency, exploring new feedstocks, and developing innovative applications for renewable urea. Differentiation is achieved through various means, including proprietary technology for sustainable production, robust service models that offer agronomic support, strong channel strength through established distribution networks, and the ability to provide customized solutions to large agricultural enterprises. However, the market faces challenges such as margin pressure due to the fluctuating cost of biomass feedstocks and the capital-intensive nature of production. Compliance costs associated with environmental regulations and certifications also pose a hurdle. Despite these, continuous innovation and strategic localization efforts remain central to navigating the complexities of the Renewable Urea market and securing long-term growth.
Renewable Urea Key Companies
- Yara International
- Nutrien Ltd.
- CF Industries Holdings, Inc.
- OCI N.V.
- EuroChem Group AG
- Koch Fertilizer, LLC
- SABIC (Saudi Basic Industries Corporation)
- Acron Group
- Indian Farmers Fertiliser Cooperative Limited (IFFCO)
- Coromandel International Limited
- TogliattiAzot
- Qatar Fertiliser Company (QAFCO)
- Borealis AG
- Haifa Group
- China National Chemical Corporation (ChemChina)
- Shandong Hualu-Hengsheng Chemical Co., Ltd.
- Hubei Yihua Chemical Industry Co., Ltd.
- Agrium Inc.
- Sinofert Holdings Limited
- Grupa Azoty S.A.
Renewable Urea Market Ecosystem
Ecosystem Participants
- Biomass Feedstock Suppliers — These entities are responsible for providing sustainable and renewable raw materials, such as agricultural residues, forestry waste, and dedicated energy crops, which are critical for the production of renewable urea. Their role involves cultivating, harvesting, and pre-processing biomass to meet the quality and quantity requirements of biorefineries, ensuring a consistent and cost-effective supply chain.
- Their operational responsibilities include managing land resources, implementing sustainable harvesting practices, and optimizing logistics for biomass transportation to minimize environmental impact and maintain supply stability. Collaboration with local communities and adherence to certification standards are crucial for long-term viability.
- Technology Providers & Licensors — These companies specialize in developing and licensing advanced biomass conversion technologies, such as gasification, pyrolysis, and subsequent ammonia and urea synthesis processes. They offer expertise in process design, engineering, and integration, enabling the efficient and sustainable production of renewable urea from various feedstocks.
- Their role involves continuous R&D to improve process efficiency, reduce energy consumption, and enhance product purity. They often partner with project developers and manufacturers to implement bespoke solutions, providing technical support and training throughout the plant lifecycle.
- Renewable Urea Manufacturers — These are the core producers who operate biorefineries to convert biomass into renewable urea. They manage the entire production process, from feedstock intake and conversion to urea granulation and packaging. Their focus is on achieving economies of scale, optimizing operational costs, and ensuring product quality that meets agricultural and industrial standards.
- Manufacturers are also responsible for quality control, regulatory compliance, and often engage in R&D for product differentiation, such as developing enhanced efficiency fertilizers. They play a pivotal role in bridging the gap between biomass resources and end-user markets.
- Distributors & Retailers — This segment encompasses entities involved in the storage, transportation, and sale of renewable urea to end-users. They ensure efficient logistics, market access, and customer service. Their networks include agricultural cooperatives, wholesale distributors, and retail outlets that directly serve farmers and industrial clients.
- Their responsibilities include inventory management, regional market analysis, and providing technical support to customers regarding product application. Effective distribution is critical for ensuring timely delivery and widespread availability of renewable urea.
- Farmers & Agricultural Enterprises — As the primary end-users, these stakeholders apply renewable urea fertilizers to enhance crop yield and quality. Their adoption decisions are influenced by factors such as product efficacy, cost-effectiveness, environmental benefits, and adherence to sustainable farming certifications. They represent the ultimate demand for renewable urea.
- Their role extends to providing feedback on product performance and contributing to the development of application best practices. Their increasing demand for sustainable inputs drives innovation and expansion throughout the entire renewable urea value chain.
- Government & Regulatory Bodies — These organizations establish policies, regulations, and incentives that shape the renewable urea market. They set environmental standards, provide subsidies for green fertilizers, and develop certification schemes for sustainable products, playing a crucial role in fostering market growth and ensuring environmental compliance.
- Their activities include monitoring market practices, promoting R&D in sustainable technologies, and facilitating international trade agreements that support the adoption of renewable urea. Their influence is critical in accelerating the transition to a greener agricultural sector.
Report Coverage & Key Deliverables
The report delivers a comprehensive analysis of the Renewable Urea, combining quantitative data with qualitative insights. It offers an in-depth exploration of market dynamics, growth drivers, restraints, opportunities, and challenges that are currently shaping the industry. This analysis is designed to provide stakeholders with a clear understanding of the market's trajectory, enabling informed strategic decision-making. The report covers historical market performance from 2021 to 2025 and provides a robust forecast extending to 2033, offering a forward-looking perspective on industry trends and potential shifts. By detailing market segmentation across various categories and providing regional and country-level insights, the study assists businesses in identifying high-growth areas and tailoring their market entry strategies. Furthermore, the competitive landscape section offers a comprehensive overview of key players, their strategies, and market positioning, providing invaluable intelligence for competitive benchmarking and partnership opportunities. This holistic approach ensures that the report serves as an essential resource for investors, manufacturers, suppliers, and other industry participants seeking to capitalize on the evolving Renewable Urea market.
Report Coverage
- Market Size Estimates (historical and forecast)
- This section provides precise market size valuations in USD Billion for the historical period (2021-2025) and offers forward-looking projections up to 2033, derived through a rigorous methodology combining primary and secondary research with advanced statistical modeling to ensure accuracy and reliability.
- Detailed Segmentation And Revenue Analysis
- The report meticulously segments the Renewable Urea market by source, application, form, and end-user, presenting a granular revenue analysis for each segment. This breakdown enables stakeholders to identify key growth pockets and understand the revenue contribution of various market components, facilitating targeted investment and product development strategies.
- Regional And Country-Level Insights
- Offering an exhaustive geographical analysis, this section covers market performance and trends across North America, Europe, Asia Pacific, Latin America, and Middle East & Africa. It highlights regional growth drivers, regulatory landscapes, and market maturity, providing a comparative perspective to inform localized business strategies and expansion plans.
- Competitive Benchmarking Of Key Players
- A thorough competitive landscape analysis profiles leading companies in the Renewable Urea market, detailing their strategic initiatives, product portfolios, market shares, and recent developments. This benchmarking helps businesses understand competitor positioning and identify potential partners or acquisition targets.
- Customization Options Based on Specific Requirements
- Clients can avail customization options to tailor the report content to their precise needs, including deeper analysis of specific segments, regions, or competitive aspects. This flexibility ensures that the delivered insights are highly relevant and actionable for unique strategic objectives, maximizing the value derived from the research.
Recent Industry Insights
The Renewable Urea industry trends over the last 12-18 months have been marked by a surge in strategic partnerships and technological advancements aimed at scaling up sustainable production. Companies are increasingly investing in pilot projects and commercial-scale facilities for biomass-to-urea conversion, often leveraging government grants and incentives for green technologies. There's a noticeable shift towards exploring diverse renewable feedstocks beyond traditional agricultural waste, including municipal solid waste and industrial by-products, to enhance resource efficiency and reduce reliance on single sources. Regulatory landscapes are evolving, with more countries introducing carbon pricing mechanisms and subsidies for low-carbon fertilizers, creating a more favorable environment for renewable urea. Additionally, consumer and enterprise demand for sustainably produced food and agricultural inputs is driving manufacturers to adopt greener supply chains, further accelerating market growth. This period has also seen increased R&D into improving the energy efficiency of ammonia synthesis, a critical step in urea production, to further reduce the overall carbon footprint of renewable urea.
Key Market Developments
- April 2025: Yara International announced a significant investment in a new pilot plant in Norway to explore advanced green ammonia and urea production technologies, aiming to decarbonize fertilizer manufacturing.
- February 2025: Nutrien Ltd. partnered with a leading bioenergy firm in the United States to secure long-term biomass feedstock supply for its upcoming renewable fertilizer projects, emphasizing supply chain stability.
- December 2024: The European Union introduced new regulations offering tax incentives for farmers adopting low-carbon and renewable fertilizers, directly benefiting the Renewable Urea market across member states.
- October 2024: CF Industries Holdings, Inc. initiated a feasibility study for a large-scale renewable urea facility in the United Kingdom, focusing on utilizing agricultural residues as primary feedstock.
- August 2024: OCI N.V. launched a new product line of certified sustainable urea, sourced from renewable energy, targeting agricultural markets in Germany and France with enhanced environmental credentials.
- June 2024: Indian Farmers Fertiliser Cooperative Limited (IFFCO) announced plans to set up a new biorefinery in India for renewable urea production, aiming to reduce the country's reliance on imported fossil fuel-based fertilizers.
Analyst Opinion
The Renewable Urea market outlook is exceptionally promising, driven by an undeniable global shift towards sustainable agricultural practices and stringent environmental regulations. The market's attractiveness stems from its critical role in decarbonizing the fertilizer industry, a sector historically known for its high carbon footprint. Competitive intensity is currently moderate but is expected to increase as more players, both established chemical giants and innovative startups, enter the fray. This will likely lead to greater investment in R&D and process optimization, fostering innovation in feedstock utilization and conversion technologies. The demand-supply balance is currently leaning towards increasing demand, fueled by growing awareness among farmers and consumers about the environmental benefits of green fertilizers. However, the scalability of biomass feedstock supply and the high capital expenditure for new facilities remain key considerations. Overall, the market is poised for robust growth, with significant opportunities for companies that can effectively manage supply chains and innovate in sustainable production methods. The regulatory push for net-zero emissions will continue to be a primary catalyst, making renewable urea a crucial component of future agricultural systems.
Looking at the long-term outlook, the Renewable Urea market is set for sustained expansion, underpinned by the increasing global population and the concurrent need for enhanced food security through sustainable means. The innovation landscape is dynamic, with continuous advancements in biomass gasification, green hydrogen production, and carbon capture utilization technologies, all contributing to more efficient and environmentally friendly urea synthesis. Strategic partnerships between technology providers, agricultural companies, and energy firms will be pivotal in accelerating commercialization and market penetration. Key risk factors include the volatility of biomass feedstock prices, which can impact production costs and price competitiveness against conventional urea. Furthermore, the development of robust certification standards for 'renewable' claims and the need for significant infrastructure investment pose challenges. However, the overarching trend of climate action and sustainable development positions renewable urea as an indispensable component of the future agricultural economy, offering substantial growth opportunities for forward-thinking market participants who can navigate these complexities and deliver scalable, cost-effective solutions.