It's been two years since Kachan & Co. first published its definition of what industries and categories constitute cleantech.

A lot happens in two years, so it's time to refresh our taxonomy.

A clean technology taxonomy, a list of nested categories, is important. It shows where a clean technology “fits.” It helps vendors understand their competitive sets. It defines and helps investors understand the breadth of the sector and its sub-categories, and helps research and data organizations report consistently.

Ones available two years ago were lacking, out of date or not comprehensive enough. So we took the time to develop our own, influenced by others as we described here two years ago, when we first crowdsourced and validated our work with the cleantech community.

Our investment paid off. The Kachan cleantech taxonomy has emerged as one of the leading definitions of cleantech (cited in places like here, here, here, here, here and here.)

But progress marches on. Industries don't stay still very long. Two years later, it's now time to revisit and improve our work. So the following is our firm's latest take on the cleantech taxonomy, i.e. what industries constitute cleantech and how they're organized, for your feedback and input.

Kachan 2012 cleantech taxonomy overview

A reminder of some of the factors affecting work like this:

  • It required discipline to remember the exercise was a classification for technologies, i.e. when hardware/software or other systems are involved. It was not a categorization of larger climate change initiatives, for instance… just where tech that’s supposed to get commercialized is involved, and where entrepreneurs and investors hope to make a return.
  • It forced the internal discussion of whether nuclear is a clean technology. While some argue nuclear has no place in cleantech, we feel otherwise. As we learned researching a Kachan report on the subject, there are important nuclear-related innovations being pursued to derive power from non-weaponizable fuels, new reactor designs that can't melt down or be turned into terrorist weapons and new R&D aimed at cracking that other historical nut of nuclear power: waste.
  • It forced a focus on cleantech-related innovation. For instance, just because recycling is a category doesn’t mean that everything in the recycling industry is cleantech. Likewise semiconductors. Or hydro. But these areas are ripe for clean technology innovation, and there are new cleantech breakthroughs happening in each there today. Hence their inclusion.

The most important changes in this new version are:

  • Renaming of energy efficiency to just efficiency - Efficiencies are now being sought in as many areas of cleantech as possible, not just in the obvious places like energy, water and food. For instance, in an attempt to reduce the creation of new "stuff", a category of "collaborative consumption systems" are emerging that deserve recognition. So we've broadened the category to include these and other new technologies being developed to foster efficiencies across the board. Vehicle sharing, incl. peer-to-peer carsharing, bike sharing and other vehicle systems, has been relocated here from transportation.
  • ICT stays a "layer" within all eight categories of cleantech - Information and communication technologies (ICT) today play an even greater role in cleantech than they did two years ago. Yet, even after much internal debate, we decided not to call ICT out here as a separate high-level category. It was recognized that ICT's primary value is in making most other aspects of cleantech better, e.g. smarter buildings, more efficient energy management, more effective distribution and better remote sensing. Because it touches everything, it shouldn't be consigned to its own silo, went the rationale. Even though some investors, say, specifically seek out only ICT-related investments in cleantech.
  • Energy storage embellished - There have been new developments in energy storage in the last two years, particularly in mechanical storage. Our storage section has been augmented and expanded and reorganized to reflect this.
  • Fuel cells moved to energy generation - Yes, fuel cells can be considered a way to store energy. But most commercial applications today involve power and heat generation. So they've been relocated from storage to energy generation.
  • More detail in nuclear technologies - Informed by our recent in-depth report on Emerging Nuclear Innovations, we learned a lot about types of new upcoming nuclear tech that stands to make nuclear vastly safer to run, less expensive, less risky as a terrorist target and waste-free, and updated our nuclear taxonomy accordingly.
  • Reorganization of data center technologies - Data center efficiency improvement has been low-hanging fruit for many companies since our last taxonomy. The efficiency category previously called "electronics & appliances" has been renamed "data centers & devices" and now contains more technologies like component efficiency improvement and intelligent power management in addition to virtualization.
  • Agricultural technology significantly embellished - We've been conducting analysis for a forthcoming Kachan report on breakthrough new agricultural cleantech companies, and have created a dramatically expanded taxonomy of agricultural technology as a result. It's reflected in this new version. Look for even more detail, including leading vendors in each category, in our report.

A big thank you to Jeff Wen, Shannon Payne, Megan Amaral and Lucia Siplakovic of Kachan & Co., who each played valuable roles in helping shape this latest analysis.

Have thoughts of your own? Want to help influence this new taxonomy? Consider this another 'crowdsourcing' cycle—you can weigh in before we call this final. Please leave a comment with your feedback below. We'll review and possibly fold in your thinking before we update our master definition page and chart deck here.

In outline form, Kachan & Co's latest taxonomy of what fits where in cleantech:

  • Renewable energy generation
    • Wind
      • Turbines
      • Components, incl. gearboxes, blades, towers
    • Solar
      • Crystalline silicon
      • Thin film
      • Other emerging photovoltaic
      • PV module technologies
      • Inverters
      • Thermal
      • Concentrated solar power
        • Thermal
        • Photovoltaic
      • Financing providers
      • Systems
    • Renewable fuels
      • Ethanol
      • Cellulosic ethanol
      • Biobutanol
      • Biodiesel
      • Methanol
      • Drop-in synthetic fuels
      • Biogas
      • Hydrogen [when produced from non-fossil sources]
    • Marine
      • Tidal
      • Wave
      • Run-of-river and other small scale hydro
      • Ocean thermal
    • Biomass
      • Wood combusion
    • Geothermal
      • Natural aquifer
      • Hot dry rock enhanced
    • Fuel cells
      • PEM
      • DMFC
      • SOFC
      • MCFC
      • Zinc air
    • Waste-to-energy
      • Waste heat recovery
      • Anaerobic digestion
      • Landfill gas
      • Gasification
      • Plasma torching
    • Nuclear
      • New fission designs
      • Fusion
      • Non-uranium fuels
      • Waste disposal
    • Emerging
      • Osmotic power
      • Kinetic power
      • Others
    • Measurement & analytics
      • Software systems
      • Sensor and other hardware
  • Energy storage
    • Batteries
      • Wet cells (e.g. flow, lead-acid, nickel-cadmium, sodium -sulfur)
      • Dry cells (e.g. zinc-carbon, lithium iron phosphate)
      • Reserve batteries
      • Charging & management
    • Thermal storage
      • Molten salt
      • Ice
      • Chilled water
      • Eutectic
    • Mechanical storage
      • Pumped water
      • Compressed air
      • Flywheels
      • Other moving mass
    • Super/ultra capacitors
    • Hydrogen storage
  • Efficiency
    • Smart grid
      • Transmission
        • Sensors & quality measurement
        • Distribution automation
        • High voltage DC
        • Superconductors
        • High voltage control devices
      • Demand management/response
      • Management
        • Advanced metering infrastructure (AMI) & smart meters
        • Monitoring & metering
        • Networking equipment
        • Quality & testing
        • Self repairing technologies
        • Power conservation
        • Power protection
        • Data analysis systems
    • Green building
      • Design
        • Green roofs
      • Building automation
        • Software & data analytics
        • Monitoring, sensors and controllers
        • Metering
        • Networking & communication
      • Lighting
        • Ballasts & controllers
        • Solid state lighting
        • CFLs
        • Daylight harvesting
      • Systems
        • HVAC
        • Refrigeration
        • Water heating
      • Consulting/facilities management
        • ESCOs
    • Cogeneration
      • Combined heat and power (CHPDH)
    • Data centers & devices
      • Component efficiency improvement
      • Virtualization
      • Intelligent power management
      • Smart appliances
    • Semiconductors
    • Collaborative consumption systems
      • Bartering
      • Bike sharing
      • Carpool/Ride sharing
      • Car sharing
      • Collaborative workspace
      • Co-housing
      • Coworking
      • Garden sharing
      • Fractional ownership
      • Peer-to-peer lending
      • Seed swap
      • Shared taxi
      • Time banks
      • Virtual currencies
  • Transportation
    • Vehicles
      • Improved internal combustion
      • Hybrid electric
      • Plug in hybrids
      • All electric
      • eBikes
      • New vehicle types
      • Rail transport innovation
      • Water transport innovation
      • Components
      • System integration
    • Traffic management
      • Fleet management
      • Traffic & route management
      • Lighting & signals
      • Parking management systems
      • Behavior management
    • Fueling/charging infrastructure
      • Vehicle-to-grid (V2G)
      • Fast charging
      • Battery swapping
      • Induction
      • Alternative fuel conversion
  • Air & environment
    • Carbon sequestration
      • Carbon capture & storage
        • Geological
        • Ocean
        • Mineral
        • Bio capture, incl. algae
        • Co2 re-use
      • Geoengineering
      • Biochar
      • Forestry/agriculture
    • Carbon trading/offsets
      • Software systems
    • Emissions control
      • Sorbents & scrubbers
      • Biofiltration
      • Cartridge/electronic
      • Catalytic converters
    • Bioremediation
    • Recycling & waste
      • Materials reclamation
      • New sorting technologies
      • Waste treatment
      • Waste management & other services
    • Monitoring & compliance
      • Toxin detection
      • Software systems
      • Sensors & other measurement/testing hardware
  • Clean industry
    • Materials innovation
      • Nano
        • Gels
        • Powders
        • Coatings
        • Membranes
      • Bio
        • Biopolymers
        • Biodegradables
        • Catalysts
        • Timber reclamation
      • Glass
        • Chemical
        • Electronic
        • PV
      • Chemical
        • Composites
        • Foils
        • Coatings
      • Structural building material
        • Cement
        • Drywall
        • Windows
      • Ceramics
      • Adhesives
    • Design innovation
      • Biomimicry
      • Software
    • Equipment efficiency
      • Efficient motors
      • Heat pumps & exchangers
      • Controls
    • Production
      • Construction/fabrication
      • Resource utilization
      • Process efficiency
      • Toxin/waste minimization
    • Monitoring & compliance
      • Software systems
      • Automation
      • Sensors & other measurement/testing hardware
    • Advanced packaging
      • Packing
      • Containers
  • Water
    • Production
      • Desalination
      • Air-to-water
    • Treatment
      • Filtration
      • Purification
      • Contaminate detection
      • Waste treatment
    • Transmission
      • Mains repair/improvement
    • Efficiency
      • Recycling
      • Smart irrigation
      • Aeroponics/hydroponics
      • Water saving appliances
    • Monitoring & compliance
      • Software systems
      • Sensors & other measurement/testing hardware
  • Agriculture
    • Crop farming
      • Land management
      • Bioengineering
      • Natural fertilizers and amendments
      • Precision fertilization
      • Biological weed, pest and disease control
      • Precision irrigation
      • Tools and equipment
      • Waste innovations
      • Transport decay prevention
    • Controlled environment agriculture
      • Hydroponics & aeroponics
      • Vertical farming
      • Improved greenhouses
    • Sustainable forestry
      • Lake and waterway management
      • Precision forestry
    • Animal farming, CAFOs
      • Closed loop
      • Waste innovations
    • Aquaculture
      • Health & yield
      • Containment
      • Waste innovations
      • Water quality