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// Configuration object for centralized settings
const TabbedNavConfig = {
  DESKTOP_BREAKPOINT: 1201,
  DEBOUNCE_DELAY: 250,
  OPEN_FIRST_TAB: true,
  CLOSE_TAB_ON_MOUSEOUT: false
};

// Custom config for tabbed hero containers
const tabbedHeroConfig = {
  ...TabbedNavConfig,
  OPEN_FIRST_TAB: false,
  CLOSE_TAB_ON_MOUSEOUT: true
};

// Function to determine the appropriate config based on container context
function getConfigForContainer(container) {
  // Check if container has closest ancestor with [data-tabbed-hero="true"]
  const heroAncestor = container.getAttribute('data-tabbed-hero') === 'true'   ? container : container.closest('[data-tabbed-dropdown="true"]');
  
  if (heroAncestor) {
    return tabbedHeroConfig;
  }
  
  // Check for specific data-instance attributes (if you still want to support them)
  // const instance = container.getAttribute('data-instance');
  // if (instance === 'two') {
  //   // You can still have specific instance configs if needed
  //   return {
  //     ...TabbedNavConfig,
  //     OPEN_FIRST_TAB: false,
  //     CLOSE_TAB_ON_MOUSEOUT: true
  //   };
  // }
  
  // Default config
  return TabbedNavConfig;
}

class TabbedNavigation {
  constructor(container, config = TabbedNavConfig) {
    this.container = container;
    this.config = config;
    this.activeItem = null;
    this.isDesktop = window.innerWidth >= this.config.DESKTOP_BREAKPOINT;
    this.hasMouseListeners = false;
    this.megamenuParent = null;
    this.megamenuObserver = null;
    
    // Initialize bound handlers - these will be reused across reinitializations
    this.mouseEnterHandler = this.handleMouseEnter.bind(this);
    this.mouseLeaveHandler = this.handleMouseLeave.bind(this);
    this.resizeHandler = this.debounce(this.handleResize.bind(this), this.config.DEBOUNCE_DELAY);
    this.handleMegamenuToggle = this.handleMegamenuToggle.bind(this);
    
    this.init();
  }

  init() {
    // Cache DOM elements fresh each time
    this.navItems = [...this.container.querySelectorAll('.dwc-tabbed-nav-list__li')];
    this.elementsCache = new Map();
    
    this.cacheElements();
    this.setupAccessibility();
    this.setupMegamenuObserver();
    this.bindEvents();

    // Set initial state
    this.updateLayout();
    this.setBackText()

    // Show first item on page load only if desktop, not nested, and OPEN_FIRST_TAB is true
    if (this.navItems.length > 0 && this.isDesktop && this.config.OPEN_FIRST_TAB) {
      setTimeout(() => {
        const firstItem = this.navItems[0];

        // Count how many .dwc-tabbed-nav-container ancestors this.container has
        let count = 0;
        let current = this.container.parentElement;
        while (current) {
          if (current.classList?.contains('dwc-tabbed-nav-container')) {
            count++;
          }
          current = current.parentElement;
        }

        const isNested = count >= 1;

        if (!isNested && this.elementsCache.has(firstItem)) {
          this.showTab(firstItem);
        }
      }, 0);
    }
  }

  // Setup observer for megamenu parent
  setupMegamenuObserver() {
    // Find the .brx-has-megamenu parent
    this.megamenuParent = this.container.closest('.brx-has-megamenu');
    
    if (this.megamenuParent) {
      // Set initial inert state
      this.updateInertState();
      
      // Create a MutationObserver to watch for class changes
      this.megamenuObserver = new MutationObserver((mutations) => {
        mutations.forEach((mutation) => {
          if (mutation.type === 'attributes' && mutation.attributeName === 'class') {
            this.updateInertState();
          }
        });
      });
      
      // Start observing the megamenu parent for class changes
      this.megamenuObserver.observe(this.megamenuParent, {
        attributes: true,
        attributeFilter: ['class']
      });
    }
  }

  // Update inert state based on megamenu open/closed state
  updateInertState() {
    if (!this.megamenuParent) return;
    
    const isOpen = this.megamenuParent.classList.contains('open');
    
    if (isOpen) {
      this.container.removeAttribute('inert');
    } else {
      this.container.setAttribute('inert', '');
    }
  }

  // Handle megamenu toggle (for manual triggering if needed)
  handleMegamenuToggle() {
    this.updateInertState();
  }

  // Method to clean up event listeners and reset state
  cleanup() {
    // Remove all event listeners
    this.container.removeEventListener('click', this.handleClick);
    this.container.removeEventListener('keydown', this.handleKeydown);
    this.container.removeEventListener('focus', this.handleFocus);
    
    // Remove mouse listeners if they exist
    if (this.hasMouseListeners) {
      this.container.removeEventListener('mouseenter', this.mouseEnterHandler, true);
      this.container.removeEventListener('mouseleave', this.mouseLeaveHandler, true);
    }
    
    // Remove resize listener
    window.removeEventListener('resize', this.resizeHandler);
    
    // Clean up megamenu observer
    if (this.megamenuObserver) {
      this.megamenuObserver.disconnect();
      this.megamenuObserver = null;
    }
    
    // Reset state
    this.activeItem = null;
    this.hasMouseListeners = false;
    this.megamenuParent = null;
    
    // Clear caches
    if (this.elementsCache) {
      this.elementsCache.clear();
    }
    this.navItems = [];
    
    // Reset all tab states and accessibility attributes
    const allNavItems = this.container.querySelectorAll('.dwc-tabbed-nav-list__li');
    allNavItems.forEach(item => {
      const button = item.querySelector('.dwc-tabbed-nav-list__li__button') || 
                    item.querySelector('.dwc-tabbed-nav-list__li__btn-txt');
      const content = item.querySelector('.dwc-tabbed-nav-list__li__content');
      
      // Remove classes
      item.classList.remove('active');
      
      // Reset button attributes
      if (button) {
        button.removeAttribute('role');
        button.removeAttribute('aria-controls');
        button.removeAttribute('aria-expanded');
        button.removeAttribute('aria-selected');
        button.removeAttribute('tabindex');
        button.removeAttribute('id');
      }
      
      // Reset content attributes
      if (content) {
        content.removeAttribute('role');
        content.removeAttribute('aria-labelledby');
        content.removeAttribute('id');
        content.removeAttribute('aria-hidden');
        content.style.maxHeight = '';
      }
      
      // Remove data attributes
      item.removeAttribute('data-tab-index');
    });
    
    // Reset nav list role
    const navList = this.container.querySelector('.dwc-tabbed-nav-list');
    if (navList) {
      navList.removeAttribute('role');
    }
    
    // Remove inert attribute
    this.container.removeAttribute('inert');
  }

  // Public method to reinitialize the navigation
  reinitialize() {
    this.cleanup();
    this.isDesktop = window.innerWidth >= this.config.DESKTOP_BREAKPOINT; // Use config breakpoint
    this.init();
  }

  // Cache DOM elements to avoid repeated queries
  cacheElements() {
    const uniqueIdBase = `tab-${Date.now()}`;
    
    this.navItems.forEach((item, index) => {
      const button = item.querySelector('.dwc-tabbed-nav-list__li__button') || 
                    item.querySelector('.dwc-tabbed-nav-list__li__btn-txt');
      const content = item.querySelector('.dwc-tabbed-nav-list__li__content');
      
      this.elementsCache.set(item, {
        button,
        content,
        uniqueId: `${uniqueIdBase}-${index}`,
        index
      });
    });
  }

  setupAccessibility() {
    const navList = this.container.querySelector('.dwc-tabbed-nav-list');
    if (!navList) return;
    
    navList.setAttribute('role', 'tablist');
    
    for (const [item, cache] of this.elementsCache) {
      const { button, content, uniqueId, index } = cache;
      
      if (button) {
        button.setAttribute('role', 'tab');
        button.setAttribute('aria-controls', `${uniqueId}-panel`);
        button.setAttribute('aria-expanded', 'false');
        button.setAttribute('aria-selected', 'false');
        button.setAttribute('tabindex', '0');
        button.setAttribute('id', `${uniqueId}-tab`);
      }
      
      if (content) {
        content.setAttribute('role', 'tabpanel');
        content.setAttribute('aria-labelledby', `${uniqueId}-tab`);
        content.setAttribute('id', `${uniqueId}-panel`);
        content.setAttribute('aria-hidden', 'true');
      }
      
      item.setAttribute('data-tab-index', index);
    }
  }

  bindEvents() {
    // Store bound handlers for cleanup
    this.handleClick = this.handleClick.bind(this);
    this.handleKeydown = this.handleKeydown.bind(this);
    this.handleFocus = this.handleFocus.bind(this);
    
    // Single event delegation for better performance
    this.container.addEventListener('click', this.handleClick);
    this.container.addEventListener('keydown', this.handleKeydown);
    this.container.addEventListener('focus', this.handleFocus, true);
    
    // Passive resize listener for better performance
    window.addEventListener('resize', this.resizeHandler, { passive: true });
    
    this.updateMouseListeners();
  }

  updateMouseListeners() {
    if (this.isDesktop && !this.hasMouseListeners) {
      this.container.addEventListener('mouseenter', this.mouseEnterHandler, true);
      this.container.addEventListener('mouseleave', this.mouseLeaveHandler, true);
      this.hasMouseListeners = true;
    } else if (!this.isDesktop && this.hasMouseListeners) {
      this.container.removeEventListener('mouseenter', this.mouseEnterHandler, true);
      this.container.removeEventListener('mouseleave', this.mouseLeaveHandler, true);
      this.hasMouseListeners = false;
    }
  }

  // Helper method to get sibling nav items (nav items in the same container level)
  getSiblingNavItems(navItem) {
    // Find the direct parent container of this nav item
    const navItemContainer = navItem.closest('.dwc-tabbed-nav-list');
    if (!navItemContainer) return [];
    
    // Get all nav items that are direct children of the same container
    const siblingItems = [...navItemContainer.querySelectorAll('.dwc-tabbed-nav-list__li')];
    
    // Filter to only include items that are siblings (not the navItem itself)
    // and check if they belong to any TabbedNavigation instance
    return siblingItems.filter(item => item !== navItem);
  }

  handleFocus(e) {
    if (!this.isDesktop) return;

    const button = e.target.closest('[role="tab"]');
    if (!button) return;
    
    const navItem = button.closest('.dwc-tabbed-nav-list__li');
    if (!navItem || !this.elementsCache.has(navItem)) return;
    
    this.handleTabInteraction(navItem, 'focus');
  }

  handleClick(e) {
    const navItem = e.target.closest('.dwc-tabbed-nav-list__li');
    if (!navItem || !this.elementsCache.has(navItem)) return;
    
    const button = e.target.closest('.dwc-tabbed-nav-list__li__button, .dwc-tabbed-nav-list__li__btn-txt');
    if (!button) return;
    
    e.preventDefault();
    this.handleTabInteraction(navItem, 'click');
  }

  handleKeydown(e) {
    const button = e.target.closest('[role="tab"]');
    if (!button) return;
    
    const navItem = button.closest('.dwc-tabbed-nav-list__li');
    if (!navItem || !this.elementsCache.has(navItem)) return;
    
    const { index: currentIndex } = this.elementsCache.get(navItem);
    
    switch (e.key) {
      case 'Enter':
      case ' ':
        e.preventDefault();
        this.handleTabInteraction(navItem, 'keyboard');
        break;
      case 'ArrowRight':
      case 'ArrowDown':
        e.preventDefault();
        this.focusNextTab(currentIndex);
        break;
      case 'ArrowLeft':
      case 'ArrowUp':
        e.preventDefault();
        this.focusPrevTab(currentIndex);
        break;
      case 'Home':
        e.preventDefault();
        this.focusTab(0);
        break;
      case 'End':
        e.preventDefault();
        this.focusTab(this.navItems.length - 1);
        break;
    }
  }
  
  handleMouseEnter(e) {
    if (!this.isDesktop) return;
    
    const navItem = e.target.closest('.dwc-tabbed-nav-list__li') || 
                   (e.target.matches('.dwc-tabbed-nav-list__li') ? e.target : null);
    if (!navItem || !this.elementsCache.has(navItem)) return;
    
    this.handleTabInteraction(navItem, 'hover');
  }

  handleMouseLeave(e) {
    if (!this.isDesktop) return;
    
    // Only close tabs if CLOSE_TAB_ON_MOUSEOUT is enabled
    if (this.config.CLOSE_TAB_ON_MOUSEOUT) {
      // Check if mouse is leaving the entire container
      const rect = this.container.getBoundingClientRect();
      const { clientX, clientY } = e;
      
      // Check if mouse position is outside the container bounds
      const isOutsideContainer = (
        clientX < rect.left || 
        clientX > rect.right || 
        clientY < rect.top || 
        clientY > rect.bottom
      );
      
      if (isOutsideContainer) {
        this.hideAllTabs();
      }
    }
    // If CLOSE_TAB_ON_MOUSEOUT is false, keep content visible (original behavior)
  }

  // Unified method to handle all tab interactions with nesting support
  handleTabInteraction(navItem, interactionType) {
    if (!this.elementsCache.has(navItem)) return;
    
    if (this.isDesktop) {
      // Simply hide siblings and show the target - works for all scenarios
      this.hideSiblingTabs(navItem);
      this.showTab(navItem);
    } else {
      // Mobile accordion behavior
      if (interactionType === 'click' || interactionType === 'keyboard') {
        this.toggleTabMobile(navItem);
      }
    }
  }

  // Hide only sibling tabs (same container level)
  hideSiblingTabs(navItem) {
   // console.log('Nav Item: ', navItem)
    const siblings = this.getSiblingNavItems(navItem);
    
    siblings.forEach(sibling => {
      
         //console.log('sibling: ', sibling)
      // Only hide siblings that have the active class to avoid affecting other instances
      if (sibling.classList.contains('active')) {
        this.hideSiblingTab(sibling);
      }
    });
  }

  // Hide a sibling tab (used when we know it's a sibling from another instance)
  hideSiblingTab(navItem) {
    const button = navItem.querySelector('.dwc-tabbed-nav-list__li__button') || 
                  navItem.querySelector('.dwc-tabbed-nav-list__li__btn-txt');
    const content = navItem.querySelector('.dwc-tabbed-nav-list__li__content');
    
    if (content && button) {
      content.setAttribute('aria-hidden', 'true');
      button.setAttribute('aria-expanded', 'false');
      button.setAttribute('aria-selected', 'false');
      navItem.classList.remove('active');
      
      // Also handle mobile accordion collapse
      if (!this.isDesktop) {
        content.style.maxHeight = '0';
      }
    }
  }

  // Mobile-specific toggle behavior with proper nesting support
  toggleTabMobile(navItem) {
    if (!this.elementsCache.has(navItem)) return;
    
    const isActive = navItem.classList.contains('active');
    
    if (isActive) {
      this.collapseTab(navItem);
    } else {
      // Close sibling tabs and open this one
      this.hideSiblingTabs(navItem);
      this.expandTab(navItem);
    }
  }

  toggleTab(navItem) {
    if (!this.elementsCache.has(navItem)) return;
    
    if (this.isDesktop) {
      this.handleTabInteraction(navItem, 'click');
    } else {
      this.toggleTabMobile(navItem);
    }
  }

  showTab(navItem) {
    if (!this.elementsCache.has(navItem)) return;
    
    const { button, content } = this.elementsCache.get(navItem);
    
    if (content && button) {
      content.setAttribute('aria-hidden', 'false');
      button.setAttribute('aria-expanded', 'true');
      button.setAttribute('aria-selected', 'true');
      navItem.classList.add('active');
    }
    
    this.setActiveTab(navItem);
  }

  hideTab(navItem) {
    if (!this.elementsCache.has(navItem)) return;
    
    const { button, content } = this.elementsCache.get(navItem);
    
    if (content && button) {
      content.setAttribute('aria-hidden', 'true');
      button.setAttribute('aria-expanded', 'false');
      button.setAttribute('aria-selected', 'false');
      navItem.classList.remove('active');
    }
    
    // Only clear activeItem if it belongs to THIS navigation instance
    // and it's the exact item being hidden
    if (this.activeItem === navItem && this.navItems.includes(navItem)) {
      this.activeItem = null;
    }
  }

  expandTab(navItem) {
    if (!this.elementsCache.has(navItem)) return;
    
    // Close sibling tabs
    this.hideSiblingTabs(navItem);
    
    this.showTab(navItem);
    
    // Smooth height animation
    const { content } = this.elementsCache.get(navItem);
    if (content) {
      const height = content.scrollHeight;
      content.style.maxHeight = `${height}px`;
    }
  }

  collapseTab(navItem) {
    if (!this.elementsCache.has(navItem)) return;
    
    this.hideTab(navItem);
    
    const { content } = this.elementsCache.get(navItem);
    if (content) {
      content.style.maxHeight = '0';
    }
  }

  hideAllTabs() {
    this.navItems.forEach(item => this.hideTab(item));
  }

  setActiveTab(navItem) {
    // Only update aria-selected for tabs in THIS navigation instance
    this.navItems.forEach(item => {
      const cache = this.elementsCache.get(item);
      if (cache?.button) {
        cache.button.setAttribute('aria-selected', item === navItem ? 'true' : 'false');
      }
    });
    
    // Only set activeItem if this navItem belongs to THIS navigation instance
    if (this.navItems.includes(navItem)) {
      this.activeItem = navItem;
    }
  }

  focusTab(index) {
    if (index >= 0 && index < this.navItems.length) {
      const cache = this.elementsCache.get(this.navItems[index]);
      if (cache?.button) {
        cache.button.focus();
      }
    }
  }

  focusNextTab(currentIndex) {
    const nextIndex = (currentIndex + 1) % this.navItems.length;
    this.focusTab(nextIndex);
  }

  focusPrevTab(currentIndex) {
    const prevIndex = currentIndex === 0 ? this.navItems.length - 1 : currentIndex - 1;
    this.focusTab(prevIndex);
  }

  handleResize() {
    const wasDesktop = this.isDesktop;
    this.isDesktop = window.innerWidth >= this.config.DESKTOP_BREAKPOINT; // Use config breakpoint
    
    if (wasDesktop !== this.isDesktop) {
      this.updateMouseListeners();
      this.updateLayout();
    }
  }

  updateLayout() {
    const currentlyActive = this.activeItem;

    // Reset all states
    this.hideAllTabs();

    // Clear inline styles
    this.navItems.forEach(item => {
      const cache = this.elementsCache.get(item);
      if (cache?.content) {
        cache.content.style.maxHeight = '';
      }
    });

    if (this.isDesktop) {
      // Determine if this tab instance is nested
      let count = 0;
      let current = this.container.parentElement;
      while (current) {
        if (current.classList?.contains('dwc-tabbed-nav-container')) {
          count++;
        }
        current = current.parentElement;
      }
      const isNested = count >= 1;

      if (!isNested && this.config.OPEN_FIRST_TAB) {
        if (currentlyActive) {
          this.showTab(currentlyActive);
        } else if (this.navItems.length > 0) {
          this.showTab(this.navItems[0]);
        }
      }
    }
  }

  setBackText(){
    let tabElement = document.querySelector('.dwc-tabbed-nav-container');
    let tabBackText = tabElement.getAttribute('data-back-text')
    document.querySelectorAll('.dwc-tabbed-nav-list__li__button').forEach(tabBtn => {
        const textContent = tabBtn.textContent.trim();
        const tabIcon = tabBtn.querySelector('.dwc-tabbed-nav-list__li__arrow-icon');
        if (tabIcon) {
            tabIcon.setAttribute('data-text', textContent);
            tabIcon.setAttribute('data-back-text', tabBackText);
        }
    });
  }

  // Simple debounce for resize
  debounce(func, wait) {
    let timeout;
    return function executedFunction(...args) {
      const later = () => {
        clearTimeout(timeout);
        func(...args);
      };
      clearTimeout(timeout);
      timeout = setTimeout(later, wait);
    };
  }

  // Public method to destroy the instance completely
  destroy() {
    this.cleanup();
    // Additional cleanup can be added here if needed
  }

  // Public method to manually update inert state (if needed)
  updateInert() {
    this.updateInertState();
  }
}

// Simplified initialization on DOM ready
document.addEventListener('DOMContentLoaded', function() {
  const tabbedNavContainers = document.querySelectorAll('.dwc-tabbed-nav-container');
  
  tabbedNavContainers.forEach(container => {
    // Skip if this container is nested inside another dwc-tabbed-nav-container
    const parentNavContainer = container.parentElement.closest('.dwc-tabbed-nav-container');
    if (parentNavContainer) {
      return; // Skip nested containers
    }
    
    // Get the appropriate config for this container
    const config = getConfigForContainer(container);
    
    // Initialize with the determined config
    new TabbedNavigation(container, config);
  });
});

// For dynamic content - Updated version
window.initTabbedNav = function(container, customConfig = null) {
  if (container && container.classList.contains('dwc-tabbed-nav-container')) {
    // Check if this is a nested container
    const parentNavContainer = container.parentElement.closest('.dwc-tabbed-nav-container');
    if (parentNavContainer) {
      return null; // Don't initialize nested containers
    }
    
    // Use custom config if provided, otherwise determine config automatically
    const config = customConfig || getConfigForContainer(container);
    return new TabbedNavigation(container, config);
  }
  return null;
};

/*
// TO REINITIALIZE USE THIS
// Create an instance of TabbedNavigation
const tabbedNav = new TabbedNavigation(document.querySelector('.dwc-tabbed-nav-container'));

// Call reinitialize on the instance
tabbedNav.reinitialize();

// TO USE WITH CUSTOM CONFIG
const customConfig = {
  DESKTOP_BREAKPOINT: 768,
  DEBOUNCE_DELAY: 300,
  OPEN_FIRST_TAB: false,  // This will prevent first tab from opening automatically
  CLOSE_TAB_ON_MOUSEOUT: true  // This will close tabs when mouse leaves container
};
const tabbedNavCustom = new TabbedNavigation(document.querySelector('.dwc-tabbed-nav-container'), customConfig);

// TO UPDATE ON URL CHANGE
function onUrlChange() {
    setTimeout(function () {
const tabbedNav = new TabbedNavigation(document.querySelector('.dwc-tabbed-nav-container'));
tabbedNav.reinitialize();

    }, 1500); // Delay execution by 2 seconds
}

// Listen for popstate event (history navigation)
window.addEventListener('popstate', onUrlChange);

// Listen for hashchange event (URL hash change)
window.addEventListener('hashchange', onUrlChange);

// Handle pushState and replaceState
(function (history) {
    const pushState = history.pushState;
    const replaceState = history.replaceState;

    history.pushState = function (state) {
        if (typeof history.onpushstate == "function") {
            history.onpushstate({ state: state });
        }
        const result = pushState.apply(history, arguments);
        onUrlChange(); // Call the function when pushState is used
        return result;
    };

    history.replaceState = function (state) {
        if (typeof history.onreplacestate == "function") {
            history.onreplacestate({ state: state });
        }
        const result = replaceState.apply(history, arguments);
        onUrlChange(); // Call the function when replaceState is used
        return result;
    };
})(window.history);

*/

console.log('%c<Jamie Sheehan Web Design Mega Menu Pro Tabbed Navigation v1.0>', 'color: #b388eb');

Maron & bp Castellón Project Spotlight: Bio-Feedstock Traceability for Customs Compliance

June 15, 2026

In this post...

All Articles

At bp Castellón, import duty classification on bio-feedstocks represents a significant and recoverable cost.

The refinery uses biowaste-derived feedstocks — used cooking oil (UCO), soybean expeller oil (SBEO), and palm oil mill effluent (POME) — as inputs for HVO and SAF production. Under Spanish customs authority classification, each of these materials carries an import duty of between 2% and 7.7%. At commercial production volumes, those rates add up to a significant recurring cost that directly affects the viability of the biofuels programme.

A pathway exists to mitigate these costs.

The RPA regime (Régimen de Perfeccionamiento Activo, or Inward Processing) allows import duties on feedstock to be deferred and applied to the finished product instead. For HVO and SAF, the finished product duty rate is 0%. Qualifying for RPA can be a challenge though, as it requires a full, auditable traceability of bio-feedstock from import, processing, to finished product.

That is the hurdle Maron Systems was brought in to help with.

What the Refinery Already Had

bp Castellón wasn’t starting from scratch. Maron OAS was already adopted across several departments as the site’s primary oil accounting tool, handling fence-line movement quantities, inventory records, and the monthly site-wide balance and loss calculations. The daily reconciliation work meant the underlying data was already being captured in the system:

  • Imports recorded at the individual tank level
  • Bio-feedstock tank compositions maintained
  • Internal movements tracked from feedstock tanks to process units
  • Production movements into finished product tanks

The data existed. The missing connection was a link across the full chain, presented in a way that customs authorities would accept.

What Was Built

A FIFO-based tracking algorithm was developed within OAS to track feedstock consumption in the order each shipment arrives. Bio-feedstocks and products derived from them are typically blended, which makes proving origin through physical testing almost impossible. This is why the model is accounting-based rather than molecular.

As feedstock enters a process unit, the system attributes that consumption to the earliest outstanding import batch first, working forward chronologically. The corresponding production output of HVO or SAF is then associated with those specific feedstock inputs.

The result is a traceable chain from a specific import of cargo, through its proportional consumption in processing, to its contribution to a finished product volume. This traceability layer was designed to integrate within the daily OAS workflow bp Castellón already operates.

From that chain, OAS generates reports documenting individual feedstock imports and their proportional contribution to finished product volumes. These reports are designed to form the documentary basis of an RPA submission to Spanish customs authorities.

The core traceability capability is in place. Following changes to operational processes on site, the OAS configuration requires updating to reflect how the refinery currently runs. That work is scoped and the RPA application remains the commercial objective.

Why This Matters for the Industry

The biofuels sector is under growing pressure to prove the origin of feedstock materials, whether it’s for regulatory compliance or commercial credibility. As governments tighten the criteria for what qualifies as sustainable aviation fuel or renewable diesel, the ability to trace a specific cargo through the full production cycle is now a baseline expectation instead of a differentiator.

Compliance is not the only driver. With refining margins under pressure and current market volatility, the ability to recover mitigatable trade levies is a meaningful lever.

The underlying data may exist within refinery systems. What has been missing is the layer that consolidates and processes the data in a way regulators can recognize.

The collaboration with bp Castellón shows how existing OAS infrastructure can be extended to meet that requirement, without building an entirely separate system or creating a data burden for operations teams.

While the RPA application is specific to Spain, the traceability model applies wherever import duty regimes create an incentive to account for feedstock consumption at the shipment level. Refineries processing bio-feedstocks across Europe are dealing with variations of this same challenge. For sites already running OAS, the data infrastructure to pursue RPA or an equivalent is already in place. The traceability layer Maron built at bp Castellón is the model for how to use it.

What This Means for Your Refinery

The collaboration with bp Castellón is a starting point. Refineries at different stages of their biofuels programmes will have different configuration requirements, and projects like this rarely follow a linear trajectory.

Rather than delivering a fixed solution, Maron works alongside refineries as those demands develop, reconfiguring OAS to stay aligned with what is happening in real-time. The value reflected is a system that keeps pace with the workflow, instead of one that has to be replaced when it changes.

If duty recovery is on your agenda, the infrastructure to pursue it may already be closer than you think. Get in touch with the Maron team at sales@maronsystems.co.uk to learn more.

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Additional Benefits

  • Accelerated financial results for real-time decision making
  • Automated hydrocarbon pricing based on quality inspection results for accountants
  • Incorporating historical oil losses per location into transactions to reduce/eliminate oil loss claims
  • Identify differences between test method nominated versus method performed by inspection companies
  • Communicate real-time test results as they are available for prompt trading opportunities
  • Inspection cost savings from use of Navarik Inspection Price Estimator
  • All data centralised with the ability to extract key information for data analytics