{"id":4831,"date":"2026-06-03T06:24:34","date_gmt":"2026-06-03T05:24:34","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/alternative-fuel\/"},"modified":"2026-10-25T12:07:42","modified_gmt":"2026-10-25T12:07:42","slug":"alternative-fuel","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/alternative-fuel\/","title":{"rendered":"Alternative Fuel"},"content":{"rendered":"\n<section class=\"ols-revision-page ols-alternative-fuel-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      --soft-red: #fff7f7;\n      --soft-purple: #f7f0ff;\n      --soft-green: #f0f7f1;\n      --soft-yellow: #fff8e6;\n      --red: #c81e1e;\n      --gold: #c9973a;\n      --green: #3f8f46;\n      --grey-text: #667085;\n      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22px; }\n    .ols-image-card-body h3 { margin: 0 0 8px; font-size: 22px; line-height: 1.25; color: var(--navy); }\n    .ols-image-card-body p { margin: 0; font-size: 15px; line-height: 1.6; color: var(--body-text); }\n\n    .ols-pollutant-table-wrap, .ols-comparison-table-wrap {\n      overflow: hidden;\n      border-radius: 22px;\n      border: 1px solid var(--border);\n      background: #ffffff;\n      margin-top: 18px;\n      box-shadow: var(--inner-shadow);\n    }\n\n    .ols-table {\n      width: 100%;\n      border-collapse: collapse;\n      table-layout: fixed;\n    }\n\n    .ols-table th {\n      background: var(--navy);\n      color: #ffffff;\n      padding: 16px;\n      text-align: left;\n      font-size: clamp(14px, 1.2vw, 17px);\n      font-weight: 700;\n      overflow-wrap: anywhere;\n      word-break: normal;\n    }\n\n    .ols-table td {\n      padding: 16px;\n      border-bottom: 1px solid var(--border);\n      font-size: clamp(14px, 1.15vw, 16px);\n      line-height: 1.45;\n      color: var(--body-text);\n      vertical-align: middle;\n      overflow-wrap: anywhere;\n      word-break: normal;\n    }\n\n    .ols-table tr:last-child td { border-bottom: none; }\n    .ols-table img { max-width: 92px; max-height: 92px; width: auto; height: auto; display: block; margin: 0 auto; border-radius: 12px; }\n    .ols-table .ols-icon-cell { width: 18%; text-align: center; }\n    .ols-table .ols-name-cell { width: 32%; }\n    .ols-table .ols-consequence-cell { width: 50%; }\n\n    .ols-h5p-card { background: linear-gradient(135deg, #ffffff 0%, #f7f0ff 100%); }\n    .ols-h5p-frame { margin-top: 22px; padding: 18px; border-radius: 24px; background: #ffffff; border: 1px solid var(--border); box-shadow: inset 0 0 0 1px rgba(28, 36, 75, 0.03); }\n\n    .ols-infographic-full { width: 100%; margin: 6px 0 30px; }\n    .ols-infographic-title { margin: 0 0 18px; }\n    .ols-infographic-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }\n    .ols-info-panel { border: 1px solid var(--border); border-radius: 20px; background: linear-gradient(135deg, #ffffff, #f8fbff); padding: 18px; box-shadow: var(--inner-shadow); }\n    .ols-info-panel h3 { margin: 0 0 8px; font-size: 22px; line-height: 1.25; color: var(--navy); }\n    .ols-info-panel p { margin: 0; font-size: 16px; line-height: 1.6; color: var(--body-text); font-weight: 300; }\n    .ols-info-panel img { width: 100%; height: auto; max-height: 190px; object-fit: contain; display: block; margin-top: 14px; border-radius: 14px; border: 1px solid rgba(28, 36, 75, 0.10); padding: 12px; background: #ffffff; }\n\n    .ols-faq-list { display: grid; gap: 14px; margin-top: 20px; }\n    .ols-faq-item { border: 1px solid var(--border); border-radius: 20px; background: #ffffff; padding: 18px 20px; box-shadow: var(--inner-shadow); }\n    .ols-faq-item h3 { margin: 0 0 8px; font-size: 20px; line-height: 1.3; color: var(--navy); }\n    .ols-faq-item p { margin: 0; }\n\n    .ols-related-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-top: 18px; }\n    .ols-related-item { border: 1px solid var(--border); border-radius: 18px; padding: 18px; background: #ffffff; color: var(--navy); text-decoration: none; font-weight: 600; line-height: 1.5; transition: transform 0.2s ease, box-shadow 0.2s ease; }\n    .ols-related-item:hover { transform: translateY(-2px); box-shadow: 0 10px 22px rgba(28, 36, 75, 0.08); }\n\n    @media (max-width: 1050px) {\n      .ols-main { max-width: none; }\n      .ols-related-grid, .ols-infographic-grid, .ols-image-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }\n    }\n\n    @media (max-width: 760px) {\n      .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card, .ols-faq-card { padding: 24px 18px; border-radius: 22px; }\n      .ols-note-title { align-items: flex-start; }\n      .ols-related-grid, .ols-infographic-grid, .ols-image-grid { grid-template-columns: 1fr; }\n      .ols-figure-card { border-radius: 22px; }\n      .ols-figure-image { min-height: 220px; padding: 14px; }\n      .ols-table, .ols-table thead, .ols-table tbody, .ols-table th, .ols-table td, .ols-table tr { display: block; width: 100%; }\n      .ols-table thead { display: none; }\n      .ols-table tr { border-bottom: 1px solid var(--border); background: #ffffff; }\n      .ols-table tr:last-child { border-bottom: none; }\n      .ols-table td { display: grid; grid-template-columns: minmax(110px, 36%) minmax(0, 1fr); gap: 12px; align-items: start; border-bottom: 1px solid rgba(28, 36, 75, 0.08); padding: 14px; overflow-wrap: anywhere; }\n      .ols-table td:last-child { border-bottom: none; }\n      .ols-table td::before { content: attr(data-label); font-weight: 700; color: var(--navy); overflow-wrap: anywhere; }\n      .ols-table td.ols-icon-cell { display: flex; justify-content: center; align-items: center; }\n      .ols-table td.ols-icon-cell::before { display: none; }\n      .ols-table img { max-width: 120px; max-height: 120px; }\n    }\n  \n    .ols-figure-placeholder .ols-placeholder-box { border: 2px dashed #c9973a; background: #fffaf0; border-radius: 16px; padding: 26px 22px; font-weight: 700; color: #7a4b12; text-align: center; line-height: 1.6; }\n    .ols-figure-placeholder .ols-figure-image { background: transparent; }\n    .ols-figure-placeholder { background: #ffffff; border: 1px solid rgba(28, 36, 75, 0.12); border-radius: 22px; padding: 14px; margin: 18px 0 6px; }\n    .ols-figure-placeholder .ols-figure-caption p { margin: 10px 0 0; font-size: 14px; color: #667085; text-align: center; }\n<\/style>\n\n  <aside class=\"ols-sidebar\">\r\n  <div class=\"ols-sidebar-header\">\r\n    <h3>Revision Notes<\/h3>\r\n    <p>A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Topic 6 Organic Chemistry I<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/\">Introduction to Organic Chemistry<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/iupac-rules\/\">IUPAC Rules<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/alkene\/\">Alkene<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/alcohol\/\">Alcohol<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/halogenoalkanes\/\">Halogenoalkanes<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/aldehyde\/\">Aldehyde<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ketone\/\">Ketone<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/carboxylic-acid\/\">Carboxylic Acid<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/ester\/\">Ester<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/introduction-to-organic-chemistry\/isomerism\/\">Isomerism<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/\">Alkanes<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/\">Alkanes from Crude Oil<\/a>\r\n\r\n            <ul class=\"ols-subtopic-list\">\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/fractional-distillation\/\">Fractional Distillation<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/cracking\/\">Cracking<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/reforming\/\">Reforming<\/a>\r\n              <\/li>\r\n            <\/ul>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/\">Alkanes as Fuel<\/a>\r\n\r\n            <ul class=\"ols-subtopic-list\">\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/combustion\/\">Combustion<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/oxides-of-sulfur\/\">Oxides of Sulfur<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/oxides-of-nitrogen\/\">Oxides of Nitrogen<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/catalytic-converter\/\">Catalytic Converter<\/a>\r\n              <\/li>\r\n            <\/ul>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/alternative-fuel\/\">Alternative Fuel<\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/\">Reactions of Alkanes<\/a>\r\n\r\n            <ul class=\"ols-subtopic-list\">\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/free-radical-substitution\/\">Free Radical Substitution<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/initiation\/\">Initiation<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/propagation\/\">Propagation<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/termination\/\">Termination<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/further-substitution\/\">Further Substitution<\/a>\r\n              <\/li>\r\n            <\/ul>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/\">Alkenes<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/alkene-bonding\/\">Alkene Bonding<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/geometric-isomerism\/\">Geometric Isomerism<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/electrophilic-addition-mechanism\/\">Electrophilic Addition Mechanism<\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/\">Reactions of Alkenes<\/a>\r\n\r\n            <ul class=\"ols-subtopic-list\">\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/halogens\/\">Halogens<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/hydrogen-halide\/\">Hydrogen Halide<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/bromine-water\/\">Bromine Water<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/hydrogen\/\">Hydrogen<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/steam\/\">Steam<\/a>\r\n              <\/li>\r\n              <li>\r\n                <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/reactions-of-alkenes\/kmno4\/\">KMnO4<\/a>\r\n              <\/li>\r\n            <\/ul>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/polymerisation-reactions\/\">Polymerisation Reactions<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/polymer-waste\/\">Polymer Waste<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/halogenoalkanes\/\">Halogenoalkanes<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alcohols\/\">Alcohols<\/a>\r\n      <\/li>\r\n\r\n    <\/ul>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Next Topics<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-7-modern-analytical-techniques-i\/\">Topic 7 Modern Analytical Techniques I<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/\">Topic 5 Formulae, Equations &amp; Amounts<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-4-inorganic-chemistry-and-the-periodic-table\/\">Topic 4 Inorganic Chemistry &amp; The Periodic Table<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n<\/aside>\r\n\r\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      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href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/\">Edexcel<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/\">Topic 6 Organic Chemistry I<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/\">Alkanes<\/a> \/\n        <span>Alternative Fuel<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Alternative Fuel<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to pollutants from fuel combustion, biofuels, alcohol fuels, biodiesel and the advantages and disadvantages of replacing fossil fuels with renewable plant-based fuels.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Paper 2<\/div>\n          <div class=\"ols-badge\">Topic 6: Organic Chemistry I<\/div>\n          <div class=\"ols-badge\">9CH0\/02<\/div>\n        <\/div>\n      <\/header>\n<!-- 3D card: bioethanol-carbon-neutral (22 Oct 2026) -->\n<!-- Copyright (c) 2026 Dr. Mohammed Al-Fatah, onlinelearningsystem.net. 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text-align:center; font-size:11px; font-style:italic; color:#aab0c0;\n}\n.ols-cc-bio-001 a{color:#aab0c0; text-decoration:none;}\n.ols-cc-bio-001 a:hover{text-decoration:underline;}\n.ols-bio-001 .bio-seg button{display:inline-flex; align-items:center;}\n.ols-bio-001 .bio-seg button .bio-n{display:inline-flex; align-items:center; justify-content:center; width:20px; height:20px; margin-right:9px; border-radius:50%; font-size:11px; font-weight:600; background:rgba(37,99,235,0.10); color:#2563eb; flex:0 0 auto;}\n.ols-bio-001 .bio-seg button[aria-pressed=\"true\"] .bio-n{background:#ffffff; color:#2563eb;}\n<\/style>\n\n<div class=\"bio-head\">\n  <h2 class=\"bio-title\">Carbon Neutral Fuels: Bioethanol and Hydrogen<\/h2>\n  <p class=\"bio-sub\">Choose a step to follow the carbon atoms (gold rings) from the air into a crop, into ethanol and back into the air, then compare hydrogen.<\/p>\n<\/div>\n\n<div class=\"bio-stage\" id=\"bioStage\">\n  <canvas class=\"bio-canvas\" id=\"bioCanvas\"><\/canvas>\n  <div class=\"bio-overlay\" id=\"bioOverlay\"><\/div>\n  <div class=\"bio-caption\" id=\"bioCaption\"><\/div>\n  <div class=\"bio-hint\" id=\"bioHint\">Drag to rotate<\/div>\n  <div class=\"bio-badges\" id=\"bioBadges\"><\/div>\n<\/div>\n\n<div class=\"bio-controls\">\n  <div class=\"bio-row\">\n    <span class=\"bio-rowlab\">Step<\/span>\n    <div class=\"bio-seg\" role=\"group\" aria-label=\"Step\">\n      <button type=\"button\" data-step=\"1\" aria-pressed=\"true\"><span class=\"bio-n\">1<\/span>Photosynthesis<\/button>\n      <button type=\"button\" data-step=\"2\" aria-pressed=\"false\"><span class=\"bio-n\">2<\/span>Fermentation<\/button>\n      <button type=\"button\" data-step=\"3\" aria-pressed=\"false\"><span class=\"bio-n\">3<\/span>Burning ethanol<\/button>\n      <button type=\"button\" data-step=\"4\" aria-pressed=\"false\"><span class=\"bio-n\">4<\/span>The carbon count<\/button>\n      <button type=\"button\" data-step=\"5\" aria-pressed=\"false\"><span class=\"bio-n\">5<\/span>Hydrogen<\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"bio-row\">\n    <span class=\"bio-rowlab\">View<\/span>\n    <button type=\"button\" class=\"bio-pill\" id=\"bioResetV\">Reset view<\/button>\n  <\/div>\n<\/div>\n\n<div class=\"bio-info\">\n  <h3 id=\"bioInfoTitle\"><\/h3>\n  <p id=\"bioInfoText\"><\/p>\n  <div class=\"bio-facts\" id=\"bioFacts\"><\/div>\n  <div class=\"bio-key\">\n    <span><i class=\"k-ball\" style=\"background:#464a54\"><\/i>Carbon<\/span>\n    <span><i class=\"k-ball\" style=\"background:#ececf0\"><\/i>Hydrogen<\/span>\n    <span><i class=\"k-ball\" style=\"background:#cd2d28\"><\/i>Oxygen<\/span>\n    <span><i class=\"k-ball\" style=\"background:#fff;border:2px solid #d69618\"><\/i>Carbon atom followed<\/span>\n  <\/div>\n<\/div>\n\n<script src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/JS\/bioethanol-carbon-neutral.js?v=20261025p\"><\/script>\n<\/section>\n\n<p class=\"ols-cc-bio-001\">&copy; Dr. Mohammed Al-Fatah &#8211; <a href=\"https:\/\/www.onlinelearningsystem.net\" target=\"_blank\" rel=\"noopener\">onlinelearningsystem.net<\/a><\/p>\n\n\n      <section class=\"ols-h5p-card ols-h5p-inline ols-h5p-recap\">\n<span class=\"ols-h5p-kicker\">Before you start<\/span>\n<h2>GCSE Recap: Burning Fuels and Photosynthesis<\/h2>\n<p>Answer three quick GCSE questions before you start.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"693\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">1<\/div>\n          <h2>Why Alternative Fuels Are Needed<\/h2>\n        <\/div>\n\n        <p>Most <strong>fossil fuels<\/strong> are obtained from <strong>crude oil<\/strong>. Crude oil is a <strong>non-renewable resource<\/strong>, so it will eventually be depleted if it continues to be used faster than it forms.<\/p>\n        <p>Alternative fuels have been developed to reduce reliance on finite fuel reserves. Important examples include <strong>alcohols<\/strong> such as ethanol and <strong>biodiesel<\/strong>, both of which can be produced from plant material.<\/p>\n\n        <div class=\"ols-definition-box\">\n          <p><strong>Definition:<\/strong> A renewable fuel is a fuel made from resources that can be replaced or regrown on a short timescale compared with fossil fuels.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n          <div class=\"ols-figure-image\">\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-28-fossilbiofuel.jpg\" alt=\"Two-column poster: fossil fuels from ancient material, finite and non-renewable, against biofuels from recently grown plants, renewable\">\n          <\/div>\n          <div class=\"ols-figure-caption\">\n            <p>Biofuels are produced from recently living plant material, whereas fossil fuels are made from ancient biological material over very long timescales.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Same Molecule, Different Label<\/h2>\n<p>Apply the definition of a renewable fuel to two sources of methane.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-129\" class=\"h5p-iframe\" data-content-id=\"129\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alternative Fuel MCQ: Why Biogas Is Renewable but Natural Gas Is Not\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">2<\/div>\n          <h2>Pollutants from Fuel Combustion<\/h2>\n        <\/div>\n\n        <p>Burning fuels in engines can release several pollutants. The exact products depend on the conditions inside the engine, including oxygen supply, temperature and whether the fuel burns completely.<\/p>\n\n        <div class=\"ols-pollutant-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th class=\"ols-icon-cell\">Pollutant source<\/th>\n                <th class=\"ols-name-cell\">Pollutant<\/th>\n                <th class=\"ols-consequence-cell\">Environmental consequence<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td class=\"ols-icon-cell\" data-label=\"Pollutant source\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-27-pollutantchart.jpg\" alt=\"Five-row chart of pollutants from burning fuels: nitrogen oxides, CO, CO\u2082, unburnt hydrocarbons and soot, with origin and effect\"><\/td>\n                <td data-label=\"Pollutant\"><strong>Nitrogen oxides<\/strong><br>Formed when N<sub>2<\/sub> and O<sub>2<\/sub> from the air react at the very high temperature reached inside the engine.<\/td>\n                <td data-label=\"Environmental consequence\">NO is toxic and can form smog. NO<sub>2<\/sub> is toxic and acidic and forms acid rain.<\/td>\n              <\/tr>\n              <tr>\n                <td class=\"ols-icon-cell\" data-label=\"Pollutant source\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/CO.jpg\" alt=\"Carbon monoxide warning icon.\"><\/td>\n                <td data-label=\"Pollutant\"><strong>Carbon monoxide<\/strong><\/td>\n                <td data-label=\"Environmental consequence\">Toxic gas formed during incomplete combustion.<\/td>\n              <\/tr>\n              <tr>\n                <td class=\"ols-icon-cell\" data-label=\"Pollutant source\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Global-Warming.jpg\" alt=\"Global warming image representing carbon dioxide.\"><\/td>\n                <td data-label=\"Pollutant\"><strong>Carbon dioxide<\/strong><\/td>\n                <td data-label=\"Environmental consequence\">Contributes towards global warming.<\/td>\n              <\/tr>\n              <tr>\n                <td class=\"ols-icon-cell\" data-label=\"Pollutant source\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/skel-83-propane-hydrocarbon.svg\" alt=\"Propane drawn with wedge and hashed bonds\"><\/td>\n                <td data-label=\"Pollutant\"><strong>Unburnt hydrocarbons<\/strong><br>Formed because not all fuel burns in the engine.<\/td>\n                <td data-label=\"Environmental consequence\">React with nitrogen oxides in sunlight to form <strong>photochemical smog<\/strong> and ground-level ozone.<\/td>\n              <\/tr>\n              <tr>\n                <td class=\"ols-icon-cell\" data-label=\"Pollutant source\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Soot.jpg\" alt=\"Soot and particulate pollution.\"><\/td>\n                <td data-label=\"Pollutant\"><strong>Soot and particulates<\/strong><\/td>\n                <td data-label=\"Environmental consequence\">Cause global dimming and respiratory problems.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> Link each pollutant to both its origin and its consequence. For example, nitrogen oxides form at high engine temperatures and contribute to acid rain and smog.<\/p>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Name the Pollutant<\/h2>\n<p>Read each situation and pick the pollutant responsible as quickly as you can.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-128\" class=\"h5p-iframe\" data-content-id=\"128\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alternative Fuel Quick Fire: Which Pollutant Is Responsible?\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card green\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">3<\/div>\n          <h2>Biofuels from Renewable Resources<\/h2>\n        <\/div>\n\n        <p><strong>Biofuels<\/strong> are fuels produced from biological material, especially plant material. They are described as renewable because the raw materials can be regrown.<\/p>\n        <p>Biofuels are often considered more carbon neutral than fossil fuels because the <strong>carbon dioxide released during combustion<\/strong> can be partially offset by the <strong>carbon dioxide absorbed during plant growth<\/strong>.<\/p>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Key idea:<\/strong> Biofuels are not automatically zero-carbon. The carbon dioxide released when they burn may be partly balanced by photosynthesis during plant growth, but growing, processing and transporting the fuel can still involve emissions.<\/p>\n        <\/div>\n\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-card-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Oil.jpg\" alt=\"Oil barrel representing fossil fuels.\">\n            <\/div>\n            <div class=\"ols-image-card-body\">\n              <h3>Fossil fuels<\/h3>\n              <p>Crude-oil based fuels are non-renewable because the reserves are finite.<\/p>\n            <\/div>\n          <\/div>\n\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-card-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-29-biofuelroutes.jpg\" alt=\"Two production routes: sugar crop fermented to ethanol and distilled; vegetable oil with methanol to biodiesel; CO\u2082 loop with a caveat\">\n            <\/div>\n            <div class=\"ols-image-card-body\">\n              <h3>Alternative fuels<\/h3>\n              <p>Plant-based fuels can be renewable if the crops or raw materials are regrown sustainably.<\/p>\n            <\/div>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Follow the Carbon<\/h2>\n<p>Use three equations to count the carbon dioxide absorbed and released, then judge the result.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"694\"><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">4<\/div>\n          <h2>Alcohol Fuels and Biodiesel<\/h2>\n        <\/div>\n\n        <p><strong>Alcohol fuels<\/strong> such as ethanol can be produced by the <strong>fermentation of sugars<\/strong> obtained from plants. Because the raw materials can be regrown, ethanol is considered a renewable fuel source.<\/p>\n        <p><strong>Biodiesel<\/strong> is produced by reacting <strong>vegetable oils<\/strong> with <strong>methanol<\/strong> in the presence of an <strong>alkali catalyst<\/strong>. This converts the oils into a mixture of <strong>methyl esters<\/strong>, which is the fuel used in diesel engines in place of fossil-based diesel.<\/p>\n\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-card-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-mv-07-displayed.svg\" alt=\"Displayed formulae of ethanol\" width=\"1434\" height=\"864\">\n            <\/div>\n            <div class=\"ols-image-card-body\">\n              <h3>Alcohol fuels<\/h3>\n              <p>Ethanol can be made by fermentation of sugars from plants.<\/p>\n            <\/div>\n          <\/div>\n\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-card-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/renewable.jpg\" alt=\"Renewable plant growth image.\">\n            <\/div>\n            <div class=\"ols-image-card-body\">\n              <h3>Biodiesel<\/h3>\n              <p>Vegetable oils react with methanol using an alkali catalyst to make biodiesel.<\/p>\n            <\/div>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-warning-box\">\n          <p><strong>Common mistake:<\/strong> Do not describe biodiesel as crude-oil based. It is made from vegetable oils and methanol, so it is an alternative to fossil-based diesel.<\/p>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Where Does the Methanol Come From?<\/h2>\n<p>Use the way biodiesel is made to judge its carbon balance.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-130\" class=\"h5p-iframe\" data-content-id=\"130\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alternative Fuel MCQ: Fossil Methanol in Biodiesel\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card yellow\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">5<\/div>\n          <h2>Advantages and Disadvantages of Biofuels<\/h2>\n        <\/div>\n\n        <p>Biofuels can reduce dependence on fossil fuels, but their production can also compete with food production and land use.<\/p>\n\n        <div class=\"ols-comparison-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Advantages<\/th>\n                <th>Disadvantages<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Advantages\"><strong>Reduction in use of fossil fuels<\/strong><br>Biofuels reduce reliance on finite fossil fuel resources.<\/td>\n                <td data-label=\"Disadvantages\"><strong>Fewer food crops may be grown<\/strong><br>Land and crops may be diverted from food production to fuel production.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Advantages\"><strong>Biofuels are renewable<\/strong><br>Plant material can be regrown if managed sustainably.<\/td>\n                <td data-label=\"Disadvantages\"><strong>Engines may need modifying<\/strong><br>Ethanol-rich fuels attack the seals and fuel lines of older engines, and ethanol releases less energy per litre than petrol.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Advantages\"><strong>Biofuels are more carbon neutral<\/strong><br>The CO<sub>2<\/sub> released when bioethanol or biodiesel burns may be partly offset by the CO<sub>2<\/sub> absorbed as the crop grew.<\/td>\n                <td data-label=\"Disadvantages\"><strong>Rainforests may be cut down to provide land<\/strong><br>Deforestation damages habitats and can increase net carbon emissions.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Advantages\"><strong>Crude oil is conserved as a chemical feedstock<\/strong><br>Burning less of it as fuel leaves more crude oil for making organic compounds.<\/td>\n                <td data-label=\"Disadvantages\"><strong>Shortage of fertile soils<\/strong><br>Large-scale fuel crop production can increase pressure on fertile land.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Advantages\"><strong>Lower risk of large-scale fossil fuel pollution<\/strong><br>Less extraction and transport of fossil fuels can reduce the risk of major pollution events.<\/td>\n                <td data-label=\"Disadvantages\"><strong>Environmental pressure<\/strong><br>Intensive farming can cause water stress, habitat loss and soil degradation.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-image-grid\">\n          <div class=\"ols-image-card\">\n            <div class=\"ols-image-card-image\">\n              <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t4-img-30-biofuelbalance.jpg\" alt=\"Balance scale weighing four advantages of biofuels against five disadvantages, from renewability to land use and energy per litre\">\n            <\/div>\n            <div class=\"ols-image-card-body\">\n              <h3>Reduced fossil fuel use<\/h3>\n              <p>Using biofuels can decrease dependence on finite crude-oil resources.<\/p>\n            <\/div>\n          <\/div>\n\n          <div class=\"ols-image-card\">\n            \n            <div class=\"ols-image-card-body\">\n              <h3>Food crop competition<\/h3>\n              <p>Growing fuel crops can reduce the land available for food crops.<\/p>\n            <\/div>\n          <\/div>\n\n          <div class=\"ols-image-card\">\n            \n            <div class=\"ols-image-card-body\">\n              <h3>Deforestation risk<\/h3>\n              <p>Rainforests may be cleared to provide land for biofuel crop production.<\/p>\n            <\/div>\n          <\/div>\n\n          <div class=\"ols-image-card\">\n            \n            <div class=\"ols-image-card-body\">\n              <h3>Land and water pressure<\/h3>\n              <p>Large-scale crop growth can put pressure on fertile soils and water supplies.<\/p>\n            <\/div>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Judging Green Claims<\/h2>\n<p>In each round, pick the one statement that is accurate.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-131\" class=\"h5p-iframe\" data-content-id=\"131\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alternative Fuel Summary: Judging Green Claims About Fuels\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">6<\/div>\n          <h2>Common Exam Mistakes<\/h2>\n        <\/div>\n\n        <ul>\n          <li>Do not say biofuels are completely carbon neutral. It is more precise to say they may be <strong>more carbon neutral<\/strong> because plant growth can offset some CO<sub>2<\/sub> released during combustion.<\/li>\n          <li>Do not confuse <strong>carbon monoxide<\/strong> with <strong>carbon dioxide<\/strong>. Carbon monoxide is toxic, while carbon dioxide contributes towards global warming.<\/li>\n          <li>Do not forget that <strong>nitrogen oxides<\/strong> form from nitrogen in the air at high engine temperatures, not from nitrogen inside the fuel.<\/li>\n          <li>Do not list only advantages of biofuels. Examiners often expect a balanced evaluation including food crop competition, land use and deforestation.<\/li>\n        <\/ul>\n      <\/article>\n\n      \n\n      <section class=\"ols-infographic-full\" aria-label=\"Alternative fuel summary\">\n        <h2 class=\"ols-infographic-title\">Alternative Fuel Summary<\/h2>\n        <div class=\"ols-infographic-grid\">\n          <div class=\"ols-info-panel\">\n            <h3>Fossil fuels<\/h3>\n            <p>Crude-oil fuels are non-renewable and will eventually be depleted.<\/p>\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Oil.jpg\" alt=\"Oil barrel representing non-renewable fossil fuels.\">\n          <\/div>\n          <div class=\"ols-info-panel\">\n            <h3>Biofuels<\/h3>\n            <p>Alcohols and biodiesel can be made from plant-based renewable resources.<\/p>\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/biofuel-renewable.jpg\" alt=\"Biofuel produced from plant material.\">\n          <\/div>\n          <div class=\"ols-info-panel\">\n            <h3>Pollutants<\/h3>\n            <p>Combustion can produce CO, CO<sub>2<\/sub>, nitrogen oxides, unburnt hydrocarbons and particulates.<\/p>\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/pollution.jpg\" alt=\"Pollution image representing combustion pollutants.\">\n          <\/div>\n          <div class=\"ols-info-panel\">\n            <h3>Trade-offs<\/h3>\n            <p>Biofuels reduce fossil fuel use but may increase pressure on food crops, forests and fertile soils.<\/p>\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/infertility.jpg\" alt=\"Infertile soil image representing pressure on fertile land.\">\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-faq-card\">\n        <h2>Alternative Fuel FAQ<\/h2>\n        <p>Use these questions to check the main exam ideas about pollutants and plant-based fuels.<\/p>\n\n        <div class=\"ols-faq-list\">\n          <div class=\"ols-faq-item\">\n            <h3>Why are fossil fuels described as non-renewable?<\/h3>\n            <p>Fossil fuels are non-renewable because they are formed over very long timescales and are being used faster than they can be replaced.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>Why are biofuels described as renewable?<\/h3>\n            <p>Biofuels are described as renewable because their raw materials, such as plant crops, can be regrown.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>Why can biofuels be more carbon neutral than fossil fuels?<\/h3>\n            <p>The carbon dioxide released during biofuel combustion can be partly offset by carbon dioxide absorbed during plant growth.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>How is biodiesel made?<\/h3>\n            <p>Biodiesel is produced by reacting vegetable oils with methanol in the presence of an alkali catalyst.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>What are the main disadvantages of growing crops for biofuels?<\/h3>\n            <p>Less land may be available for food crops, rainforests may be cut down and there may be greater pressure on fertile soils and water supplies.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <!-- author card (moved to the end, 10 Oct 2026) -->\n      <div class=\"ols-author\">\n          <img decoding=\"async\"\n            class=\"ols-author-avatar-img\"\n            src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\"\n            alt=\"Dr. Mohammed Al-Fatah\"\n          >\n\n          <div class=\"ols-author-content\">\n            <h2 class=\"ols-author-title\">Written by: Dr. Mohammed Al-Fatah<\/h2>\n            <p class=\"ols-author-description\">Chemistry specialist revision notes for A Level Chemistry.<\/p>\n\n            <a\n              class=\"ols-linkedin-pill\"\n              href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\"\n              target=\"_blank\"\n              rel=\"noopener noreferrer\"\n            >\n              <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\n                <path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"\/>\n              <\/svg>\n              View LinkedIn Profile\n            <\/a>\n          <\/div>\n        <\/div>\n\n\n      <section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Continue revising Topic 6 Organic Chemistry I using these connected revision notes.<\/p>\n\n        <div class=\"ols-related-grid\">\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/fuel\/combustion\/\">Combustion<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/fractional-distillation\/\">Fractional Distillation<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/cracking\/\">Cracking<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/crude-oil\/reforming\/\">Reforming<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkanes\/reactions\/free-radical-substitution\/\">Reactions of Alkanes<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-6-organic-chemistry-i\/alkenes\/\">Alkenes<\/a>\n        <\/div>\n      <\/section>\n\n      <!-- OLS Author Copyright Footprint \/ Attribution Card -->\n      <section class=\"ols-attribution-card ols-attr-std\" aria-label=\"Copyright notice\">\n<style id=\"ols-attribution-card-css\">.ols-attribution-card.ols-attr-std{background:linear-gradient(135deg,#ffffff,#f8fbff);border:1px solid rgba(28,36,75,0.14);border-radius:28px;box-shadow:0 18px 45px rgba(28,36,75,0.10);padding:34px;margin:24px 0;overflow:hidden;font-family:Poppins,Arial,sans-serif;box-sizing:border-box}.ols-attribution-card.ols-attr-std *{box-sizing:border-box}.ols-attribution-card.ols-attr-std p{margin:0;font-size:14px;line-height:1.65;font-weight:300;color:#667085}.ols-attribution-card.ols-attr-std strong{font-weight:700;color:#1C244B}@media (max-width:760px){.ols-attribution-card.ols-attr-std{padding:24px 18px;border-radius:22px}}<\/style>\n<p><strong>Copyright notice:<\/strong> This OLS revision content, including the explanations, layout, diagrams, tables and embedded learning structure, is authored for Online Learning System by Dr. Mohammed Al-Fatah. 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