Hydrogen Markets 2006
Existing and Emerging Applications
| Publication Date | June 2006 |
|---|---|
| Publisher | Visiongain |
| Product Type | Report |
| Pages | 332 |
| ISBN Number | not applicable |
| Product Code | VIS00011 |
Buy this product or for assistance call +44 20 7060 7474
Summary
Please Note: Reports are sold based on the user licenses indicated. The reports will be accessible in Flash format via an online reading room on the publisher website, allowing viewing and printing capabilities only. Within one to two business days after placing the order,the client will receive an email with information on accessing their purchase.
"World Hydrogen Generation 2006: Established and Emerging Markets" is a 300-page study of the current status of the hydrogen and hydrogen generation industries and includes a detailed review of whether or not there is to be success found from expansion into energy storage and transportation. The traditional hydrogen markets of petroleum refining, unconventional oil refining, semiconductor fabrication, annealing stainless steel and annealing ferrous metals are looked at in detail, are as the use of hydrogen through the decade for galvanizing and brazing operations, for sintering, within the float glass industry and for hydrogenation.The study lists the reasons why the hydrogen industry may not be able to create the lower hydrogen prices needed to become predominant in the emerging energy storage and transportation markets and also discusses in detail how these chasms may be crossed successfully. Today hydrogen prices, determined by both the method of generation and the feedstock, are acceptable for industrial uses but unacceptable for energy applications and are currently rising rather than falling. Producing hydrogen at a reduced cost is the greatest challenge facing the industry today.
The report also details the move to fuel cells for transportation and the intricacies of building a hydrogen world, including the need for a new and more reliable storage and distribution system and also details what would be needed to move to a hydrogen internal combustion engine. Projections of stationary fuel cell use for energy applications and the growth in that sector in the coming years is detailed, as is the amount of hydrogen to be used for automotive applications through 2010.
Also examined are the annual unit sales and the corresponding yearly sales revenues of electrolysers, large stream reformers and small reformer sales through 2010. Annual production through 2010 for Methanol, ammonia and hydrogen are also given and discussed extensively.
Questions Addressed
- What are expected usage trends of hydrogen in existing industrial applications?
- Can hydrogen become a staple in the transportation industry?
- Are hydrogen internal combustion engines viable?
- What are expected usage trends of hydrogen in petroleum refining?
- What impact will fuel cells have upon hydrogen demand?
- How will hydrogen be used in stationary energy applications?
- What demand will traditional hydrogen generation equipment experience?
- What will be the impact of new hydrogen generation techniques?
Quantifies
- Hydrogen use in key industrial applications
- Hydrogen for internal combustion engines
- Electrolyser unit sales and value
- Large reformer unit sales and value
- Small reformer unit sales and value
- Hydrogen in stationary applications
- Hydrogen use in transportation (auto and total)
Study Topics
- Industrial applications
- Hydrogen generation
- Auto applications
- Fuel Cells
Content
- Section One - Executive Summary
- 1.1 A Pattern Seen Before - Much Hype
- 1.2 The Hydrogen Industry Overview
- 1.2.1 Production and Distribution
- 1.2.2 Transportation and Small Scale Power Production
- 1.2.3 Nuclear Energy: The Last Technology of the Future
- 1.3 Conceptualizing the Hydrogen Economy:
- 1.3.1 Enabling Developments and Synergies Needed
- 1.4 The Thrust of this Report
- 1.4.1 Evaluation of Hydrogen Generation and Markets for
- Hydrogen Through 2015
- 1.4.2 Discussion of Economic and Technological Perspectives
- of Hydrogen Generation Through the next Decade
- Section Two - The Landscape Of The Hydrogen Industry
- 2.1 Overview
- 2.2 Merchant Hydrogen vs. Hydrogen Generation Equipment
- 2.3 Merchant Hydrogen
- 2.3.1 Merchant Hydrogen Leaders
- 2.4 Hydrogen Production
- 2.4.1 Feedstocks, Coal, Naptha and Biomass
- 2.4.2 Hydrogen from Steam Reforming
- 2.4.3 Hydrogen from Coal
- 2.4.4 Coal and Methanol
- 2.4.5 Electrolysers and Hydrogen Production
- 2.4.6 Electrolyser Hydrogen Production Volumes and Costs
- 2.4.7 Electrolytic Hydrogen from Renewable Energy Sources
- 2.5 Unconventional Hydrogen Generation
- 2.5.1 Hydrogen on Demand
- 2.5.2 Chemical Feedstocks
- 2.5.3 Thermal Chemical
- 2.5.4 Concentrating Solar
- 2.6 Technologies and Markets
- Section Three - Hydrogen Markets Today
- Petroleum Refining and Other Fuels
- 3.1 An Existing Market and a Future Opportunity
- 3.2 Overall Size of the Hydrogen Market
- 3.3 Petroleum Refining
- 3.4 Conclusions
- 3.5 The Uses of Hydrogen in Refining
- 3.6 Hydro-Cracking Growth
- 3.7 The Immediate Future of Oil and what it portends for Hydrogen Producers
- 3.8 Factors Depressing Demand for Hydrogen within the Petroleum Industry
- 3.8.1 Peak Oil
- 3.8.1.1 No New Super Giant Fields
- 3.8.1.2 Why a Hiatus between Peaks
- 3.8.1.3 Future Supply and Demand
- 3.8.1.4 Improved Extraction Techniques for Declining Oil Fields:
- 3.8.2 Our Projections for Oil Production over the Course of the Next Five Years
- 3.9 Effects of the Peak - Hydrogen Used in Petroleum Refining
- 3.10 The Impact of Biofuels on Hydrogen Production
- 3.10.1 Liquid Biofuels
- 3.10.2 Biodiesels
- 3.10.3 Overall Biofuel Production
- 3.11 Factors Conducing to an Increase in Demand for Hydrogen within the Petroleum Industry
- 3.11.1 Do Unconventional Fossil Fuel Resources Represent Opportunity?
- 3.11.2 Heavy Oil
- 3.11.3 Tar Sand Resources
- 3.11.4 Oil Shale
- 3.11.5 Projections for Unconventional Oil Production
- 3.11.6 Who Wins?
- 3.12 Syngas and Synfuel: An Alternative Scenario for Hydrogen Producers
- 3.12.1 Use of Coal
- 3.12.2 Synfuel Factors for Success
- 3.13 Impact of Distillate Fuels
- 3.14 How Environmental Concerns Work to the Advantage of Hydrogen Producers
- 3.15 Overall Impact of Alternative Fuels on Hydrogen Production
- 3.15.1 Hirsch Findings
- 3.16 Producing Hydrogen for Refineries - the Fossil Fuel Conundrum
- 3.16.1 Rising Demand and Prices for Natural Gas
- 3.16.2 Non-Natural Gas Gasification Techniques
- 3.16.3 The Problem of Refining Capacity
- 3.17 Projections for Hydrogen Generation for Oil Refining
- Section Four - Hydrogen Markets Today
- Ammonia Production, Methanol, Metal Processing, Float Glass and Others
- 4.1 Ammonia Production
- 4.1.1 The Size of the Ammonia Industry
- 4.1.2 Ammonia Production Methods and Influence on Hydrogen Producers
- 4.1.3 The Ammonia Manufacturing Process and Participants
- 4.1.4 The Future of Hydrogen Feedstocks for Ammonia Production
- 4.1.5 How Future Markets for Ammonia Impact the Hydrogen Industry
- 4.1.5.1 Fertilizer Growth
- 4.1.6 Current Hydrogen Usage in the Ammonia Industry
- 4.2 Methanol
- 4.2.1 Methanol Products
- 4.2.2 Emerging Methanol Applications
- 4.2.2.1 Methanol and Hydrogen on Demand
- 4.2.2.2 Methanol Reformers
- 4.3 Hydrogen Use in Metal Processing
- 4.3.1 Annealing of Metals
- 4.3.1.1 Use of Hydrogen in the Annealing of Ferrous Metals
- 4.3.1.2 Annealing of Nonferrous Metals
- 4.3.2 Brazing
- 4.3.3 Galvanizing
- 4.3.4 Sintering
- 4.3.4.1 Powdered Metal Growth
- 4.3.5 Welding
- 4.3.6 Opportunities in the Metal Heat Treating Industries
- 4.4 Float Glass
- 4.4.1 Hydrogen in the Float Glass Industry
- 4.4.2 Opportunities
- 4.5 Hydrogenated Oils
- 4.6 Semiconductor Manufacturing
- 4.7 Other Markets
- Section Five - Emerging Market For Hydrogen: Transportation
- 5.1 Hydrogen for Transportation
- 5.2 Fuel Cells for Transportation
- 5.3 Hydrogen for Transportation, Conclusions
- 5.4 The Real Extent of the Fuel Cell Market Today
- 5.5 Hydrogen Usage in Transportation Today and Tomorrow
- 5.6 The Why and How of Hydrogen in Transportation
- 5.6.1 The Why
- 5.6.2 The Climate Change Argument and Its Implications
- 5.6.3 Fossil Fuel Scarcity
- 5.6.3.1 Methane Hydrates
- 5.7 Industry Initiatives -Much Ado About Nothing?
- 5.8 The Automotive Industry and the Hydrogen Economy
- 5.8.1 The Fuel Cell Hoopla
- 5.8.2 Plug In Hybrids
- 5.8.3 Battery Technology
- 5.9 The Oil Companies and Hydrogen
- 5.10 Toward Widespread Use of Hydrogen Powered Vehicles
- 5.10.1 Power Plants
- 5.10.2 Fuel Cells, Alone and in Context
- 5.11 The State of the Art and What It Means for Transportation
- 5.11.1 Polymer Electrolyte Membrane
- 5.11.2 PEM Limitations Today
- 5.11.2.1 Complex
- 5.11.2.2 Cost
- 5.11.2.3 Hydration Solved
- 5.11.2.4 Heat Management and Diffusion
- 5.11.2.5 Sensitivity to Some Contaminants and Corrosion
- 5.11.2.6 Overall Bulk
- 5.11.2.7 Expense of Hydrogen Storage
- 5.11.2.8 Principal Hydrogen Storage Techniques
- 5.12 Feasible Forecasting in Regard to Fuel Cells
- 5.12.1 Technology Development and Technology Failures
- 5.12.2 Further Projections for Hydrogen Usage in Fuel Cell Vehicles
- 5.13 Hydrogen Internal Combustion Engines
- 5.13.1 Hydrogen Internal Combustion Engine Chasms
- 5.13.2 Hydrogen Hybrid Fuel Injection
- 5.13.3 Hythane
- 5.13.4 Hydrogen Internal Combustion Engine Prospects
- 5.13.5 Projections for Hydrogen Usage in Internal Combustion Engines
- 5.14 Hydrogen Generation and Distribution for Transportation
- 5.14.1 Chicken and the Egg
- 5.14.2 Distributed Generation vs. Centralized Generation
- 5.14.3 Limited Choice of Generation Models in Distributed Models
- 5.14.4 Generation by Means of Electrolysis
- 5.14.5 Renewables Globally
- 5.14.6 On Board Hydrogen on Demand Generation
- 5.14.6.1 The Collier Reformer
- 5.15 Hydrogen Fuel for Other Modes of Transport
- 5.15.1 Importance of Other Modes of Transport
- in Terms of Energy Consumption
- 5.15.2 Rail transport
- 5.15.3 Heavy Equipment:
- 5.15.4 Mine Locomotives and Loaders
- 5.15.5 Two-wheeled vehicles
- 5.15.6 Watercraft
- 5.15.7 Aircraft
- 5.15.7.1 How Airlines Cope with Rising Fuel Prices
- 5.16 The Overall Competitive Environment for Hydrogen Powered Vehicles
- 5.16.1 Hybrid Electric Vehicles
- 5.16.2 Plug-in Hybrids
- 5.16.3 New types of Heat Engines
- 5.16.3.1 Design Diversity in Novel Heat Engines
- 5.16.4 Internal Combustion Engines Powered by Unconventional Fossil Fuels
- 5.16.6 Internal Combustion Engines Powered by Biofuels
- 5.16.6.1 Biofuels are Here Today
- 5.16.7 Vehicles Using Improved Batteries or Other Electrical Storage Technologies
- 5.16.8 Radically Different Models of Transportation from Those Prevailing at Present
- 5.17 Summarizing the Future of Hydrogen in Transportation Systems
- Section Six - Stationary And Portable Energy Generation Using Hydrogen
- 6.1 Hydrogen beyond Transportation
- 6.2 Stationary Fuel Cells-General Issues
- 6.3 Initial Markets
- 6.3.1 Backup Power for Cellular Base Stations:
- 6.3.1.1 Cellular Success is not Ensured due to Competing Technologies
- 6.3.2 Remote Power
- 6.3.3 Premium Power
- 6.3.4 Financial Industry Data Centers
- 6.3.5 Utility Scale Electrical Generation
- 6.3.6 Auxiliary Power for Large Commercial and Recreational Vehicles
- 6.3.7 Hydrogen Powered Heat engines for Stationary Generation
- 6.3.8 Military and Naval Applications
- 6.3.9 Robotic Drones for Surveillance and Remote Combat Operations
- 6.3.10 Widespread Adoption of Directed Energy Weapons
- 6.3.11 Naval Submarines
- 6.3.12 Auxiliary Power on Naval Ships
- 6.3.13 Mainstream Propulsion Applications in the Armed Forces
- 6.3.14 Field Radios and Battlefield Computers
- 6.3.15 Industrial Robots
- 6.3.16 Power for Personal and Portable Electronics
- 6.3.16.1 Rival Technologies for Personal Power
- 6.4 Summary of Opportunities for Hydrogen in Stationary and Portable Power
- 6.5 Hydrogen Usage in Stationary Power Applications
- Section Seven - Producers Of Merchant Hydrogen For Industry Use
- 7.1 Introduction
- 7.2 Merchant Hydrogen
- 7.3 Economics of Merchant Hydrogen
- 7.4 Air Products and Chemicals, Inc.
- 7.5 Praxair, Inc.
- 7.6 Air Liquide
- 7.7 The BOC Group
- 7.8 Linde Gas
- Section Eight - Hydrogen Generation - Technologies And Manufacturers
- Steam Reforming, Partial Oxidation, and Autothermal Reforming
- 8.1 Overview
- 8.2 Steam Reforming, Partial Oxidation, and Autothermal Reforming
- 8.3 A Description of the Processes
- 8.3.1 Steam reforming
- 8.3.2 Partial oxidation
- 8.3.3 Autothermal reforming
- 8.4 Economics of Steam Reforming
- 8.5 Steam Reforming of Syngas from Coal, Methanol, or Biological Sources
- 8.6 Reforming of Liquid Hydrocarbons
- 8.7 Drawbacks and Limitations of Steam Reforming
- 8.8 Carbon Sequestration and Disposal Issues
- 8.9 Manufacturers of Large Scale Centralized Reforming Facilities
- 8.10 Competitive Context
- 8.11 Projected Sales for Large Scale Reformers
- 8.12 Manufacturer Rankings and Profiles (Large Scale Reformers)
- 8.12.1 Air Liquide
- 8.12.2 Aker Kvaerner
- 8.12.3 Axsia Howmar
- 8.12.4 Caloric
- 8.12.5 CB&I Howe-Baker
- 8.12.6 Foster Wheeler
- 8.12.7 Haldor Topso
- 8.12.8 Husky Energy
- 8.12.9 KBR
- 8.12.10 Lurgi AG
- 8.12.11 Mahler Advanced Gas Systems
- 8.12.12 Mitsubishi Kakoki Kaisha, Ltd.
- 8.12.13 Pan American Enterprises, Inc.
- 8.12.14 Sacre-Davey Innovations
- 8.12.15 Technip
- 8.12.16 The BOC Group
- 8.12.17 Toyo Engineering Corporation
- 8.12.18 Uhde High Pressure Technologies
- 8.12.19 UOP LLC
- 8.13 Small Reformers
- 8.13.1 Small Reformers for Transportation
- 8.13.2 Sales Projections for Small Reformers
- 8.14 Small Reformer Producer Profiles
- 8.14.1 Aspen Products Group, Inc.
- 8.14.2 Collier Technologies, Inc.
- 8.14.3 Ener1
- 8.14.4 H2Gen
- 8.14.5 Hydrocore
- 8.14.6 HyGear
- 8.14.7 HyRadix
- 8.14.8 IdaTech
- 8.14.9 InnovaTek
- 8.14.10 Intelligent Energy
- 8.14.11 Nuvera
- 8.14.12 Osaka Gas
- 8.14.13 The Heatric Division of Meggitt, PLC
- 8.14.14 UltraCell
- 8.14.15 UTC Power
- 8.14.16 ZTEK
- Section Nine - Hydrogen Generation - Electrolysers
- 9.1 Limited Role
- 9.2 The Business Case for Electrolysers
- 9.3 Electrolyser Market Projections
- 9.4 Profiles and Rankings
- 9.4.1 Avalence LLC
- 9.4.2 Hamilton Sundstrand
- 9.4.3 Hydrogenics Corporation
- 9.4.4 Idroenergy
- 9.4.5 ITM Power, Ltd.
- 9.4.6 Norsk Hydro Electrolysers
- 9.4.7 Proton Energy Systems
- 9.4.8 Teledyne Technologies
- 9.5 Other Electrolyser Manufacturers
- 9.5.1 AccaGen
- 9.5.2 Ammonia Casale
- 9.5.3 Ceramatec
- 9.5.4 Claind
- 9.5.5 Gardner Watts Ltd.
- 9.5.6 Grupo De Nora
- 9.5.7 H3Energy
- 9.5.8 Hydrogen Technology Applications, Inc.
- 9.5.9 ILT Piel
- 9.5.10 Parker Balston
- 9.5.11 SiGen
- 9.5.12 Southwest Electrolyser
- Section Ten - Other Techniques For Hydrogen Generation
- 10.1 Beyond Steam Reforming, Partial Oxidation, and Water Electrolysis
- 10.2 Overview of Unconventional Technologies
- 10.2.1 Biomass Reforming
- 10.2.2 Production of Hydrogen from the Activities of Biological Organisms
- 10.2.3 Hydrogen Solar
- 10.2.4 Solazyme, Incorporated
- 10.3 Thermal Chemical Hydrogen Splitting
- 10.3.1 Sulfur thermal chemical cycles
- 10.3.2 Calcium bromine cycle:
- 10.3.3 Other thermal cycles
- 10.3.4 Nuclear Thermal Chemical Splitting
- 10.3.5 General Atomics
- 10.3.6 Solar Thermal Chemical Generation
- 10.3.7 SHEC Labs
- 10.3.8 Solar Energy Limited
- 10.3.9 Johnson Matthey Fuel Cells Ltd & HelioTech A/S
- 10.3.10 H-Ion Solar, Incorporated
- 10.4 Novell Hydrocarbon Reforming Technologies
- 10.4.1 Syngas International Corporation
- 10.4.2 Alchemix Corporation
- 10.4.3 Clean Energy Systems, Incorporated
- 10.4.4 Virent Energy Systems, Incorporated
- 10.4.5 MRT
- 10.4.6 StarTech Environmental Corporation
- 10.4.7 PowerNova
- 10.5 Unclassifiable
- 10.5.1 Genesis World Energy
- 10.5.2 Alternate Energy Corporation
- 10.5.3 Xogen Power, Incorporated
- 10.5.4 NuElement, Incorporated
- 10.5.5 Hydrogain Technologies
- 10.6 Hydrogen-on-demand Systems
- 10.6.1 Millennium Cell
- 10.6.2 Hydrogen Power, Inc.
- 10.6.3 Safe Hydrogen LLC
- 10.6.4 Engineuity Research and Development, Ltd.
- 10.6.5 Trulite Inc.
- 10.6.6 Powerball Technologies LLC
- 10.7 Experimental Processes Awaiting Commercialization
- 10.7.1 Direct photo catalytic splitting of water
- 10.7.2 Biomimetic processes
- 10.7.3 Direct water cracking
- 10.7.4 Direct methane cracking
- 10.8 Hydrogen Generation Component and Subassembly Manufacturers
- 10.8.1 HTC Hydrogen Technologies Corporation
- 10.8.2 Hy9 Corporation
- 10.8.3 Johnson Matthey PLC
- 10.8.4 Power+Energy
- 10.8.5 Precision Combustion, Incorporated
- 10.8.6 QuestAir Technologies, Inc.
- 10.8.7 REB Research and Consulting
- 10.8.8 Stewart Warner South Wind Corporation
- 10.8.9 Wellman CJB, Limited
- 10.9 Summary and Conclusions
- Section Eleven - The Renewable Energy Sources Grid
- 11.1 The Reality Is
- 11.2 The Notion of Hydricity
- 11.3 Contemplating a Transition
- 11.4 How a Renewable Electrical Grid Would Differ from a Fossil Fuel Grid - How the Differences Affect a Hydrogen Economy
- 11.4.1 The Legacy Grid
- 11.4.2 Electrical Generation
- 11.4.3 Wind Power, Challenger or Challenged?
- 11.4.4 Stabilizing a Renewable Grid
- 11.5 The Place of Other Energy Sources in the Renewable Grid
- 11.5.1 Hydroelectric
- 11.5.2 Solar Energy
- 11.5.3 Photovoltaic devices
- 11.5.4 Concentrating Solar
- 11.5.5 Biofuel
- 11.5.6 Geothermal
- 11.5.7 Ocean Power
- 11.5.8 Fusion
- 11.6 The Renewable Grid and Transportation
- 11.7 Financing the Hydrogen Economy
- 11.8 The Government's Role - Past and Present
- 11.9 No Big Hydrogen?
- Section Twelve - The Iceland Experiment
- 12.1 About the Experiment
- 12.2 The Iceland Roadmap from Fifty Thousand Feet
- 12.3 What It Would Mean if it Could Be Done
- 12.4 The Mother of All Pilots
- Charts And Figures
- Chart 1: Annual Consumption of Hydrogen, 2005-2010, World Market
- Chart 2: Annual use of Hydrogen, 2011-2016, World Market
- Chart 3: Volume of Global Oil Discoveries per Decade 1930 - 1990, World Market
- Chart 4: Global Oil Production, 2005-2010, World Market
- Chart 5: Annual use of Hydrogen for Unconventional Oil Refining 2005-2010, World Market
- Chart 6: Annual use of Hydrogen for Petroleum Refining, 2005-2010, World Market
- Chart 7: Annual Production of Ammonia, 2005-2010, World Market
- Chart 8: Annual use of Pure Hydrogen in Ammonia Production 2005-2010, World Market
- Chart 9: Annual Production of Methanol, 2005-2010, World Market
- Chart 10: Consumption of Pure Hydrogen within the Methanol Industry 2005-2010, World Market
- Chart 11: Annual use of Hydrogen for Annealing Ferrous Metals 2005-2010, World Market
- Chart 12: Annual use of Hydrogen for Annealing Stainless Steel 2005-2010, World Market
- Chart 13: Annual use of Hydrogen for Brazing Operations, 2005-2010, World Market
- Chart 14: Annual use of Hydrogen for Galvanizing, 2005-2010, World Market
- Chart 15: Annual use of Hydrogen for Sintering, 2005-2010, World Market
- Chart 16: Annual use of Hydrogen for the Float Glass Industry 2005-2010, World Market
- Chart 17: Annual use of Hydrogen for Hydrogenation, 2005-2010, World Market
- Chart 18: Annual use of Hydrogen for Semiconductor Fabrication 2005-2010, World Market
- Chart 19: Annual use of hydrogen in Terrestrial Transportation, Best Case 2011-2016, World Market
- Chart 20: Annual use of hydrogen in Terrestrial Transportation, Worst Case 2011-2016, World Market
- Chart 21: Use of Hydrogen in ICE Vehicles, 2007-2011, World Market
- Chart 22: Annual use of Hydrogen in ICE Vehicles, 2011-2016, World Market
- Chart 23: Percentage of Petroleum Fuels Dedicated to Various Forms of Transportation 2005
- Chart 24: Use of Hydrogen in Automotive Transportation, 2005-2010, World Market
- Chart 25: Use of Hydrogen in Stationary Fuel Cells, 2005-2010, World Market
- Chart 26: Large Steam Reformer Annual Unit Sales, 2005-2010, World Market
- Chart 27: Large Steam Reformer Annual Unit Sales Revenues 2005-2010, World Market
- Chart 28: Small Reformer Annual Unit Sales, 2005-2010, World Market
- Chart 29: Small Reformer Annual Unit Sales Revenue, 2005-2010, World Market
- Chart 30: Electrolyser Annual Unit Sales, 2005-2010, World Market
- Chart 31: Electrolyser Annual Unit Sales Revenues, 2005-2010, World Market
Delivery Details
REPORT:Despatched within 3 to 5 working days.
Related Products
Chemicals
call +44 (0) 20 7060 7474
or email us
Resources
Why Report Buyer?
Advertising/Affiliates
View Our Publishers
News
About Us
Meet Us
Jobs
Contact Us
Categories and Subcategories











